**The resources selected for the 2019 NCF-Envirothon Current Issue are intended to express a diversity

of perspectives related to the topic, “Agriculture and the Environment: Knowledge and Technology to

Feed the World.” The views and opinions expressed in the articles below represent the views and

opinions of the authors themselves, not the NCF-Envirothon or NC Envirothon staff or committee

members. **

**Please note that PDF versions of the articles are included for ease of printing. Hyperlinks embedded

within these PDFs are included for reference only, and are NOT official resources of the 2019 NCF-

Envirothon competition. Hyperlinks to the articles’ original forms are included at the bottom of the PDFs

where applicable. **

Key Topic # 1 Resources

1. Biodiversity conservation and agricultural sustainability: towards a new paradigm of ‘eco-agriculture’landscapes – Please note that the blue/greyed-out sections are NOT for study for the 2019 NCFEnvirothon competition and are included for context only.

2. Study: Bioenergy Decisions Involve Wildlife Habitat and Land Use Trade-offs

3. Could soils help save the climate?

4. Ecosystem services and agriculture: tradeoffs and synergies

5. Linking Ecologists and Traditional Farmers in the Search for Sustainable Agriculture

Key Topic # 2 Resources

1. Soil Has a Microbiome, Too

2. Soil Health Growers

3. Soil Health and Soil Health Institute Featured on American Farmer TV Series (Video – 9:00)

4. The Hope in Healthy Soil’ Video Series- Chapter 3: Do not Disturb- No Till Farming (Video- 3:29)

5. The Hope in Healthy Soil’ Video Series- Chapter 5: The Benefits of Going Under ‘Cover’ (Video- 5:57)

Key Topic # 3 Resources

1. Beyond conservation agriculture- Please note that the following sections are the ONLY sections forstudy for the 2019 NCF Envirothon competition:

a. The Many Sections of Agriculture across the Globeb. Trade-offs Concerning Conservation Agriculture in Smallholder Agriculturec. Assessing Current Approaches to Sustainable Intensification from Systems Agronomy

Perspectived. How can Systems Agronomy Move Forwarde. Outlooks and Challenges

2. North Carolina Farm Family Awarded for Conservation Practices

3. Why Industrial Farms Are Good for the Environment

4. Organic farming not always best for the planet

The highlighted resources will be used in the LUC7 Envirothon.

Please note the pages for Farming for Bees. Students are NOT responsible for the entire publication.

5. What Is Sustainable Agriculture

Key Topic # 4 Resources

1.A Diversity of Bees Is Good for Farming

2.Cover Crops – Organic Farming

3.Farming for Bees- Please note that the following pages are the ONLY pages for study in the 2019 NCFEnvirothon competition (refer to page numbers in document): pgs. 1-15; 26-29; 34-36

4.Forest farming economic, environmental benefits

Key Topic # 5 Resources

1. Can meat actually be eco-friendly?

2. Sharing North Carolina Agribusiness Exports with the World

3. Urban Agriculture Could Potentially Produce a Tenth of the World's Food. Is Grass Really the Best Usefor Your Yard?

Key Topic # 6 Resources

1. A controversial technology could save us from starvation … if we let it

2. Battlefield

3. Biotechnology Frequently Asked Questions

4. Engineering Honesty: USDA Moves to Disclose “GMOs”

5. Opinion- When Genetic Engineering is an environmentally friendly choice

6. The Future of Agriculture

7. Next Generation –USDA…Learning Opportunities for new farmers 7 ranchers

8. Ag Technology

9. Breaking Ground

Phil. Trans. R. Soc. B (2008) 363, 477–494

doi:10.1098/rstb.2007.2165

Biodiversity conservation and agriculturalsustainability: towards a new paradigm

of ‘ecoagriculture’ landscapes

Published online 25 July 2007

Sara J. Scherr1 and Jeffrey A. McNeely2,*

One con

*Autho

1Ecoagriculture Partners, Washington, DC 20001, USA2World Conservation Union—IUCN, 1196 Gland, Switzerland

The dominant late twentieth century model of land use segregated agricultural production from areasmanaged for biodiversity conservation. This module is no longer adequate in much of the world. TheMillennium Ecosystem Assessment confirmed that agriculture has dramatically increased itsecological footprint. Rural communities depend on key components of biodiversity and ecosystemservices that are found in non-domestic habitats. Fortunately, agricultural landscapes can bedesigned and managed to host wild biodiversity of many types, with neutral or even positive effects onagricultural production and livelihoods. Innovative practitioners, scientists and indigenous landmanagers are adapting, designing and managing diverse types of ‘ecoagriculture’ landscapes togenerate positive co-benefits for production, biodiversity and local people. We assess the potentialsand limitations for successful conservation of biodiversity in productive agricultural landscapes, thefeasibility of making such approaches financially viable, and the organizational, governance andpolicy frameworks needed to enable ecoagriculture planning and implementation at a globallysignificant scale. We conclude that effectively conserving wild biodiversity in agricultural landscapeswill require increased research, policy coordination and strategic support to agricultural communitiesand conservationists.

Keywords: ecoagriculture; landscape; biodiversity conservation; agricultural production;rural livelihoods

1. INTRODUCTIONThe Millennium Ecosystem Assessment (MA) docu-

mented the dominant impacts of agriculture onterrestrial land and freshwater use, and the criticalimportance of agricultural landscapes in providing

products for human sustenance, supporting wildspecies biodiversity and maintaining ecosystem services(MA 2005). Yet global demand for associated

agricultural products is projected to rise at least 50%over the next two decades (UN Millennium Project

2005). The need to reconcile agricultural productionand production-dependent rural livelihoods withhealthy ecosystems has prompted widespread inno-

vation to coordinate landscape and policy action(Breckwoldt 1983; Jackson & Jackson 2002;McNeely & Scherr 2003; Acharya 2006). However,

the dominant national and global institutions—for policy,business, conservation, agriculture and research—have

been shaped largely by ‘mental models’ that assumeand require segregated approaches.

This paper will discuss a new paradigm, ‘ecoagri-

culture’: integrated conservation–agriculture landscapesin which biodiversity conservation is an explicit objectiveof agriculture and rural development, and the latter are

explicitly considered in shaping conservation strategies.Sections 2 and 3 present the rationale for scaled-up

tribution of 16 to a Theme Issue ‘Sustainable agriculture I’.

r for correspondence (jam@iucn.org).

477

action to promote ecoagriculture landscapes, and definethe approach. Section 4 assesses the current state ofecoagriculture knowledge and practice, in relation toagricultural technology, landscape management, finan-cial viability, and supportive policies and investments.Section 5 outlines strategic actions required to mobilizeecoagriculture initiatives on a scale that would have ameaningful impact on global challenges for agriculturalproduction and ecosystem management.

2. THE CHALLENGE OF MANAGINGAGRICULTURAL LANDSCAPES IN THETWENTY-FIRST CENTURYCurrent trends suggest that, during the twenty-firstcentury, a continuing and growing demand foragricultural and wild products and ecosystem serviceswill require farmers, agricultural planners and con-servationists to reconsider the relationship betweenproduction agriculture and conservation of biodiversity.

(a) The current ecological footprint of agricultureNearly one-third of terrestrial lands have agriculturalcrops or planted pastures as a dominant land use(accounting for at least 30% of total area), thus havinga profound ecological effect on the whole landscape.Another 10–20% of land is under extensive livestockgrazing; and approximately 1–5% of food is producedin natural forests (Wood et al. 2000). The ‘humanfootprint’ analysis of Sanderson et al. (2002) estimated

This journal is q 2007 The Royal Society

478 S. J. Scherr & J. A. McNeely Biodiversity and agricultural sustainability

that 80–90% of lands habitable by humans is affected bysome form of productive activity. More than 1.1 billionpeople, most agriculture-dependent, now live within theworld’s 25 biodiversity ‘hot spots’, areas described byecologists as the most threatened species-rich regions onEarth (Cincotta & Engelman 2000; Myers et al. 2002).

Both extensive lower-yield and intensive higher-yield agricultural systems have profound ecologicaleffects. Millions of hectares of forests and naturalvegetation have been cleared for agricultural use andfor harvesting timber and wood fuels, and empiricalevidence suggests that intensification rarely results insaving ‘land for nature’(Angelsen & Kaimowitz 2001).Half the world’s wetlands have already been converted;California alone has lost 91% of its wetlands (WWF2005). Overuse and mismanagement of pesticidespoison water and soil, while nitrogen and phosphorusinputs and livestock wastes have become majorpollutants of surface water, aquifers, and coastalwetlands and outlets. Between 1890 and 1990, thetotal amount of biologically available nitrogen createdby human activities increased ninefold, and humanactivity now produces more nitrogen than all naturalprocesses combined (MA 2005). Agrochemical nutri-ent pollution from the US farm belt is the principalcause of the biological ‘dead zone’ in the Gulf ofMexico 1500 km away (Rabalais et al. 2002), andsimilar impacts are felt in the Baltic Sea and along thecoasts of China and India. Environmental impacts oflivestock are extensive (Steinfeld et al. 2006).

Some introduced agricultural crops, livestock, treesand fishes have become invasive species, spreadingbeyond their planned range and displacing nativespecies (Matthews & Brand 2004; Mooney et al.2005). Concerns about genetically modified cropvarieties include their potential to become invasivespecies or to hybridize with wild relatives, leading to theloss of biodiversity (NAS 2002; Oksman-Caldentey &Barz 2002; Omamo & von Grebmer 2005). Agriculturefragments the landscape, breaking formerly contiguouswild species populations into smaller units that aremore vulnerable to extirpation. Farmers generally havesought to eliminate wild species from their lands inorder to reduce the negative effects of pests, predatorsand weeds. However, these practices often harmbeneficial wild species like pollinators (Buchmann &Nabhan 1996), insect-eating birds and other speciesthat prey on agricultural pests.

These threats posed by agriculture to conservationhave been a key motivator for conservationists to developprotected areas where agricultural activity is officiallyexcluded or seriously circumscribed. Nonetheless, theMA (Hassan et al. 2005) calculated that more than 45%of 100 000 protected areas (PAs) had more than 30% oftheir land area under crops. In light of political andeconomic realities, many recently designated PAs inseveral African countries explicitly permit biodiversity-friendly agriculture, usually in areas considered categoryVor VI in the IUCN system (IUCN 1994).

(b) Meeting increased demand for agricultural

products in ecologically sensitive areas

Human population is expected to grow from a littleover 6 billion today to over 8 billion by 2030, an

Phil. Trans. R. Soc. B (2008)

increase of approximately one-third, with another 2–4billion added in the subsequent 50 years (Cohen 2003).But food demand is expected to grow even faster, as aresult of growing urbanization and rising incomes, andif hunger is reduced among 800 million peoplecurrently undernourished (UN Millennium Project2005). More land will surely be required to grow crops,even more so if biofuels become a greater contributorto energy needs. In Africa alone, land in cerealproduction is expected to increase from 102.9 Mha in1997 to 135.3 Mha in 2025 (Rosegrant et al. 2005).Global consumption of livestock products is predictedto rise from 303 million metric tonnes in 1993 to 654million tonnes in 2020 (Delgado et al. 1999).

Tilman et al. (2001) predict that feeding a popu-lation of 9 billion using current methods could result inconverting another 1 billion hectares of natural habitatto agricultural production, primarily in the developingworld, together with a doubling or tripling of nitrogenand phosphorous inputs, a twofold increase in waterconsumption and a threefold increase in pesticide use.A serious limiting factor is expected to be water, as 70%of the freshwater used by people is already devoted toagriculture (Rosegrant et al. 2002). Scenarios preparedby the MA thus suggest that agricultural production inthe future will have to focus more explicitly onecologically sensitive management systems (Carpenteret al. 2005).

Below are four major reasons why meeting increaseddemand for agricultural products will often requireecoagriculture systems.

(i) Most of the increased food production will begrown domestically and increasingly in more ‘marginal’or ‘fragile’ landsAn estimated 90% of food products consumed in mostcountries will be produced by those countries. Totalexport levels increased sharply between 1961 and2000, but agricultural exports still accounted for onlyapproximately 10% of production (McCalla 2000).This pattern seems unlikely to change over the next fewdecades, even though continuing globalization ofagriculture will influence product mix and prices. Areduction in developed world subsidies could furtherspur export agriculture in the developing world (Rungeet al. 2003). Changes will depend not only onproductivity and quality, but also on shifts in relativetransport costs for international shipping and internaloverland transport, and the distances between majorpopulation centres, ports and agricultural regions.Large and growing interior populations in largecountries will continue to be fed mainly by local andnational producers.

The declining rate of growth in yields in places likePunjab in India, the US Midwest and the MekongDelta indicates that most new production may notcome from the areas of highest current grain pro-ductivity, and some areas are already experiencingdeclining yields or productivity of inputs (Rosegrant &Clein 2003). While yields may increase somewhat inthese places, through greater input use, plant breeding,biotechnology and improved irrigation efficiency(Runge et al. 2003), marginal costs are likely to behigh, as are the environmental costs.

Biodiversity and agricultural sustainability S. J. Scherr & J. A. McNeely 479

Moreover, lower-productivity lands (drylands, hill-sides and rainforests) now account for more than two-thirds of total agricultural land in developing countries(Nelson et al. 1997). Because current yields arerelatively low, technologies already existing can doubleor even triple yields, with adequate investment, marketdevelopments and attention to good ecosystem hus-bandry (UN Millennium Project 2005). Extensivegrain monocultures are not likely to be sustainable insuch areas, calling for more diversified land useapproaches. Though the bulk of new production willcome mainly from existing croplands, the mostpromising areas with significant new land for agricul-ture are in places like the forest and savannah zones ofBrazil and Mozambique, which are the main remaininglarge reservoirs of natural habitat. These habitats willbe seriously damaged by highly simplified, highexternal-input production systems, but an ecoagricul-ture approach could significantly reduce the damage.

(ii) Wild products continue to be important for local foodsupply and livelihoodsPeople in low-income developing countries and sub-regions will continue to rely on harvesting wild species.Wild greens, spices and flavourings enhance local diets,and many tree fruits and root crops serve to assuage ‘pre-harvest hunger’ or provide ‘famine foods’ when crops orthe economy fails. Frogs, rodents, snails, edible insectsand other small creatures have long been an importantpart of the rural diet in virtually all parts of the world(Paoletti 2005). Bushmeat is the principal source ofanimal protein in humid West Africa and other forestregions, and efforts to replace these with domesticlivestock have been disappointing. Fisheries are themain animal protein source of the poor worldwide. InAfrica and many parts of Asia, more than 80% ofmedicines still come from wild sources. Gathered woodfuel remains the main fuel for hundreds of millions ofpeople, while forests and savannahs provide criticalinputs for farming in the form of fodder, soil nutrients,fencing, etc. (McNeely & Scherr 2003). Achieving foodsecurity therefore will require the conservation of theecosystems providing these foods and other products.

(iii) Agricultural systems will need to diversify to adaptto climate changeStrategic planning for agricultural development hasbegun to focus on adaptation of systems to climatechange, anticipating rising temperatures and moreextreme weather events. The US Department ofAgriculture and the International Rice ResearchInstitute have both concluded that with each 18Cincrease in temperature during the growing season, theyields of rice, wheat and maize drop by 10% (Tan &Shibasaki 2003; Brown 2004). Cash crops such ascoffee and tea, requiring cooler environments, will alsobe affected, forcing farmers of these crops to movehigher up the hills, clearing new lands as they climb.Montane forests important for biodiversity are likely tocome under increasing threat. Effective responses toclimate change will require changing varieties andmodified management of soils and water, and newstrategies for pest management as species of wild pests,their natural predators, and their life cycles change in

Phil. Trans. R. Soc. B (2008)

response to climates. Increasing landscape and farm-scale diversity are likely to be an important response forrisk reduction (Jackson et al. 2005).

(iv) Agricultural sustainability will require investmentin ecosystem managementMeeting food needs and economic demand foragricultural products will be constrained by widespreadresource degradation that is already either reducingsupply or increasing costs of production. Up to 50% ofthe globe’s agricultural land and 60% of ecosystemservices are now affected by some degree ofdegradation, with agricultural land use the chief causeof land degradation (MA 2005; Bossio et al. 2004).Half the world’s rivers are seriously depleted andpolluted and 60% of the world’s 227 largest rivershave been significantly fragmented by large dams,many built to supply irrigation water. Estimates are that20% of irrigated land suffers from secondary saliniza-tion and waterlogging, induced by the build-up of saltsin irrigation water (Wood et al. 2000). The food systemwill also have to address, or adapt to, the collapse inharvests of wild game and wild fisheries in manyregions around the world, due to overexploitation andhabitat loss or pollution (Hassan et al. 2005).Considerable investments will be required to rehabili-tate degraded resources and ecosystems upon whichfood supplies, particularly of the rural poor, depend(UN Millennium Project 2005).

(c) Meeting increased demand for

ecosystem services

Conservation of wild biodiversity (genes, species andecosystems) is considered by many to be an ethicalimperative. At the same time, conservation alsosupports ‘ecosystem services’—ecological processesand functions that sustain and improve human well-being (Daily 1997). Ecosystem services can be dividedinto four categories: (i) provisioning services, or ecosys-tems that provide food, timber, medicines and otheruseful products, (ii) regulating services such as floodcontrol and climate stabilization, (iii) supporting servicessuch as pollination, soil formation and water purifi-cation, and (iv) cultural services, which are aesthetic,spiritual or recreational assets that provide bothintangible benefits and tangible ones such as ecotourismattractions (Kremen & Ostfeld 2005). ‘Provisioning’historically has been seen as the highest priority serviceprovided by agricultural landscapes. But it is nowrecognized that even the ‘bread baskets’ and ‘rice bowls’of the world also provide other ecosystem services, suchas water supply and quality, or pest and disease control,that are also important (Wood et al. 2000).

The conservation community is moving towardsan ‘ecosystem approach’ to conserving biodiversity,in light of the dependence of protected areas on asupportive matrix of land and water use, and creationof biological corridors (Convention on BiologicalDiversity 2000). The international community hasset a goal of having at least 10% of every habitat typeunder effective protection by 2015 (The NatureConservancy 2004). This strategy, if successful, willprotect many species and ecological communities.But some estimates suggest that more than half of all

480 S. J. Scherr & J. A. McNeely Biodiversity and agricultural sustainability

species exist principally outside PAs, mostly inagricultural landscapes (Blann 2006). For example,conservation of wetlands within agricultural land-scapes is critical for wild bird populations (Heimlichet al. 1998). Such species will be conserved onlythrough initiatives by and with farmers. The conceptof agriculture as ecological ‘sacrifice’ areas is nolonger valid in many regions, because agriculturallands both perform many ecosystem services andprovide essential habitat to many species.

(i) Agricultural landscapes provide critical watershedfunctionsMany of the world’s most important watersheds aredensely populated and under predominantly agricul-tural use, and most of the rest are in agricultural landuse mosaics where crop, livestock and forest pro-duction influence hydrological systems (Wood et al.2000). In such regions, agriculture can be managed tomaintain critical watershed functions, such as main-taining water quality, regulating water flow, rechargingunderground aquifers, mitigating flood risks, moderat-ing sediment flows, and sustaining freshwater speciesand ecosystems. This has led to the concept of ‘greenwater’: that terrestrial land, soil and vegetationmanagement have critical roles in the hydrologicalcycle (de Vries et al. 2003). Effective management ofgreen water encompasses the choice of water-conser-ving crop mixtures, soil and water management(including irrigation), maintenance of soils to facilitaterainfall infiltration, vegetation barriers to slow move-ment of water downslopes, year-round soil vegetativecover and maintenance of natural vegetation in riparianareas, wetlands and other strategic areas of thewatershed. Well-managed agricultural landscapes canalso provide protection against extreme natural events.With increased water scarcity and more frequentextreme weather events predicted in coming decades,the capacity of agricultural systems to sustain water-shed functions is likely to be a priority consideration inagricultural investment and management.

(ii) Agricultural landscapes maintain ‘green space’,recreational opportunities, healthy habitats and aestheticbeauty in human settlementsWith accelerating urbanization worldwide, the loss ofnatural habitats and natural features has become acentral concern for planners and residents, as well asfarmers operating in peri-urban areas. Agriculture canprotect green spaces for aesthetic and recreationvalues, and help to finance the maintenance ofgreen space for wildlife habitat and ecosystemservices. Overall positive outcomes for human habitatand aesthetics require adequate management of cropand livestock wastes, air pollution (smoke, dust andodours) and polluting run-off.

3. ECOAGRICULTURE: INTEGRATINGPRODUCTION AND CONSERVATION ATA LANDSCAPE SCALEThe challenges described earlier are unlikely to be metby the solutions of industrial agriculture, the originalgreen revolution, sustainable agriculture and natural

Phil. Trans. R. Soc. B (2008)

resource management (with its primary focus onsustaining the resources underpinning production), oreven the ecotechnology approach of Swaminathan(1994) with its focus on the farmer’s field, althoughall of these have major elements to contribute.Approaches to biodiversity conservation also need tomove beyond the wild biodiversity focus of strictlyprotected areas and the modest goals of integratedconservation and development projects. We arguethat ecoagriculture—a fully integrated approach toagriculture, conservation and rural livelihoods, withina landscape or ecosystem context—is needed inmany regions.

(a) Ecoagriculture landscapes

Ecoagriculture explicitly recognizes the economic andecological relationships and mutual interdependenceamong agriculture, biodiversity and ecosystem ser-vices (figure 1). Ecoagriculture landscapes aremosaics of areas in natural/native habitat and areasunder agricultural production. Effective ecoagricul-ture systems rely on maximizing the ecological,economic and social synergies among them, andminimizing the conflicts.

The term ‘landscape’ itself is functionally defined,depending upon the spatial units needed or actuallymanaged by the group of stakeholders working togetherto achieve biodiversity, production and livelihood goals.Ecoagriculture landscapes are land use mosaics with:

— ‘natural’ areas (with high habitat quality and nichesto ensure critical elements for habitat or ecosystemservices that cannot be provided in areas underproduction), which are also managed to benefitagricultural livelihoods either through positivesynergies with production or other livelihoodbenefits,

— agricultural production areas (productive, profitableand meeting food security, market and livelihoodneeds), which are also configured and managed toprovide a ‘matrix’ with benign or positive ecologicalqualities for wild biodiversity and ecosystem ser-vices, and

— institutional mechanisms to coordinate initiatives toachieve production, conservation and livelihoodobjectives at landscape, farm and community scales,by exploiting synergies and managing trade-offsamong them.

The concept of ecoagriculture further recognizesthat agriculture-dependent rural communities arecritical (and sometimes the principal) stewards ofbiodiversity and ecosystem services. While protectednatural areas are essential in ecoagriculture landscapesto ensure critical habitat for vulnerable species,maintain water sources and provide cultural resource,these resources often may be owned or managed bylocal communities and farmers.

(b) Biodiversity and ecosystem services

in ecoagriculture landscapes

Conservation of biodiversity in ecoagriculture land-scapes embraces all three elements of agriculturalbiodiversity defined by the Convention on Biological

conservation ofbiodiversity and

ecosystemservices

Some ecosystem processes andfunctions help to maintain wildbiodiversity.

wild biodiversity

Some ecosystem processes andfunctions benefit humans.These are called ecosystem services.

ecosystem services

beneficial services withinlandscape, such as:

• pollination• pest control• soil fertility• water quality

beneficial services outside landscape, such as:

• carbon sequestration• flood protection

sustainable agricultural production

ecosystem process and function, such as:

• primary production • decomposition• nutrient cycling• gene flow and evolutionary

processes• hydrology

community and household-levelbenefits such as:

• protection of natural capital• compensation payments for ecosystem services

sustainablelivelihoods

Figure 1. Ecosystem services are a key to the synergies between conservation, sustainable agricultural production andsustainable livelihoods (after Buck et al. 2004).

Biodiversity and agricultural sustainability S. J. Scherr & J. A. McNeely 481

Diversity: genetic diversity of domesticated crops,animals, fish and trees; diversity of wild species onwhich agricultural production depends (such as wildpollinators, soil micro-organisms and predators ofagricultural pests); and diversity of wild species andecological communities that use agricultural land-scapes as their habitat (Convention on BiologicalDiversity 2002).

Although wild biodiversity and ecosystem servicesare closely linked, they are not synonymous. Alandscape with relatively intact wild biodiversity islikely to provide a full complement of ecosystemservices. However, many ecosystem services can alsobe provided by non-native species, or by com-binations of native and non-native species in heavilymanaged settings such as permanent farms. Theimplication is that even where wild biodiversity hasbeen significantly reduced to make way for food andfibre production, high levels of ecosystem servicescan often still be provided through intentional landmanagement practices. On the other hand, managingan ecoagriculture landscape for ecosystem servicesdoes not automatically ensure that wild biodiversitywill be protected adequately. Thus, wild biodiversityand ecosystem services both require explicit consider-ation in ecoagriculture systems.

(c) Ecoagriculture approaches

Broadly, ecoagriculture landscapes rely on six basicstrategies of resource management, three focused onthe agricultural part of the landscape and three on thesurrounding matrix.

In production areas, farmers sustainably increaseagricultural output and reduce costs in ways thatenhance the habitat quality and ecosystem services:

— minimize agricultural wastes and pollution,— manage resources in ways that conserve water, soils,

Phil. Trans. R. Soc. B (2008)

and wild flora and fauna, and

— use crop, grass and tree combinations to mimic theecological structure and function of natural habitats.

Farmers or other conservation managers protect andexpand natural areas in ways that also provide benefits

for adjacent farmers and communities:

— minimize or reverse conversion of natural areas,— protect and expand larger patches of high-quality

natural habitat, and

— develop effective ecological networks and corridors(McNeely & Scherr 2003).

The relative area and spatial configuration of

agricultural and natural components (and otherelements, such as physical infrastructure andhuman settlements) are key landscape design issues

(Forman 1995). The conservation of wild speciesthat are highly sensitive to habitat disturbance—asare some of those most endangered or rare globally—

requires large well-connected patches of naturalhabitat. But many wild species, including many thatare threatened and endangered, can coexist in

compatibly managed agricultural landscapes, evenin high-yielding systems.

Numerous approaches to agriculture, conservation

and rural development contribute components, man-agement practices and planning frameworks that can beapplied in ecoagriculture landscapes. The outcomes of

planning and negotiations among the multiple stake-holders in any particular landscape will take diverseforms depending on the context of local cultures and

philosophies of land management.Ecoagriculture landscapes with documented joint

benefits for agricultural production, biodiversity con-servation and rural livelihoods include these threeexamples.

482 S. J. Scherr & J. A. McNeely Biodiversity and agricultural sustainability

(i) Kalinga Province, The PhilippinesFor centuries, the Kalinga indigenous people of ThePhilippines have supported local livelihoods andconserved mountain biodiversity through integratedlandscape management. Communities manage theirwatersheds to ensure a continual supply of water tocommunal irrigation systems, and in recent years over150 ha of integrated rice terraces (including fish andvegetable production) have been rehabilitated. Indi-genous forests are managed for sustainable harvest ofwild animals for protein, leading to an 81% rateof intact forest in Kalinga Province (Gillis &Southey 2005).

(ii) Transboundary co-management in Costa Ricaand PanamaThe Gandoca–Manzanillo National Wildlife Refuge onCosta Rica’s Caribbean coast connects with Panama’sSan Pondsak National Wildlife Refuge. This 10 000 harefuge is co-managed by local communities, non-governmental organizations (NGOs) and governmentagencies. Small farm agro-ecosystems are integral toregional biodiversity conservation. Over 300 farmershold secure land titles in the refuge’s buffer zone. Aregional small farmers’ cooperative (SmallholderAssociation of Talamanca, APPTA) supports over1500 small farmers to become Central America’slargest volume organic producer and exporter, gener-ating 15–60% increases in small-farmer revenue.Conservation-based carbon offset schemes arebeing developed to provide additional revenue forstewardship-focused farming.

(iii) Community dryland restoration in Rajasthan, IndiaFor most of the past century, drought and environ-mental degradation severely impaired the livelihoodsecurity of local communities within Rajasthan’s ArvariBasin. Twenty years ago, the Tarun Bharat Sangh, avoluntary organization based in Jaipur, India, initiateda community-led watershed restoration programme.The programme reinstated ‘johads’, a traditionalindigenous technology for water harvesting. Johadsare simple concave mud barriers, built across small,uphill river tributaries to collect water. As the waterdrains through the catchment area, johads encouragegroundwater recharge and improve hillside forestgrowth, while providing water for irrigation, wildlife,livestock and domestic use. Over 5000 johads nowserve over 1000 villages in the region, and arecoordinated by village councils. Landscape changesinclude restoration of the Avari River, which had notflowed since the 1940s, and the return of native birdpopulations (Narain et al. 2005).

(d) Where ecoagriculture approaches are needed

Ecoagriculture approaches may be relevant to someextent in all agricultural landscapes, in light of their focuson improving landscape performance vis-a-vis three goals(agricultural production, biodiversity conservation andlivelihoods). Synergies may be most apparent, and trade-offs least difficult, in areas with less productiveagricultural lands (so that the opportunity costs ofprotecting or restoring habitats are lower), and inheterogeneousareaswhere farmsare already interspersed

Phil. Trans. R. Soc. B (2008)

with hills, forests and abandoned farms (Jackson &Jackson 2002). Nonetheless, the need to reconcileincreased agricultural productivity and livelihoods witheffective conservation of biodiversity and ecosystemservices may be most critical in agriculture-dominatedlandscapes. Ecoagriculture approaches offer opportu-nities for integrated action, at a lower overall cost, toachieve Millennium Development Goals for poverty,hunger, water, and sanitation and environmental sustain-ability (Scherr & Rhodes 2005). Ecoagriculture alsoprovides a strategy for implementing nationalcommitments to multilateral environmental conven-tions, including the Convention on Biological Diversity(CBD), the Framework Convention on Climate Change,Ramsar and the Convention to Combat Desertification.

But it is important to consider the situations underwhich integrated versus segregated land use is likely tobe especially advantageous, and the scale at whichintegration is desirable (Balmford et al. 2001; Greenet al. 2005). For example, where most biodiversity islikely to be lost in the transition from pristine toextensive systems or if key species are very sensitive tofragmentation, then segregated systems might beindicated at a coarser grain. But where the transitionfrom extensive to intensive agriculture will result ingreater biodiversity loss, then integrated low-intensityagriculture finely interspersed with natural areas maybe most desirable.

Real costs are associated with the cross-sectoralplanning and coordination and technical innovationsneeded to achieve impacts at a landscape scale. Thesemust be considered in prioritizing private, public andcivic ecoagriculture investments. Top prioritieswould be:

(i) agricultural landscapes located in or aroundcritical habitat areas for wild species of local,national or international importance (e.g. land-scapes in the highly threatened habitats of theAtlantic Forest of Brazil, now dominated byfarming),

(ii) degraded agricultural landscapes where restoredecosystem services will be essential to achieveboth agricultural and biodiversity benefits (suchas the dryland farming and pastoral regions ofWest Africa),

(iii) agricultural landscapes that must also functionto provide critical ecosystem services (such asthe densely populated landscapes of Europe andJava), and

(iv) peri-urban agricultural systems, where carefulmanagement is required to protect ecological,wildlife and human health.

No assessment has been done of the geographicalscale and location of such priority areas for ecoagricul-ture development strategies (as distinct from agriculture-or conservation-led development), but undertaking suchanalyses is a critical step to guide policy action.

4. THE STATE OF ECOAGRICULTUREKNOWLEDGE AND PRACTICELittle effort has been devoted to explicitly pursuingagricultural development and biodiversity conservation

Biodiversity and agricultural sustainability S. J. Scherr & J. A. McNeely 483

objectives jointly at a landscape scale, so experience ispoorly documented and the science is immature andpoorly synthesized across disciplines. Removing majorbarriers to the widespread development of ecoagricul-ture landscapes requires answering questions like thefollowing.

— How can agricultural production systems contributeto conserving biodiversity while maintaining orincreasing productivity?

— How can agricultural and natural areas be jointlymanaged to produce adequate ecosystem services,including wildlife habitat, at a landscape scale?

— How can ecoagriculture approaches become morefinancially viable for farmers and other stakeholders?

— How can communities, institutions and govern-ments mobilize and develop the institutions andpolicies needed for ecoagriculture landscapes?

The current state of knowledge on these fourquestions is considered below.

(a) Production systems that support biologically

diverse ecoagriculture landscapes

Since the 1960s, the ‘improved seed–fertilizer–pesticide(irrigation)’ paradigm has characterized both industrialagriculture in developed countries and the originalgreen revolution in developing countries. This pro-duction model involved short-term, plot-level pro-duction of a small number of crops, generally inmonoculture stands (to increase efficiency in use ofexternal inputs and mechanization, maximize the flowof natural resources to harvestable products). Wild floraand fauna were considered direct competitors forresources or harvested products, and thus eliminated,while water was diverted from wetlands and naturalhabitats for irrigation.

More ecologically benign production systems wereretained in many traditional systems that for ecological,cultural or economic reasons were not effectivelyincorporated into the industrial model. Such systemssought to build on, rather than replace, naturalecosystems. Different modern approaches have focusedon different aspects of ecological synergy, arising fromdifferences in discipline, philosophy, problem focus orgeographical conditions. Agroecology, permaculture(Mollison 1990), conservation agriculture (FAO2001), agroforestry (Huxley 1999), organic agriculture(IFOAM 2000) and sustainable agriculture (Pretty1999) have focused principally on maintaining theresource base for production, through managingnutrient cycles, protecting pollinators and beneficialmicro-organisms, maintaining healthy soils and con-serving water. They sought to reduce the ecological‘footprint’ of farmed areas and the damage to wildspecies from toxics, soil disturbance and waterpollution, but most focused on farm-scale action,rather than coordinating efforts among farmers andothers to achieve demonstrable biodiversity benefits ata landscape scale.

To protect wild fauna and flora, ecoagriculturelandscapes must provide protection of nesting areasfrom disturbance, diverse perennial cover for protec-tion from predators, adequate access to clean water

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throughout the year, territorial access between dis-persed population groups to ensure provide minimumviable populations genetically and demographically,all-season access to food from diverse sources, viablepopulations of predators and prey, healthy populationsof other species with which they are interdependent(such as their pollinators), and biologically active soils.Many of these functions can be provided by healthypatches and networks of natural habitat (discussed in§5), but production areas also play a critical role. Toachieve these attributes in production areas, agricul-tural and conservation innovators are pursuingstrategies such as minimizing agricultural pollution ofnatural habitats, managing conventional croppingsystems in ways that enhance habitat quality, anddesigning farming systems to mimic the structure andfunction of natural ecosystems. A key challenge forfarmers is to do so in ways that also maintain orincrease agricultural output, reduce overall productioncosts or enhance the market value of their products inorder to meet their broader livelihood needs whileconserving biodiversity.

(i) Minimizing agricultural pollution of natural habitatsReducing agrochemical use and livestock wastes inhigh-input production systems can greatly benefitwildlife. For example, high-nutrient or toxic run-offinto waterways (a problem for both natural andsynthetic forms of nitrogen) can dramatically reduceaquatic biodiversity. Major advances have been made inmethods to reduce and improve the efficiency offertilizer use, through better timing and methods ofapplication.

Agricultural pesticides may also kill non-targetinsects and weeds that constitute the food base forinsect- and grain-eating species. Integrated pestmanagement systems have effectively used varietalcrop mixes, pest monitoring and management practicesto reduce the need for pesticides (Kogan 1998).Cellular and molecular biology have been used to tailorpesticides to affect only specific pests. New ecologicaland biochemical research techniques are revealing anunexpected sophistication of host–pest relations thatcould revolutionize agricultural pest control in thefuture (Wittenberg & Cock 2001).

Pretty’s (2005) meta-review of farmer experiencefound gains in both productivity and biodiversity fromreduced chemical use in developing counties. Forexample, the System of Rice Intensification mobilizesbiological interactions in plant–soil systems, ratherthan external inputs, to raise yields significantly whilereducing costs (Uphoff et al. 2006). Meanwhile, newwhole-farm planning approaches minimize run-off ofagrochemical and livestock waste into aquatic systemsby improving storage systems, managing fields toimprove infiltration and reduce run-off, and establish-ing buffer zones to filter pollutants before they enterstreams (Coombe 1996).

(ii) Managing production systems to enhancehabitat qualityFarmers and conservationists have modified manage-ment of soil, water, fire and vegetation to transformcrop fields into useful habitat for species, or to enhance

484 S. J. Scherr & J. A. McNeely Biodiversity and agricultural sustainability

their value as ‘corridors’ connecting natural habitatareas in the landscape (McNeely & Scherr 2003; Clay2004). Buck et al. (2006) reviewed 79 studies whereinvestigators quantified biodiversity (usually speciesrichness) associated with 18 specific agriculturalpractices. The strategy most often correlated with theconservation of wild biodiversity was the maintenanceof adjacent hedgerows, windbreaks or woodlots; 18studies documented positive correlations with eighttaxa. Organic agriculture was correlated with anincrease in seven taxa in eight studies (Peach et al.2001; Klein & Sutherland 2003; Kleijn et al. 2006).Shaded tropical crop production (especially coffee andcacao) had higher species richness of three higher taxaby eight different studies (Buck et al. 2007).

Research has also found that many of these practicesprovide additional benefits to farmers, such as usefulby-products, reduced risk of crop loss during droughts,diversified food and income sources and reducedvulnerability to environmental risks. For example,following the October 1998 Hurricane Mitch (theworst natural disaster to strike Central America in 200years), researchers found that farms using agroecolo-gical practices suffered 58% less damage in Honduras,70% less in Nicaragua and 99% less in Guatemalathan those using conventional farming methods(Bunch 2000).

Impacts of conservation practices may be speciesspecific. For example, cotton is an inhospitable habitatfor many songbirds, particularly due to very high levelsof pesticide use in conventional systems. Butapproaches such as conservation tillage and stripcover cropping reduce the ecological impact of cottonfields. Cederbaum et al. (2004) examined the effects ofclover strip cover cropping with conservation tillageversus conventionally grown cotton with either conven-tional or conservation tillage on avian and arthropodspecies composition and field use in Georgia, USA.Strip cover fields had higher bird densities and biomassand higher relative abundance of arthropods thaneither conservation tillage or conventional fields.During migration and breeding periods, total birddensities on strip cover fields were 2–6 and 7–20 timesgreater than on conservation and conventional fields,respectively. Although the clover treatment attractedthe highest avian and arthropod densities, conservationfields still provided more wildlife and agronomicbenefits than conventional management. Thereduction of inputs possible with the clover systemallows farmers to reduce costs associated with conven-tional cotton production. Transgenic cotton has beendeveloped to significantly reduce the need for pesti-cides, with observed benefits for biodiversity (Cattaneoet al. 2006).

The organic farming industry has only recentlybegun to develop standards that explicitly addressconservation of wild biodiversity. But Hole et al. (2005)found that a wide range of taxa, including birds,mammals, invertebrates and arable flora can benefitfrom organic management through increases inabundance and/or species richness. Managementpractices, such as prohibition or reduced use ofchemical pesticides and inorganic fertilizers, protectionof non-cropped habitats, and preservation of mixed

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farming, are particularly beneficial for farmland wild-life. Though yields from organic systems are still oftenlower than those in conventional systems, the gap isnarrowing and research is accumulating that showshow agricultural production systems primarily orexclusively dependent on organic inputs can producesuperior agronomic and economic results (Uphoffet al. 2006).

Carefully targeted management practices appliedto relatively small areas of cropped or non-croppedhabitats within conventional agriculture may alsoprovide valuable biodiversity benefits (Trewavas2001). Weibull et al. (2003) found that wild speciesrichness generally increased with landscape hetero-geneity on a farm scale, and habitat type had a majoreffect on species richness for most groups, with mostspecies found in pastures and leys (lands temporarilysown with grass). The level of motivation of thefarmer to maintain biodiversity on the farmstead wasmore predictive of biodiversity outcomes thanspecific practices.

(iii) Modifying farming systems to mimic natural ecosystemsFrom a wild biodiversity conservation perspective, theideal agricultural production systems for ecoagriculturelandscapes mimic the structure and function of naturalecosystems (Leakey 1999; Lefroy et al. 1999; Jackson &Jackson 2002; Blann 2006). In humid and sub-humidforest ecosystems, farms would mimic forests, withproductive tree crops, shade-loving understory cropsand agroforestry mixtures; in grassland ecosystems,production systems would rely more on perennialgrains and grasses, and economically useful shrubsand dryland tree species. Annual crops would becultivated in such systems, but as intercrops, ormonoculture plots interspersed in mosaics of perennialproduction and natural habitat areas. Domesticatedcrop and livestock species diversity would be encour-aged at a landscape scale, and intra-species geneticdiversity would be conserved in situ at least at anecosystem scale, to ensure system resilience andecological diversity.

Multi-story agroforest systems, tree fallows andcomplex home gardens are especially rich in wildbiodiversity (Cairns & Garrity (1999); Schroth et al.2004; Leakey & Tehoundjeu 2001). For example,Siebert (2002) found that canopy height, tree, epiphyte,liana and bird species diversity, vegetation structuralcomplexity, per cent ground cover by leaf litter, and soilcalcium, nitrate nitrogen and organic matter levels intopsoils were all significantly greater in shaded than insun-grown farms, while air and soil temperatures, weeddiversity and per cent ground cover by weeds weresignificantly greater in sun farms. Recent research inCentral America has identified polyculture com-binations and management systems that significantlyimprove the productivity of coffee, cocoa, banana,timber and other commercial tree products in thesecomplex systems (e.g. Beer et al. 2000).

New and improved perennial crops can substitutefor products now provided by annuals, such as fruits,leafy vegetables, spices and vegetable oils. Perennialcrops can be more resilient and involve less soil andecosystem disturbance than annual crops, and provide

Biodiversity and agricultural sustainability S. J. Scherr & J. A. McNeely 485

much greater habitat value, especially if grown inmixtures and mosaics ( Jackson & Jackson 1999;Leakey & Tchoundjeu 2001). Breeding efforts arealso underway to perennialize annual grains and tomimic ecosystem functions of natural grasslands; insome cases, yields are becoming competitive withconventional varieties (de Haan et al. 2007). This is asignificant research opportunity. Increased demand forlivestock products in turn raises demand for animalfeed, including for higher-quality pastures, fodder orinputs for concentrates. While historically low grainprices have meant that corn and soy have beendominant feedstocks during the past few decades,alternatives abound, including perennial grass, shruband tree species that can be grown more sustainably inmarginal lands, as industrial processes adapt. More-over, the future of industrial-type intensive, grain-fedlivestock production is uncertain in the face ofemerging zoonotic infectious diseases and associatedpollution, opening more economic opportunity forsubstitutes from rotational grazing and even pastoralsystems (Nierenberg 2005). Crops for biofuels arepoised to become one of the fastest-growing segmentsof agricultural production, and although short-terminvestments have favoured annual crop sources in thedeveloped world (as a way to absorb subsidy-drivensurpluses), grasses, shrubs and tree sources may bemore economic and sustainable options once thetechnical challenges of processing cellulosic sourcesare overcome (Ruark et al. 2006).

(iv) Major gapsThe development of agricultural practices and systemsthat explicitly support wild biodiversity is in its infancy.Buck et al. (2006) highlight numerous critical knowl-edge gaps, especially knowledge about the link betweendiversity and ecosystem function, and the relationshipsbetween below- and above-ground biodiversity.Methods being used to assess biodiversity impacts areinadequate, and generally fail to evaluate the impact onregional or global diversity, or to interpret thesignificance of an individual member of a speciesfound at a particular site. Researchers still find itdifficult to link plot-based analysis with landscape-scaleimpacts (Tomich et al. 2004).

Even where successful biodiversity and productionoutcomes are well documented, the underlying bio-logical or ecological mechanisms may be poorlyunderstood. The potential contributions and threatsof genetically modified organisms to biodiversity inecoagriculture landscapes have not been explored.Little of the existing crop breeding research in generalhas been considered within an ecoagriculture frame-work. Rather, most have focused on addressingproblems at the ‘end-of-pipe’ to offset existing pro-blems rather than rethinking the ecological manage-ment system, or even considering potential trade-offs ofrisks and benefits.

Redford & Richter (1999) propose that researchersmuch more systematically assess the impact of differentresource management options on specific components ofbiodiversity (the function, structure and composition ofcommunities/ecosystems, populations/species, geneticdiversity and option space; Redford & Richter 1999;

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Swift et al. 2004). Then, where ecoagriculture systemsare successful in increasing populations of wild species,new methods for managing them may be needed tominimize conflicts. The major gap is the miniscule levelof international and national public investment inresearch documenting and evaluating existing ecoagri-culture production systems, or in pursuing agriculturaland conservation research to improve biodiversity-supporting and financially viable production systems.

(b) Managing ecoagriculture landscapes for both

production and conservation

The ecoagriculture approach encompasses both biodi-versity-friendly agricultural production systems andpractices, and their management in mosaics withnatural areas and other landscape features to meetconservation, livelihood and production goals. Onepremise of ecoagriculture is that ecosystem services cancome from both production and conservation areas,especially if they are coordinated and managed forthat purpose. Improved tools, greater demand forlandscape-scale action and reassessment of long-sustained traditional agro-ecosystems, have led tosubstantial progress over the past two decades in layingout the basic parameters for biophysical managementof ecoagriculture landscapes, if not location-specificguidance. Social and institutional aspects of landscapemanagement are addressed in §4d.

(i) New tools for landscape assessmentDespite the importance of agricultural landscapes forbiodiversity conservation, only a small fraction ofpublished conservation biology studies has been under-taken in agricultural landscapes (Buck et al. 2004), sodeveloping a baseline for assessing change is difficult.Most studies of the biodiversity impacts of particularagricultural practices and even the work of biodiversity-oriented groups like the Rainforest Alliance havefocused on farm-level indicators. Meanwhile, a reviewof basic biodiversity research found very little empiricaldata on the contributions of wild species and naturalecosystem conditions to agricultural productivity(Jackson et al. 2005). Landscape ecology has providedus with the analytical language and tools to system-atically examine the interactions between farmed andunfarmed areas (Forman 1995; Wojtkowski 2004). Thescience of ‘countryside biogeography’ has recentlybegun to work on biodiversity patterns in complexlandscape mosaics, which shows how different land useelements and configurations support different wildspecies (Daily et al. 2000). Sophisticated landscapemodelling and remote sensing tools are becomingavailable (e.g. Dushku et al. 2007; Scherr et al. 2007a).

(ii) Maintaining natural habitats for terrestrial speciesin agricultural landscapesA common goal in ecoagriculture landscapes is toconserve a broad range of terrestrial species native tothe area. This includes species that are relativelyresilient to habitat fragmentation and agriculturalland use, as well as species that are rare or locally orglobally threatened, and those that require largerextensions of minimally disturbed habitat. The pro-spects for achieving this in agricultural landscapes

486 S. J. Scherr & J. A. McNeely Biodiversity and agricultural sustainability

depends on the degree of fragmentation and functionalconnectivity of natural areas, the habitat quality ofthose areas, the habitat quality of the productive matrixand the behaviour of farmers.

Efforts to maintain natural habitats in farming areasare longstanding, principally through diverse types ofagricultural set-aside schemes (Kleijn & Baldi 2005).Based on a meta-analysis of 127 published studies, VanBuskirk & Willi (2005) found that land withdrawn fromconventional production of crops unequivocallyenhances biodiversity in North America and Europe.The number of species of birds, insects, spiders andplants is 1–1.5 standard deviation units higher on set-aside land, and population densities increase by 0.5–1standard deviation units. Set-aside land may beespecially beneficial for desirable taxa because NorthAmerican bird species that have suffered populationdeclines reacted most positively to set-aside agricul-tural land. Larger and older plots protect more specieswith higher densities, and set-aside land is moreeffective in countries with less-intensive agriculturalpractices and higher fractions of land removed fromproduction. For many commercial crop monocultures,leaving field margins uncultivated for habitat protec-tion does not reduce total yields, as inputs were appliedmore economically on the rest (Clay 2004).

However, landscape-scale interventions specificallydesigned to protect habitats for biodiversity (thatinclude but coordinate and go beyond farm- andplot-specific interventions) are much more effective.A recent review of evidence from North America onhow much habitat is ‘enough’ in agricultural land-scapes (Blann 2006) concluded that strategies need toconsider habitat needs within the landscape history andcontext. Adequate habitat patch size and connectivitymust be maintained, but ‘adequate’ must beconsidered in relation to matrix influence and patchcondition (sinks and ecological traps, patch locationand configuration, edge effects and boundary zones).Smaller patches of natural habitat may be sufficient ifadjacent agricultural patches are ecologically managed.

Based on studies from Central America, Harveyet al. (2005) conclude that landscape connectivitybetween large patches of forest can be effectivelymaintained through retention of tree cover on thefarm, such as live fences, windbreaks, and hedges ingrazing lands and agricultural fields. Sayer & Maginnis(2005) describe effective approaches for forest land-scape restoration in mixed use mosaics.

(iii) Protecting habitats for freshwater aquatic biodiversityProtection or establishment of native vegetation buffersalong streams, rivers and riparian systems is critical forbiodiversity conservation (Blann 2006). Data from theUS suggest a minimum buffer width of 25 m to providenutrient and pollutant removal, 30 m to providetemperature and microclimate regulation and sedimentremoval, a minimum of 50 m to provide detrital inputand bank stabilization and over 100 m to provide forwildlife habitat functions. Wetlands should be pro-tected, and the critical function zone of wetlandsshould be maintained in natural vegetation. The latestguideline in North America is that at least 10% of awatershed and 6% of any sub-watershed should

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comprise wetlands. Molden et al. (2005) and Blann(2006) emphasize the importance of re-establishinghydrological connectivity and natural patterns foraquatic ecosystems. Based on literature review andfield experiments, van Noordwijk et al. (2007) con-clude that watershed functions in agricultural land-scapes can be effectively provided through strategicspatial configuration of perennial natural vegetationand planted vegetation, with maintenance of continu-ous soil cover enhancing infiltration.

Maintaining seasonal flood pulse dynamics in flood-plains involves restoring floodplains and protectingthem from developments that disconnect riversthrough levees and water level management (Blann2006). If floodplains must be used for agriculture,ecologists recommend using agroforestry and otherapproaches compatible with natural cycles rather thanmonocultures requiring annual ploughing and fertiliza-tion. Sendzimir & Flachner (2007) present an exampleof river floodplain polyculture in the Tisza River Basinin Hungary that exploits flooding as an engine ofbiodiversity. Natural floodplains, unconstrained byhydro-engineering infrastructure, sustained a diversityof habitats and the elevational structure in the land-scape. They further maintained hydraulic connectionsthat sustain nursery and migratory functions, storedwater during times of drought, and distributed andmixed fallen fruit in novel combinations that stimulatedagro-biodiversity and the cultivation of hundreds ofvarieties of fruits and nuts, as well as fisheries.

(iv) Optimizing agriculture–natural habitat interactionsin landscape mosaicsBiologically diverse agricultural systems and land-scapes can contribute to control of pests and diseases,provide new economic species, and buffer environ-mental changes and challenges (Jackson et al. 2005;Thompson et al. 2007). Ricketts (2004) investigatedthe role of tropical forest remnants as sources ofpollinators for surrounding coffee crops in Costa Rica,observing bee activity and pollen deposition rates atcoffee flowers, including 10 species of native bees andthe introduced honeybee, Apis mellifera. Bee speciesrichness, overall visitation rate and pollen depositionrate were all significantly higher in sites withinapproximately 100 m of forest fragments than in sitesfarther away. The vast majority of pollination in coffeeplantations more than 100 m from a forest was by theintroduced honeybee. Forest fragments near coffeeplantations increased both the amount and stability ofpollination services by reducing dependence on a singleintroduced species. Kremen et al. (2002) found similarresults for pollinators of watermelon fields near and farfrom natural woodlands in California.

(v) Major gapsThe past two decades have revolutionized the potentialfor landscape-scale assessment and scientific under-standing of the ecological functioning of diverse typesof agricultural landscapes. A framework for consideringkey management guidelines and broad parameters isnow in place, but empirical or even ecologicalmodelling evidence needed for managing ecoagricul-ture landscapes (e.g. size and shape of natural areas

Biodiversity and agricultural sustainability S. J. Scherr & J. A. McNeely 487

required to sustain ecological functions, impacts onagricultural productivity of natural vegetation andspecies) is lacking. Agreed methods do not yet existfor integrated monitoring of livelihood, biodiversityand agricultural outcomes at a landscape scale,although this challenge is being taken up (Scherr &Meredith 2005; Buck et al. 2007). Rigorous under-standing of the potential benefits and costs foragriculture of associated wild flora and fauna, and keyecosystem services, is lacking (Jackson et al. 2005).

Molden et al. (2007) highlights numerous practicesto manage irrigation water in ways that also supportbiodiversity. But these are not widely implementedbecause they are not part of the institutions, incentivestructures and education related to irrigation. Little ofthe new science has been shared with farmers or evenwith agronomists and other specialized agriculturalscientists and technicians. The science is often missingthat informs real-life innovations that local people canmake to modify ecological impacts of managementactivities. Technical assistance services for farmersrarely address landscape management issues. Lack ofrigorous data and analysis about ecoagricultureimpacts and potentials is a key constraint to increasedinvestment in and policy support for ecoagriculture.The complexity of ecoagriculture landscapes andmanagement, multiple objectives and lack of infor-mation on interactions have made it difficult for projector community managers to document outcomeseffectively or to compare results across sites. Inter-national collaborative research on tropical forestmargins is rare (Palm et al. 2005).

(c) Achieving financial viability

of ecoagriculture landscapes

Investing and engaging in ecoagriculture systems willrequire that all key elements—farm production, natureconservation and associated institutions for collectivelandscape management—be adequately financed. Ifecoagriculture systems are to be widely adopted aroundthe world, then incomes (defined to include not onlycash but also other livelihood components) for farmersin those systems need to be at least as high, or higher,than in less biodiversity-friendly production systems,and other non-monetary benefits will be key. Market-based innovations could provide many opportunitiesfor scaling up ecoagriculture.

(i) Making ecoagriculture systems more profitablefor farmers and investorsContrary to common assumptions, farmers and theircommunities often have strong economic and socialrationales for supporting biodiversity conservation: toreduce production costs, raise or stabilize yields;improve product quality; protect their right to farm/herd/harvest wild products in and around protectedareas; comply cost-effectively with environmentalregulations; conserve biodiversity and ecosystemservices critical to their own livelihoods; access productmarkets that require biodiversity-friendly productionsystems; earn payments for ecosystem services; orconserve species and landscapes of special cultural,spiritual or aesthetic significance to them.

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Many ecoagriculture systems are, in fact, moreprofitable or less risky than alternatives. McNeely &Scherr (2003) present 28 examples that clearlydemonstrated positive economic benefits, and anotherfive cases had a neutral impact on incomes (despitemajor benefits for wild biodiversity). Farm incomes haddoubled or tripled in ecoagriculture landscapes withirrigated rice in The Philippines, dairy systems in Braziland the US, and improved fallow systems in Africa.

Investment needs to be targeted to produce theresearch and management breakthroughs that willenable farmers to raise output and/or reduce theircosts while protecting and enhancing biodiversity.Community non-monetary benefits from use andnon-use values of biodiversity, including inputs forfarming and processing, medicines and cultural valuesare also important. Pearce (2005) documents financialand economic contributions of ecosystem services andbiodiversity to poverty reduction and vice versa.

Communities are organizing themselves regionallyto improve market linkages, reduce marketing costsand connect directly with buyers. Communities need tounderstand and meet the quality and time demands ofinterested buyers and to enter into and fully respectcommercial contracts. They also need technicalassistance to improve product quality and managecommercial contracts, and gain access to harvestfinance and credit for post-harvest product processingand handling facilities/technologies. Development ofinnovations at all points in the marketing chain canreduce costs for trading, storage, transport, bulking,grading, etc. and thus improve returns from marketingproducts from polycultures and multi-productlandscapes.

(ii) Develop product markets that reward ecosystemstewardshipNew market niches are beginning to develop foragricultural products that are certified to be ‘green’.Producers or products are certified by independent thirdparties to have positive or neutral effects on biodiversity,based on criteria such as reduced agrochemical pol-lution, protection of natural areas, use of productionpractices that do not interfere with key natural processesor species lifecycles and participation in the developmentof landscape-scale wildlife corridors (Millard 2007).A 2005 review by Ecoagriculture Partners found morethan 70 such green certification systems, ranging from‘salmon-friendly’ certification of farms protecting criticalstream habitats in the northwest United States to‘conservation beef ’ to Rainforest Alliance-certifiedcommodities in Latin America ( Y. Fukui 2005,unpublished data). The Sustainable AgricultureInitiative Platform and the Sustainable Food Lab areworking with suppliers to enhance sustainability, includ-ing some elements of biodiversity.

New markets are also developing for products basedon sustainable harvest of wild species, or on thedomestication of wild species (such as extracts, spices,medicinals, construction materials and fruits; STCP2005). The use of marketing labels for agriculturalproducts coming from particular geographical regions,originally focused on quality, culture and taste, isbeing adopted for products labelled as supporting

488 S. J. Scherr & J. A. McNeely Biodiversity and agricultural sustainability

conservation of high-biodiversity-value landscapes.Demand is growing as the food industry becomesmore sensitive to reputation issues around environ-ment, and advocates promote new institutional pro-curement policies (Rainforest Alliance 2006), althoughconsumers remain motivated more by human health-related issues. Concerns about bio-terrorism andhealth, combined with low-cost monitoring tech-nologies, could enable farm-to-consumer farm producttracking to become more common in high- and middle-income countries, reducing the relative costs ofmanaging value chains for eco-certified products.

(iii) Reward farmers and farming communities forecosystem servicesA major potential driver for ecoagriculture land-scapes is payments to farmers or herders/ranchersand their communities for conserving biodiversityimportant to outsiders, and for conserving otherecosystem services using management practices thatalso conserve biodiversity. Such compensation cur-rently takes various forms, including payments foraccess to species or habitats (e.g. research permits;hunting, fishing or gathering permits for wild species;or ecotourism); payments for biodiversity conserva-tion management (e.g. conservation easements, landleases, conservation concessions or managementcontracts); tradable rights under ‘cap-and-trade’regulations (e.g. wetland mitigation credits, tradabledevelopment rights and biodiversity offset credits)and support for biodiversity-conserving businesses(e.g. business investments or eco-labelling of greenproducts; Scherr et al. 2007a).

An estimated $6000 million is spent worldwide onland trusts and conservation easements, a third indeveloping countries, with a large proportion in farmand ranchlands. Direct conservation and biodiversitypayments for flora and fauna by governments amountto at least $3000 million, most in the US, Europe andChina. Roughly, 20% of the farmland in the EU isunder some form of agri-environment scheme tocounteract the negative impacts of modern agricultureon the environment, at a cost of approximately US$1.5billion (approx. 4% of the EU expenditure on theCommon Agricultural Policy). In the US, approxi-mately US$45 million is spent on regulatory offsets forbiodiversity, including conservation banking, and suchprogrammes have been initiated in Australia andFrance (Ecosystem Marketplace 2006). New modelsare emerging for payments by private sector companies,utilities and municipalities for ecosystem servicesessential to businesses, and to reduce ecological risks.For example, at least $20 million in voluntarybiodiversity offsets have been documented, half indeveloping countries (Ecosystem Marketplace 2006).

Thus, the size of payments is already considerable,although their effectiveness in achieving biodiversityobjectives and in supporting biodiversity-friendlyproduction systems at landscape scale is quite mixed(Scherr et al. 2006). The potential future contributionof these new payments and markets to financingecoagriculture landscapes will depend on the ‘rules ofthe game’ and institutions that are currently beingdeveloped (Scherr et al. 2007b).

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(iv) Major gapsNew mechanisms have arisen over the past decade toreward and finance biodiversity conservation andbiodiversity-friendly agriculture, but most of theseare modest in scale or modestly effective at landscapescale. Little research has been done on the structuresand institutions in product market chains thatfacilitate biologically diverse production. Nor hasany systematic assessment been done of overallagricultural investment and finance and how it mightbe shaped to better support biodiversity. Certificationprocesses for agricultural products (and wild productssustainably harvested) can be expanded, streamlined,designed for landscape-scale impact, enable low-income people to participate (IITA 2001; Molnar2003). Still, most demand in developing countries isfor domestic markets and seeking lowest-cost supply,so it is crucial to focus on reducing costs across themarket value chain (not only at the level of theproducer). More explicit attention is needed tomobilize payments for ecosystem services to supportecoagriculture landscapes. Finance through carbonemission offsets is the greatest unexploited opportu-nity, but further technical research is needed to lowercosts of organizing landscape-scale action and moni-toring performance. The trade-offs and synergiesamong different ecosystem services for differentproduction and conservation strategies need to bemore fully understood and addressed.

(d) Mobilizing ecoagriculture: from community

action to global impacts

Ecoagriculture landscape innovators often identifytheir major constraint to be institutional barriers ratherthan technical or even financial ones (Bumacas et al.2007). Key institutional challenges include inadequatecommunity-level organizations for ecoagricultureaction, landscape-scale planning, policies at variouslevels and mechanisms to achieve equitable outcomesin ecoagriculture landscapes.

(i) Organization of communities for ecoagricultureA core feature of ecoagriculture landscapes is the role ofresident local farming or pastoral communities as keystewards, decision makers and managers of biodiver-sity. Public agencies may operate forests and protectedareas, but their viability and sustainability depend onthe matrix of private land uses in the landscape.Economic and social incentives can motivate collectiveaction of local communities. Hundreds of community-based organizations have been documented to mobilizeor engage in landscape-scale ecoagriculture initiatives(e.g. Campbell 1994; Brookfield et al. 2002; Imhoff2003; Isely & Scherr 2003; McNeely & Scherr 2003;Rhodes & Scherr 2005). The institutions leading theseinitiatives are ‘hybrids’ fusing conventional farmercooperatives, rural development committees and com-munity-based conservation organizations (Buck et al.2004). In The Philippines, for example, local farmer-based Landcare groups are linked with conservationorganizations, municipal governments and researchorganizations to revegetate hillsides, conserve biodi-versity in populated PAs and improve water quality(Cramb & Culasero 2003). An important implication is

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the central role of communities in biodiversity con-servation, especially outside PAs. Conservationorganizations need to embrace and reorient their roleexplicitly to support local community stewardship inways that respect and realistically address thecentral role of agriculture and livelihoods in planningand implementation methodologies (e.g. Bumacaset al. 2007).

(ii) Landscape-scale planning and governanceTo achieve objectives at the landscape scale requires aprocess of collective action to support producers andcoordinate action among key stakeholders in the land-scape, often across sectors with a historical legacy ofdistrust. Development or adaptation of institutions forengagement, coordination and governance of ecoagri-culture become the critical challenges. Scaling up andsustaining ecoagriculture landscapes that involvemultiple stakeholders requires a process, and usuallyan institution, that will enable multi-stakeholder assess-ment, planning, implementation and monitoring foradaptive management. Currently, ecoagriculture initiat-ives take numerous forms, mobilized by communityorganizations, public agencies, NGOs or national/inter-national projects. Methodologies that have beendeveloped to assist the planning and governance processinclude landscape ‘visioning’ and ‘scenario-building’processes, participatory landscape modelling, commu-nity biodiversity assessments and guidelines for ‘adap-tive collaborative management’ (Buck et al. 2001;Edmunds & Wollenberg 2001). Multi-stakeholdertrust-building processes and negotiation platforms arebeing adapted to the specific context of agriculture–biodiversity conflict situations (e.g. Hemmati 2007).Diversity of approaches is expected and desirable, butmore systematic and comparative evaluation of effec-tiveness in achieving sustainable processes and out-comes is lacking.

(iii) Policies that support ecoagriculture landscapesEcoagriculture innovators around the world highlightthe need for a more supportive policy environment forecoagriculture, or simply the removal of major policybarriers (Mattison & Norris 2005; Rhodes & Scherr2005; Robertson & Swinton 2005). Core policy needs,at local, national and international scales are: (i)compatibility and coordination of agricultural develop-ment and biodiversity conservation policies, (ii)environmental legislation that embraces the potentialsand rights of farming communities as conservators ofbiodiversity, and (iii) the removal of public subsidies foragricultural systems and investments that harmbiodiversity.

Consumers, policy makers and investors arebeginning to focus on the link between agricultureand conservation, and responding with new demandson the agricultural system, through systems ofvoluntary certification, industry standards and gov-ernment regulation (e.g. SCBD 2005, DecisionsIII/11, V/5 and VI/5). Ecosystem/landscape-scaleprogrammes and projects are being initiated bygovernment agencies and NGOs, often in multi-stakeholder partnerships, and financed throughpublic budgets (e.g. in India and China) and

Phil. Trans. R. Soc. B (2008)

international development loans (e.g. Fernandes2004). Initiatives to achieve these policy objectivesinclude the Central America Presidents’ jointcommitment to promote environmentally friendlyagriculture, the removal of agricultural subsidies inAustralia, and the recommendations from Commu-nities to the Millennium Summit. New politicalcoalitions are being formed to promote integratedcross-sectoral policies, bringing in voices and sectorsnot traditionally involved in either agricultural orconservation policy, such as municipal governments(in the context of political decentralization), urbanconsumer groups, international financial organiz-ations concerned with screening investments forenvironmental sustainability, parts of the foodindustry, public health advocates and ‘good govern-ance’ movements seeking to reduce wasteful spend-ing on subsidies.

At the international policy level, ecoagriculturestrategies are being integrated into the work pro-grammes of the relevant international conventions.For example, the CBD has adopted a new biodi-versity goal of 30% of agricultural areas underbiodiversity-friendly management by 2010 (CBD2006), and will focus on agriculture in meetingsduring 2008, as will the Commission on SustainableDevelopment. Rules developing under the WorldTrade Organization will need to be carefully scruti-nized to ensure that they do not disadvantageproducers in ecoagriculture landscapes.

Some countries, notably Australia, Brazil andIndia, have adopted legislation that explicitly recog-nizes the rights of indigenous and other localcommunities to manage and conserve forests andnatural habitats (Ellsworth 2004; Molnar et al. 2004).The Convention on Biological Diversity and otherinternational bodies are beginning to focus onopportunities for community-led conservation,although many elements of the conservation commu-nity are still uncomfortable directly addressing andsupporting agricultural development.

Policy changes can enhance the financial viability ofecoagriculture by removing government subsidies andfiscal incentives for biodiversity-harming productionsystems, in particular subsidies for agrochemical inputsand water, rules for commodity payment support thatlimit crop rotations, subsidies that favour annual cropsover perennials, and intensive livestock productionsystems over grazing systems, and tax incentives forvegetation clearing.

(iv) Achieving social equityEfforts to maintain or promote ecoagriculture land-scapes are often instigated, complicated or impeded bythe serious social inequities characterizing ruralregions in many parts of the world. Indigenouscommunities are documenting their effective ecoagri-culture systems in their efforts to reclaim land rightsfrom the state. Corporate agribusinesses are seeking topromote ecoagriculture to ensure their ‘social licenseto operate’. Ecoagriculture strategies that coordinatethe use and management of landscape resources canhelp resolve resource disputes between farmers andpastoralists. Community groups and advocates for the

490 S. J. Scherr & J. A. McNeely Biodiversity and agricultural sustainability

poor are promoting ecoagriculture policies as a way toprotect and restore biodiversity and ecosystem servicesimportant to the poor.

Ecoagriculture approaches can create more‘space’ for equitable outcomes by identifyingsynergies between local livelihood benefits andbenefits for agricultural economies and biodiversity,and by justifying stronger rights for poor producersover natural resources. But ecoagriculture systemsare both context specific and the result of nego-tiations among diverse actors. To achieve equitableoutcomes will require that poor and disenfranchisedgroups within the landscape organize themselves forpolitical strength, that they join coalitions withother stakeholders, and that they be supportedstrategically in their negotiations with more power-ful groups.

(v) Major gapsWhile this survey of ecoagriculture innovators reportsnumerous promising institutional models—at com-munity, landscape and policy levels—the conditionsunder which such innovations are most likely toemerge, or can be successfully applied, are poorlyunderstood. Effective cross-sectoral politicalcoalitions have seldom arisen to advocate for reconcil-ing conflicting agriculture and environmental policies.Ecoagriculture strategies are not well integrated intopublic investment plans, including the PovertyReduction Strategies of low-income countries anddonor strategies designed to support the MDGs.Rural farming communities are largely unrepresentedat most international environmental policy forums,and environmental interests generally are absent fromfarming organizations. Local organizations find itdifficult to access the specialized knowledge generatedby others and are poorly integrated into ecosystem orwatershed planning and policy processes at local,national or international levels. Few conservationorganizations have staff with agricultural expertise.Most international and national policy and legalframeworks separate action on agricultural pro-ductivity, ecosystem management and rural liveli-hoods, and policy-making institutions reflect thisseparation. Most policy makers are unfamiliar withthe opportunities for ecoagriculture, or of alternativepolicies and laws that would enable ecoagricultureactivities and outcomes. Mainstreaming ecoagricul-ture will require that strategically important insti-tutions—responsible for policy, research, andmarkets—modify how they do business to embraceecoagriculture vision and strategies.

5. ACHIEVING ECOAGRICULTUREAT A GLOBALLY MEANINGFUL SCALEThis review found many examples of apparentlysuccessful approaches linking biodiversity conservationwith sustainable agriculture. On the other hand, thecurrent knowledge base and institutional arrangementsare clearly inadequate to meet the objectives notedabove across diverse ecosystems and productionsystems. To enable ecoagriculture landscapeapproaches to expand to a globally significant scale

Phil. Trans. R. Soc. B (2008)

will require at least three elements: new knowledge,institutional capacity, and an enabling policy andmarket environment.

(a) Produce and share knowledge

for ecoagriculture

The challenge of shaping agricultural landscapes tomeet joint production, conservation and livelihoodgoals will require a dramatic scaling up and refocusingof research, in national research systems, the centersupported by the Consultative Group for Inter-national Agricultural Research, centres of conserva-tion science, national academies of science, anduniversities. Priorities are to understand theinteraction and dynamics of conservation and pro-duction areas; to develop production systems(including improved varieties of more diversedomesticated species) that explicitly meet biodiversityobjectives and mimic natural ecosystems; and to makemore elements of farming systems ecologicallysustainable, including industrial processing, packa-ging, transport, etc. Ecoagriculture systems thatappear to be successful need to be fully documented,both in terms of landscape-scale outcomes andspecific interventions. Mapping of spatial overlaysbetween important agricultural areas (in terms ofnational product supply or local livelihoods) andimportant biodiversity will be essential.

(b) Build capacity for ecoagriculture

Knowledge innovation systems need to be reshaped toprovide services to rural resource stewards, and toaccelerate exchange of practical knowledge amongthem and across sectors. Rural communities must beacknowledged as key stewards of biodiversity conserva-tion, and professional conservation organizations,public agencies and others need to reorient theiractivities to reflect this reality and provide services tocommunity-based organizations, as well as to otherstakeholder groups. Conservation organizations needto fully embrace farming partners, develop agriculturalexpertise and aggressively advocate for sustainableagriculture investment in coordination with conserva-tion strategies.

(c) Promote markets and policies that support

ecoagriculture

Technical and local organizational opportunities andinitiatives for ecoagriculture are unlikely to be success-ful unless major policy barriers are removed, andsupportive policies developed. To advocate for thisagenda, beneficiaries of ecosystem services provided byagricultural landscapes, new economic actors in theproduct value chain and advocates for reinvigoratedrural development need to form new politicalcoalitions. In North America, Europe, Japan, Australiaand many developing countries, shifting of governmentfunds from agricultural commodity subsidies topayments for ecosystem services (including carbonemission offsets) in ecoagriculture landscapes couldprovide initial funding to build institutions and farmercapacity for ecoagriculture. Ecoagriculture offers cost-effective approaches for national investment strategiesto achieve the Millennium Development Goals.

Biodiversity and agricultural sustainability S. J. Scherr & J. A. McNeely 491

Strategic changes in the food industry, institutionalprocurement, eco-certification of agricultural productsand financial investors’ oversight of agriculturalinvestments can be mobilized to shift financialincentives towards ecoagriculture. At the internationalpolicy level, opportunities exist to integrate ecoagri-culture strategies into the work programmes of theinternational environmental conventions, and toensure that rules of the World Trade Organizationsupport ecoagriculture landscapes.

6. CONCLUSIONThe transformation of agricultural production fromone of the greatest threats to global biodiversity andecosystem services to a major contributor toecosystem integrity is unquestionably a key challengeof the twenty-first century. Many elements ofecoagriculture landscapes could also help to achievethe critical goals of agricultural sustainability, resi-lience of food systems and adaptation to climatechange. To realize these potentials, the agriculturaland conservation research and policy communitieswill need to re-evaluate and coordinate theirpriorities and strategies.

The authors would like to thank Louise Buck, TonyCavalieri, Ken Chomitz, Tom Gavin, Jeffrey Milder, SethShames and two anonymous reviewers for their insightfuland valuable comments on an earlier version of this paper.They also thank Seth Shames and Shruti Vaidyanathan ofEcoagriculture Partners for their assistance in manuscriptpreparation.

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healthy, productive soils checklist for growers

www.nrcs.usda.gov

Managing for soil health is one of the best ways farmers can increase crop productivity while improving the environment.

Results are often realized immediately and last well into the future. Following

are four basic principles to improving the health of your soil.

1. Minimize disturbance

2. Maximize soil cover

3. Maximize biodiversity

4. Maximize presence of living roots

Use the checklist on the back of this page to determine if you’re using core Soil

Health Management System farming practices. It is important to note that not all

practices are applicable to all crops. Some operations will benefit from just one soil health practice while others may require additional practices for maximum benefit.These core practices form the basis of a Soil Health Management System that can

help you optimize your inputs, protect against drought, and increase production.

United States Department of Agriculture USDA is an equal opportunity provider, employer, and lender.

March 2017

Soil Health Management Systems Include:What is it? What does it do? How does it help?

Conservation Crop RotationGrowing a diverse number of

crops in a planned sequence

to increase soil organic matter

and biodiversity in the soil.

• Increasesnutrientcycling• Managesplantpests(weeds,

insects,anddiseases)• Reducessheet,rill

andwinderosion• Holdssoilmoisture• Addsdiversitysosoil

microbescanthrive

• Improvesnutrientuseefficiency• Decreasesuseofpesticides• Improveswaterquality• Conserveswater• Improvesplantproduction

Cover CropAn un-harvested crop grown as

part of planned rotation to provide

conservation benefits to the soil.

• Increasessoilorganicmatter• Preventssoilerosion• Conservessoilmoisture• Increasesnutrientcycling• Providesnitrogenforplantuse• Suppressesweeds• Reducescompaction

• Improvescropproduction• Improveswaterquality• Conserveswater• Improvesnutrientuseefficiency• Decreasesuseofpesticides• Improveswaterefficiencytocrops

No TillA way of growing crops without

disturbing the soil through tillage.

• Improveswaterholdingcapacityofsoil

• Increasesorganicmatter• Reducessoilerosion• Reducesenergyuse• Decreasescompaction

• Improveswaterefficiency• Conserveswater• Improvescropproduction• Improveswaterquality• Savesrenewableresources• Improvesairquality• Increasesproductivity

Mulch TillageUsing tillage methods where

the soil surface is disturbed

but maintains a high level of

crop residue on the surface.

• Reducessoilerosionfromwindandrain

• Increasessoilmoistureforplants• Reducesenergyuse• Increasessoilorganicmatter

• Improveswaterquality• Conserveswater• Savesrenewableresources• Improvesairquality• Improvescropproduction

MulchingApplying plant residues or other

suitable materials to the soil

surface to compensate for loss of

residue due to excessive tillage.

• Reduceserosionfromwindandrain

• Moderatessoiltemperatures• Increasessoilorganicmatter• Controlsweeds• Conservessoilmoisture• Reducesdust

• Improveswaterquality• Improvesplantproductivity• Increasescropproduction• Reducespesticideusage• Conserveswater• Improvesairquality

Nutrient ManagementManaging soil nutrients to meet crop

needs while minimizing the impact

on the environment and the soil.

• Increasesplantnutrientuptake• Improvesthephysical,

chemicalandbiologicalpropertiesofthesoil

• Budgets,supplies,andconservesnutrientsforplantproduction

• Reducesodorsandnitrogenemissions

• Improveswaterquality• Improvesplantproduction• Improvesairquality

Pest ManagementManaging pests by following an

ecological approach that promotes

the growth of healthy plants with

strong defenses, while increasing

stress on pests and enhancing the

habitat for beneficial organisms.

• Reducespesticideriskstowaterquality

• Reducesthreatofchemicalsenteringtheair

• Decreasespesticiderisktopollinatorsandotherbeneficialorganisms

• Increasessoilorganicmatter

• Improveswaterquality• Improvesairquality• Increasesplantpollination• Increasesplantproductivity

United States Department of Agriculture

Smithsonian.com

Soil Has a Microbiome, TooThe unique mix of microbes in soil has a profound effect on which plants thrive and which ones die

The microbes living in soil may be crucial for healthy plants. What’s more, soil microbiomes are hyperlocal, varying immensely from place to nearbyplace. (blueenayim/iStock)

By Carrie Arnoldsmithsonian.com August 11, 2016

The Netherlands, home to windmills and clogs, legalized prostitution and marijuana, is also home to intensively farmed cropland. Holland’s small size and largepopulation have meant that the country his historically needed savvy agriculturalists to feed its people. But as it grows less and less of its own food, the governmenthas to buy out farmers to return cropland to a wilder state.

When this program started several decades ago, according to Martijn Bezemer, a biologist at the Netherlands Institute of Ecology, conservationists would simply stopplanting and let the land be, or they would strip off the top layer of soil and leave the sandy subsoil exposed to the elements. Neither approach met with muchsuccess. It seemed that no matter how long they waited for a healthy grassland to take hold, the soil, degraded after decades of high-intensity farming, wasn’trecovering.

The government recruited Bezemer to try and speed up the restoration process. His group began experimenting with the process of inoculating degraded soils withdirt from healthy ecosystems. Just as physicians could treat many intestinal problems by transplanting gut microbes from a healthy person into a sick one, Bezemer’sgroup wanted to use healthy microbes to treat a sick ecosystem.

Their initial work in greenhouses and on small plots impressed Machiel Bosch, a nature manager for the government who was helping to oversee the restorationprocess in the Netherlands. Several years ago, when Bosch received a new parcel of land, he invited Bezemer to try his soil microbial transplants on a larger scale.

The results were recently published last month in the journal Nature Plants, revealing that small soil inoculations from grassland or heathland could help determinewhich plants would colonize the area and thrive in the future. “You don’t get the right plants if you don’t have the right soil,” says Bezemer.

Scoop up a handful of soil. The dirt you hold in your palms forms the basis of the life around you, from the earthworms crawling in your garden to the raptorshundreds of feet in the air. But soil is not just a lifeless pile of earth. Symbiotic fungi living in plant roots—known as mycorrhiza—help the plants extract vitalnutrients. Other microbes break down decaying plants and animals, replenishing the materials used by the plants.

Historically, scientists believed that soil microbes were broadly similar around the world, from Asia to South America More recent work has revealed, however, thatmicrobial populations are actually hyper-local, explains Vanessa Bailey, a microbiologist at Pacific Northwest National Labs. The soil she studies at the foot ofRattlesnake Mountain in Washington State is actually quite different from the soil at the top, with an elevation change of just 3500 feet.

What this means for scientists is two-fold. For one, it means that microbial diversity in soil alone is probably far more immense than anyone had anticipated. “Wehave the tools now to describe microbes in much greater detail than even five or ten years ago,” said Noah Fierer, a microbiologist at the University of Colorado atBoulder. “Yet 80 percent of the soil microbes in Central Park are still undescribed. There’s a lot of diversity to reckon with.”

The second implication is that two different ecosystems, even those in close proximity, could have very different microbes living in their soil. A plant might survivedrought not because of something inherent to its physiology, but because of the assortment of symbiotic microbes in the dirt, Fierer said. Plant the seeds elsewhere,and they may not be able to germinate, grow and thrive without the proper mixture of bacteria and fungi. As researchers began learning more about the depth andcomplexity of these interactions, Bezemer realized that could explain why his native country’s attempts at returning farmland to native ecosystems was failing.

The process could work, Bezemer believed, if the right soil was present. At first, he tried moving the soil wholesale. It wasn’t a problem for small projects in pots andgreenhouses, but scaling any projects up would be difficult, as soil is heavy and hard to move. Still, these early trials gave Bezemer enough data to show that seedsdid better when they were planted in soil taken from other ecosystems where those species thrived.

Not only did the plants grow better, but the transplanted soil also prevented weeds and other non-desired plants from dominating the new system before the nativespecies had a chance to take hold.

For Bezemer, the problem with this approach was the amount of soil needed. To adequately convert farmland to grass or heathland across the Netherlands,conservationists would effectively have to strip all of the soil from healthy ecosystems. But if microbes were the important factor, then maybe he didn’t need massivequantities of dirt.

Since no one knew exactly what microbes were important and in what quantities, Bezemer couldn’t simply sprinkle bacteria on the desired area. But, he theorized,perhaps small amounts of soil contained enough microbes to get the system started and set it on the desired path.

In some of the plots, the researchers removed the old layer of topsoil and exposed the sandy subsoil. In others, however, they left the existing topsoil intact. They thencovered it with a centimeter or two of soil from either grassland or heathland, sowed a variety of seed, and waited.

The experiment took six years, but the data clearly showed that the donor soil steered the former agricultural land towards an ecosystem that looked like the originalsource. Grassland soil created grassland, heathland became heathland. Stripping the topsoil allowed for stronger donor soil effects, and the ecosystems also recoveredfaster.

Bailey, who published her own study earlier this year on how climate change might affect soil microbes, says that these results show not only the effects of donor soilon ecosystem restoration, but also how competition between soil microbes can affect how plants grow. The likely reason that the inoculations had less of an effectwhen the topsoil wasn’t removed was competition between the existing microbes and the ones in the transplanted soil.

“Microbes behave in surprising ways, and we need a better understanding of how they colonize soil and of all of the different ecological processes that thesemicrobes carry out. We really have no idea,” Bailey said. Scientists still don’t know how and why these soil transplants work, just as they really don’t know muchabout why fecal transplants are so successful in humans. This paper shows, however, that the soil transplants do in fact work, Bailey says.

Fierer praised the study, saying it “highlights the links between soil and ecosystem health, showing the power that changing soil can have,” but also raised a note ofcaution. The researchers may have used a much smaller amount of soil than previous experiments, but it would still take massive amounts of dirt to restore evensmall areas. Nor can anyone be sure what in the soil is driving the ecological changes. Bezemer and other soil experts agree that it’s almost certainly the microbes,but given the complexity of soil, nothing can yet be ruled in or out.

Soil remains an ecological black box for scientists. Even now, researchers are just beginning to understand how microbes that we can’t even see could potentiallyshape the world around us.

About Carrie Arnold

Carrie Arnold is a freelance science writer from Virginia. She covers all aspects of the living world and has written for a variety of publications including Mosaic,Aeon, Scientific American, Discover, National Geographic, and Women’s Health. When she’s not writing, you can find her drinking coffee, knitting, cycling andannoying her cat.

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9/4/2018 North Carolina Farm Family Awarded for Conservation Practices

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North Carolina Farm Family Awarded forConservation PracticesA North Carolina farm family is looking out for their land by continuing conservationpractices

STATE HOME AG EDUCATION AG PRODUCTS AGRIBUSINESS AGRITOURISM FAMILY FARMSLOCAL MAGAZINE

By Joanie Stiers - December 2, 2017

John Gross checks out the tobacco at his farm. Photo by Jeffrey S. Otto/Farm Flavor Media

Farmer John Gross remembers some poor conservation practices 30 years ago

that left gullies in neighboring farmers’ fields, sometimes deep enough to meet

his eyeballs.

a d f h k s v

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John saw then the consequences that continue to motivate his conservation

practices now. More than ever before, the Gross family taps opportunities to

conserve soil, water and nutrient resources on their farm, from time-tested grass

waterways to precision placement of fertilizers using global- positioning

satellites.

“We’ve always had the mentality that if we don’t look after the land, it’s not going to look after us,” says John,

who owns and operates Gross Farms with his wife Tina and their family. “We’ve been putting in terraces,

waterways and diversions, and all types of conservation practices since I started farming with my dad back in

the mid-1980s.”

In recognition of the family’s efforts, Gross Farms won the distinction of North Carolina Outstanding

Conservation Farm Family of the Year in 2016 for their extensive and lengthy history of conservation practices.

The family grows 1,700 acres of conventional and organic tobacco, soybeans and small grains in central North

Carolina. They also manage 150 acres of forestry and grow 25 acres of produce, including pumpkins and

strawberries. Their produce and annual corn maze draw hundreds for memorable on-farm experiences that

provide opportunities to learn about modern agriculture, including their farm’s conservation approach.

“We’re big on agriculture education here,” Tina says. “You have opportunities to educate and that’s when you

realize that the general public really does not understand how agriculture impacts their life every day.”

9/4/2018 North Carolina Farm Family Awarded for Conservation Practices

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John and Tina Gross and their children Cody, Colton, Kassidy and Makayla run Gross Family Farms in

Sanford, N.C. Photo by Jeffrey S. Otto/Farm Flavor Media

Leaders in Land Stewardship

In recent years, Gross Farms has installed various conservation land structures, including more than 6 acres of

grassed waterways, 11,200 feet of terraces and 1,800 feet of diversions in Lee and Harnett counties. The family

uses an alphabet soup of government cost- share or technical assistance programs, such as the North Carolina

Agriculture Cost Share Program, Environmental Quality Incentives Program and Conservation Stewardship

Programs, to help put these practices in place to protect soil and water resources while improving productivity

of their farm.

9/4/2018 North Carolina Farm Family Awarded for Conservation Practices

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In addition, the family practices conservation tillage, including high-tech strip-till. This method leaves most of

the previous crop residue undisturbed to protect the soil and uses satellite technology to till, fertilize, and plant

into the same strip of soil.

“We try to make the public aware of what’s going on with conservation practices and strip tillage and things like

that,” John says. “When you tell them about it, they’re really surprised there is that much involved or that much

goes into it.”

Farm visitors can see the grassy waterways and terraces that protect soil, the cover crops that hold soil

nutrients, and even the food plots that benefit wildlife. But what they don’t see is the grid-soil sampling, or the

soil tests taken with GPS across a field. With that information, John makes site- specific nutrient decisions to

apply fertilizers at the right rate in the right place. The public also doesn’t see the automatic shut-offs on the

sprayer, which use satellite guidance to turn off sections of the sprayer to prevent overlap and reduce pesticide

use.

More research and improved technologies will continue to present his farm with conservation options. All the

while, John and Tina instill in their kids the same desire to protect the land and the drive to do it.

“My sons didn’t see the erosion that I saw, but they understand how it works,” John says. “We just strive to

leave the land in better shape than we found it.”

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9/4/2018 What Is Sustainable Agriculture? | Union of Concerned Scientists

https://www.ucsusa.org/food-agriculture/advance-sustainable-agriculture/what-is-sustainable-agriculture#.W46O0c5KgdW 1/8

en español

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9/4/2018 What Is Sustainable Agriculture? | Union of Concerned Scientists

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What Is Sustainable Agriculture?Contents

Sustainable agriculture 101Sustainable agriculture practicesSustainable agriculture scienceSustainable agriculture and farm policy

There’s a transformation taking place on farmsacross the United States.

For decades, we’ve produced the bulk of our foodthrough industrial agriculture—a system dominatedby large farms growing the same crops year afteryear, using enormous amounts of chemicalpesticides and fertilizers that damage soils, water,air, and climate. This system is not built to last,because it squanders and degrades the resourcesthat it depends on.

But a growing number of innovative farmers andscientists are taking a different path, moving towarda farming system that is more sustainable—environmentally, economically, and socially. Thissystem has room for farms of all sizes, producing adiverse range of foods, fibers, and fuels adapted tolocal conditions and regional markets. It uses state-of-the-art, science-based practices that maximizeproductivity and profit while minimizing environmentaldamage.

Some proponents of industrial agriculture claim that its impacts are the price we must pay to “feed theworld.” In fact, a growing body of scientific evidence has debunked this claim, showing that a moresustainable model can be just as profitable—and can meet our needs for the long haul.

Sustainable agriculture 101

OK, so sustainable agriculture is the wave of the future. But what is it, exactly?

In agriculture, sustainability is a complex idea with many facets, including the economic (a sustainablefarm should be a profitable business that contributes to a robust economy), the social (it should deal fairlywith its workers and have a mutually beneficial relationship with the surrounding community), and theenvironmental.

Environmental sustainability in agriculture means good stewardship of the natural systems and resourcesthat farms rely on. Among other things, this involves:

Building and maintaining healthy soilManaging water wiselyMinimizing air, water, and climate pollutionPromoting biodiversity

9/4/2018 What Is Sustainable Agriculture? | Union of Concerned Scientists

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There’s a whole field of research devoted to achieving these goals: agroecology, the science ofmanaging farms as ecosystems. By working with nature rather than against it, farms managed usingagroecological principles can avoid damaging impacts without sacrificing productivity or profitability.

Does Sustainable = Organic?

While most Americans may not have heard of hairy vetch, prairie strips, or other core features ofsustainable farms, anyone who has been to a supermarket lately knows about organic food. The organicfarming movement, which dates back to the early 20th century, incorporates a system of sustainabilitypractices that have been codified into specific certification standards by the US Department of Agriculture.Farms that comply with the standards can label their produce as “USDA Organic”—a feature that moreand more food shoppers are looking for.

“Organic” and “sustainable” aren’t quite synonyms: current organic standards leave room for somepractices that are not optimal from a sustainability point of view, and not all farmers who use sustainablepractices qualify for USDA certification or choose to pursue it.

Still, the certified organic fruits and vegetables at your supermarket are highly likely to have beenproduced more sustainably than their conventionally grown neighbors. So if your rule of thumb is “look forthe organic label”, you’re unlikely to go wrong.

Sustainable agriculture practices

Over decades of science and practice, several key sustainable farming practices have emerged—forexample:

Rotating crops and embracing diversity. Planting a variety of cropscan have many benefits, including healthier soil and improved pestcontrol. Crop diversity practices include intercropping (growing a mix ofcrops in the same area) and complex multi-year crop rotations.

Planting cover crops. Cover crops, like clover or hairy vetch, areplanted during off-season times when soils might otherwise be left bare.These crops protect and build soil health by preventing erosion,replenishing soil nutrients, and keeping weeds in check, reducing theneed for herbicides.

9/4/2018 What Is Sustainable Agriculture? | Union of Concerned Scientists

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Reducing or eliminating tillage. Traditional plowing (tillage) preparesfields for planting and prevents weed problems, but can cause a lot ofsoil loss. No-till or reduced till methods, which involve inserting seedsdirectly into undisturbed soil, can reduce erosion and improve soil health.

Applying integrated pest management (IPM). A range of methods,including mechanical and biological controls, can be appliedsystematically to keep pest populations under control while minimizinguse of chemical pesticides.

Integrating livestock and crops. Industrial agriculture tends to keepplant and animal production separate, with animals living far from theareas where their feed is produced, and crops growing far away fromabundant manure fertilizers. A growing body of evidence shows that asmart integration of crop and animal production can be a recipe for moreefficient, profitable farms.

Adopting agroforestry practices. By mixing trees or shrubs into theiroperations, farmers can provide shade and shelter to protect plants,animals, and water resources, while also potentially offering additionalincome.

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Managing whole systems and landscapes. Sustainable farms treatuncultivated or less intensively cultivated areas, such as riparian buffersor prairie strips, as integral to the farm—valued for their role incontrolling erosion, reducing nutrient runoff, and supporting pollinatorsand other biodiversity.

A key theme connecting many of these practices is diversification. “Keep it simple” is good advice in manysituations, but when it comes to agriculture, the most sustainable and productive systems are morediverse and complex—like nature itself.

Sustainable agriculture science

The latest science—much of it coming out of research centers in the nation’s bellwether farm states—shows how agroecological practices can support productive, profitable farms. For instance, an ongoingstudy at Iowa State University’s Marsden Farm research center has shown that complex crop rotationsystems can outperform conventional monoculture in both yield and profitability.

Crop breeding research is also crucial to the success of a more sustainable agroecological system,providing farmers with access to a broad range of crop varieties that can be readily adapted to farm-specific conditions and practices. Breeding research programs have dwindled in recent years, leavingfarmers increasingly reliant on a limited set of varieties tailored to the needs of industrial farms.

9/4/2018 What Is Sustainable Agriculture? | Union of Concerned Scientists

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To help farmers adopt sustainable practices, it’s vitally important that we continue to support agroecologyresearch, along with outreach and education to help farmers make effective use of the science. Towardthis end, UCS has coordinated a statement, signed by over 450 scientists and other experts, calling forincreased public investment in agroecological research.

Sustainable agriculture and farm policy

While US farm policy continues to put the lion’s share of public resources behind subsidizingoverproduction of corn and other commodity crops, there have been some encouraging signs. The mostrecent versions of the Farm Bill have included provisions to support more organic farming, to make iteasier for fruit and vegetable farmers to qualify for crop insurance, and to help farmers adopt moresustainable practices on their own working lands.

But if we want to see sustainable farming become the dominant model in the US, we need to go muchfurther. UCS has published a series of reports and issue briefs that offer recommendations for promotingsustainable agriculture through farm policy, as part of our overall goal of transforming our food system toprovide healthy, affordable, fairly and sustainably produced food for all Americans. We encourage you totake a look–and then contact your representatives to ask them to support sustainable agriculture.

Turning Soils into Sponges: How Farmers Can Fight Floods and Droughts (2017)

Floods and droughts in farm country do billions of dollars in damage every year.Farmers can reduce that damage by building healthier soils. Learn more >

Photo: NCinDC/CC BY-ND 2.0, Flickr

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Smithsonian.com

A Diversity of Bees Is Good for Farming—AndFarmers’ WalletsA new study shows that if more species of bees are available topollinate blueberry flowers, blueberries get fatter

Bee biodiversity farmingBees from a single species aren’t as effective in pollinating as bees from a diversity of species, anew study shows. (© Romulic-Stojcic/Lumi Images/Corbis)

By Natasha Geilingsmithsonian.com May 9, 2014

The world has a serious bee problem, and not the kind that involves the tiny insect’s unwelcome buzzing at anoutdoor picnic: Honeybees are dying with frightening rapidity (American farmers lost 31 percent of theirhoneybee colonies in the 2012/2013 winter), and no one knows why. That’s a huge issue for anyone who likesfood, because honeybees are the world’s most important commercial pollinator—the Food and AgricultureOrganization of the United Nations estimates that of 100 crops that produce 90 percent of the world’s food, 71 ofthose are bee-pollinated. Lose honeybees, and our supermarkets’ produce aisles could look almost barren.

Honeybees are the most prevalent pollinator used in commercial agriculture for a simple reason: They’re easilymanaged and manipulated by humans. Honeybees are a social insect, meaning that they form and live in large,well-organized groups. Farmers can take advantage of this by coaxing and keeping large honeybee populationson hand; honeybees can also be carted throughout a farm and released in large numbers at the farmer’s will. Forthese reasons, honeybees account for 80 percent of insect pollination in agricultural crops.

But honeybees aren’t the only bees in the pollination game—nor are they, necessarily, the most effective. Thereare more than 20,000 species of bees, and 4,000 of those are native to North America (the honeybee is not one ofthem). These native pollinators are—in some conditions—actually better pollinators than honeybees, but they’reharder to control. “There has been a lot of research done in the past year looking at wild bees and theircontribution to pollination—in a lot of systems wild bees enhance pollination that ways that managed bees likehoneybees don’t,” explains Hannah Burrack, Associate Professor at North Carolina State University (NCSU).

Earlier this year, a group of bee researchers published a study in Science linking biodiversity of bees toimproved crop yields—biodiversity being a sort of insurance policy for our food system. But because wild beesaren’t as easily managed as honeybees, farmers might be hesitant to instate practices that would draw nativepollinators to their fields.

Now, new research from Burrack and her colleagues at NCSU suggests that increasing the diversity of theirpollinators might do more than benefit a farmer’s crop—it could benefit their bottom-line enough to offset theinitial investment in increasing biodiversity, making the effort worth it. The research was published today in theopen-access journal PLOS ONE.

“The interest in my lab for this project grew out of those grower interactions,” Burrack notes. “They wanted toknow who their pollinators were and how they were interacting and benefiting, potentially, their crops.”

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Alongside David Tarpy, a honeybee biologist at NSCU, Burrack and others measured the effect of beebiodiversity on an important North Carolina crop: blueberries. They selected a number of commercial blueberryfarms, which they visited once a week during bloom season for a two-year period. Before the bloom seasonstarted, the scientists placed cages over a select number of branches—a control group—to keep pollinatorstemporarily away. During the bloom season (a four to five week period) the scientists would walk through therows for a set period of time, counting and identifying the species of bees that were present—they found fivedistinct groups: honey bees, bumble bees, southeastern blueberry bees, carpenter bees and small native bees.

Then they would regularly expose the caged branches to pollinators in one of three ways: they would uncage thebranch and allow any present pollinators to visit for a set period of time (open pollination), they would exposethe branch to only one species of bee to test that bee’s efficiency on a per-visit basis (single visit pollination) orthey would simply keep the branch covered, testing how much pollination could come from the specific shrub’sflowers pollinating themselves (closed pollination).

A honey bee pollinates a blueberry blossom in Arkansas.A honey bee pollinates a blueberry blossom in Arkansas. (© Bill Barksdale/AgStockImages/Corbis)

Fifty days after the bloom period, the scientists returned to the farms and collected the blueberries that resultedfrom the open-pollinated, single-visit or closed-pollination experiments. Because the group was looking at theaffect of increased biodiversity on crop yields, they specifically looked at results from open-pollination duringtimes when they had counted an abundance of bee species in the particular farm.

“If we had a greater number of wild bees present, a greater number of those functional groups, we saw anincrease of about 3.66 seeds per berry,” Burrack explains. “And the cool thing about blueberries is that thenumber of seeds directly relates to berry size, so we could relate that to something that is economicallymeaningful to the growers.” In other words, more pollination via different types of bees leads to more seedsbeing produced by the berries, which eventually results in fatter, heavier berries.

Using the price the farmers’ set per pound for their blueberries, the authors found that if two different species ofbee pollinated the blueberries, a farm would see a $311 crop yield per acre; for three bee species, it wouldbe $622; for four, $933, and so on. Since the scientists only observed five distinct species, they can’t speculateon the effect of biodiversity beyond five—but they assume that eventually the relationship would flatline (andadded species would no longer mean bigger berries), but they didn’t reach that threshold naturally in thestudy. All told, Burrack and her colleagues calculated that for every additional species, the North Carolinablueberry industry could expect an additional $1.4 million in yield increase.

“We could put an economic value on the potential value associated with these native bees, which is reallyhelpful because the next step we want to look at is how you can enhance diversity,” Burrack says. “For acommercial grower, one of the important considerations for them is going to be whether or not the practices theycan do to enhance diversity are offset by an increase in value to the crop.”

So why does a diverse group of bees create better crops? A couple factors are at play here. First, “A flower isreceptive to fertilization for 1-2 days (unlike human eggs), so it doesn’t shut down new seed formation once onebee visits. That means multiple bees contribute to the pollination of a single fruit,” Burrack notes.

But why don’t multiple bees of the same species (for example, the fruit from the branches screened for single-visit pollination) help to form berries as fat as those produced through open pollination? The authors speculatethat different species thrive under different weather conditions—honeybees, for example, perform best duringcalm, warm, sunny days, whereas a southeastern blueberry bee can work in inclement weather. In NorthCarolina, where weather during bloom season is incredibly variable, it helps to have a diversity of bees so thatone can always be pollinating, rain or shine. The scientists also speculate that weather might not be the onlything that impacts the bees—moving forward, they want to test whether agricultural managing practices mightalso have different effects on different bee species.

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As climate change impacts weather patterns and makes extreme weather more likely, a diversity of bees that canwork in variant weather under various farming systems could be a huge boost to farmers. Adding more nativeand wild bees to agriculture might have a strong financial benefit, but it’s not an easy transition to make. Forone, native wild bee populations are also dropping—an analysis by the Xerces Society, a non-profit focused onpreserving invertebrate wildlife, suggests that 30 percent of America’s native bumblebees are threatened byextinction. Native wild bees are also harder to manage, and practices that might foster their survival—such asthe planting of a non-crop foraging habitat—take away valuable land and time.

But, as the NCSU study suggests, farmers might have an economic reason to invest in biodiversity. Moreover, amore diverse group of pollinators is a more resilient group against disturbances human and natural, so increasingthe biodiversity of pollinators can not only benefit farmers in the short-term through increasing crop yields, butalso in the long-term by protecting against agricultural disturbances caused by weather, land-use or disease.

“Different bees do different things,” Burrack explains. “A diverse bee community is, in perhaps multiple ways,more stable than a community that’s dominated by any one species.”

About Natasha Geiling

Natasha Geiling

Natasha Geiling is an online reporter for Smithsonian magazine.

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CCoovveerr CCrrooppss ffoorr OOrrggaanniicc FFaarrmmss by Keith R. Baldwin and Nancy G. Creamer

Contents How Cover Crops Affect the Soil—Page 2 Establishing Cover Crops—Page 11 Managing Cover Crop Residue—Page 11

The Economics of Planting Cover Crops—Page 12 Cover Crops for the Southeast—Page 12 Recommended Reading—Page 17

over crops are pivotal parts of every organic farmer’s management scheme. They are crucial to the main goals of building soil health and

preventing soil erosion. Cover crops are also important tools for increasing fertility and controlling weeds, pathogens, and insects in organic crops.

In this publication, we will discuss planting, growing, and incorporating cover crops as amendments into the soil. Our discussion will include the following topics:

• How cover crops affect the soil, including how they impart nitrogen for cash crops and how they can be used to control crop pests and diseases. We will also point out some concerns of grow-ing cover crops, such as the potential for them to rob soil of moisture needed for cash crops and to harbor damaging insects and pathogens.

Figure 1. Millet is planted in fields where cover crops are incorporated into the soil. (Photo courtesy of USDA) • Establishing cover crops involves

using a drill and cultipacking the field. • Managing cover crop residue. The

residue can be incorporated or left on the surface after using a kill method.

• The economics of planting cover crops. Each farmer must consider the cost of establishing the cover crop and its benefits.

CC

• Cover crops for the Southeast. We review recommended winter and summer cover crops and how they fit specific cropping schemes.

• Recommended resources for further study.

HOW COVER CROPS AFFECT THE SOIL

Soil Erosion

The best place to begin our discussion of cover crops is to focus on how they help to reduce one of the most serious, persistent threats to long-term farm productivity and the environment—soil erosion. Cover crops do this partially by keeping the soil covered during rainy periods when it might normally be bare and subject to erosion by rainfall. Langdale et al. (1991) concluded that cover crops reduced soil erosion by 62 percent based on a comparison of bare soil and soil planted with a cover crop in the southeastern United States.

Erosion decreases topsoil, and it also causes sedimentation of our rivers, reservoirs, and estuaries. Sedimentation occurs when runoff from rainfall carries eroded soil and deposits it into waterways. In time, sediment deposits produce losses of aquatic habitat that are extremely difficult to reverse. The short-term costs of soil erosion include nutrient losses in runoff from farm fields and negative impacts to the soil’s physical structure.

Soil scientists have estimated that the United States has lost 30 percent of its topsoil in the past 200 years due to agricultural practices that leave bare, fallow soils for a significant portion of the year.

(Tyler et al., 1994)

How well do cover crops help to prevent soil erosion? During the fall, winter, and early spring, this depends largely on when the cover crop is established. Timing is particularly important in the fall because late planting of legume crops, such as hairy vetch, can result in poor stands and small plants with limited root systems. If the cover crop is established early, however, its vigorous fall growth protects soil and reduces erosion. Because of its rapid growth in fall and its continued growth during winter, cereal rye (Secale cereale) provides excellent protection from erosion during the winter. The use of cover crops in no-till systems provides extended erosion control because residue is left on the surface after the cover crop is killed and the subsequent cash crop is planted.

How Cover Crops Improve the Soil Increase soil organic matter through

additions of plant biomass. Form soil aggregates, which stabilize soil

and reduce runoff and erosion. Increase soil porosity and decrease soil

bulk density to promote root growth. Improve soil tilth, which reduces crusting

and increases the rate of water infiltration. Encourage populations of soil microbes,

micro- and macro-arthropods and earthworms, all of which contribute to efficient nutrient cycling and improvements in soil structure.

Soil Moisture

One of the most important considerations in growing cover crops is their impact on soil moisture. During the summer months, cover crops left on the surface can help to conserve soil moisture by reducing evaporation from the surface and by increasing water infiltration. However,

Organic Production—Cover Crops for Organic Farms 2

grown too late in the spring, cover crops can draw moisture down from the soil’s upper layer, where it will be needed for seed germination and stand establishment of subsequent cash crops.

Thus, knowing when to kill and incor-porate cover crops in the spring is a balancing act. The goal is to produce the greatest possible amount of biomass, or living matter, with the cover crop, which maximizes fertilizer values, while not depleting soil moisture. Timing is every-thing.

In early spring, while cover crops are still actively growing, farmers should begin monitoring soil moisture. During years with normal to dry weather patterns, the best time to kill cover crops is usually two weeks before planting cash crops (depending on weather forecasts). Biomass yield and nitrogen (N) production by legume cover crops may not be at their maximum levels at this point. However, in most seasons, sufficient rainfall for ade-quate crop emergence will occur during the two-week preplant period or within the week immediately following planting. In wet years or when a rainy period is forecast, the cover crop can be killed immediately before soil preparation and planting of spring crops.

With these weather windows in mind, a farmer can create a plan to produce the highest possible cover crop biomass and biomass N yields. Studies show that when cover crop kill is delayed from early April to early May, the yields of hairy vetch, cereal rye, and mixtures of both increase by an average of 160 percent in the Maryland piedmont and by 83 percent in the coastal plain (Clark et al., 1994). In Clark’s study, the N contents of hairy vetch and hairy vetch-rye mixtures were 1.6 to 2 times

greater at the late kill date: They ranged from 65 to 100 pounds N per acre for early kill, and from 135 to 200 pounds N per acre for late kill. Based on those considerations and by monitoring soil moisture and ob-taining rainfall predictions, a farmer can decide on the best possible times for killing and incorporating a cover crop.

Weed Management

Cover crops and surface crop residues can be used to control or inhibit weeds in subsequent cash crops in three basic ways:

• By smothering and shading them so they don’t receive adequate air and light.

• By outcompeting them for nutrients. • By producing an effect known as

allelopathy, the toxic effect on weed seed germination and seedling growth that occurs as residues of some cover crops decompose.

The primary way to suppress weed seed germination and growth is to have a vigorous cover crop stand. Such a stand will simply out-compete weed seeds for light and nutrients (Teasdale and Daughtry, 1993). When the cover crop is killed, its thick residues remain on the surface and hinder weed growth by physically modifying the amount of natural light, soil temperature, and soil moisture that is necessary for weed seed germination.

It’s important to note that suppressing weeds by smothering them becomes less effective as cover crop residues decompose. How fast residues decompose depends on several variables. For instance, warm temperatures, rainfall, and field tillage can speed up the decomposition rate. Another important factor is the C:N ratio, the carbon-to-nitrogen ratio of different kinds of crop residues. Residues with a high C:N ratio, such as mature small grain cover

Organic Production—Cover Crops for Organic Farms 3

crops like rye (which has a C:N ratio of around 50), have a much slower decom-position rate than legumes like hairy vetch (which has a C:N ratio of around 12). Mix-tures of legumes and small grains have an intermediate rate of decomposition (a C:N ratio of around 25).

Cover crop residues also interfere with weed emergence through the allelopathic effect (Creamer at al., 1996a). Scientists are still researching the many (and sometimes mysterious) allelopathic effects that one plant has on another through its allelo-chemicals, the chemicals a plant releases into the environment that can be toxic to other plants. Some scientists believe that the specific allelopathic effects of certain plants are enhanced by chemicals produced by actinomycetes, algae, fungi, or other microbes associated with particular plant root systems in the upper soil layers (Putnam, 1988). Where and how these allelochemicals originate is often hard to discern. Each chemical’s biological activity may be reduced or enhanced by other factors, such as microbe action in the soil and oxidation. Other factors, such as

environmental conditions, insects, or disease pressure, can speed up the detrimental effects of allelochemicals on weeds.

In one study, researchers found that cereal rye residues on the soil surface suppressed most common annual broadleaf and grassy weeds for four to eight weeks (Smeda and Weller, 1996). Thus, using a rye cover crop could eliminate the need for a soil-applied herbicide at transplanting without depressing yield. The authors indicated, however, that post-emergence weed control of escaped weeds might be necessary in some years.

Researchers have reported that the cover crops listed in Table 1 have shown allelopathic effects on certain weeds. We should note that the allelopathic effects of crimson clover and hairy vetch are more apparent if the cover crop is incorporated rather than left on the surface in no-till management (Teasdale and Daughtry, 1993).

Table 1. A summary of research on the allelopathic effects of cover crops

Cover Crop Weeds Suppressed Investigator and Publication Date

Hairy vetch Lambsquarters, yellow foxtail, yellow nutsedge, pitted morningglory

Teasdale et al., 1993 White et al., 1989

Crimson clover Pitted morningglory, wild mustard, Italian ryegrass

Teasdale et al., 1993 White et al., 1989

Cereal rye Lambsquarters, redroot pigweed, common ragweed

Barnes and Putnam, 1986 Schilling et al., 1985 Masiunas, 1995

Wheat Morningglory, prickly sida Liebl and Worsham, 1983 Velvetbean Yellow nutsedge, chickweed Hepperly et al., 1992

Fujii et al., 1992 Sorghum sudangrass Annual ryegrass Forney and Foy, 1985

Organic Production—Cover Crops for Organic Farms 4

Disease Management

The impact of cover crops on pathogens—agents in the soil, such as bacteria or viruses, that cause disease—can be good, bad, or nonexistent. This impact varies broadly depending on individual circum-stances and situations. A cover crop can act as a host for soilborne pathogens, or it can serve as an effective form of biological control for other plant pathogens. Incorporating cover crop residues can, in some cases, provide an organic food base that encourages pathogen growth (Phillips et al., 1971). On the other hand, some cover crops, such as brassicas (cabbage and mustard), can actually decrease soil pathogen populations (Lewis and Papa-vizas, 1971; Subbarao and Hubbard, 1996).

The impact of a cover crop on a pathogen involves many variables. Principally, it depends upon the pathogen’s nature and life cycle requirements. For example, if the pathogen survives best on surface residue and the cover crop residue is left on the soil surface as mulch, then the pathogen may survive until the next crop is planted and the level of disease may increase (Fawcett, 1987). Many plant diseases are associated with surface residue, for example, fungal and bacterial leaf blights (Boosalis and Cook, 1973).

At the same time, the increases in soil organic matter provided by cover crops can enhance biological control of soilborne plant pathogens. This comes about both through direct antagonism and by competition for available energy, water, and nutrients (Sumner et al., 1986). Organisms that cause disease can also be affected by changes in temperature, moisture, soil compaction, and bulk density, as well as nutrient dynamics. Whether or not the cover crop is in the

same family of plants (taxonomically related) to the subsequent cash crop can also influence whether or not disease cycles are interrupted or prolonged.

Nematode Management

Nematodes are enough of a concern in the sandy soils of the southeastern U. S. to give them individual attention when consider-ing disease management. The root-knot nematode (Meloidogyne spp.) is particularly troublesome in the Southeast. Agricultural scientists have more questions than answers concerning how to reduce pop-ulations of nematodes with cover crops. They are struggling to find a selection of crop rotations with cover crops that can address a wide variety of nematodes that have a very diverse host range (Reddy et al., 1986). They are also unclear, at this point, as to how some cover crops reduce the population levels of certain nematode species.

Examples of Nematode-Control Success with Warm-Season Legumes Warm season legume cover crops are effective in reducing populations of some plant-parasitic nematodes:

Rhoades and Forbes (1986) reported that hairy indigo and joint vetch cover crops (coupled by mulching with clippings of cowpea) were highly effective for maintaining low populations of B. longicaudatus and M. incognita nematodes.

Rodriguez-Kabana et al. (1992) reported that velvetbean was effective in lowering population densities of several root-knot species (present simultaneously) in greenhouse and field tests. Unfortunately, this is not always the case in field tests.

Organic Production—Cover Crops for Organic Farms 5

For instance, some green manure or cover crops placed in a rotation can reduce damage by one nematode species but not others. In a study in Florida, the warm-season legumes, which included pigeonpea, crotalaria, hairy indigo, velvetbean, and joint vetch, reduced root-knot nematode damage in a subsequent snapbean crop when the crop was compared to one produced in fallow. These same cover crops, however, were no more effective than fallow in reducing damage from sting (Belonolaimus longicaudatus) and lesion (Pratylenchus brachyurus) nematodes.

In some cases, a cover crop can reduce populations of one parasitic nematode but serve as a host that increases populations of other nematodes. While two researchers (McSorley and Gallaher) reported in 1991 that sorghum-sudangrass cover crops reduced levels of root- knot nematodes, Rhoades and Forbes (1986) found that a sorghum-sudangrass cover crop increased populations of B. longicaudatus and M. incognita nematodes. Farmers attempting to use crop rotations for controlling one nematode species must be aware that these rotations could benefit other damaging nematodes present in the field (McSorley and Dickson, 1995). Potential rotation crops should be evaluated for their effects on as many different damaging nematodes as possible.

Cover Crop Tip

Organic growers commonly plant rapeseed, mustard, and other brassicas as rotation crops to “clean-up” soil during winter months. These plants have been shown to suppress a wide range of parasitic nematodes.

(Bending and Lincoln, 1999)

Insect Management

Cover crops can be both a blessing and a drawback because they attract both beneficial and harmful insects to farm fields (Altieri and Letourneau, 1982; Andow, 1988). When a cover crop matures or dies, both the beneficial and pest insects may move to cash crops. The resulting effect on insect pest populations on the farm (an effect that also depends on several environmental factors) can present frustrating dilemmas for a farmer. For example, in a study in 1991, researchers found that a rye cover crop helped to reduce fruitworm populations in the tomato crop that followed it. But the rye cover also led to increased stinkbug damage (Roberts and Cartwright, 1991).

To create the best situation, a farmer grows a cover crop to attract beneficial insects before the damaging insects arrive. The beneficial insects are attracted by the moisture, shelter, pollen, honeydew, nectar, and potential insect prey associated with the cover crop. These beneficial insects subsist in the cover crop and then move into the vegetable crop to attack arriving pest insects. Several studies show that this approach is often successful. Researchers in Georgia reported high densities of big-eyed bugs, lady beetles, and other beneficial insects in vetches and clovers that moved into ensuing tomato crops (Bugg et al., 1990). In a more recent study, a researcher reported that assassin bugs destroyed Colorado potato beetles feeding on eggplant that had been planted into strip-tilled crimson clover (Phatak, 1998).

Organic Production—Cover Crops for Organic Farms 6

Nitrogen Fixation

One of the most significant contributions that legume cover crops make to the soil is the nitrogen (N) they contain. Legume cover crops fix atmospheric N in their plant tissues in a symbiotic or mutually beneficial relationship with rhizobium bacteria. In association with legume roots, the bacteria convert atmospheric N into a form that plants can use. As cover crop biomass decomposes, these nutrients are released for use by cash crops. Farmers should make an effort to understand this complex process because it will help them to select the proper legumes for their cropping plan, calculate when to incorporate cover crops and plant cash crops that follow, and plan fertilizer rates and schedules for those cash crops. Above all, they need to inoculate legume seed before planting with the appropriate Rhizobium species.

Cover Crop Tip

Nonleguminous cover crops, typically grasses or small grains, do not fix nitrogen. Nonethe-less, they can be effective in recovering min-eralized nitrogen from soil after crops are harvested.

The N associated with cover crop biomass undergoes many processes before it is ready to be taken up for use by cash crops. The process begins with biomass N, which is the nitrogen contained in mature cover crops. From 75 to 90 percent of the nitrogen content in legume cover crops is contained in the aboveground portions of the plant, with the remaining N in its roots and nodules (Shipley et al., 1992).

When legume or grass cover crops are killed and incorporated into the soil, living microorganisms in the soil go to work to

decompose plant residues. The biomass nitrogen is mineralized and converted first to ammonium (NH4) and then to nitrate compounds (NO3) that plant roots can take up and use. The rate of this mineralization process depends largely on the chemical composition of the plant residues that are involved (Clement et al., 1995), and on climatic conditions.

Determining the ratio of carbon to nitrogen (C:N) in the cover crop biomass is the most common way to estimate how quickly biomass N will be mineralized and released for use by cash crops. As a general rule, cover crop residues with C:N ratios lower than 25:1 will release N quickly. In the southeastern U. S., legume cover crops, such as hairy vetch and crimson clover, killed immediately before corn planting generally have C:N ratios of 10:1 to 20:1 (Ranells and Wagger, 1997). Residues with C:N ratios greater than 25:1, such as cereal rye and wheat, decompose more slowly and their N is more slowly released.

A study conducted in 1989 reported that 75 to 80 percent of the biomass N produced by hairy vetch and crimson clover residues was released eight weeks after the cover crops were incorporated into the soil (Wagger, 1989a). This amounted to 71 to 85 pounds of N per acre. However, not all of the released N was taken up by the subsequent corn crop. The corn utilized approximately 50 percent of the N released by both residues. (This value may be con-sidered the N uptake efficiency of corn from legume residues. This value is similar to the N uptake efficiency of corn from inorganic fertilizer sources, such as ammonium nitrate.) The N not taken up by the follow-ing crops may still contribute to soil health. Living microbes in the soil may use the nitrogen to support population growth and microbial activity in the soil.

Organic Production—Cover Crops for Organic Farms 7

As with just about everything else when it comes to farming, the practice of growing cover crops to produce nitrogen in the soil is complicated by many variables. Weather, differences in growing seasons, the types of cover crops involved, and the timing of cover crop desiccation to produce the opti-mum benefit all come into play. Amassing experience in cover crop production is simply the best way for a farmer to learn how to deal with the interplay of all these variables.

Legumes Versus Grasses. As we’ve seen above, legume cover crops play a vital role in producing N for subsequent cash crops. What part do nonleguminous cover crops, which do not produce nitrogen, have in the cropping scheme?

Organic farmers often plant nonlegumi-nous winter cover crops to trap the soil N that is left over from summer cash crops and to prevent this N from leaching out of the root zone or running off the field. Generally, grass cover crops are very effective—much more so than legumes—in trapping and recovering N from the soil. Grass and legume cover crop mixtures are more efficient than legumes alone in trapping leftover N in the soil, but don’t do as effective a job as straight grass cover crops.

There are many advantages, however, to planting cover crops that are grass and legume mixtures called bicultures. Researchers (Clark et al., 1994) reported that a cereal rye-hairy vetch biculture successfully scavenged potentially leach-able N from the soil, and also added fixed N for use by an ensuing corn crop. Addi-tionally, the cover crop used excess water in the soil, which also helped limit N leaching losses.

Grass species establish ground cover more quickly than legume monocultures, and their root growth remains active in the cooler temperatures of autumn (Ranells and Wagger, 1997). Cover crop mixtures that include grasses can, therefore, prevent soil erosion more effectively. Growing deep-rooted and shallow-rooted cover crops together will also help a farmer to make better use of water and other resources throughout the soil profile.

Legumes or Grasses? How To Choose a Cover Crop Generally, cover crop selection is based on each farmer’s situation and production goals. For example, if the purpose of a cover is to provide readily available, biologically fixed nitrogen for cash crops, then the farmer should choose a legume, such as hairy vetch or cowpea. If the cover crop will be managed as a surface mulch for weed suppression or incorporated to improve soil quality, then the farmer should choose a grass cover crop, such as cereal rye or a sorghum-sudangrass mix. Both of these grass cover crops can produce large amounts of biomass with high C:N ratios at maturity, and both are reported to suppress some weeds.

Farmers can also more effectively manipulate nitrogen cycling with mixed cover crop species. Combining mature cereals, which have high carbon to nitro-gen (C:N) ratios and break down slowly, with legumes, which have low C:N ratios and break down more quickly, can influ-ence decomposition of cover crop residues. The decomposition of such cover crop mixtures will occur more quickly than that of cereal alone, releasing N more quickly for uptake by cash crops.

Organic Production—Cover Crops for Organic Farms 8

Planting mixtures of cover crops can help a farmer to use the allelopathic potential of the cover crops to suppress weeds. Allelo-pathic suppression of weeds depends on both the cover crop and the weed. There-fore, a broader spectrum of weed control may be possible by growing a mixture of cover crops, with each species contributing allelopathic activity towards specific weed species (Creamer and Bennett, 1997).

Mixtures of cover crops can also be planted to influence insect populations. Species that may not produce much biomass or biomass N may be included in mixtures to attract beneficial insects into the cropping system.

Measuring Cover Crop Nitrogen. To ensure that cash crops receive enough nutrients, farmers must accomplish these calculations in this sequence:

1. Determine the biomass produced. 2. Determine the nutrient levels in that

biomass. 3. Predict how quickly the biomass will

decompose, releasing nutrients for cash crops.

4. Calculate whether additional nutrients are required for the desired crop yields.

Cover Crop Tip

Calculating the nutrient levels released by green manures for a subsequent cash crop normally requires three measurements: • The amount of biomass (dry weight). • The nutrient composition of the cover

crop. • The decomposition rate of the cover crop

during the cash cropping season.

To estimate yield, take cuttings from several areas in the field. Dry and weigh the samples. Use a yardstick or metal frame of known dimensions and clip the plants at ground level within the known area. Dry the samples in an oven at about 140°F for 24 to 48 hours until they are crunchy dry. Use the following equation to determine per acre yield of dry matter: Yield (lb/acre) = Total weight of dried samples (lb) X 43,560 sq ft Area (sq ft) sampled 1 acre For example, two 3 feet by 3 feet (9 sq ft or 1 sq yd) samples weigh 2.5 pounds. The dried biomass yield equals: Yield (lb/acre) = 2.5 lb X 43,560 sq ft = 6,050 lb/acre. 18 sq ft 1 acre

Though not as accurate, yield can be estimated from the height of the cover crop and the percentage of ground it covers. At 100 percent ground coverage and a 6-inch height, most nonwoody legumes contain roughly 2,000 pounds per acre of dry matter. For each additional inch, add 150 pounds.

For example, a hairy vetch cover crop is 18 inches tall and has 100 percent ground coverage. The first 6 inches of dry biomass weighs roughly 2,000 pounds. The 12 additional inches of growth weighs 150 pounds per inch. The additional weight is:

12 X 150 = 1,800 lb,

and the total weight of the cover crop dry matter is:

2,000 + 1,800 = 3,800 lb If the stand has less than 100 percent ground coverage, multiply the total weight by the percentage of ground covered, represented as a decimal number (the percentage divided by 100). If the percentage of ground covered in the example above is 60 percent, then the weight of the dry matter is: 3,800 X 0.60 (60/100) = 2,280 pounds of dry biomass (Adapted from Sarrantonio, 1998)

Organic Production—Cover Crops for Organic Farms 9

These calculations normally require three measurements: the amount of biomass (dry weight), the nutrient composition of the cover crop, and the decomposition rate of the cover crop during the cash cropping season.

Farmers can estimate the amount of nitrogen in a cover crop by estimating the total biomass yield of the cover crop and the percentage of nitrogen in the plants when they’re killed. A simple process for the assessment is explained in Managing Cover Crops Profitably (Sarrantonio, 1998:

For cereal rye, the height relationship is a bit different. Cereal rye produces approxi-mately 2,000 pounds per acre of dry matter at an 8-inch height and 100 percent ground coverage. For each additional inch, add 150 pounds, as before, and multiply by the percentage of ground covered, represented as a decimal (the percentage divided by100). For most small grains and other annual grasses, start with 2,000 pounds per acre at a 6-inch height and 100 percent of ground covered. Add 300 pounds for each additional inch, and multiply by the per-centage of ground covered, represented as a decimal (the percentage divided by 100).

To calculate the amount of nitrogen in the dried cover crop biomass, multiply the dry biomass yield times the percentage of nitrogen expressed as a decimal (percentage of N divided by 100). For the hairy vetch cover crop example above with 100 percent cover and an estimated 4 percent nitrogen at flowering: Total N (lb/acre) = 3,800 lb/acre X .04 (4 ÷ 100) = 152 lb N per acre

Annual legumes typically have between 3.5 and 4.0 percent nitrogen in the above-

ground biomass prior to flowering, and 3.0 to 3.5 percent at flowering. After flowering, nitrogen in the leaves decreases quickly as it accumulates in the growing seeds. Most cover crop grasses contain 2.0 to 3.0 per-cent nitrogen before flowering and 1.5 to 2.5 percent after flowering. Other cover crops, such as Brassica species and buck-wheat, will generally be similar to, or slightly below, grasses in their N concen-tration. To precisely determine the per-centage of nitrogen in the cover crop, send a plant sample to a laboratory for a chem-ical analysis. The N.C. Department of Agri-culture Plant Analysis Lab provides that service for $4 per sample.

As discussed previously, not all of the nitrogen contained in the cover crop residue will be available to the cash crop. To conservatively estimate the amount that will be available to the following crop, multiply legume biomass nitrogen, as calculated above, by 0.50 if the cover crop residue will be incorporated and by 0.40 if the residue will be left on the soil surface.

From the example above, if the hairy vetch is incorporated in the soil in early May in a normal spring, then the nitrogen available from the hairy vetch to the cash crop will be: Available N (lb/acre) = 152 lb N per acre X .50 = 76 lb N per acre.

If the hairy vetch is left on the soil surface in early May in a normal spring, then the nitrogen available from the hairy vetch to the next crop will be: Available N (lb/acre) = 152 lb N per acre X .40 = 61 lb N per acre

These availability coefficients will change, depending on the weather. In dry or cold

Organic Production—Cover Crops for Organic Farms 10

and wet springs, the soil microorganisms responsible for mineralization of the organic nitrogen in the cover crop residue will be less active. The mineralization rate will be reduced, and a lesser fraction of the nitrogen will be available to the following cash crop. In almost all cases, the availa-bility coefficient of a small grain cover crop, such as cereal rye, will be very low. Very little N in the residue will be released for use by the cash crop.

ESTABLISHING COVER CROPS

Using a drill to sow cover crops into a conventionally prepared seedbed is the most reliable way to obtain a uniform stand. However, in a no-till situation, a no-till grain drill can also be used successfully, provided that the residue from the previous crop is not excessive and the soil is moist enough to allow the drill to penetrate to the desired planting depth. Seeds may be broadcast if the soil has been disked and partially smoothed, but seeding rates should be increased by 20 percent.

It is best to cultipack the field after broad-casting to firm the soil around the seeds. Crimson clover, in particular, can be established quite easily with this method. In a limited number of trials, aerial seeding of crimson clover into a standing crop, such as soybeans, has proven successful. An innovative system that has shown promise in North Carolina and other southeastern states is to allow crimson clover to reseed itself naturally.

MANAGING COVER CROP RESIDUE

In organic systems, cover crops may be killed and incorporated into the soil by tillage, mowing, undercutting, or rolling. Details about these methods are included in

another publication within this series: “Conservation Tillage on Organic Farms.”

Should Farmers Leave Cover Crops on the Surface Or Incorporate Them?

In a wet growing season, incorporating legumes into the soil may produce the highest yields in cash crops that follow. However, under relatively dry growing conditions, cover crop residue left on the surface will help to conserve soil moisture.

In no-till organic production systems, cover crops are usually killed mechanically and left on the surface as a mulch. Each kill method has its benefits and drawbacks:

Undercutting utilizes a steel bar that is drawn several inches underneath the soil surface (usually beneath a plant bed), severing the top growth and crown of the plant from the roots and leaving the sur-face and aboveground biomass undisturb-ed. The main advantage of undercutting is that it leaves the cover crop intact and the large pieces break down more slowly, enhancing weed suppression.

Mowing with a flail mower leaves the finely chopped residue evenly distri-buted over the bed. The residue tends to decompose quickly, so high biomass is desirable.

Rolling the cover crop often includes crimping the cover crop stems, which damages each plant’s vascular system and causes it to die. Rolling keeps the above-ground part of the plant attached to the root system. As with undercutting, rolled plants decompose more slowly than those killed by mowing and, consequently, control weeds for a longer period of time (Lu et al., 2000). To facilitate seeding into

Organic Production—Cover Crops for Organic Farms 11

rolled or undercut cover crops, farmers should plant in the same direction as they rolled the cover crop.

THE ECONOMICS OF PLANTING COVER CROPS

Researchers are just beginning to investi-gate the long-term profitability of using cover crops in horticultural systems. Farmers using cover crops have additional expenses due to seed, seeding, and man-agement. However, cover crops allow a farmer to reduce costs for fertilizers, pest and disease control, and extensive tillage. They also represent a long-term investment in soil resources. Relative to these benefits and to the potential returns from high-value horticultural crops, the cost of cover cropping is comparatively minor.

Legume cover crops are generally reported to have more profitability potential than grass cover crops because they contribute nitrogen to the subsequent cash crop, reducing input costs (Roberts et al., 1998). Grass cover crops may, in fact, consume soil N that could be used by the cash crop. Hairy vetch may be among the more promising cover crops. It contributes N to the soil, and it also improves the soil’s structure and water-holding capacity. In doing so, it also increases the effectiveness of fertilizer-applied N (Lichtenberg et al., 1994; Hanson et al., 1993).

We would like to emphasize that all of these benefits may not always lead to increased profits for farmers. Allison and Ott (1987) reviewed studies investigating the economics of using legume cover crops in conservation tillage systems. They concluded that legume cover crops increase profitability if they enhance the yield of the succeeding crop. But they decrease profitability when used as the sole source of

nitrogen in a corn cropping system. If nitrogen prices, which increase with energy prices, continue to rise, legume cover crops may become cost-effective N sources.

In studies where cover crop systems are reported to be less profitable than conven-tional systems, the lower profitability is attributed to the establishment cost of the cover crop. In these studies, the benefits of using the cover crop (increased yields and reduced amounts of applied N) do not outweigh the establishment cost of the cover crop (Bollero and Bullock, 1994; Hanson et al., 1993).

Each farmer must determine how to account for the less apparent, long-term benefits—such as reduced soil erosion, increased organic matter content, improved soil physical properties, reduced nitrate leaching, and enhanced nutrient cycling.

COVER CROPS FOR THE SOUTHEAST

Which winter and summer legume and grass cover crops perform well in the southeastern United States? Our descriptions of recommended cover crops are drawn primarily from three sources: Duke (1981), Sarrantonio (1994), and Bowman et al. (1998). An electronic source we found very useful was the University of California at Davis (UCD) Sustainable Agriculture Cover Crop Resource Page at http://www.sarep.ucdavis.edu/ccrop/ (UCD, 2001). For more information on the cover crops listed, or to find information about other potential cover crops, refer to these references, which are listed in the “Recommended Reading” section of this publication.

Organic Production—Cover Crops for Organic Farms 12

Recommended Winter Species

Examples of winter legume cover crops include crimson clover, hairy vetch, Austrian winter pea (Pisum sativum arvense), and subterranean clover (Trifolium subter-raneum). Cereal rye, wheat, and oats are also commonly used as small grain cover crops and in mixtures with the legumes mentioned above. Generally, winter cover crops are planted in early fall and allowed to grow until mid-spring, at which time the crop is incorporated by tillage, or killed and left as a surface mulch into which another crop is planted.

Winter Legumes

Clover, Vetch & Winter Peas—What Are Their Limitations?

Hairy vetch tends to be more winter hardy than the other winter legumes and can generally be planted later in the season. Hairy vetch also adapts better to sandy soils than crimson clover, although crimson clover will provide adequate dry matter production on most well-drained, sandy loams.

In contrast, crimson clover grows faster in the spring, thereby maturing and obtaining peak dry matter production approximately three to four weeks before hairy vetch. Adequate dry matter and nitrogen production will be obtained with a soil pH from 5.8 to 6.0. Soil testing will help determine P and K fertilizer requirements. It is important to inoculate legumes with the proper strain of N-fixing bacteria.

Hairy vetch (Vicia villosa). Hairy vetch forms a very dense cover and, if planted with a tall growing species like rye, will climb and produce a great deal of biomass.

Hairy vetch is probably the most commonly used cover crop in the United States, in part because it is so widely adapted. Hairy vetch is seeded at 20 to 30 pounds per acre, with the lower rate used if the vetch is drilled or planted in mixtures. At mid-bloom, hairy vetch can be easily killed by undercutting or mowing. Be aware that hairy vetch can harbor root-knot nematodes (Meloidogyne spp.), soybean cyst (Heterodera glycines), and various cutworms. Susceptible vegetable crops should be temporarily separated in a rotation. If allowed to produce mature seed, vetch can also be viewed as a weed in subsequent small grain crops.

Crimson clover (Trifolium incarnatum). Crimson clover stands upright and blooms about three to four weeks earlier than hairy vetch. It grows vigorously in fall and winter and has good reseeding ability. It is not widely adapted, however, and is more appropriate in warmer climates. Crimson clover has good shade tolerance and can be overseeded into fall vegetable crops in September. Seeding rates vary from 15 to 25 pounds per acre, with the lower rate being used when the seed is drilled.

Subterranean clover (Trifolium subterraneum). Subterranean clover is a relatively low growing winter annual with prostrate stems. In late spring, subterra-nean clover develops seeds below ground (much like peanuts), which gives it an excellent reseeding ability. Subterranean clover forms a thick mat when left on the surface as a mulch and has been shown to suppress weeds in vegetable crops planted into the mulch. Subterranean clover does not produce as much biomass as other cool-season legumes grown in the South, but biomass yield can reach 5,500 pounds per acre with a nitrogen concentration of between 2 and 3 percent. Subterranean

Organic Production—Cover Crops for Organic Farms 13

clover is seeded at 8 to 15 pounds per acre between mid-September and mid-October.

Austrian winter pea (Pisum sativum arvense). Austrian winter pea is succulent and viney and can climb when planted with small grain crops. It grows vigorously and will suppress weeds while growing, but it decomposes rapidly and is not a good choice for a surface mulch and weed control. Austrian winter pea does well in a mixture with oats, barley, rye, or wheat. Seed is drilled at 60 to 90 pounds per acre and can be sown through October.

Winter Nonlegumes

Cereal rye (Secale cereale). Rye is one of the most commonly used winter cover crops. It grows 3 to 6 feet tall and has an extensive, fibrous root system. It performs well when mixed with hairy vetch, which will use it for climbing support. Rye can tolerate a wide variety of soil types and climatic conditions and is considered to be weed suppressive when managed as a mulch. Of all the small grains, rye is the best scavenger of excess soil nitrogen in the fall. The seeding rate is 100 pounds per acre.

Annual ryegrass (Lolium multiflorum). Annual ryegrass is a noncreeping bunchgrass. In the spring it can grow 2 to 4 feet tall. Annual ryegrass can be difficult to control and can become a serious weed if it produces seed. Ryegrass requires considerable nitrogen and water. If these are limited, it may not be a good choice. Ryegrass has a very fibrous, dense root system that protects against soil erosion while improving water infiltration and soil tilth. Dry matter yield can average between 1,300 and 2,000 pounds per acre, with an average nitrogen content of 1.5 percent.

Normally seeded in the fall, seeding rates are between 20 and 30 pounds per acre.

Other cereal grasses. All of the cereal grasses will produce biomass ranging from 2,000 to 6,000 pounds per acre with nitrogen concentrations between 1 and 2 percent. Biomass accumulation depends, in part, on how early in the spring the cover crop is killed. The high end of the range represents a kill date in mid- to late May. At this late date, however, the biomass carbon to nitrogen (C:N) ratio will normally be greater than 50:1, a ratio at which soil microbes would immobilize any mineralized nitrogen. Small grains are normally drilled at 100 pounds of seed per acre.

• Wheat (Triticum aestivum) provides a good overwintering ground cover and also provides the option of harvesting the grain.

• Barley (Hordeum vulgare) biomass production peaks about two weeks earlier than wheat, and about the same time as crimson clover. Barley, grown as a smother crop, has been shown to suppress winter annual weeds in cropping systems, but must be planted in September or early October to reduce winter kill.

• Oats (Avena sativa) grow well in cool weather and provide rapid ground cover in the fall. Some growers plant spring oats in the fall to produce a winter-killed mulch for early spring no-till vegetable plantings. However, spring oats may not always winter-kill in mild winters.

Recommended Summer Species

There is growing interest in the use of short-season summer annual legumes or grasses as cover crops and green manures in cropping systems. Summer annual legumes

Organic Production—Cover Crops for Organic Farms 14

and grasses can provide benefits between the harvest of spring vegetable crops and the planting of fall vegetables or small grains. While additional legumes and grasses are being evaluated for use, the following species are currently the best options.

Summer Legumes

Cowpea (Vigna unguiculata). Other common names for this species are blackeyed, crowder, and southern pea. Cowpea is a fast growing, summer cover crop that adapts to a wide range of soil conditions. Cowpeas have a deep taproot, tolerate drought, and compete well against weeds. Cowpeas produce 3,000 to 4,000 pounds of dry biomass per acre, which contains 3 to 4 percent nitrogen. Maxi-mum biomass is achieved in 60 to 90 days. Residues are succulent and decompose readily when incorporated into the soil. Cowpeas can be planted in the spring (after all danger of frost) through late summer. Cowpea seeds can be drilled in rows 6 to 8 inches apart at 40 pounds per acre or broad-cast at approximately 75 pounds per acre. Higher seeding rates are necessary in late summer when soil moisture is likely to be limited. Recommended cultivars include Iron Clay and Red Ripper. Plants normally grow up to 24 inches tall, but some culti-vars can climb when planted in mixtures with other species. Good mixture options are sorghum-sudangrass and German foxtail millet. When mowed or undercut, cowpeas have the potential for consider-able regrowth in some years.

Soybean (Glycine max). Soybean is one of the most economical choices for a summer legume cover crop. It is an erect, bushy plant that grows 2 to 4 feet tall, establishes quickly, and competes well with weeds. When grown as a green manure crop, late

maturing cultivars usually give the highest biomass yield and fix the most nitrogen. If well established, soybean will withstand short periods of drought. The viney, forage types (for example, the cultivars Quail-haven and Laredo) have the potential to produce more biomass than traditional soybean cultivars.

Velvetbean (Mucuna deeringiana). Velvetbean is a vigorously growing, warm-season annual legume native to the tropics and well adapted to southern U. S. condi-tions. It performs well in sandy and infer-tile soils. Most cultivars are viney, and stems can grow as much as 10 meters. Velvetbean is an excellent green manure crop, producing high amounts of biomass that decompose readily to provide nitrogen for a cash crop. Velvetbean does best when direct-seeded into warm soils in 38-inch rows. Velvetbean seed should not be drilled, because the very large seed can be damaged in conventional drills.

Sunnhemp (Crotalaria juncea). Sunnhemp is a tall, herbaceous, warm-season annual legume with erect fibrous stems. It has been used extensively for soil improvement and green manuring in the tropics. It competes with weeds, grows rapidly, and can reach a height of 8 feet in 60 days. It can tolerate poor, sandy soils and drought, but requires good drainage. Sunnhemp tolerates moderate acidity, but a soil pH below 5 can limit growth. Sunnhemp should be drilled or seeded in rows 38 inches apart at 30 pounds per acre. The growing season in the continental U.S. is not long enough to produce viable seed. Sunnhemp becomes fibrous with age, but the plants are succulent for about eight weeks after seeding. Sunnhemp is often planted in midsummer after cool-season vegetables or sweet corn crops are harvested. It will produce high biomass and biomass

Organic Production—Cover Crops for Organic Farms 15

nitrogen in 45 to 60 days. Seed is not readily available at this writing in early 2006, but availability may increase if demand increases. While some Crotalaria species are toxic to animals, sunnhemp forage is not. Sunnhemp should not to be confused with showy crotalaria, a noxious weed species.

Summer Nonlegumes

Buckwheat (Fagopyrum esculentum). Buckwheat is a very rapidly growing broadleaf summer annual, which can flower in four to six weeks. It reaches 30 inches in height and is single-stemmed with many lateral branches. It has both a deep taproot and fibrous roots. It can be grown to maturity between spring and fall vegetable crops, suppressing weed growth and recycling nutrients during that period. It is succulent, easy to incorporate, and decomposes rapidly. Buckwheat flowers are very attractive to insects, and some farmers use this cover to attract beneficial insects into cropping systems. Buckwheat is an effective phosphorous scavenger. The main disadvantage to buckwheat is that it sets seed quickly and, if allowed to go to seed, may become a weed in cash crops. Thus, the optimal time to incorporate buckwheat is one week after flowering, before seed is set. Buckwheat can be planted anytime in the spring, summer, or fall, but is frost-sensitive.

Sorghum sudangrass (Sorghum bicolor × Sorghum sudanense). Sorghum sudangrass is a hybrid of grain sorghum and sudangrass. It is a warm-season annual grass, most often planted from late spring through mid-summer. It grows well in hot, dry conditions and produces a large amount of biomass. Often reaching 6 feet in height, it can be mowed to enhance biomass production. Sorghum sudangrass is very

effective at suppressing weeds and has been shown to have allelopathic properties. The roots of sorghum sudangrass are good foragers for nutrients and help control erosion. Sorghum sudangrass does well when planted in mixtures, providing effective support for viney legumes like velvetbean. If frost-killed, the residue can provide a no-till mulch for early planted spring crops like broccoli. When stressed by drought or by frost, this cover crop can produce prussic acid, which is toxic to cattle.

German (foxtail) millet (Setaria italica). German or foxtail millet is an annual warm-season grass that matures quickly in the hot summer months. It is one of the oldest of cultivated crops. German millet has a fairly low water requirement. Because of its shallow root system, however, it doesn’t recover easily after a drought. Grain formation requires 75 to 90 days. German millet forms slen-der, erect, and leafy stems that can vary in height from 2 to 4 feet. The seed can be drilled from mid-May through August at a rate of 10 to 15 pounds per acre. A small seeded crop, German millet requires a relatively fine, firm seedbed for adequate germination. To avoid early competition from germinating weed seed, it should be closely drilled in the row or sown in a stale seedbed—a seedbed that has been prepared, with early emerged weeds killed just before planting the cover crop. Coarse, sandy soils should be avoided.

Pearl millet (Pennisetum glaucum). Pearl millet is a tall annual bunchgrass that grows 4 to 10 feet tall. It is also often referred to as cattail millet because its long, dense, spike-like inflorescences resemble cattails. Though it performs best in sandy loam soils, pearl millet is well adapted to soils that are sandy, infertile, or both. Pearl

Organic Production—Cover Crops for Organic Farms 16

millet can be planted from late April through July at a rate of 15 to 20 pounds per acre. Pearl millet matures in 60 to 70 days. In North Carolina studies, pearl millet was not as readily killed by mechanical methods (mowing and undercutting) as German or Japanese millet.

Japanese millet (Enchinochloa frumen-tacea). Japanese millet is an annual grass that grows 2 to 4 feet tall. It resembles and may have originated from barnyard grass. Japanese millet is commonly grown as a late-season green forage. If weather conditions are favorable, it grows rapidly and will mature from seed in as little as 45 days. Japanese millet can be planted from April to July at a rate of 10 to 15 pounds per acre. It performs poorly on sandy soils.

RECOMMENDED READING

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Roberts, R.K., J.A. Larson, D.D. Tyler, B.N. Duck, and K.D. Dillivan. 1998. Economic analysis of the effects of winter cover crops on no-tillage corn yield response to applied nitrogen. Journal of Soil and Water Conservation. 53:280-284.

Roberts, B.W., and B. Cartwright. 1991. Cover crop, nitrogen, and insect interactions. In W.L. Hargrove (Ed.). Cover Crops for Clean Water. pp.164-167. Soil and Water Conservation Society. Ankeny, IA.

Rodriguez-Kabana, R., J. Pinochet, D.G. Robertson, C.F. Weaver, and P.S. King. 1992. Horsebean (Canavalia ensiformis) and crotalaria (Crotalaria spectabilis) for the management of Meloidogyne spp. Nematropica. 22:29-35.

Sarrantonio, M. 1998. Building soil fertility and tilth with cover crops. In A. Clark (Ed.). Managing Cover Crops Profitably, 2nd Ed. pp. 22-23. Sustainable Agriculture Network, Handbook Series 3. Beltsville, MD.

Sarrantonio, M. 1994. Northeast Cover Crop Handbook. Rodale Institute. Emmaus, PA.

Schilling, D.G., R. A. Liebl, and A.D. Worsham. 1985. Rye (Secale cereat L.) and wheat (Triticum aestivum L.) mulch: The suppression of certain broadleaved weeds and the isolation and identification of phytotoxins. In A.C. Thompson (Ed.). The Chemistry of Allelopathy: Biochemical Interactions Among Plants. pp. 243-271. Symp. Ser. 268. American Chemical Society. Washington, D.C.

Shipley, P.R., J.J. Meisinger, and A.M. Decker. 1992. Conserving residual corn fertilizer nitrogen with winter cover crops. Agronomy Journal. 84:869-876.

Smeda, R.J., and S.C. Weller. 1996. Potential of rye (Secale cereale) for weed management in transplant tomatoes (Lycopersicum esculentum). Weed Science. 44:596-602.

Subbarao, K.V., and J.C. Hubbard. 1996. Interactive effects of broccoli residue and temperature on Verticillium dahliae micro-sclerotia in soil and on wilt in cauliflower. Phytopathology. 86:1303-1310.

Sullivan, P.G., D.J. Parrish, and J.M. Luna. 1991. Cover crop contributions to N supply and water conservation in corn production. American Journal of Alternative Agriculture. 6:106-113.

Teasdale, J.R. 1993. Interaction of light, soil moisture, and temperature with weed suppression by hairy vetch residues. Weed Science. 41:46-51.

Teasdale, J.R., and C.S.T. Daughtry. 1993. Weed suppression by live and desiccated hairy vetch. Weed Science. 41:207-212.

Tyler, D.D.,M.G. Wagger, D.V. McCracken, W.L. Hargrove, and M.R. Carter. 1994. Role of conservation tillage in sustainable agriculture in the southern United States. Conservation Tillage in Temperate Agroecosystems. pp. 209-229. Lewis Publishers Inc. Boca Raton, FL.

University of California at Davis (UCD). 2001. University of California Sarep Cover Crop Resource Page. Online: http://www.sarep.ucdavis.edu/ccrop/

Wagger, M.G. 1989a. Time of dessication effects on plant composition and subsequent nitrogen release from several winter annual cover crops. Agronomy Journal. 81:236-241.

Wagger, M.G. 1989b. Cover crop management and nitrogen rate in relation to growth and yield of no-till corn.. Agronomy Journal. 81:533-538.

White, R.H., A.D. Worsham, and U. Blum. 1989. Allelopathic potential of legume debris. Weed Science. 37:674-679.

Additional Reading

Araya, M., and E.P. Caswell-Chen. 1994. Penetration of Crotalaria juncea, Dolichos lablab and Sesamum indicum roots by Meloidogyne javanica. Journal of Nematology. 26:238-240.

Bergersen, F.J., J. Brockwell, R.R. Gault, L. Morthorpe, M.B. Peoples, and G.L. Turner. 1989. Effects of available soil nitrogen and rates of inoculation on nitrogen fixation by irrigated soybeans and evaluation of delta 15N methods for

Organic Production—Cover Crops for Organic Farms 19

measurement. Australian Journal of Agricultural Research. 40:763-780.

Boosalis, M.G., and G.E. Cook. 1973. Plant diseases. In Conservation Tillage, Conference Proceedings. pp. 114-125. Soil Conservation Society of America. Ankeny, IA.

Brunson, K.E., C.R. Stark, Jr., M.E. Wetzstein, and S.C. Phatak. 1995. Economic comparisons of alternative and conventional production technologies for eggplant in souther Georgia. Journal of Agribusiness. 13:159-173.

Bugg, R.L., F.L. Wackers, K.E. Brunson, J.D. Dutcher, and S.C. Phatak. 1991. Cool-season cover crops relay intercropped with cantaloupe: Influence on a generalistic predator, Geocoris punctipes (Hemiptera: Lygaeidae). Journal of Economic Entomology. 84:408-415.

Burgos, N.R., and R.E. Talbert. 1996. Weed control by spring cover crops and imazethapyr in no-till southern pea (Vigna unguiculata). Weed Technology. 10:893-899.

Chapman, A.L., and R.J.K. Myers. 1987. Nitrogen contributed by grain legumes to rice grown in rotation on the Cununurra soils of the Ord irrigation area, Western Australia. Australian Journal of Experimental Agriculture. 27:155-163.

Creamer, N.G., M.A. Bennett, B.R. Stinner, and J. Cardina. 1996b. A comparison of four processing tomato production systems differing in cover crop and chemical inputs. Journal of the American Society of Horticultural Science. 121:559-568.

Dillard, H.R., and R.G. Grogan. 1985. Influence of green manure crops and lettuce on sclerotial populations of Sclerotinia minor. Plant Disease. 69:579-582.

Ditsch, D.C., M.M. Alley, K.R. Kelley, and Y.Z. Lei. 1993. Effectiveness of winter rye for accumulating residual fertilizer N following corn. Journal of Soil and Water Conservation. 48:125-132.

Einhellig, F.A. 1996. Interactions involving allelopathy in cropping systems. Agronomy Journal. 88:886-893.

Ess, D.R., D.H. Vaughan, J.M. Luna, and P.G. Sullivan. 1994. Energy and economic savings from the use of legume cover crops in Virginia corn production. American Journal of Alternative Agriculture. 9:178-185.

Hargrove, W.L. 1991. Cover Crops for Clean Water. Proceedings of an International Conference. West Tennessee Experiment Station. April 9-11, 1991. Jackson, TN. Soil and Water Conservation Society. Ankeny. 198 pp.

Haynes, R.J. 1980. Competitive aspects of the grass-legume association. Advances in Agronomy. 33:227-261.

Holderbaum, J.F., A.M. Decker, J.J. Meisinger, F.R. Mulford, and L.R. Vough. 1990. Fall seeded legume cover crops for no-tillage corn in the humid East. Agronomy Journal. 82:117-124.

Kelly, T.C., Y.C. Lu, A.A. Abdul-Baki, and J.R. Teasdale. 1995. Economics of a hairy vetch mulch system for producing fresh-market tomatoes in the mid-Atlantic region. Journal of the American Society of Horticultural Science. 120:854-860.

Kloepper, J.W., R. Rodriguez-Kabana, J.A. McInroy, and R.W. Young. 1992. Rhizosphere bacteria antagonistic to soybean cyst (Heterodera glycines) and root-knot (Meloidogyne incognita) nematodes: Identification by fatty acid analysis and frequency of biological control activity. Plant and Soil. 139:75-84.

Kuo, S., E.J. Jellum, and U.M. Sainju. 1995. The effect of winter cover cropping on soil and water quality. Proceedings of the Western Nutrient Management Conference. pp.56-64. Salt Lake City, UT.

McCracken, D.V., M.S. Smith, J.H. Grove, C.T. MacKown, and R.L. Blevins. 1994. Nitrate leaching as influenced by cover cropping and nitrogen source. Soil Science Society of America Journal. 58:1476-1483.

Mojtahedi, H., G.S. Santo, and R.E. Ingham. 1993. Suppression of Meloidogyne

Organic Production—Cover Crops for Organic Farms 20

chitwoodi with sudangrass cultivars as green manure. Journal of Nematology. 25:303-311.

Muller, M.M., V. Sundman, O. Soininvaara, and A. Merilainen. 1988. Effect of chemical composition on the release of nitrogen from agricultural plant materials decomposing in soil under field conditions. Biology and Fertility of Soils. 6:78-83.

Nwonwu, F.O.C., and P.C. Obiaga. 1988. Economic criteria in the choice of weed-control methods for young pine (Pinus caribaea var. hundurensis Barr and Golf) plantations. Weed Research. 28:181-184.

Ofori, C.F., and W.R. Stern. 1987. Cereal-legume intercropping systems. Advances in Agronomy. 26:177-204.

Patrick, Z.A., T.A. Toussoun, and W.C. Snyder. 1963. Phytotoxic substances in arable soils associated with decomposition of plant residues. Phytopathology. A53:152-161.

Peoples, M.B, and E.T. Craswell. 1992. Biological nitrogen fixation: Investments, expectations, and actual contributions to agriculture. Plant and Soil. 141:13-39.

Phillips, S.H. 1984. Other pests in no-tillage and their control. In R.E. Phillips and S.H. Phillips (Eds.). No Tillage Agriculture. pp. 171-189. Van Nostrand Reinhold Co. New York, NY.

Power, J.F., and J.W. Doran. 1988. Role of Crop Residue Management in Nitrogen Cycling and Use. ASA Special Publication No. 51. pp. 101-113. American Society of Agronomy. Madison, WI.

Ranells, N.N., and M.G. Wagger. 1992. Nitrogen release from crimson clover in relation to plant growth stage and composition. Agronomy Journal. 84:424-430.

Rice, E.L. 1974. Allelopathy. Academic. New York, NY.

Roberson, E.B., S. Sarig, C. Shennan, and M.K. Firestone. 1995. Nutritional management of microbial polysaccharide production and aggregation in an agricultural soil.

Soil Science Society of America Journal. 59:1587-1594.

Roberson, E.B., S. Sarig, and M.K. Firestone. 1991. Cover crop management of polysaccharide-mediated aggregation in an orchard soil. Soil Science Society of America Journal. 55:734-739.

Roberts, J.L., and F.R. Olson. 1942. Interrelationships of legumes and grasses grown in association. Agronomy Journal. 32:695-701.

Sainju, U.M., and B.P. Singh. 1997. Winter cover crops for sustainable agricultural systems: Influence on soil properties, water quality, and crop yields. HortScience. 32:21-28.

Shennan, C. 1992. Cover crops, nitrogen cycling, and soil properties in semi-irrigated vegetable production systems. HortScience. 27:749-754.

Smith, M.S., W.W. Frye, and J.J. Varco. 1987. Legume winter cover crops. Advances in Soil Science. 7:95-139.

Wyland, L.J., L.E. Jackson, W.E. Chaney, K. Klonsky, S.T. Koike, and B. Kimple. 1996. Winter cover crops in a vegetable cropping system: Impacts on nitrate leaching, soil water, crop yield, pests and management costs. Agriculture, Ecosystems and Environment. 59:1-17.

Organic Production—Cover Crops for Organic Farms 21

The Organic Production publication series was developed

by the Center for Environmental Farming Systems,

a cooperative effort between

North Carolina State University, North Carolina A&T State University, and the

North Carolina Department of Agriculture and Consumer Services.

The USDA Southern Region Sustainable Agriculture Research and Education Program

and the USDA Initiative for Future Agriculture and Food Systems Program provided funding in support of the Organic Production publication series.

David Zodrow and Karen Van Epen of ATTRA contributed to the technical writing, editing, and formatting of these publications.

Prepared by

Keith R. Baldwin

Program Leader, ANR/CRD Extension Specialist—Horticulture

North Carolina A&T State University

Nancy G. Creamer Director, Center for Environmental Farming Systems

North Carolina State University College of Agriculture and Life Sciences

Published by NORTH CAROLINA COOPERATIVE EXTENSION SERVICE

AG-659W-03 07/2006—BS

E06-45788 Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, nationalorigin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governmentscooperating.

FARMING FOR BEESGuidelines for Providing

Native Bee Habitat on Farms

The Xerces SocietyFOR INVERTEBRATE CONSERVATION

Mace Vaughan, Jennifer Hopwood, Eric Lee-Mäder, Matthew Shepherd,Claire Kremen, Anne Stine, and Scott Hoffman Black

FARMING FOR BEES Guidelines for Providing Native Bee Habitat on Farms

Mace VaughanJennifer Hopwood

Eric Lee-MäderMatthew Shepherd

Claire KremenAnne Stine

Scott Hoffman Black

The Xerces Society for Invertebrate Conservation

Oregon • California • Minnesota • NebraskaNew Jersey • North Carolina • Texas

www.xerces.org

© 2015 by The Xerces Society for Invertebrate Conservation

The Xerces Society for Invertebrate Conservation is a nonprofit organization that protects wildlife through the conservation of invertebrates and their habitat. Established in 1971, the Society is at the forefront of invertebrate protection, harnessing the knowledge of scientists and enthusiasm of citizens to implement conservation programs worldwide. The Society uses advocacy, education, and applied research to promote invertebrate conservation.

The Xerces Society for Invertebrate Conservation628 NE Broadway Ste. 200 , Portland, OR 97232

tel 503.232.6639 • fax 503.233.6794 • www.xerces.org

Regional offices in California, Minnesota, Nebraska, New Jersey, North Carolina, and Texas.

The Xerces Society is an equal opportunity employer and provider.

AcknowledgmentsWe thank the Alice C. Tyler Perpetual Trust, Audrey & J.J. Martindale Foundation, Columbia Foundation, Cascadian Farm, CS Fund, Ceres Trust, Cinco, Clif Bar Family Foundation, Disney Worldwide Conservation Fund, The Dudley Foundation, Edward Gorey Charitable Trust, The Elizabeth Ordway Dunn Foundation, Endangered Species Chocolate LLC, Gaia Fund, General Mills, Irwin Andrew Porter Foundation, Richard & Rhoda Goldman Fund, Organic Farming Research Foundation, Panta Rhea Foundation, Sarah K. de Coizart Article TENTH Perpetual Charitable Trust, Swimmer Family Foundation, Turner Foundation, Inc., the USDA Natural Resources Conservation Service, The White Pine Fund, Whole Foods Market and their vendors, Whole Systems Foundation, and Xerces Society members for their generous financial support that led to the production of these guidelines.

Appreciation goes to our fantastic group of farmer-partners for helping to build upon our experience, and for graciously allowing us to highlight their great conservation work in case studies and photos, including Vilicus Farms, East Multnomah Soil and Water Conservation District’s Headwaters Farm, the Kerr Center, the Muir Glen Organic team at General Mills, Brian and Rhoda Gibler, DeLano Farm, Hedgerow Farms, Inc., Tadlock Farms, Sturm Berry Farm, the University of California–Davis Sustainable Agriculture Research Facility, Whitted Bowers Farm, Chet Halunen at Standish Bogs, and Omeg Orchards. We also thank the following contributors who helped by reviewing early drafts of these guidelines:Robbin Thorp, University of California–Davis; and Sarina Jepsen and Katharina Ullmann, the Xerces Society. We also would like to thank all of the scientists conducting field research on crop pollination by native bees. Without the support and hard work of these scientists and reviewers, this guide would not have been possible.

Editing: Kara West, Sara Morris, and Matthew Shepherd. Layout: Sara Morris.

Printing: Print Results, Portland, OR.

PhotographsCovers: front—pollinator planting adjacent to blueberry farm (photograph by Don Keirstead, New Hampshire NRCS); back—bumble bee covered with pollen (photograph by Nancy Adamson, The Xerces Society).

We are grateful to the photographers for allowing us to use their wonderful photographs. The copyright for all photographs is retained by the photographers. None of the photographs may be reproduced without permission from the photographer. If you wish to contact a photographer, please contact the Xerces Society at the address above.

Additional copiesA copy of these guidelines may be downloaded for free from the Xerces Society website, available at: http://www.xerces.org/guidelines-farming-for-bees/. Hard copies are also available for purchase through the Xerces Store at: http://www.xerces.org/store/.

Fourth Edition (revised)First published in 2004. The second edition was published in July 2007, and the third edition was published in December 2011. This fourth edition revised reprint was published in January 2015.

Contents

POLLINATOR BASICS1 Introduction 1

2 What Are Native Bees? 3Some of the Many Crop-Visiting Bees 5

3 Why Farm for Native Bees? 7Native Bees Are Very Efficient 7Native Bees Are Diverse and Stable 8Native Bees May Provide Additional Revenue 8Native Bee Habitat Supports Health of Managed Bees 9Pollinator Habitat Provides Other Benefits 9Case Study: Pollinator Conservation Brings Life Back to California Farm 10

CONSERVATION ACTION4 Three Steps to Success 12

Recognize Resources Already on the Farm 12Adapt Existing Farm Practices 14Provide Habitat for Pollinators on Farms 15Case Study: Leveraging Existing Natural Areas for Blueberry Pollination in Oregon 16

5 Where to Provide Habitat 18Potential Areas for Bee Habitat on Farms 18Site Characteristics to Consider 21Case Study: Integrating Pollinator Habitat into Dryland Fields 24

6 Creating Foraging Habitat 26Plant Selection 26Establishing Pollinator Habitat 30Choosing Garden Plants 33Planting Forage Cover Crops 34Consider Bees When Rotating Crops 36Case Study: North Carolina Farm Sets the Stage for Pollinators 37

7 Protecting and Creating Bee Nest Sites 38Nesting Sites for Ground-Nesting Bees 38Nests for Wood- or Tunnel-Nesting Bees 40Bumble Bee Nests 44Case Study: Pollination Insurance for Massachusetts Cranberries 45

8 Insecticides and Pollinators 48Lethal and Sublethal Effects of Insecticides 49Reducing the Need for Insecticides 50Reducing the Risk from Insecticides 50Case Study: Protecting Pollinators While Fighting an Invasive Pest 54

9 Technical and Financial Assistance 57

10 Conclusion 59

APPENDICES

Appendix A: Natural History of Native Bees 61

Appendix B: Plants for Bees 64

Appendix C: Pollinator Habitat Checklist 69

Appendix D: Resources: Tools, Websites, and Publications 70

Appendix E: Literature Cited 75

1The Xerces Society for Invertebrate Conservation

Value of Native Bees to Agriculture

ӧ Native bees pollinated approximately $3 billion of crops in the year 2000.

ӧ There are approximately 4,000 species of native bees in North America, hundreds of which contribute significantly to the pollination of farm crops.

ӧ Even when honey bees are present in fields, native bees contribute significantly to crop pollination.

ӧ When honey bees are in short supply, native bees can act as an insurance policy when habitat is present.

ӧ Habitat installed on farms to support wild bees can increase crop pollination and yield, and thus farm profits, with time.

ӧ A diverse bee community improves crop pollination services and provides more stable pollination in variable weather conditions.

Native Bees Compared to Honey Bees

ӧ Native bees pollinate apples, cherries, squash, watermelon, blueberries, cranberries, raspberries, and tomatoes far more effectively than honey bees on a bee-per-bee basis.

ӧ Many native bee species forage earlier or later in the day than honey bees.

ӧ Native bees will often visit flowers in wet, cloudy, or cool conditions when honey bees remain in the hive.

ӧ Direct interactions between native bees and honey bees on flowers can improve the effectiveness of honey bees as pollinators of hybrid seed crops by causing them to move more frequently between rows of male and female plants.

ӧ Even without interactions on flowers, the presence of wild bees and managed blue orchard bees increases the effectiveness of honey bees in almond orchards by increasing their inter-row movement

ӧ Honey bee crop pollination is not a complete substitute for the pollination services provided by a diverse community of wild bees.

Animals pollinate roughly 35% of all crops grown in the world. More than 75% of the world’s 115 principal crop species are dependent on or benefit from animal pollination, and these insect-pollinated crops provide nutrients essential to human health. In addition to improving the yield of most crop species, recent research demonstrates that pollinators such as bees also improve the nutritional value and commercial quality.

In North America, bees were responsible for roughly $20 billion in agricultural production in 2000. Most large-scale crops are pollinated by managed hives of the European honey bee (Apis mellifera). However, the number of managed honey bee hives is declining in the United States due to pests, diseases, aggressive strains of honey bees, reduced sources of pollen and nectar, pesticide exposure, and Colony Collapse Disorder, highlighting the risks involved in relying on a single insect to pollinate so much of our food supply.

In 2006, the National Academy of Sciences published Status of Pollinators in North America. The report highlights the decline of both honey bees and wild native bees across North America, the causes and consequences of this decline, and makes recommendations on conservation steps that can be taken to slow or reverse pollinator losses. These Farming for Bees guidelines were highlighted in the report as an important tool for pollinator conservation and increasing populations of crop-pollinating native bees.

In the past, native bees and feral honey bees could meet all of a farmer’s pollination needs for orchards, berry patches, squash and melons, vegetable seed, sunflowers, and other insect-pollinated crops. These farms were relatively small and close to areas of natural habitat that harbored adequate numbers of

Introduction

1

1

2 Farming for Bees

pollinators to accomplish the task that now requires imported colonies of honey bees. Nearby natural areas also served as a ready source of new pollinators that could re-colonize farms and provide pollination services if insecticide applications killed resident bees.

Today, however, many agricultural landscapes are much more extensive and lack sufficient habitat to support native pollinators. In spite of this reduction in areas of habitat, the value of the pollination services that native bees provide in the United States is estimated to be worth about $3 billion per year. Research conducted across North America further demonstrates that native bees still play an important role in crop pollination, so long as landscapes around farms supply forage and nest sites.

The purpose of these guidelines is to provide information about native bees and their habitat requirements so that farmers can manage the land around their fields to provide the greatest advantage for these crop pollinators. These guidelines will help growers and conservationists:

ӧ understand how simple changes to farm practices can benefit native pollinators and farm productivity;

ӧ protect, enhance, or restore habitat to increase the ability of farmlands to support these bees; and ӧ ultimately increase a grower’s reliance upon native bees for crop pollination.

Making small changes to increase the number of native pollinators on a farm does not require a lot of work. Subtle changes in farm practices can involve identifying and protecting nesting sites and forage, choosing cover crop species that provide abundant pollen and nectar, allowing crops to go to flower before plowing them under, or changing how pesticides are applied in order to have the least negative impact on bees.

Farmers with more time and interest can create additional pollinator habitat in unproductive areas on the farm, or they can fine-tune the design of conservation buffers, such as hedgerows or grassed waterways, to provide maximum benefit for crop-pollinating native bees. For example, semi-bare, untilled ground or wooden nest blocks can be added to existing wildlife habitat, hedgerows can be supplemented with a wide variety of wildflowers and shrubs that provide bloom throughout the growing season, or a pesticide-free buffer zone can be maintained around field edges.

Finally, managing marginal areas of a farm for native bees should not be confused with beekeeping. There are no hives, no need for special safety equipment, and no reason to handle any bees. In addition, most of these valuable pollinators do not sting!

Native mining bee visiting a highbush blueberry. Blueberries, and their close relatives cranberries, benefit from buzz pollination, a service only native bees can provide. (Photograph by Nancy Adamson, The Xerces Society.)

2 Farming for Bees

3The Xerces Society for Invertebrate Conservation

North America is home to about 4,000 species of native bees, most of which go overlooked. These insects are not the familiar European honey bee, nor are they wasps or other aggressive stinging insects.

Native bees come in a wide range of sizes and colors, from tiny sweat bees less than a ¼" long to bumble and carpenter bees bigger than 1". While some of these species may look “bee-like”, with hairy stripes of yellow, white, or black, they also may be dark brown, black, or metallic green or blue, with stripes of red, white, orange, yellow, or even mother-of-pearl. Many look like flying ants or flies. Most are solitary, with each female creating and provisioning her own nest without the help of sister worker bees. And, most are unlikely to sting.

About 70% of native bees nest in the ground and, in most cases, a solitary female excavates her own nest tunnel. From this tunnel, the bee digs a series of underground brood cells, into which she places a mixture of pollen and nectar and lays an egg.

Most other bees nest in narrow tunnels in wood, usually pre-existing holes such as those made by beetle larvae, or in the center of pithy twigs. Females of these wood-nesting bees create a line of brood cells, often using materials such as leaf pieces or mud as partitions between cells. Once the nest is complete, the solitary female generally dies. Her offspring will remain in the nest for about 11 months, passing through the egg, larva, and pupa stages before emerging as an adult to renew the cycle the next year.

Bumble bees are the most noticeable social bees in the United States. There are about 45 species. Bumble bees nest in small insulated cavities, such as abandoned rodent burrows, that are found under rocks or tussocks of grass. Depending upon the species, their colonies may have up to several hundred worker bees by mid-summer.

What Are Native Bees?

2

The life cycle of squash bees is closely tied to their host plant. Here, three males wait for females to arrive in a squash blossom. (Photograph by Nancy Adamson, The Xerces Society.)

3

Solitary or Social?

Asked to think of a bee nest, many people picture the hexagonal wax comb and humming activity of a honey bee hive, created by the shared labor of thousands of workers and containing enough stored honey to feed the colony throughout winter.

The nests of native bees are quite different. Most of the 4,000 species of native bees in North America are solitary. Each female constructs and supplies her own nest, which consists of a narrow tunnel and a few brood cells stocked with nectar and pollen. She lives only a few weeks as an adult and dies after her nest is completed.

Bumble bees are social bees that live in a colony and share the labor of foraging and rearing brood. But, unlike honey bee nests, most bumble bee nests are a random-looking cluster of ball-shaped brood cells and waxy pots, and are occupied by only a few dozen to a few hundred bees. Bumble bees store only a few days’s supply of nectar, and the colony does not survive beyond the fall.

4 Farming for Bees

Except for bumble bees and many sweat bees, most native bees are solitary. However, these solitary bees may occur in great numbers over a patch of ground where many females construct and provision their individual nests close together.

Bees’s common names often reflect their nest-building habits: miner, carpenter, leafcutter, mason, plasterer, or carder. Other names depict behavioral traits. For example, bumble bees make a loud humming noise while flying, cuckoo bees lay eggs in other bees’ nests, and sweat bees like to drink salty perspiration.

One key to recognizing bees is noticing their behavior and comparing it with that of other insects. Bees collect only pollen and nectar to feed their young. Any insect that looks like a bee, wasp, or fly, with large quantities of pollen stored on its legs or body, is likely one of our native bees.

Wasps, on the other hand, are predators in search of insect or spider prey to feed their young, and nectar to fuel their flight. They typically have fewer hairs and a more pointed abdomen. Some flies also look like bees. Again, they will never have pollen packed onto their legs. These bee-like flies often will hover in the air around flowers, without moving, before quickly dashing off—a behavior seldom seen in true bees.

For more details about the life cycle and natural history of the various native bees, see Appendix A or pick up a copy of Attracting Native Pollinators, Bees of the World, or Bee Pollinators in Your Garden. (See Appendix D for complete references.)

Named for their nest-building habits, leafcutter bees use pieces of leaves and flower petals to seal their nests. Unlike many other groups of bees, leafcutters carry pollen on their abdomen rather than on their back legs. (Photograph by Mace Vaughan, The Xerces Society.)

4 Farming for Bees

Yellowjacket Wasps Are Not Bees

This is a yellowjacket wasp, not a bee. Notice its relative lack of hair and very pointed abdomen. Most native bees are unlikely to sting. The yellowjackets and other wasps you see eating rotting fruit and hanging around picnics are not bees, nor are they significant crop pollinators. (Photograph by Whitney Cranshaw, Colorado State University, Bugwood.org.)

5The Xerces Society for Invertebrate Conservation

(Photographs by: Mace Vaughan, The Xerces Society1, 2; Nancy Adamson3, The Xerces Society; Rollin Coville4, 5, 6.)

Some of the Many Crop-Visiting Bees

5The Xerces Society for Invertebrate Conservation

Bees come in all sizes and colors, from tiny to large and from black to metallic green. Some bees that you may see on crops include (clockwise from top left) bumble bees1; honey bees2; small carpenter bees3; green sweat bees4; leafcutter bees5; and squash bees6.

6 Farming for Bees6 Farming for Bees

Sunflower bee on plains coreopsis. (Photograph by Jennifer Hopwood, The Xerces Society.)

7The Xerces Society for Invertebrate Conservation

Growers should consider the needs of native bees in their farm management and on-farm conservation practices because these insects provide a helpful role in crop pollination, increasing yields and farm profit. They also can provide an insurance policy if honey bees become harder to acquire, or continue to increase in cost. In this chapter, we go into more depth about other reasons we should protect or provide habitat for native bees.

Native Bees Are Very EfficientMany species of native bee are much more effective than honey bees at pollinating flowers on a bee-per-bee basis. For example, only 250 female orchard mason bees (genus Osmia, also called blue orchard bees) are required to effectively pollinate an acre of apples, a task that would require 1.5–2 honey bee hives—approximately 15,000–20,000 foragers.

There are many reasons for this increased efficiency. Many native bees, such as mason and bumble bees, are active in cooler and wetter conditions than honey bees. In addition, the range of foraging behaviors is more diverse in native bees than in honey bees alone. For example, nectar-foraging honey bees often never contact the anthers (pollen-producing structures) in many orchard crops, unlike orchard mason bees that forage for both pollen and nectar on every flower visit. Alfalfa flowers are shaped in a way that discourages honey bees from foraging; the alkali bee (Nomia melanderi) can easily forage on these flowers. Also, some native bees specialize in one type of flower. Squash bees (genus Peponapis), for example, primarily visit flowers from the squash plant family (the cucurbits). The females often start foraging before dawn and the males even spend the night in the flowers, which results in very effective pollination and larger fruits.

Unlike honey bees, bumble bees and many other native bees perform buzz pollination, in which the bee grabs onto a flower’s stamens and vibrates her flight muscles, releasing a burst of pollen from deep pores in the anther. This behavior is highly beneficial for the cross-pollination of blueberries, cranberries, tomatoes, and peppers, among other plants. Although tomatoes do not require a pollinator to set fruit, buzz-pollination by bees results in larger, more abundant, and tastier fruit.

Honey bees also use nectar to pack the pollen into their pollen baskets for transport back to the hive. The nectar wets the pollen, decreasing its viability and holding it fast. Many native bees, in contrast, use dense patches of hair to transport dry pollen back to their nests. This dry pollen is much more available for plant pollination. Furthermore, some native bees, such as the orchard mason bee, transport pollen on the underside of their abdomens, which makes the pollen very accessible for transfer among flowers.

Why Farm for Native Bees?

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8 Farming for Bees

Mason bees are one of the native species that can be reared easily—and even sold to home gardeners—in paper nest tubes. (Photograph by Mace Vaughan, The Xerces Society.)

Native Bees Are Diverse and StableUnless they are killed by insecticides, good habitat can support strong and diverse communities of native pollinators. If a population of one bee species declines because of natural cycles of parasites or disease, other native bee species can fill the gap, thus providing a stable, reliable source of pollination.

A recent research finding provides further support that a diverse community of wild bees can provide stable crop pollination. In over 40 crops worldwide, pollination by native wild bees increased yields in all of the crops studied, while pollination by the honey bee only increased yields in 14% of those same crops. Even in crops stocked with honey bees, honey bees did not fully replace the pollination services provided by wild pollinators.

Native Bees May Provide Additional RevenueHabitat installed on farms to support bees can see increases in numbers of bees, as well as increases in pollination and yield of bee-pollinated crops. Meadow plantings can pay for themselves within 3–5 years, and hedgerow plantings within 5–10 years.

Farms that provide habitat for native bees may promote themselves as wildlife-friendly or sustainable. When faced with many choices about where and from whom to purchase produce, many consumers will choose farms that are “pollinator-friendly” or “wildlife-friendly” over others. In addition, if a small farm is open to tours or u-pick visits—an increasing trend, especially at vineyards and pumpkin patches—beautiful hedgerows and other habitat improvements for pollinators and wildlife can be promoted. A farm could even host a tour showcasing its resident beneficial insects.

In addition, some species of wood-nesting (also called tunnel-nesting) bees may be reared in nest tubes and sold at local farmers markets or produce stands for home gardeners looking for efficient, local, and gentle (non-stinging) pollinators.

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How Native Bees Benefit Crops

If enough natural habitat is close by, native bees can provide all of the pollination necessary for many crops.

Native bee communities can be very diverse in crop systems. For example, 51 species of native bees have been observed visiting watermelon, sunflower, or tomato crops in California, and over 45 species of bees have been recorded pollinating berry crops in Maine and Massachusetts. In addition, 67 species of native bees visit blueberries in Nova Scotia, and 62 have been recorded visiting highbush blueberry in Michigan. Over 180 species of bees have been documented in Pennsylvania apple orchards during the growing season.

Native pollinators have been shown to nearly triple the production of cherry tomatoes in California.

Wild native bees improve the pollination efficiency of honey bees in hybrid sunflower seed crops by causing them to move between male and female rows more often. Only the fields abundant with both native bees and honey bees had 100% seed set.

Native bees also improve the pollination efficiency of honey bees and fruit set in almond orchards by causing honey bees to move between rows more often.

Research suggests that in the absence of imported honey bees, canola growers in Alberta, Canada, make more money from their land if 30% is left in natural habitat, rather than planting it all. This habitat supports populations of native bees close to fields, which increase bee visits and seed production in the adjacent crop.

A diverse bee community improves crop pollination services, even when honey bees are present, and provides more stable pollination in variable weather conditions.

Crop pollination by honey bees cannot fully replace the pollination services provided by a diverse community of wild bees.

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Native plants visited by bees can have other uses as well. For example, in some areas of the United States federal and state agencies need large amounts of native seed for habitat restoration efforts. It is possible that such a market exists in your area and that native shrubs and wildflowers could be grown as a source of seeds or cuttings. This kind of crop would have the dual benefits of providing wonderful forage for native insects and another source of revenue for the farm.

Native Bee Habitat Supports Health of Managed BeesIn addition to supporting wild bees, flower-rich habitat on farms can support honey bee health. One of the factors thought to contribute to declines and high annual losses of honey bee colonies is a lack of pollen and nectar in the landscape. Deficient nutrition can negatively impact the development and survival of honey bee colonies. Honey bees reared on multiple sources of pollen have improved immune system function, and are better equipped to survive parasitism by microsporidian parasites (Nosema ceranae).

Pollinator Habitat Provides Other BenefitsIn addition to the benefits of pollination, restoring or creating habitat has other ecological benefits. If placed along drainage ditches or field edges, these conservation plantings can reduce erosion of farm soils and thus save the cost of cleaning out ditches or tail-water ponds. They can also reduce the loss of irrigation water and the leaching of pesticides and fertilizers. When firmly established, native plant habitat created adjacent to fields can supplant the sources of weed seeds that were growing in those same places. Over the long-term, removing the weed seed bank will lead to a reduction in the amount of time, resources, and herbicides used to maintain these areas.

This habitat will also support other wildlife. Beneficial insects, such as parasitic wasps and predaceous beetles, will take up residence and help reduce the number of pest insects on a crop. Snags (dead standing trees) left along stream banks or field edges for tunnel-nesting bees will also provide perches and nest sites for woodpeckers and other birds. Owls and other raptors may take up residence in restored habitat* and can help control rodent populations. Protecting, enhancing, restoring, and creating habitat for pollinators will have wider benefits for both a farmer’s bottom line and for wildlife.

An abundance of farewell-to-spring blossoms fill a successful and aesthetically pleasing pollinator habitat installation at this organic vegetable farm. (Photograph by Brianna Borders, The Xerces Society.)

*NOTE: Due to wildlife safety concerns, we recommend attaching habitat signs to the top hole of the fence post or plugging the top hole with a bolt and nut. Alternatively, posts which do not have holes—such as solid wood stakes—should be used.

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Case Study: Pollinator Conservation Brings Life Back to California FarmDriving through the farm fields of Colusa County in California’s Central Valley is a good way to dispel any sentimental image of farmland as lush, pastoral, and nature-rich. Massive monoculture acreages push right up against dusty roadsides, with virtually no wild plants in sight. The banks of irrigation ditches and road edges are sprayed constantly with herbicides and disked until the dry soil takes on the consistency of powdered sugar—and pests are suppressed with mammoth boom sprayers and aerial crop dusters. The only nature that takes root in the midst of these farmlands tends to be the toughest weeds like mustard and yellow star thistle, and highly mobile cropland pests like starlings and ground squirrels.

Yet, in the midst of this unlikely backdrop one company is seeking to reverse the trend and bring a little bit of nature back to Colusa County. Working with Xerces staff, Muir Glen Organic Tomatoes has launched one of the largest native plant hedgerow projects in the area. This effort not only provides pollinator habitat adjacent to one of their processing facilities near the town of Williams, but also functions as a living demonstration site and outdoor teaching facility for Muir Glen’s local network of organic tomato farmers. Established in 2012, the mile-long hedgerow has restored a formerly barren and compacted dirt roadside to create a vibrant, functional, and beautiful pollinator corridor.

The background behind this success is rooted in the particular value that native bees offer to agriculture. Recognizing how research now demonstrates a strong link between buzz pollination by bumble bees and increased tomato yields, Muir Glen worked with Xerces to design a complex, highly diverse hedgerow made up of dozens of species of native shrubs, bunch grasses, and wildflowers that would attract those and other native bees with both food sources and nesting habitat.

As a first step in this process, the project team worked to immediately stop erosion and soil loss at the site by terracing the roadside slope to establish a level planting area. The slope was further stabilized with straw erosion-control waddles, and the soil was amended with compost to add back organic matter and soil microorganisms.

Then, as a second step, the team hand-planted hundreds of the larger plants along the top of the slope, including elderberry, manzanita, deergrass, California lilac, coyotebrush, California buckthorn, showy milkweed, bladderpod, bush lupine, and many others. After planting, these transplants were initially supported with a single drip irrigation line and were heavily mulched with almond shells from local orchards. Because these native plants are highly drought-adapted, irrigation only needs to be maintained for the first two years of establishment before being removed in the third year.

Finally, supplementing the larger plants along the lower part of the slope, a diverse understory of native wildflowers, like California poppy, lacy phacelia, and Bolander’s sunflower, was direct-seeded to further stabilize the soil and expand the plant diversity.

To ensure that the hedgerow is functioning as intended, Muir Glen and Xerces partnered with University of California–Davis scientists to monitor the abundance and diversity of bees using the new hedgerow and to compare those findings against the abundance and diversity of bees found in the field edge areas of other farmland nearby (where hedgerows were not present). Amazingly, after only the first year, the findings were dramatic—nearly twice as many bees were found at the Muir Glen hedgerow as were found on the edges of other nearby farm fields.

Supplementing these findings, additional research conducted by scientists at University of California–Berkeley now demonstrates that, in California’s Central Valley, farmers can typically expect to see a return on investment within 10 years for the costs involved in planting a hedgerow (this time can be cut in half with USDA financial assistance through Farm Bill conservation programs). That return on investment comes in the form of enhanced crop pollination, and in reduced pest damage due to the increased numbers of beneficial insects that prey upon crop pests.

While financial returns and crop yields are a key part of the equation, Muir Glen’s success story runs deeper. A once-dry, desolate landscape now stands as a green, life-filled example of what is possible. This is a significant step in a new farm paradigm that will be necessary for others to follow if wild pollinators are going to have a role in agriculture, both in Colusa County and beyond.

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Hundreds of plants were hand-planted as part of this hedgerow project. Irrigation was maintained for the first two years to insure proper establishment while their root systems developed. (Photograph by Eric Lee-Mäder, The Xerces Society.)

One of the benefits of landscaping with native plants is their drought tolerance. In this hedgerow, irrigation was removed after two years of establishment, even though the area was experiencing a prolonged drought. (Photograph by Jessa Kay Cruz, The Xerces Society.)

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Because farmers have busy schedules and tight budgets, we promote a three-step approach to pollinator conservation that takes these constraints into account.

1. Recognize the native bees and bee habitat that are already on the farm.

2. Adapt existing farm and land management practices to avoid causing undue harm to the bees already present.

3. Provide habitat for native bees on and around the farm.

The first two steps require very little outlay of cash and a relatively small time commitment. The third step—developing habitat—requires more thought and effort. Our hope is that the details provided here will make this more-intensive third step straightforward for those interested in taking actions to increase the number of native pollinators on their farms. By following this approach, farmers can ease into pollinator conservation and determine whether spending additional time and money is worthwhile.

Recognize Resources Already on the FarmThe photos in this guide and the resources listed in Appendix D provide tools for learning to recognize native bees already visiting fields. By observing the flowers in a crop, growers and conservationists likely will notice bees other than honey bees and even discover that these other species are abundant, especially if the farm is located close to natural areas.

Finding Important Plants

After noticing the native bees that are present, learning to recognize plants that support native bees is also important. The best of these flowers will be crawling with many insects, mostly bees, and may be found in many places, including roadsides or field borders, around farm buildings, or under power lines. These flowers, which may seem like a distraction from a crop, are in fact helping local bees reproduce with greater success: the more forage available means the more offspring visiting the farm the following year. If competition with a crop is a concern, look carefully for those plants blooming before and after a crop comes into bloom. These are a critical resource for supporting the bees that forage on the target crop.

Three Steps to Success

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Finding Nests

Look for nest sites around the property. Nests of ground-nesting bees likely occur in semi-bare patches of soil in well-drained areas, often on slopes. Wood-nesting bees will be in beetle tunnels in snags or in elderberry, sumac, blackberry, or other shrubs with soft-centered twigs. Bumble bees may be nesting in old rodent burrows or under tussocks of grass. Be on the lookout everywhere.

To find ground or bumble bee nests, pay attention to bees flying low over the ground where flowers are not present, especially if they look like they are searching for something (that is, moving back and forth over a small patch of ground and occasionally landing).

Most bees are active on warm sunny days, from mid-morning through the afternoon. Some, however, may be active early in the morning (for example, squash bees), while others will continue flying late in the evening (bumble bees). One to thousands of bees may be present at a nest site, and they may be as small as a medium-sized ant (less than ¼") to larger than a honey bee (¾").

In the case of ground-nesting solitary bees, the nest entrance will be visible only when the adults are active, the timing of which varies from species to species. The nests that these bees occupy appear as small holes in the ground, often with piles of excavated soil around the entrance. In some cases, they may look like the entrance to an ant nest or a worm hole.

In summary, all areas left untilled—woodlots, riparian corridors, utility easements, road edges, and conservation areas, as well as unused land around fields, farm buildings, and service yards—can provide forage and nest sites. These sites have relatively undisturbed conditions that allow bee plants and nests to become well-established, and they may be enhanced with the addition of key native flowering plants and/ or nest site materials (see following chapters for details).

Beetle-riddled snags, such as this one, are another important nesting site for solitary bees. (Photograph by Jennifer Hopwood, The Xerces Society.)

Bees seen entering or leaving holes in the ground are a sure sign of an active nest site. (Photograph by Mace Vaughan, The Xerces Society.)

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Adapt Existing Farm PracticesWhether or not growers or conservationists take the time to identify specific sites harboring ground-nesting bees or forage plants, farm management practices can be adjusted to take important pollinator resources into account. One important step is to minimize the risk to bees from pesticide applications. Reducing pesticide drift and creating buffer zones around a crop—for example, the outermost 20' of a crop—will go a long way toward protecting bees nesting or foraging in field margins.

Minimizing the practice of fencerow to fencerow farming, so that crop fields retain an uncultivated, untilled field margin, will provide areas where ground nests and forage may become established.

Depending upon the cropping system and the plants raised, farmers also may consider letting plants flower whenever possible (as happens already in many cases). Allowing crops such as lettuce, arugula, radish, broccoli, potatoes, endive, kale, brussel sprouts, cilantro, basil, and forage legumes to bolt before tilling provides an additional source of forage for bees.

Staggering planting of a single crop variety or choosing multiple varieties with different flowering periods also helps support pollinators by extending the period over which flowers are available. This allows more time for populations of native bees to forage on a crop, increasing their reproductive success.

Another way to support native bees and their habitat is to leave areas supporting native bees alone as much as possible. For example, sites with ground nests should be protected from tilling or insecticide applications. Rodent burrows can be left for bumble bee nests, and beetle-riddled snags should be left for mason and leafcutter bees. Sites on which good forage plants grow should be protected from disking, insecticides, and herbicides.

If good forage plants also happen to be weeds, rethink whether the need to remove the weeds outweighs the value of the pollinators these plants support. It makes sense to remove the source of noxious weeds, of course, but it is worth giving a second thought to less invasive species. Weeds also may be an important resource in dry late summer conditions, and can extend the reproductive season of the few species of native bees that produce many generations per year, like bumble bees and some sweat bees.

Native bees may also take up residence in a field. For example, squash bees are tightly connected with their cucurbit host flowers and may dig vertical tunnels in the ground near the host plants. Because the cells containing the next generation are typically concentrated 6"–12" below the surface of the ground, plowing these nests kills most of the developing bees. Therefore, those farmers discovering squash bees living in fields of melons and squash could try setting their plows at shallower depths, ideally less than 6", or investigate the use of no-till options.Flowers providing nectar and pollen are a necessary part of pollinator

habitat. (Photograph by Jennifer Hopwood, The Xerces Society.)

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Xerces Society Pollinator Habitat Assessment Guide

The Xerces Society developed a Pollinator Habitat Assessment Form and Guide to help farmers and conservationists assess specific habitat features on and around the farm for value to pollinators, and to evaluate and prioritize future habitat enhancements. This comprehensive planning tool is available at: http://www.xerces.org/wp-content/uploads/2009/11/PollinatorHabitatAssessment.pdf

In addition, see Appendix C for a Pollinator Habitat Checklist with potential pollinator foraging and nesting habitat features on farms.

Provide Habitat for Pollinators on FarmsFarmers who want to take a more active role in increasing the numbers of native bees around farms can do three things to make the land more hospitable for pollinators.

ӧ Increase the available foraging habitat to include a range of plants blooming at different times to provide nectar and pollen throughout the seasons.

ӧ Create nesting sites by providing suitable ground conditions or tunnel-filled lumber and appropriate nesting materials. About 70% of bee species nest in the ground and 30% use tunnels bored into wood. Bumble bees—a small, but very important group of bees for crop pollination—require small cavities in which to fashion their nests.

ӧ Reduce the risk to bees from the use of insecticides and herbicides, which directly kill pollinators or the plants they rely on. Select less toxic insecticides or utilize alternative strategies to manage pest insects and minimize the use of insecticides.

The chapters that follow detail how to enhance habitat for native bees, starting with choosing sites for habitat improvements within and around the farm landscape. The next three chapters address the major constraints to populations of native bees: forage availability, nest site availability, and pesticide use. In each chapter we describe how to provide these habitat resources and/ or how specific farm management practices may be altered to reduce the impacts on crop-pollinating native bees. It is important to keep in mind that a wider range of ecological conditions on a farm will attract a greater diversity of species.

A hedgerow of native flowering shrubs flanked by native bunch grasses offers many resources to pollinators. The fallen grass can become a haven for bumble bee nests and the shrubs provide pollen and nectar. (Photograph by Jessa Kay Cruz, The Xerces Society.)

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Providing forage for wild bees is critical for their reproductive success. When more pollen and nectar are available close to bee nest sites, female bees can forage more efficiently and lay more eggs. The ultimate result is a farm that grows an abundance of its own pollinators. Here we provide considerations on how to choose plants for pollinator habitat, gardens, and forage cover crops, and techniques to establishing foraging habitat.

Plant SelectionTo be of greatest benefit to the pollinators living around a farm, foraging habitat should contain a wide variety of plants that provide a succession of flowers throughout the growing season. The plants included in a patch or hedgerow of bee forage also should require minimal maintenance once they are established. Native plants are frequently the best choice because bees tend prefer to forage on native plants over introduced plant species. Native plants are also adapted to grow in the local climate and soils and, once established, they require little attention. However, non-invasive, non-native plants may be used when cost and/ or availability are limiting factors.

The appendices provide specific information on finding appropriate pollinator-friendly plants for restoration projects. Appendix B includes an example seed mix for a meadow planting, a regional species list for a hedgerow, and lists of cover crops and garden plants that are excellent sources of pollen and nectar for bees. Appendix D includes links to national and regional lists of plants that are important sources of forage for bees across the United States. Used with the guidelines below, and in consultation with native plant nurseries, native plant societies, or local arboretums, this information will help land managers choose regionally-appropriate plants for native bee habitat.

Plant Diversity and Bloom Time Succession

The best bee habitat contains a diversity of flowering plants. Pollinator diversity increases with increasing plant diversity. A range of flower shapes supports more bees and other beneficial insects. Bee species vary in size and have different tongue lengths; consequently, they will feed on differently-shaped flowers. There is a rough correlation between the depth of the flower tube and the length of the tongue of the bees that use them. Some very open flowers, such as asters, have nectar and pollen that is readily accessible to insects of all sizes, including bees with short tongues. Other flowers, such as lupines and penstemons, have pollen or nectar that is harder to reach and are preferred by robust bees—such as bumble bees—that can push between the petals. Focus on selecting plants known to provide abundant forage for bees (See Appendices B and D for resources).

Creating Foraging Habitat

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This diverse pollinator habitat installation, adjacent to an almond orchard on Tadlock Farms, Colusa County, California, provides forage for bees after the almond bloom in early spring. Dominant flowers in bloom are lacy phacelia, California poppy, and arroyo lupine. (Photograph by Jessa Kay Cruz, The Xerces Society.)

Foraging habitat for bees should include flowers with overlapping bloom times to provide continuous floral resources throughout the growing season. Adult bees can be seen anytime between February and November; they have longer seasons in areas with mild climates. The social bumble bees may be seen in any of these months, whereas the emergence of many solitary bees is synchronized with the flowering period of particular plants or groups of plants. Therefore, a sequence of plants—from willows in the spring to goldenrod in the fall—that provide a diversity of flowers throughout the growing season is needed to support a wide range of bee species with variable flight periods.

It is especially important to include plants that flower early in the season. Many native bees, including bumble bees and some sweat bees, produce multiple generations each year. More forage available early in the season will lead to greater reproduction and more bees in the middle and end of the year. Early forage may also induce bumble bee queens emerging from hibernation to start their nests nearby and be more successful in raising their first brood of workers.

In some regions, early blooming wildflowers are not widely available as plant material or are difficult to establish. Consider including early blooming shrubs in addition to planting wildflowers that will flower later in the spring through the fall, in order to provide season-long forage.

Diverse, blooming wildflower habitat supports bees and other beneficial insects. (Photograph by Eric Lee-Mäder, The Xerces Society.)

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Choose Plants That Complement a Particular Crop

Bees are active as adults before crops come into bloom and are still active afterwards. Therefore, plenty of forage should be on hand before and after a particular crop comes into bloom. This timing will attract bees to a farm, ensure that the local crop-pollinating bees can successfully raise many young, and offer the least competition with a focal crop.

If a farm already grows a diversity of crops, the timing of flowers produced by non-crop plants is less of a concern. The crops themselves help provide a sequence of bloom. If growing a perennial crop, such as orchards or berries, cover crops between rows may include plants like white clover that can be cut short when the crop is in flower, but then be allowed to bloom afterwards.

Use Locally Adapted Native Plants

Local native flowering plants are usually well-adapted to the growing conditions at a specific site. They thrive with minimum attention; are good sources of nectar and pollen for native bees; and are usually not weedy. In addition, many local native bees may be adapted to gather pollen and nectar from these native plants, and research indicates that even introduced bees like honey bees often prefer to forage on native plants. Horticultural varieties and hybrids, in contrast, are not always adapted to local conditions, and some may have been bred to produce showy blooms or other traits at the expense of nectar or pollen production.

When obtaining native plants, it is best to find out where the seed came from. Some plants sold as native are not from local sources and may not survive as well as plants grown from locally-collected seeds. Other potential sources of plant materials are seeds gathered from flowers in local wildlands. This requires more work and access to natural areas, but also results in locally-appropriate plants that, in the end, may be less expensive to rear.

Project Integrated Crop Pollination

To meet the needs of growers of pollinator-dependent specialty crops, Project Integrated Crop Pollination (ICP) is conducting research and extension nationwide on pollinator habitat enhancement and farm management practices that increase wild bees, as well as techniques for managing alternative bees for crop pollination.

ICP integrates habitat enhancement for wild bees, farm management practices to support bees, and use of diverse managed bee species into farm systems. Funding from the USDA Specialty Crops Research Initiative is supporting this team of scientists and outreach specialists. Project ICP research is also improving the use of alternative managed bees, such as bumble bees and mason bees, to increase the reliability of crop pollination. Project ICP has a strong economic and social component, and will assess how best to fit ICP strategies into different scales of crop production, as well as how best to share project results with specialty crop growers nationwide to achieve meaningful adoption. See Project ICP’s website for more information: www.projecticp.org.

Many mining bees emerge early in the season, when fruit trees are in bloom. They can be excellent orchard pollinators. Here, a mining bee pollinates an apple blossom. (Photograph by Nancy Adamson, The Xerces Society.)

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Avoid Invasive Plants and Alternate Pest or Disease Hosts

Avoid plant species known to be highly invasive or weedy on the farm. These plants likely will spread and dominate other species, reduce the diversity and value of the habitat, and increase maintenance demands—both in the habitat patch and elsewhere around the farm. They also may spread beyond the farm and cause problems in neighboring natural areas. For example, many mustards provide good forage for bees and work well in orchard understories where regular mowing or spraying can manage weeds. On nearby organic or row crop farms, these same mustards can spread and be a challenging weed.

In most cases, native pollinator plants do not serve as alternate hosts for crop pests or diseases, but selected plants should be cross-referenced for specific crop pest or disease associations. Research indicates that weedy borders harbor more pests than are found in diverse native plantings. This is likely because many if not most of our roadside weeds are Eurasian species that are frequently related to many of our crops.

Choose Appropriate Plants for the Site

The environmental conditions of the chosen habitat area will influence the choice of plants. Sun-loving prairie plants obviously will not do well if planted in the shade of trees, nor will shade-dwelling forest plants thrive in the sunny exposure of a prairie. It is harder to pay attention to the changes in soils, slope, exposure, and moisture across a site, but these also should be taken into account whenever possible. One way to address this situation is to take notes on the native plants growing wild in similar conditions nearby.

Planning 5–10 years ahead can also help guide plant choices. Consider the use of the land immediately around the habitat and how it will be affected by the size, structure, and/ or needs of the chosen plants when they are mature. For example, when planting a hedgerow next to a road, ditch, or service area, properly chosen trees and shrubs may serve as forage for pollinators and also grow to provide privacy or shelter from wind. If planting habitat between fields, shorter plants will be advantageous in that they will not compete with adjacent crops for sunlight. Pollinator habitat between fields will benefit from the adjacent irrigation; plants with greater water needs may grow better close to fields than farther away.

Not Sure Which Plants Might Be Weedy or Invasive in Your Region?

Visit the USDA–NRCS PLANTS Database to find lists of noxious weeds by state, as well as a list of species that are weedy or invasive or have the potential to become problematic within the United States: https://plants.usda.gov/java/noxiousDriver#state. You might also consider checking with your county for any code restrictions on noxious weed species.

Rattlesnake master (foreground) and blazing star are high-quality, native floral resources for bees and other beneficial insects. (Photograph by Jennifer Hopwood, The Xerces Society.)

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Ease of Planting and Establishment

If possible, choose species that are easy to plant and establish. This information most efficiently comes from local experts in habitat restoration. Consider consulting with staff from local offices of the Natural Resource Conservation Service (NRCS), Soil and Water Conservation District (SWCD), Cooperative Extension, native plant societies, or non-profit organizations that work on habitat restoration.

While plants are being chosen, it is worth considering what existing equipment and infrastructure are in place for planting and maintenance. For example, is equipment on hand for sowing seed, which would make it easy to create a patch of flowering forbs? How would a new planting fit into a pre-existing irrigation system?

Include Some Grasses

Although grasses do not provide nectar or high-quality pollen for foraging bees, consider including one or more species in your habitat planting. Grasses are larval host plants for some butterflies, provide potential nesting sites for bumble bee colonies, and can be overwintering habitat for bumble bee queens as well as other beneficial insects. In addition, grasses help to buffer against invasive weeds. In seed mixes, aim to include shorter-statured bunch grasses or low densities of tall grass species, in order to avoid competition with wildflowers.

Establishing Pollinator HabitatFlowers can be established from seeds or transplants, or a combination of both, depending on your goals for your habitat. If your planting is large, planting seeds is most the cost-effective approach. Additionally, some species are only available as seed. However, if you are looking for your habitat to provide resources as soon as possible, transplants will flower more rapidly than plants that establish from seed. Transplants also have a competitive advantage over weeds than seed and are more likely to survive drought once they are established. No matter the type plant material you select for your project, site preparation to reduce weed pressure as well as maintenance over time is critical for the success of the planting.

Site Preparation

Before planting either seeds or transplants, site preparation is a critical step. Site preparation involves removing existing vegetation and reducing the amount of weed seed and rhizomes in the soil, in order to reduce competition and give your plants their best shot at establishment. Depending on the abundance of weeds, more than one year of site preparation may be needed.

Site preparation can be performed using several different methods. The use of broad-spectrum herbicides is a low cost and effective approach. Repeated treatments throughout the growing season may be needed to kill existing vegetation and subsequent emerging weeds. When the use of herbicides is not an option, such as on organic farms, using clear UV-stabilized plastic to solarize existing vegetation can also be effective. Mow existing vegetation, smooth the site, and lay down the plastic, burying the edges to prevent airflow underneath the plastic. Leave the plastic in place during the hottest time of the year before removing it in early fall before the weather cools dramatically. In certain regions, soil inversion

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using a moldboard plow may be an herbicide-free option for sites that are too large for solarization (see case study on Vilicus Farms in Montana, page 24).

After existing vegetation has been removed, soils should be smoothed and lightly packed. A rake or turf roller can be used to break up clumps in small sites, and a cultipacker or tractor-drawn roller can be used at larger sites.

Establishing Seed

Local seed vendors can provide recommendations of how much seed you need for your site; generally recommended rates for wildflower plantings range from 40–60 seeds per square foot. You can also develop your own seed mix with certain proportions of particular species (see Appendix D for tools, such as a seed rate calculator). See Appendix B for an example seed mix. While the species may not be appropriate for your area, the general features of the list (bloom time succession, grass density, etc.) will help to serve as a starting point.

Early fall or dormant season planting of wildflower mixes is generally recommended for most regions of the county. Many perennial plant seeds need exposure to cold, damp conditions over time to successfully germinate. Although spring plantings are possible, they tend to favor establishment of grasses over wildflowers.

Seeds can be planted into a clean seedbed using a no-till native seed drill, a mechanical broadcaster, or can be broadcast by hand. Though low-tech and low-cost, broadcasting seeds by hand can be very effective. Seeds can be scattered onto the soil surface by hand, with hand operated crank seeders, or with ATV-mounted seed spreaders. Before spreading seed, mix the seed with an equal or greater volume of a bulking agent such as sawdust, coarse sand, vermiculite, or other inert material. The inert material will help distribute seeds of various sizes throughout the mix, and will provide visual feedback on where seed has been thrown. Then divide the mix into two separate batches and spread the batches onto the site in perpendicular passes to distribute the seed evenly across the site. Seed can then be pressed into the ground using a turf grass roller or cultipacker, which provides good seed-to-soil contact.

Native wildflower insectary strip for pollinators at University of California–Davis Sustainable Agriculture Research Facility, Yolo County. Dominant flowers in bloom are golden lupine and California phacelia. (Photograph by Jessa Kay Cruz, The Xerces Society.)

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Monarch butterfly, honey bee, and leafcutter bee all nectaring on a milkweed flower. Milkweed are highly attractive to many pollinators. (Photograph by John Anderson, Hedgerow Farms, Inc.)

Establishing Transplants

After site preparation, woody or herbaceous transplants can be installed at any time the ground can be worked. Most woody shrubs can be spaced 4'–10' apart (depending upon size at maturity), with most herbaceous plants spaced closer to 2'–3' apart. It is helpful to measure the planting areas prior to purchasing transplants, and to stage the transplants in the planting area prior to installing them in the ground.

If transplanting an herbaceous species, dig a hole the same depth as the container and place the plant within the hole so that the roots and a small portion of the stem will be covered by soil. When planting trees and shrubs, place plants within holes so that the base of the plant is slightly above the soil. Mulching is recommended to reduce weed competition and to retain moisture during the establishment phase. Recommended materials include wood chips, bark dust, weed-free straw (e.g., rice straw), nut shells, or other regionally-appropriate mulch materials that contain no viable weed seeds.

Transplant installation should be timed to avoid prolonged periods of hot, dry, or windy weather. Regardless of when planting occurs, however, the transplants should be irrigated thoroughly immediately after planting. Holes for plants can be dug and pre-irrigated prior to planting as well. Follow-up irrigation is dependent upon weather and specific site conditions, but generally even native and drought-tolerant plants should be irrigated with at least 1" of water per week (except during natural rain events), for the first two years after establishment. Long, deep watering, via drip irrigation, is best to encourage deep root system development. Irrigate at the base of plants, and avoid overhead irrigation, which encourages weed growth. Once plants are established, irrigation should be removed or greatly decreased.

Below-ground wire cages are recommended if rodent damage is likely. Similarly, plant guards may be needed to protect plants from above ground browsing or antler damage by deer.

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33The Xerces Society for Invertebrate Conservation

Ongoing Management

Newly planted areas should be clearly marked to protect them from herbicides or other disturbances. Signs can be particularly useful during the establishment phase, when the planting may not yet be easily recognizable as habitat.

Following planting, weeds should be prevented from going to seed in or adjacent to the project area during the first two years. Common weed management strategies include careful spot-spraying with herbicides, use of grass-selective herbicides to control weedy grasses, or use of mowing or string-trimming. When planted with perennial seed mixes, sites can be mowed occasionally (ideally as high as mower settings allow) during the first year after planting to prevent annual and biennial weeds from flowering and producing seed. Perennial wildflowers are slow to establish from seed, and are usually not harmed by incidental mowing in the first year after planting.

Established habitat also needs some maintenance over time. Possible management tools/ techniques to maintain wildflower plantings include mowing or burning. If mowing is used, be sure all equipment is clean and free of weed seed. Do not mow or burn during critical wildlife nesting seasons (consult your state wildlife biologist for specific guidance). After establishment, no more than 30% of the habitat area should be mowed or burned in any one year to ensure sufficient undisturbed refuge areas for pollinators and other wildlife.

Ongoing management of woody plant habitat includes removing tree guards or other materials that could impede plant growth after establishment. In most cases, irrigation can be removed from transplants by the end of the second year after planting. Ongoing herbicide use (spot-treatment) or occasional hand- weeding may be necessary to control noxious weeds.

Choosing Garden PlantsMany plants native to North America, but not necessarily native to your area, are wonderful pollinator plants and well-suited to gardens. Similarly, many other flower garden plants that originate from Europe and elsewhere provide abundant nectar and pollen. English lavender and most culinary herbs are good examples. As a general rule of thumb, heirloom varieties of perennials and herbs are the best sources of nectar or pollen. Newer hybrid flower varieties often have been bred for color or size and, in the process, may inadvertently have lost some of their ability to produce nectar and pollen. Varieties with double petals are often indicative of plants that have been extensively bred and may lack pollen and/ or nectar resources. See Appendix B for garden plant recommendations.

Long-horned bee foraging on a cosmos flower. Cosmos is a great plant to include in a farm garden or for the sale of cut flowers. These flowers hum with native bees in summer months and are easy to grow. (Photograph by Mace Vaughan, The Xerces Society.)

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Planting Forage Cover CropsFlowering cover crops are a simple and effective way to quickly increase the amount of pollen and nectar available on the farm. The ground beneath the rows of orchards, blueberries, cane crops, and vineyards, as well as the lawns around buildings, roadside strips, and fallowed fields can easily be sown with a ground cover that provides nectar and pollen for supporting native bees. Cover crops can also provide several other benefits, such as improving erosion control and soil permeability, fixing nitrogen, discouraging weeds, and harboring beneficial insects. Plant selection and the timing of crop termination are the two keys to maximizing the impact of cover crops for bees.

Plant Selection

Nectar-rich broadleaf cover crops should be prioritized when selecting cover crop species for bees. For example, various clovers, vetches, brassicas, and lacy phacelia are common cool-season cover crops that are highly attractive to various bees. Depending on the location, a variety of warm-season cover crop species such as buckwheat, sunn hemp, cowpea, and sunflower are also available. When used in combination with high-quality, permanent native plant habitat on the farm, overlapping cool-season and warm-season cover crop rotations can sustain robust bee populations throughout the year.

In recent years there has been a trend toward diverse, multi-species, cover crop seed mixes (‘cocktails’). While this practice is still in its infancy, the benefit to bees is likely significantly higher than that of single species cover crops. In particular, the inclusion of many different flowering broadleaves in a cover crop seed mix will provide an extended period of flowering, and will provide a variety of flower shapes and types to attract and sustain a diversity of bee species. Table 6.1 provides an example of a diverse, multi-species, cool-season cover crop seed mix.

While grasses are not typically attractive to bees, grass cover crops such as rye and oats provide other benefits (including benefits to soil health), and are easily integrated into diverse, multi-species seed mixes.

Finally, to reduce the possibility of increasing crop pests, we recommend caution when considering the use of cover crop plants that are closely related to cash crops. For example, if brassicas such as broccoli or cabbage are your primary cash crops, it may be advisable to minimize the use of brassica cover crops such as turnip, radish, or mustard, all of which may host the same pests and diseases.

Despite this caution, we strongly suspect that multi-species cover crops will generally reduce pests by increasing populations of the beneficial insects that prey upon them. Additional research is needed to compare the pest management benefits of multi-species versus single-species cover crops, but the overwhelming general trend revealed by most research is toward reduced pest pressure in highly diversified crop systems.

Table 6.1: Sample Cool Season Cover Crop “Cocktail”

SPECIES % OF MIX LBS/ AC.

Phacelia 8% 0.5

Crimson clover 8% 0.75

Radish (daikon) 8% 1.75

Hairy vetch 8% 5.5

Field pea 8% 40

Turnip 8% 0.5

Fava bean 2% 70

Rye 25% 15

Oats 25% 17

TOTAL 100% 151

Formulated for one acre at 25 seeds per square foot

35The Xerces Society for Invertebrate Conservation

California bumble bee visiting fava bean blooms. An excellent cool-weather cover crop, fava bean can provide forage for bees in early spring or late fall. (Photograph by Rich Hatfield, The Xerces Society.)

Cover Crop Termination and Residue Management

While necessary to prepare for cash crop rotation, terminating a cover crop can be difficult for pollinators, especially if the cover crop is still flowering at time of termination. The risks to bees from cover crop termination include direct mortality (such as being crushed by cultivation or roller-crimping equipment), and indirect harm such as the rapid loss of available food sources. Even when adult bees are not active and/ or present in a cover crop, egg-filled nests or hibernating adults may still be present in the crop residue or in the soil.

To reduce some of the impact of cover crop termination, we recommend the following:

ӧ Where possible, wait until most of the cover crop is past peak bloom (but before cover crop seeds are mature) to terminate.

ӧ Terminate with as little physical disturbance as possible (for example, roller-crimping may be less disruptive to bee nests in the soil than cultivation).

ӧ Maintain permanent conservation areas on the farm to sustain bees in the absence of the cover crop.

ӧ Leave as much cover crop residue as possible to protect nests and any dormant adult bees (such as bumble bee queens).

ӧ Minimize insecticide use in cash crops where cover crops were previously planted to avoid harming bees that may still be nesting within the cover crop residue. At a minimum you should follow an IPM plan that includes risk mitigation strategies designed to protect pollinators.

Many farmers are increasingly adopting “cover crop cocktails.” This cool-season cover crop in North Dakota includes vetch, radish, oats, turnip, phacelia, and several other species. (Photograph by Eric Lee-Mäder, The Xerces Society.)

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Limitations of Cover Crops

Although cover crops can provide a significant pollen and nectar resource for bees, it should be recognized that they do have limitations. For example, because most cover crops are temporary, they may present a “feast or famine” situation for bees with an abundance of food, followed by a food shortage. Under such circumstances wild bees may have limited reproductive success.

Additionally, because most cover crop plants are non-native, their attractiveness to native bees may be highly variable. In general, most bees attracted to cover crops tend to be species that are already relatively common. Less-common native bees often require plant communities comprised primarily of native plant species. Therefore, to maximize pollinator diversity and abundance, cover crops should be used in combination with high-quality, pesticide-free native plant habitat that is maintained in other areas on the farm.

Balancing Pollinators with USDA Cover Crop Rules

Federal crop insurance programs may have region-specific requirements for cover crop termination. These rules typically occur in the drier western states, and are intended to balance the soil–water needs of cash crops following in rotation with cover crops. They typically require the termination of cover crops in advance of cash crop planting (sometimes even before the cover crop has finished flowering).

This scenario further demonstrates the need to supplement pollinator-friendly cover crops with other conservation areas such as hedgerows, permanent wildflower meadows, and buffers. To further reduce the impact of cover crop loss, it may be possible to leave small sections of it in place (such as a single outer row), rather than terminating the entire field for cash crop rotation. Even such small sections can help sustain pollinators in the absence of other forage sources.

For current guidance on cover cropping and crop insurance rules, consult your local NRCS office or crop insurance agent. See Appendix D for sources of additional information on cover cropping.

Consider Bees When Rotating CropsIt is likely that a particular crop grown consistently in one area will develop a population of wild native bees that are regular visitors. If rotating crops, consider the possibility of moving a crop no more than a few hundred yards away. For example, pumpkin and winter squash fields may build up significant numbers of squash bees in and around the fields. Maintaining squash plantings with the landscape may help sustain these populations of specialist pollinators.

A bumble bee nectars on a phacelia bloom. Phacelia is a promising plant for pollinator-friendly cover cropping. (Photograph by Katharina Ullmann, The Xerces Society.)

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Example Wildflower Meadow Seed Mix—Northeast RegionThe seed mix below is an example of what you might consider planting to provide pollinator habitat on one acre in the Northeastern region. For larger areas, increase the rate accordingly. The mix is designed to provide season-long pollen and nectar resources on any sunny, mesic to slightly dry upland site. The species included are usually available from commercial producers.

COMMON NAME SCIENTIFIC NAME % OF MIX SEEDS/ FT2 LBS/ AC. BLOOM TIME

Golden Alexanders Zizia aurea 3% 1.8 0.41 Early

Wild blue indigo Baptisia australis 0.2% 0.12 0.2 Early

Wild lupine Lupinus perennis 0.3% 0.18 0.49 Early

Smooth penstemon Penstemon digitalis 10% 6 0.14 Early–Mid

Butterfly milkweed Asclepias tuberosa 1.5% 0.9 0.56 Mid

Dotted mint Monarda punctata 15% 9 0.26 Mid

Lavender hyssop Agastache foeniculum 8% 4.8 0.2 Mid

Marsh blazing star Liatris spicata 0.5% 0.3 0.13 Mid

Purple coneflower Echinacea purpurea 8% 4.8 1.98 Mid

Virginia mountain mint Pycnanthemum virginianum 10.5% 6.3 0.05 Mid

Wild bergamot Monarda fistulosa 15% 9 0.31 Mid

New England aster Symphyotrichum novae-angliae 5% 3 0.11 Late

Showy goldenrod Solidago speciosa 3% 1.8 0.05 Late

Big bluestem Andropogon gerardii 5% 3 1 —

Indian grass Sorghastrum nutans 5% 3 0.96 —

Little bluestem Schizachyrium scoparium 10% 6 1.86 —

TOTALS 100% 60 8.71

Find the Perfect Mix for Your Region

See Appendix D for links to regional Habitat Installation Guides and a downloadable seed mix calculator. Additionally, specially designed, Xerces-approved regional seed mixes are featured on the Xerces Society’s website at: http://www.xerces.org/pollinator-seed/.

Plants for Bees

Appendix B

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Example Hedgerow Plant List—CaliforniaThe following list represents an example of what you might plant to create a native hedgerow in California. Most of these species are commonly available from local native plant nurseries. For other additional information about installation of hedgerows, see the Habitat Installation Guides (Appendix D).

COMMON NAME SCIENTIFIC NAME MAX HEIGHT

WATER NEEDS NOTES

Early Season Blooming Species

California lilac Ceanothus ‘Concha’ 4' L Tolerates clay soils

Frosty blue California lilac Ceanothus ‘Frosty Blue’ 8’ L Tolerates clay soils

McMinn manzanita Arcostaphylos ‘McMinn’ 5’ L Tolerates clay soils

Narrowleaf willow Salix exigua 10’ H Wetland-riparian to semi-riparian species

Oregon grape Mahonia aquifolium 5’ L Drought-tolerant, but also tolerates semi-riparian conditions

Red willow Salix laevigata 20’ H Wetland-riparian to semi-riparian species; tolerates clay soils

Western redbud Cercis occidentalis 15’ L Drought-tolerant, but also tolerates semi-riparian conditions

Early–Mid Season Blooming Species

Blue elderberry Sambucus nigra var. cerulea

15’ M Host plant for the endangered Valley Elderberry Longhorn Beetle; tolerates semi-riparian conditions

California buckthorn Frangula californica 5’ L

Mule’s fat Baccharis salicifolia 8’ M Wetland-riparian to semi-riparian species

Showy penstemon Penstemon spectabilis 3’ L

Toyon Heteromeles arbutifolia 12’ L Can be an alternate host of fire blight

Mid Season Blooming Species

California buckwheat Eriogonum fasciculatum 2.5’ L Extremely drought tolerant

California wildrose Rosa californica 8’ M Tolerates clay soils; drought-tolerant, but also tolerates semi-riparian conditions; can be a host for spotted wing drosophila

Cleveland sage Salvia clevelandii 3’ L Requires good drainage

Hollyleaf cherry Prunus ilicifolia 15’ M

Narrowleaf milkweed Asclepias fascicularis 1.5’ M Sow seeds individually or transplant larger than plug-sized; host for monarch butterfly; tolerates clay soils, wet, or dry conditions

Appendix B: Plants for Bees

(continued on next page)

Bumble bee on dotted mint (Monarda punctata). Also known as “spotted beebalm”, dotted mint attracts a variety of pollinators and beneficial insects. (Photograph by Don Keirstead, New Hampshire NRCS.)

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This newly-planted hedgerow in California includes a mix of forbs and shrubs—including California poppies, California phacelia, and coyotebrush—that provide continuous forage and nesting habitat throughout the growing season. (Photograph by Jessa Kay Cruz, The Xerces Society.)

COMMON NAME SCIENTIFIC NAME MAX HEIGHT

WATER NEEDS NOTES

Mid–Late Season Blooming Species

Big saltbush Atriplex lentiformis 20’ L Tolerates clay soils; can be extremely drought-tolerant

California fuchsia Epilobium canum 3’ L

Common buttonbush Cephalanthus occidentalis 15’ M Wetland-riparian or semi-riparian species; tolerates clay soils

Gumplant Grindelia camporum 4’ L Tolerates wet or dry conditions

Nettleleaf giant hyssop Agastache urticifolia 4’ M Tolerates clay soils; tolerates semi-riparian conditions

Late Season Blooming Species

California aster Symphyotrichum chilense 5’ L Establishes better from transplant than seed; tolerates clay soils; tolerates wet or dry conditions

Canada goldenrod Solidago canadensis 3’ M Establishes better from transplant than seed; tolerates wet or dry conditions

Coyotebrush Baccharis pilularis 10’ L Dioecious; use male plants to avoid unwanted seeding; extremely drought-tolerant

Dwarf coyotebrush Baccharis pilularis ‘Pigeon Point’

2’ L Dioecious; use male plants to avoid unwanted seeding; extremely drought-tolerant

Appendix B: Plants for Bees

Notes:Water Needs abbreviations: L = low, M = medium, H = high

A Friendly ReminderBefore ordering, please ensure that all plants or seeds purchased for

pollinator habitat have NOT been treated with systemic insecticides!

67The Xerces Society for Invertebrate Conservation

A leafcutter bee foraging on white clover cover crop between rows of raspberry. (Photograph by Mace Vaughan, The Xerces Society.)

Cover Crops for PollinatorsThe following list provides examples of cover crops that have value to wild bees as well as honey bees. Most of these species are commonly available as seed from local seed dealers. See Appendix D for additional resources about cover crops.

COVER CROP LIFECYCLE

Alfalfa Perennial

Birdsfoot trefoil Perennial

Buckwheat Annual

Canola Annual

Carrot Biennial

Chickpea Annual

Cilantro Annual

Clover, berseem Annual

Clover, crimson Annual

Clover, kura Perennial

Clover, red Perennial

Clover, rose Annual

Clover, strawberry Perennial

Clover, white Perennial

Cowpea Annual

Dill Annual

Fava bean Annual

Flax Annual

Kale Biennial

Mustard, tame Annual

Partridge pea Annual

Phacelia Annual

Radish Biennial

Safflower Annual

Sainfoin Perennial

Soybean Annual

Sunflower Annual

Sunn hemp Annual

Sweet clover Biennial

Turnip Biennial

Vetch, chickling Annual

Vetch, common Annual

Vetch, hairy Annual

Vetch, purple Perennial

Small sweat bee pollinating canola blossom. (Photograph by Mace Vaughan, The Xerces Society.)

Appendix B: Plants for Bees

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Garden PlantsThis list of garden plants includes an assortment of plants, only some of which are native to North America. These plants are suitable for flower borders but not for inclusion in areas of native habitat.*

*Except in the areas within their natural distribution.

Note: When choosing plants, avoid hybrid varieties, which were often bred for showy petals at the expense of nectar or pollen production.

COMMON NAME GENUS NAME

Aster Symphyotrichum

Basil Ocimum

Bee balm Monarda

Blanketflower Gaillardia

Blazing star Liatris

Borage Borago

California poppy Eschscholzia

Catmint Nepeta

Coreopsis Coreopsis

Cosmos Cosmos

Giant hyssop Agastache

Globe gilia Gilia

Hyssop Hyssopus

Joe Pye weed Eupatorium

Lavender Lavandula

Lupine Lupinus

Marjoram Origanum

Milkweed Asclepias

Penstemon Penstemon

Phacelia Phacelia

Purple coneflower Echinacea

Rosemary Rosmarinus

Rosinweed Silphium

Russian sage Perovskia

Sage Salvia

Sunflower Helianthus

Some decorative garden plants are excellent sources of forage for bees in flower borders or insectary strips. Above, a long-horned bee pollinates a purple coneflower; below, a sunflower bee on a coreopsis bloom. (Photographs by Mace Vaughan, The Xerces Society [above], and Jennifer Hopwood, The Xerces Society [below].)

Appendix B: Plants for Bees

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Forage Habitatexisting future

Native plant field borders, buffer stripsBorders with multiple species of native wildflowers can provide floral resources for pollinators.

HedgerowsNative shrubs and small trees can provide floral resources for pollinators, as well as nesting sites.

Insectary plantingsInsectary plantings can support pollinators within or adjacent to crops, and the flowering can be timed to provide nectar and pollen when most needed to support pollinators.

Farm gardensFlower gardens planted for their beauty or cut flowers provide yet another source of nectar and pollen for bees.

Natural or semi-natural areasWoodlots, stream banks, roadsides, or other natural features can support blooming plants that, in turn, support pollinators.

Cover crops Cover crops help to build soil health, and when allowed to flower, can support pollinators. Growing a mixed cover crop will further ensure a diverse bloom.

Vegetative cover in orchard alleys or field roadsVegetative cover (e.g., white clover in alleys) can add nutrients to the soil while providing floral resources for pollinators and beneficial insects. If there are concerns about pollinators, particularly honey bees, being distracted from the crop bloom, alleys or roads may be mown when the crop is in bloom.

Nesting Habitat for Beesexisting future

Untilled areasAreas left untilled, such as hedgerows, field borders, woodlots, road edges, stream banks, and conservation areas, as well as unused land around farm buildings and service areas, all can provide nest sites needed by native bees. Poor quality or poorly irrigated land can provide some of the best sites for ground-nesting bees, because many prefer nesting in well-drained, inorganic sand and silt.

HedgerowsNative shrubs and small trees can provide nesting habitat for bees and likely provide a corridor along which bees can migrate more quickly through the agricultural landscape.

Brush piles, snagsPiles of brush and snags can provide nesting sites for tunnel-nesting bees, and bumble bees may also use brushy areas as nesting habitat.

Field borders, buffer strips Unmown borders or buffer strips planted with native grasses and wildflowers can provide undisturbed nesting habitat for bumble bees.

Pollinator Habitat Checklist

Appendix C

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A list of publications and websites (in addition to the Xerces website) that might be useful for implementing pollinator conservation measures, with a focus on materials that are written for the general public or that are available online.

ToolsPollinator Habitat Assessment Form and Guide (The Xerces Society)

http://www.xerces.org/wp-content/uploads/2009/11/PollinatorHabitatAssessment.pdfThis habitat assessment form and guide enables you to assess specific pollinator habitat features before and after project implementation in both orchard and field crop settings.

Habitat Installation Guides (The Xerces Society)http://www.xerces.org/pollinator-conservation/agriculture/pollinator-habitat-installation-guides/These regional installation guides include in-depth guidance on installing and maintaining pollinator habitat in the form of wildflower meadow plantings or hedgerows of flowering shrubs, including example seed mixes and plant list recommendations.

Seed Mix Calculator (The Xerces Society)http://www.xerces.org/pollinators-northeast-region/xerces-seed-mix-calculator/Develop your own pollinator conservation seed mix using this seed rate calculator.

Streamlined Bee Monitoring Protocol for Assessing Pollinator Habitat (Michigan State University, Rutgers University, University of California–Davis, The Xerces Society)

http://www.xerces.org/streamlined-bee-monitoring-protocol/Developed for conservationists, farmers, land managers, and restoration professionals, this guide provides instructions for assessing pollinator habitat quality and diversity by monitoring native bees. Includes an introduction to bee identification, a detailed monitoring protocol, and data sheets for different habitat types.

Assessing the Pollination of Your Watermelon (The Xerces Society)http://www.xerces.org/assessing-watermelon-pollination/A set of tools that will help you estimate the percentage pollination your watermelon are receiving and the relative contribution of different types of bees to the pollination of your crop.

Conservation Buffers (US Forest Service Technical Guide)www.unl.edu/nac/bufferguidelines/docs/conservation_buffers.pdfDesign guidelines for buffers, corridors, and greenways—including extensive information on hedgerows and windbreaks.

Resources: Tools, Websites, and Publications

Appendix D

71The Xerces Society for Invertebrate Conservation

WebsitesPollinator Conservation Resource Center (The Xerces Society)

http://www.xerces.org/pollinator-resource-center/The Pollinator Conservation Resource Center is your one-stop online source for information about protecting pollinating insects and their habitat, with regional information on plants for pollinator habitat enhancement, habitat conservation guides, nest management instructions, bee identification and monitoring resources, and a directory of pollinator plant nurseries.

USDA–Agriculture Research Service, Pollinating Insect-Biology, Management, and Systematics Research Labhttp://www.ars.usda.gov/main/site_main.htm?modecode=54280500The scientists working at this lab conduct research on native bees as crop pollinators. Their website provides information on identifying bees, pollinator plants, and making nests.

USDA Natural Resource Conservation Service (NRCS)http://www.nrcs.usda.gov The NRCS provides financial and technical assistance to support conservation efforts for pollinators and other wildlife on farms. For more information on NRCS conservation programs, contact your local NRCS or conservation district office (available at: http://offices.sc.egov.usda.gov/locator/app).

Lady Bird Johnson Wildflower Center Native Plant Information Network Recommended Specieshttp://www.wildflower.org/conservation_pollinators/The Xerces Society has collaborated with the Lady Bird Johnson Wildflower Center to create plant lists that are attractive to native bees, bumble bees, honey bees, and other beneficial insects, as well as plant lists with value as nesting materials for native bees. These lists can be narrowed down with additional criteria such as state, soil moisture, bloom time, and sunlight requirements.

Project Integrated Crop Pollinationhttp://projecticp.orgThis ongoing research project is investigating the performance, economics, and farmer perceptions of different pollination strategies in various fruit and vegetable crops. Visit their website for project news, educational events schedule, publications, and various resources for growers.

PublicationsBee Conservation

Buchmann, S. L., and G. P. Nabhan. 1996. The Forgotten Pollinators. 292 pp. Washington, D.C.: Island Press.

Delaplane, K. 1998. Bee Conservation in the Southeast. 12 pp. Athens: The University of Georgia College of Agricultural & Environmental Sciences. [Available at: http://www.ent.uga.edu/bees/BeeConservationintheSoutheastHoneyBeeProgramCAESEntomologyUGA.html]

Hatfield, R., S. Jepson, E. Mäder, S. H. Black, and M. Shepherd. 2012. Conserving Bumble Bees. Guidelines for Creating and Managing Habitat for America’s Declining Pollinators. 32 pp. Portland, OR: The Xerces Society for Invertebrate Conservation. [Available at: http://www.xerces.org/wp-content/uploads/2012/06/conserving_bb.pdf]

Isaacs, R., and J. Tuell. 2007. Conserving Native Bees on Farmland. Michigan State University Extension Bulletin E-2985. [Available at: http://nativeplants.msu.edu/uploads/files/E2985ConservingNativeBees.pdf]

Mäder, E., M. Shepherd, M. Vaughan, S. H. Black, and G. LeBuhn. 2011. Attracting Native Pollinators. Protecting North America’s Bees and Butterflies. 380 pp. North Adams, MA: Storey Publishing.

Mäder, E., M. Vaughan, M. Shepherd, and S. H. Black. 2005. Alternative Pollinators: Native Bees. 28 pp. Butte, MT: National Center for Appropriate Technology. [Available at: https://attra.ncat.org/attra-pub/summaries/summary.php?pub=75]

Appendix D: Resources: Tools, Websites, and Publications

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National Research Council. 2006. Status of Pollinators in North America. 322 pp. Washington, D.C.: National Academies Press. [Available at: http://www.nap.edu/catalog/11761.html]

USDA National Agroforestry Center. 2006-2007. Agroforestry Notes series on native bee conservation. [Available at: http://nac.unl.edu/documents/agroforestrynotes/an32g06.pdf, .../an33g07.pdf, .../an34g08.pdf, .../an35g09.pdf]

Bee Biology and IdentificationKearns, C., and J. Thomson. 2001. The Natural History of Bumble Bees. A Sourcebook for Investigations. 130 pp. Boulder: University Press of Colorado.

Moissett, B., and S. Buchmann. 2010. Bee Basics. An Introduction to Our Native Bees. 40 pp. Washington, D.C.: United States Department of Agriculture.

O’Toole, C., and A. Raw. 2004. Bees of the World. 192 pp. New York: Facts on File. [Note: Excellent resource]

Williams, P. H., R. W. Thorp, L. L. Richardson, and S. R. Colla. 2014. Bumble Bees of North America: An Identification Guide. 208 pp. Princeton: Princeton University Press.

Pesticides and BeesAdamson N., T. Ward, and M. Vaughan. 2012. Windbreaks designed with pollinators in mind. Inside

Agroforestry 20(1):8–10. [Available at: http://nac.unl.edu/documents/insideagroforestry/vol20issue1.pdf]

Hopwood, J., M. Vaughan, D. Biddinger, M. Shepherd, A. Code, E. Mäder, S. Hoffman Black, and C. Mazzacano. 2014. Are Neonicotinoids Killing Bees? A review of research into the effects of neonicotinoid insecticides on bees, with recommendations for action. 70 pp. Portland, OR: The Xerces Society for Invertebrate Conservation.

Johansen, E., L. A. Hooven, and R. R. Sagili. 2013. How to Reduce Bee Poisoning from Pesticides. Corvallis: Oregon State University. [Available at: http://bit.ly/OSU_ReduceBeePoisoning]

Johansen, C., and D. Mayer. 1990. Pollinator Protection: A Bee and Pesticide Handbook. 212 pp. Cheshire, CT: Wicwas Press.

Mäder, E., and N. L. Adamson. 2012. Organic-Approved Pesticides: Minimizing Impacts to Bees. Portland, OR: The Xerces Society for Invertebrate Conservation. [Available at: http://www.xerces.org/wp-content/uploads/2009/12/xerces-organic-approved-pesticides-factsheet.pdf]

Mäder, E., J. Hopwood, L. Morandin, M. Vaughan, and S. H. Black. 2014. Farming with Native Beneficial Insects. Ecological Pest Control Solutions. 272 pp. North Adams, MA: Storey Publishing.

Vaughan, M., G. Ferruzzi, J. Bagdon, E. Hesketh, and D. Biddinger. 2014. Agronomy Technical Note No. 9: Preventing or Mitigating Potential Negative Impacts of Pesticides on Pollinators Using Integrated Pest Management and Other Conservation Practices. 31 pp. Washington, D.C.: United States Department of Agriculture. [Available at: http://directives.sc.egov.usda.gov/OpenNonWebContent.aspx?content=34828.wba]

USEPA. 2012. RT25 Data Table. 15 pp. Washington, D.C.: Environmental Protection Agency. [Available at: http://www2.epa.gov/sites/production/files/2014-06/documents/rt25-data-revised.pdf]

Appendix D: Resources: Tools, Websites, and Publications

Male mining bee emerging from ground tunnel nest. (Photograph by Whitney Cranshaw, Colorado State University, Bugwood.org.)

73The Xerces Society for Invertebrate Conservation

Appendix D: Resources: Tools, Websites, and Publications

Crop PollinationDelaplane, K., and D. Mayer. 2000. Crop Pollination by

Bees. 344 pp. New York: CABI Publishing.

Free, J. B. 1993. Insect Pollination of Crops—2nd Edition. 768 pp. San Diego: Academic Press.

McGregor, S. E. 1976. Insect Pollination Of Cultivated Crop Plants. Originally published by the USDA in 1976. [Available at: http://www.ars.usda.gov/SP2UserFiles/Place/53420300/OnlinePollinationHandbook.pdf]

Managing Blue Orchard BeesBosch, J., and W. Kemp. 2001. How to Manage the

Blue Orchard Bee as an Orchard Pollinator. 88 pp. Beltsville, MD: Sustainable Agriculture Network.

Mäder, E., M. Spivak, E. Evans. 2010. Managing Alternative Pollinators. A Handbook for Beekeepers, Growers, and Conservationists. 186 pp. Ithaca, NY: Natural Resources, Agriculture, and Engineering Service.

Cover CroppingClark, A. (ed.). 2012. Managing Cover Crops Profitably. 3rd Ed. 248 pp. College Park, MD: SARE Outreach.

[Available at: http://www.sare.org/Learning-Center/Books/Managing-Cover-Crops-Profitably-3rd-Edition]

Ingels, C., R. Bugg, G. McGourty, and P. Christensen (eds.). 1998. Cover Cropping in Vineyards: A Grower’s Handbook. ANR Publication #3338. 162 pp. Davis: University of California, Division of Agriculture and Natural Resources.

HedgerowsDufour, R. 2000. Farmscaping to Enhance Biological Control. 40 pp. Butte, MT: National Center for Appropriate

Technology. [Available at: https://attra.ncat.org/attra-pub/summaries/summary.php?pub=145]

Earnshaw, S. 2004. Hedgerows for California Agriculture. A Resource Guide. 70 pp. Davis: Community Alliance with Family Farmers.

Robins, P., R. B. Holmes, and K. Laddish (eds.). 2001. Bring Farm Edges Back to Life! 5th Edition. Woodland, CA: Yolo County Resource Conservation District. [Available at: http://www.yolorcd.org/documents/FarmEdges_page1-7_000.pdf]

Establishing MeadowsElmore, C. L., J. J. Stapleton, C. E. Bell, and J. E. Devay. 1997. Soil Solarization: A Nonpesticidal Method for

Controlling Diseases, Nematodes, and Weeds. 17 pp. Oakland, CA: University of California. [Available at: http://vric.ucdavis.edu/pdf/soil_solarization.pdf]

USDA-NRCS Pullman Plant Materials staff. 2005. Seed Quality, Seed Technology, and Drill Calibration. 18 pp. Spokane, WA: USDA-NRCS Pullman Plant Materials Center. [Available at: www.plant-materials.nrcs.usda.gov/pubs/wapmctn6331.pdf]

Native leafcutter pollinating black raspberries. (Photograph by Mace Vaughan, The Xerces Society.)

74 Farming for Bees

Dotted mint in bloom. (Photograph by Jennifer Hopwood, The Xerces Society.)

74 Farming for Bees

75The Xerces Society for Invertebrate Conservation

Alaux, C., F. Ducloz, D. Crauser, and Y. Le Conte. 2010. Diet effects on honey bee immunocompetence. Biology Letters 10(12):2009.0986.

Bohart, G. E. 1972. Management of wild bees for the pollination of crops. Annual Review of Entomology 17:287–312.

Bosch, J., and W. Kemp. 2001. How to Manage the Blue Orchard Bee as an Orchard Pollinator. 88 pp. Beltsville, MD: Sustainable Agriculture Network.

Blaauw, B. R., and R. Isaacs. 2014. Flower plantings increase wild bee abundance and the pollination services provided to a pollination-dependent crop. Journal of Applied Ecology 51(4):890–898.

Brittain C., C. Kremen, A. Garber, and A.-M. Klein. 2014. Pollination and plant resources change the nutritional quality of almonds for human health. PLoS ONE 9(2):e90082.

Brittain, C., C. Kremen, and A.-M. Klein. 2013. Biodiversity buffers pollination from changes in environmental conditions. Global Change Biology 19(2):540–547.

Campbell, J. W., J. L. Hanula, and T. A. Waldrop. 2007. Effects of prescribed fire and fire surrogates on floral visiting insects of the blue ridge province in North Carolina. Biological Conservation 134(3):393–404.

Di Pasquale, G., M. Salignon, Y. Le Conte, L. P. Belzunces, A. Decourtye, A. Kretzschmar, S. Suchail, J.-L. Brunet, and C. Alaux. 2013. Influence of pollen nutrition on honey bee health: do pollen quality and diversity matter? PLoS ONE 8(8):e72016.

Eilers, E. J., C. Kremen, S. S. Greenleaf, A. K. Garber, and A.-M. Klein. 2011. Contribution of pollinator-mediated crops to nutrients in the human food supply. PloS ONE 6(6):e21363.

Fiedler, A. K., D. A. Landis, and M. Arduser. 2012. Rapid shift in pollinator communities following invasive species removal. Restoration Ecology 20(5):593–602.

Garibaldi, L. A., I. Steffan-Dewenter, R. Winfree, M. A. Aizen, R. Bommarco, S. A. Cunningham, C. Kremen, et al. 2013. Wild pollinators enhance fruit set of crops regardless of honey bee abundance. Science 339(6127):1608–1611.

Garibaldi, L. A., I. Steffan‐Dewenter, C. Kremen, J. M. Morales, R. Bommarco, S. A. Cunningham, et al. 2011. Stability of pollination services decreases with isolation from natural areas despite honey bee visits. Ecology Letters 14(10):1062–1072.

Greenleaf, S. S., and C. Kremen. 2006. Wild bees enhance honey bees’ pollination of hybrid sunflower. Proceedings of the National Academy of Sciences 103(37):13890–13895.

Greenleaf, S. S., and C. Kremen. 2006. Wild bee species increase tomato production and respond differently to surrounding land use in Northern California. Biological Conservation 133(1):81–87.

Greenleaf, S. S., N. M. Williams, R. Winfree, and C. Kremen. 2007. Bee foraging ranges and their relationship to body size. Oecologia 153(3):589–596.

Hanula, J. L., and S. Horn. 2011. Removing an invasive shrub (Chinese privet) increases native bee diversity and abundance in riparian forests of the southeastern United States. Insect Conservation and Diversity 4(4):275–283.

Hogendoorn, K., F. Bartholomaeus, and M. Keller. 2010. Chemical and sensory comparison of tomatoes pollinated by bees and by a pollination wand. Journal of Economic Entomology 103(4):1286–1292.

Isaacs, R., J. Tuell, A. Fiedler, M. Gardiner, and D. Landis. 2008. Maximizing arthropod-mediated ecosystem services in agricultural landscapes: the role of native plants. Frontiers in Ecology and the Environment 7(4):196–203.

Javorek, S. K., K. E. Mackenzie, and S. P. Vander Kloet. 2002. Comparative pollination effectiveness among bees (Hymenoptera: Apoidea) on lowbush blueberry (Ericaceae: Vaccinium angustifolium). Annals of the Entomological Society of America 95(3):345–351.

Klatt, B. K., A. Holzschuh, C. Westphal, Y. Clough, I. Smit, E. Pawelzik, and T. Tscharntke. 2014. Bee pollination improves crop quality, shelf life and commercial value. Proceedings of the Royal Society B: Biological Sciences 281(1775):2013–2440.

Literature Cited

Appendix E

76 Farming for Bees

Klein, A.-M., B. E. Vaissiere, J. H. Cane, I. Steffan-Dewenter, S. A. Cunningham, C. Kremen, and T. Tscharntke. 2007. Importance of pollinators in changing landscapes for world crops. Proceedings of the Royal Society B: Biological Sciences 274(1608):303–313.

Kremen, C., N. M. Williams, R. L. Bugg, J. P. Fay, and R. W. Thorp. 2004. The area requirements of an ecosystem service: crop pollination by native bee communities in California. Ecology Letters 7(11):1109–1119.

Kremen, C., N. M. Williams, and R. W. Thorp. 2002. Crop pollination from native bees at risk from agricultural intensification. Proceedings of the National Academy of Sciences 99(26):16812–16816.

Linsley, E. G. 1958. The ecology of solitary bees. Hilgardia 27(19):543–599.

Losey, J. E., and M. Vaughan. 2006. The economic value of ecological services provided by insects. Bioscience 56(4):311–323.

Michener, C. D. 2007. The Bees of the World. 2nd ed. 953 pp. Baltimore: Johns Hopkins University Press.

Morandin, L. A., and C. Kremen. 2013. Hedgerow restoration promotes pollinator populations and exports native bees to adjacent fields. Ecological Applications 23(4):829–839.

Morandin, L. A., and C. Kremen. 2013. Bee preference for native versus exotic plants in restored agricultural hedgerows. Restoration Ecology 21(1):6–32.

Morandin, L. A., and M. L. Winston. 2006. Pollinators provide economic incentive to preserve natural land in agroecosystems. Agriculture, Ecosystems & Environment 116(3):289–292.

Morse, R. A., and N. W. Calderone. 2000. The value of honey bees as pollinators of U.S. crops in 2000. Bee Culture. The Magazine of American Beekeeping 128(3):1–15.

National Research Council. 2007. Status of Pollinators in North America. 322 pp. Washington, D.C.: National Academies Press.

Potts, S. G., B. Vulliamy, A. Dafni, G. Ne’eman, and P. G. Willmer. 2003. Linking bees and flowers: how do floral communities structure pollinator communities? Ecology 84(10):2628–2642.

Rogers, S. R., D. R. Tarpy, and H. J. Burrack. 2014. Bee species diversity enhances productivity and stability in a perennial crop. PLoS ONE 9(5):e97307.

Shuler, R. E., T. H. Roulston, and G. E. Farris. 2005. Farming practices influence wild pollinator populations on squash and pumpkin. Journal of Economic Entomology 98(3):790–795.

Tuell, J. K., J. S. Ascher, and R. Isaacs. 2009. Wild bees (Hymenoptera: Apoidea: Anthophila) of the Michigan highbush blueberry agroecosystem. Annals of the Entomological Society of America 102(2):275–287.

Tyndall, J. C., L. A. Schulte, M. Liebman, and M. Helmers. 2013. Field-level financial assessment of contour prairie strips for enhancement of environmental quality. Environmental Management 52(3):736–747.

Williams, N. M., D. Cariveau, R. Winfree, and C. Kremen. 2011. Bees in disturbed habitats use, but do not prefer, alien plants. Basic and Applied Ecology 12(4):332–341.

Winfree, R., N. M. Williams, J. Dushoff, and C. Kremen. 2007. Native bees provide insurance against ongoing honey bee losses. Ecology Letters 10(11):1105–1113.

Winfree, R., N. M. Williams, H. Gaines, J. S. Ascher, and C. Kremen. 2008. Wild bee pollinators provide the majority of crop visitation across land‐use gradients in New Jersey and Pennsylvania, USA. Journal of Applied Ecology 45(3):793–802.

Appendix E: Literature Cited

Pollinators are essential to our environment. The ecological service they provide is necessary for the reproduction of nearly 85% of the world’s flowering plants. This includes more than 2/3 of the world’s crop species, whose fruits and seeds together provide over 30% of the foods and beverages that we consume. The United States alone grows more than 100 crops that either need or benefit from pollinators. The economic value of insect-pollinated crops in the United States was estimated to be between $18 and $27 billion in 2006. Native insects were responsible for pollinating an estimated $3 billion or more of this total.

With the steady decline in the number of managed honey bee colonies, and unsustainably high annual winter losses, now more than ever we should be concerned about the security of our insect-pollinated crops and our nation’s pollinator populations. Habitat conservation and management designed to benefit native bees is one important way in which we can diversify the pollinators we rely upon for agricultural production, while also supporting honey bees in farm landscapes.

These guidelines are designed to help growers and conservationists protect, enhance, and restore habitat for native bees. Inside, you will find advice on how to recognize native bee habitat, what simple changes land managers can make to protect their bees, how to choose sites and plants for restoration, how to construct nests for bees, and much more.

FforB_4ed_jan2015

BRING BACKTHE

POLLINATORS

A Xerces Society Conservation Campaign

Xerces Society's Bring Back the Pollinators campaign is based on four principles: grow pollinator-friendly flowers, protect bee nests and butterfly host plants, avoid pesticides, and spread the word. You can participate by taking the Pollinator Protection Pledge and registering your habitat on our nationwide map of pollinator corridors.

www.bringbackthepollinators.org

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U.S. DEPARTMENT OF AGRICULTURE

Biotechnology FAQs

Biotechnology Frequently Asked Questions(FAQs)1. What is Agricultural Biotechnology?

Agricultural biotechnology is a range of tools, including traditional breeding techniques,that alter living organisms, or parts of organisms, to make or modify products; improveplants or animals; or develop microorganisms for specific agricultural uses. Modernbiotechnology today includes the tools of genetic engineering.

2. How is Agricultural Biotechnology being used?

Biotechnology provides farmers with tools that can make production cheaper and moremanageable. For example, some biotechnology crops can be engineered to toleratespecific herbicides, which make weed control simpler and more e�icient. Other cropshave been engineered to be resistant to specific plant diseases and insect pests, whichcan make pest control more reliable and e�ective, and/or can decrease the use ofsynthetic pesticides. These crop production options can help countries keep pace withdemands for food while reducing production costs. A number of biotechnology-derivedcrops that have been deregulated by the USDA and reviewed for food safety by the Foodand Drug Administration (FDA) and/or the Environmental Protection Agency (EPA) havebeen adopted by growers.

Many other types of crops are now in the research and development stages. While it isnot possible to know exactly which will come to fruition, certainly biotechnology willhave highly varied uses for agriculture in the future. Advances in biotechnology mayprovide consumers with foods that are nutritionally-enriched or longer-lasting, or thatcontain lower levels of certain naturally occurring toxicants present in some food plants.Developers are using biotechnology to try to reduce saturated fats in cooking oils,

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reduce allergens in foods, and increase disease-fighting nutrients in foods. They are alsoresearching ways to use genetically engineered crops in the production of newmedicines, which may lead to a new plant-made pharmaceutical industry that couldreduce the costs of production using a sustainable resource.

Genetically engineered plants are also being developed for a purpose known asphytoremediation in which the plants detoxify pollutants in the soil or absorb andaccumulate polluting substances out of the soil so that the plants may be harvested anddisposed of safely. In either case the result is improved soil quality at a polluted site.Biotechnology may also be used to conserve natural resources, enable animals to moree�ectively use nutrients present in feed, decrease nutrient runo� into rivers and bays,and help meet the increasing world food and land demands. Researchers are at work toproduce hardier crops that will flourish in even the harshest environments and that willrequire less fuel, labor, fertilizer, and water, helping to decrease the pressures on landand wildlife habitats.

In addition to genetically engineered crops, biotechnology has helped make otherimprovements in agriculture not involving plants. Examples of such advances includemaking antibiotic production more e�icient through microbial fermentation andproducing new animal vaccines through genetic engineering for diseases such as footand mouth disease and rabies.

3. What are the benefits of Agricultural Biotechnology?

The application of biotechnology in agriculture has resulted in benefits to farmers,producers, and consumers. Biotechnology has helped to make both insect pest controland weed management safer and easier while safeguarding crops against disease.

For example, genetically engineered insect-resistant cotton has allowed for a significantreduction in the use of persistent, synthetic pesticides that may contaminategroundwater and the environment.

In terms of improved weed control, herbicide-tolerant soybeans, cotton, and cornenable the use of reduced-risk herbicides that break down more quickly in soil and arenon-toxic to wildlife and humans. Herbicide-tolerant crops are particularly compatiblewith no-till or reduced tillage agriculture systems that help preserve topsoil fromerosion.

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Agricultural biotechnology has been used to protect crops from devastating diseases.The papaya ringspot virus threatened to derail the Hawaiian papaya industry untilpapayas resistant to the disease were developed through genetic engineering. Thissaved the U.S. papaya industry. Research on potatoes, squash, tomatoes, and othercrops continues in a similar manner to provide resistance to viral diseases that otherwiseare very di�icult to control.

Biotech crops can make farming more profitable by increasing crop quality and may insome cases increase yields. The use of some of these crops can simplify work andimprove safety for farmers. This allows farmers to spend less of their time managingtheir crops and more time on other profitable activities.

Biotech crops may provide enhanced quality traits such as increased levels of beta-carotene in rice to aid in reducing vitamin A deficiencies and improved oil compositionsin canola, soybean, and corn. Crops with the ability to grow in salty soils or betterwithstand drought conditions are also in the works and the first such products are justentering the marketplace. Such innovations may be increasingly important in adaptingto or in some cases helping to mitigate the e�ects of climate change.

The tools of agricultural biotechnology have been invaluable for researchers in helpingto understand the basic biology of living organisms. For example, scientists haveidentified the complete genetic structure of several strains of Listeria andCampylobacter, the bacteria o�en responsible for major outbreaks of food-borne illnessin people. This genetic information is providing a wealth of opportunities that helpresearchers improve the safety of our food supply. The tools of biotechnology have"unlocked doors" and are also helping in the development of improved animal andplant varieties, both those produced by conventional means as well as those producedthrough genetic engineering.

4. What are the safety considerations with Agricultural Biotechnology?

Breeders have been evaluating new products developed through agriculturalbiotechnology for centuries. In addition to these e�orts, the United States Departmentof Agriculture (USDA), the Environmental Protection Agency (EPA), and the Food andDrug Administration (FDA) work to ensure that crops produced through geneticengineering for commercial use are properly tested and studied to make sure they poseno significant risk to consumers or the environment.

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Crops produced through genetic engineering are the only ones formally reviewed toassess the potential for transfer of novel traits to wild relatives. When new traits aregenetically engineered into a crop, the new plants are evaluated to ensure that they donot have characteristics of weeds. Where biotech crops are grown in proximity to relatedplants, the potential for the two plants to exchange traits via pollen must be evaluatedbefore release. Crop plants of all kinds can exchange traits with their close wild relatives(which may be weeds or wildflowers) when they are in proximity. In the case of biotech-derived crops, the EPA and USDA perform risk assessments to evaluate this possibilityand minimize potential harmful consequences, if any.

Other potential risks considered in the assessment of genetically engineered organismsinclude any environmental e�ects on birds, mammals, insects, worms, and otherorganisms, especially in the case of insect or disease resistance traits. This is why theUSDA's Animal and Plant Health Inspection Service (APHIS) and the EPA review anyenvironmental impacts of such pest-resistant biotechnology derived crops prior toapproval of field-testing and commercial release. Testing on many types of organismssuch as honeybees, other beneficial insects, earthworms, and fish is performed toensure that there are no unintended consequences associated with these crops.

With respect to food safety, when new traits introduced to biotech-derived plants areexamined by the EPA and the FDA, the proteins produced by these traits are studied fortheir potential toxicity and potential to cause an allergic response. Tests designed toexamine the heat and digestive stability of these proteins, as well as their similarity toknown allergenic proteins, are completed prior to entry into the food or feed supply. Toput these considerations in perspective, it is useful to note that while the particularbiotech traits being used are o�en new to crops in that they o�en do not come fromplants (many are from bacteria and viruses), the same basic types of traits o�en can befound naturally in most plants. These basic traits, like insect and disease resistance, haveallowed plants to survive and evolve over time.

5. How widely used are biotechnology crops?

According to the USDA's National Agricultural Statistics Service (NASS), biotechnologyplantings as a percentage of total crop plantings in the United States in 2012 were about88 percent for corn, 94 percent for cotton, and 93 percent for soybeans. NASS conductsan agricultural survey in all states in June of each year. The report issued from thesurvey contains a section specific to the major biotechnology derived field crops and

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provides additional detail on biotechnology plantings. The most recent report may beviewed at the following website: https://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-us.aspx

For a summary of these data, see the USDA Economic Research Service data feature at:https://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-us.aspx

The USDA does not maintain data on international usage of genetically engineeredcrops. The independent International Service for the Acquisition of Agri-biotechApplications (ISAAA), a not-for-profit organization, estimates that the global area ofbiotech crops for 2012 was 170.3 million hectares, grown by 17.3 million farmers in 28countries, with an average annual growth in area cultivated of around 6 percent. Morethan 90 percent of farmers growing biotech crops are resource-poor farmers indeveloping countries. ISAAA reports various statistics on the global adoption andplantings of biotechnology derived crops. The ISAAA website is https://www.isaaa.org

6. What are the roles of government in agricultural biotechnology?

Please note: These descriptions are not a complete or thorough review of all the activitiesof these agencies with respect to agricultural biotechnology and are intended as generalintroductory materials only. For additional information please see the relevant agencywebsites.

Regulatory

The Federal Government developed a Coordinated Framework for the Regulation ofBiotechnology in 1986 to provide for the regulatory oversight of organisms derivedthrough genetic engineering. The three principal agencies that have provided primaryguidance to the experimental testing, approval, and eventual commercial release ofthese organisms to date are the USDA's Animal and Plant Health Inspection Service(APHIS), the Environmental Protection Agency (EPA), and the Department of Health andHuman Services' Food and Drug Administration (FDA). The approach taken in theCoordinated Framework is grounded in the judgment of the National Academy ofSciences that the potential risks associated with these organisms fall into the samegeneral categories as those created by traditionally bred organisms.

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Products are regulated according to their intended use, with some products beingregulated under more than one agency. All government regulatory agencies have aresponsibility to ensure that the implementation of regulatory decisions, includingapproval of field tests and eventual deregulation of approved biotech crops, does notadversely impact human health or the environment.

The Animal and Plant Health Inspection Service (APHIS) is responsible for protectingU.S. agriculture from pests and diseases. APHIS regulations provide procedures forobtaining a permit or for providing notification prior to "introducing" (the act ofintroducing includes any movement into or through the U.S., or release into theenvironment outside an area of physical confinement) a regulated article in the U.S.Regulated articles are organisms and products altered or produced through geneticengineering that are plant pests or for which there is reason to believe are plant pests.

The regulations also provide for a petition process for the determination of non-regulated status. Once a determination of non-regulated status has been made, theorganism (and its o�spring) no longer requires APHIS review for movement or release inthe U.S.

For more information on the regulatory responsibilities of the FDA, the EPA and APHISplease see:

https://www.fda.gov

https://www.epa.gov

APHIS Biotechnology Regulations

Market Facilitation

The USDA also helps industry respond to consumer demands in the United States andoverseas by supporting the marketing of a wide range of agricultural products producedthrough conventional, organic, and genetically engineered means.

The Agricultural Marketing Service (AMS) and the Grain Inspection, Packers, andStockyards Administration (GIPSA) have developed a number of services to facilitate thestrategic marketing of conventional and genetically engineered foods, fibers, grains, andoilseeds in both domestic and international markets. GIPSA provides these services for

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the bulk grain and oilseed markets while AMS provides the services for foodcommodities such as fruits and vegetables, as well as for fiber commodities.

These services include:

1. Evaluation of Test Kits: AMS and GIPSA evaluate commercially available test kitsdesigned to detect the presence of specific proteins in genetically engineeredagricultural commodities. The agencies confirm whether the tests operate in accordancewith manufacturers' claims and, if the kits operate as stated, the results are madeavailable to the public on their respective websites.

GIPSA Link: https://www.gipsa.usda.gov/fgis/rapidtestkit.aspx

GIPSA evaluates the performance of laboratories conducting DNA-based tests to detectgenetically engineered grains and oilseeds, provides participants with their individualresults, and posts a summary report on the GIPSA website. AMS is developing a similarprogram that can evaluate and verify the capabilities of independent laboratories toscreen other products for the presence of genetically engineered material.

2. Identity Preservation/Process Verification Services: AMS and GIPSA o�er auditingservices to certify the use of written quality practices and/or production processes byproducers who di�erentiate their commodities using identity preservation, testing, andproduct branding.

GIPSA Link: https://www.gipsa.usda.gov/fgis/inspectionweighing.aspx

AMS Link: https://www.ams.usda.gov/fv/ipbv.htm

Additional AMS Services: AMS provides fee-based DNA and protein testing services forfood and fiber products, and its Plant Variety Protection O�ice o�ers intellectualproperty rights protection for new genetically engineered seed varieties through theissuance of Certificates of Protection.

Additional GIPSA Services: GIPSA provides marketing documents pertaining to whetherthere are genetically engineered varieties of certain bulk commodities in commercialproduction in the United States. USDA also works to improve and expand market accessfor U.S. agricultural products, including those produced through genetic engineering.

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The Foreign Agricultural Service (FAS) supports or administers numerous education,outreach, and exchange programs designed to improve the understanding andacceptance of genetically engineered agricultural products worldwide

1. Market Access Program and Foreign Market Development Program: Supports U.S. farmproducer groups (called "Cooperators") to market agricultural products overseas,including those produced using genetic engineering.

2. Emerging Markets Program: Supports technical assistance activities to promoteexports of U.S. agricultural commodities and products to emerging markets, includingthose produced using genetic engineering. Activities to support science-based decision-making are also undertaken. Such activities have included food safety training in Mexico,a biotechnology course for emerging market participants at Michigan State University,farmer-to-farmer workshops in the Philippines and Honduras, high-level policydiscussions within the Asia-Pacific Economic Cooperation group, as well as numerousstudy tours and workshops involving journalists, regulators, and policy-makers.

3. Cochran Fellowship Program: Supports short-term training in biotechnology andgenetic engineering. Since the program was created in 1984, the Cochran FellowshipProgram has provided education and training to 325 international participants, primarilyregulators, policy makers, and scientists.

4. Borlaug Fellowship Program: Supports collaborative research in new technologies,including biotechnology and genetic engineering. Since the program was established in2004, the Borlaug Fellowship Program has funded 193 fellowships in this research area.

5. Technical Assistance for Specialty Crops (TASC): Supports technical assistanceactivities that address sanitary, phytosanitary, and technical barriers that prohibit orthreaten the export of U.S. specialty crops. This program has supported activities onbiotech papaya.

Research

USDA researchers seek to solve major agricultural problems and to better understandthe basic biology of agriculture. Researchers may use biotechnology to conduct researchmore e�iciently and to discover things that may not be possible by more conventionalmeans. This includes introducing new or improved traits in plants, animals, andmicroorganisms and creating new biotechnology-based products such as more e�ective

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diagnostic tests, improved vaccines, and better antibiotics. Any USDA research involvingthe development of new biotechnology products includes biosafety analysis.

USDA scientists are also improving biotechnology tools for ever safer, more e�ective useof biotechnology by all researchers. For example, better models are being developed toevaluate genetically engineered organisms and to reduce allergens in foods.

USDA researchers monitor for potential environmental problems such as insect pestsbecoming resistant to Bt, a substance that certain crops, such as corn and cotton, havebeen genetically engineered to produce to protect against insect damage. In addition, inpartnership with the Agricultural Research Service (ARS) and the Forest Service, theCooperative States Research, the National Institute of Food and Agriculture (NIFA)administers the Biotechnology Risk Assessment Research Grants Program (BRAG) whichdevelops science-based information regarding the safety of introducing geneticallyengineered plants, animals, and microorganisms. Lists of biotechnology researchprojects can be found at https://www.ars.usda.gov/research/projects.htm for ARS and athttps://www.nifa.usda.gov/funding-opportunity/biotechnology-risk-assessment-research-grants-program-brag for NIFA.

USDA also develops and supports centralized websites that provide access to geneticresources and genomic information about agricultural species. Making these databaseseasily accessible is crucial for researchers around the world.

USDA's National Institute of Food and Agriculture (NIFA) provides funding and programleadership for extramural research, higher education, and extension activities in foodand agricultural biotechnology. NIFA administers and manages funds for biotechnologythrough a variety of competitive and cooperative grants programs. The NationalResearch Initiative (NRI) Competitive Grants Program, the largest NIFA competitiveprogram, supports basic and applied research projects and integrated research,education, and/or extension projects, many of which use or develop biotechnologytools, approaches, and products. The Small Business Innovation Research Program(SBIR) funds competitive grants to support research by qualified small businesses onadvanced concepts related to scientific problems and opportunities in agriculture,including development of biotechnology-derived products. NIFA also supports researchinvolving biotechnology and biotechnology-derived products through cooperativefunding programs in conjunction with state agricultural experiment stations at land-grant universities. NIFA partners with other federal agencies through interagency

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competitive grant programs to fund agricultural and food research that uses or developsbiotechnology and biotechnology tools such as metabolic engineering, microbialgenome sequencing, and maize genome sequencing.

USDA's Economic Research Service (ERS) conducts research on the economic aspects ofthe use of genetically engineered organisms, including the rate of and reasons foradoption of biotechnology by farmers. ERS also addresses economic issues related tothe marketing, labeling, and trading of biotechnology-derived products.

Over the centuries, as farmers have adopted more technology in their pur-suit of greater yields, the belief that ‘bigger is better’ has come to domi-nate farming, rendering small-scale operations impractical. But advances in robotics and sensing technologies are threatening to disrupt today’s

agribusiness model. “There is the potential for intelligent robots to change the eco-nomic model of farming so that it becomes feasible to be a small producer again,” says robotics engineer George Kantor at Carnegie Mellon University in Pittsburgh, Pennsylvania.

Twenty-first century robotics and sensing technologies have the potential to solve problems as old as farming itself. “I believe, by moving to a robotic agricultural system, we can make crop production significantly more efficient and more sustainable,” says Simon Blackmore, an engineer at Harper Adams University in Newport, UK. In green-houses devoted to fruit and vegetable production, engineers are exploring automation as a way to reduce costs and boost quality. Devices to monitor vegetable growth, as well as robotic pickers, are currently being tested. For livestock farmers, sensing technologies can help to manage the health and welfare of their animals. And work is underway to improve monitoring and maintenance of soil quality, and to eliminate pests and disease without resorting to indiscriminate use of agrichemicals.

Although some of these technologies are already available, most are at the research stage in labs and spin-off companies. “Big-machinery manufacturers are not putting their money into manufacturing agricultural robots because it goes against their cur-rent business models,” says Blackmore. Researchers such as Blackmore and Kantor are part of a growing body of scientists with plans to revolutionize agricultural practice. If they succeed, they’ll change how we produce food forever. “We can use technology to double food production,” says Richard Green, agricultural engineer at Harper Adams.

RIPE FOR THE PICKINGThe Netherlands is famed for the efficiency of its fruit- and vegetable-growing greenhouses, but these operations rely on people to pick the produce. “Humans are still better than robots, but there is a lot of effort going into automatic harvesting,” says Eldert van Henten, an agricultural engineer at Wageningen University in the Netherlands, who is working on a sweet-pepper harvester. The challenge is to quickly and precisely identify the pepper and avoid cutting the main stem of the plant. The key lies in fast, precise software. “We are performing deep learning with the machine so it can interpret all the data from a colour camera fast,” says van Henten. “We even feed data from regular street scenes into the neural network to better train it.”

In the United Kingdom, Green has developed a strawberry harvester that he says can pick the fruit faster than humans. It relies on stereoscopic vision with RGB cameras to capture depth, but it is its powerful algorithms that allow it to pick a strawberry every two seconds. People can pick 15 to 20 a minute, Green estimates. “Our partners at the National Physical Laboratory worked on the problem for two years, but had a brainstorm one day and finally cracked it,” says Green, adding that the solution is too commercially sensitive to share. He thinks that supervised groups of robots can step into the shoes of strawberry pickers in around five years. Harper Adams University is considering setting up a spin-off company to commercialize the technology. The big hurdle to commercialization, however, is that food producers demand robots that can pick all kinds of vegetables, says van Henten. The variety of shapes, sizes and colours of tomatoes, for instance, makes picking them a tough challenge, although there is already a robot available to remove unwanted leaves from the plants.

Another key place to look for efficiencies is timing. Picking too early is wasteful because you miss out on growth, but picking too late slashes weeks off the storage time. Precision-farming engineer Manuela Zude-Sasse at the Leibniz Institute for Agricultural Engineering and Bioeconomy in Potsdam, Germany, is attaching sensors to apples to detect their size, and levels of the pigments chlorophyll and anthocyanin. The data are fed into an algorithm to calculate developmental stage, and, when the time is ripe for picking, growers are alerted by smartphone.

So far, Zude-Sasse has put sensors on pears, citrus fruits, peaches, bananas and apples (pictured). She is set to start field trials later this year in a commercial tomato greenhouse and an apple orchard. She is also developing a smartphone app for cherry growers. The app will use photographs of cherries taken by growers to calculate growth rate and a quality score.

Growing fresh fruit and vegetables is all about keeping the quality high while minimizing costs. “If you can schedule harvest to optimum fruit development, then you can reap an economic benefit and a quality one,” says Zude-Sasse.

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A technological revolution in farming led by advances in robotics and sensing technologies

looks set to disrupt modern practice.

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ELIMINATING ENEMIES The Food and Agriculture Organization of the United Nations estimates that 20–40% of global crop yields are lost each year to pests and diseases, despite the application of around two-million tonnes of pesticide. Intelligent devices, such as robots and drones, could allow farmers to slash agrichemical use by spotting crop enemies earlier to allow precise chemical application or pest removal, for example. “The market is demanding foods with less herbicide and pesticide, and with greater quality,” says Red Whittaker, a robotics engineer at Carnegie Mellon who designed and patented an automated guidance system for tractors in 1997. “That challenge can be met by robots.”

“We predict drones, mounted with RGB or multispectral cameras, will take off every morning before the farmer gets up, and identify where within the field there is a pest or a problem,” says Green. As well as visible light, these cameras would be able to collect data from the invisible parts of the electromagnetic spectrum that could allow farmers to pinpoint a fungal disease, for example, before it becomes established. Scientists from Carnegie Mellon have begun to test the theory in sorghum (Sorghum bicolor), a staple in many parts of Africa and a potential biofuel crop in the United States.

Agribotix, an agriculture data-analysis company in Boulder, Colorado, supplies drones and software that use near-infrared images to map patches of unhealthy vegetation in large fields. Images can also reveal potential causes, such as pests or problems with irrigation. The company processes drone data from crop fields in more than 50 countries. It is now using machine learning to train its systems to differentiate between crops and weeds, and hopes to have this capability ready for the 2017 growing season. “We will be able to ping growers with an alert saying you have weeds growing in your field, here and here,” says crop scientist Jason Barton, an executive at Agribotix.

Modern technology that can autonomously eliminate pests and target agrichemi-cals better will reduce collateral damage to wildlife, lower resistance and cut costs. “We are working with a pesticide company keen to apply from the air using a drone,” says Green. Rather than spraying a whole field, the pesticide could be delivered to the right spot in the quantity needed, he says. The potential reductions in pesticide use are impressive. According to researchers at the University of Sydney’s Australian Centre for Field Robotics, targeted spraying of vegetables used 0.1% of the volume of herbicide used in conventional blanket spraying. Their prototype robot is called RIPPA (Robot for Intelligent Perception and Precision Application) and shoots weeds with a directed micro-dose of liquid. Scientists at Harper Adams are going even further, testing a robot that does away with chemicals altogether by blasting weeds close to crops with a laser. “Cameras identify the growing point of the weed and our laser, which is no more than a concentrated heat source, heats it up to 95 °C, so the weed either dies or goes dormant,” says Blackmore.

Drones with precision sprayers (insert) apply agrochemicals only where they are needed.

ANIMAL TRACKERSSmart collars — a bit like the wearable devices designed to track human health and fitness — have been used to monitor cows in Scotland since 2010. Developed by Glasgow start-up Silent Herdsman, the collar monitors fertility by tracking activity — cows move around more when they are fertile — and uses this to alert farmers to when a cow is ready to mate, sending a message to his or her laptop or smartphone. The collars (pictured), which are now being developed by Israeli dairy-farm-technology company Afimilk after they acquired Silent Herdsman last year, also detect early signs of illness by monitoring the average time each cow spends eating and ruminating, and warning the farmer via a smartphone if either declines.

“We are now looking at more subtle behavioural changes and how they might be related to animal health, such as lameness or acidosis,” says Richard Dewhurst, an animal nutritionist at Scotland’s Rural College (SRUC) in Edinburgh, who is involved in research to expand the capabilities of the collar. Scientists are developing algorithms to interrogate data collected by the collars.

In a separate project, Dewhurst is analysing levels of exhaled ketones and sulfides in cow breath to reveal underfeeding and tissue breakdown or excess protein in their diet. “We have used selected-ionflow-tube mass spectrometry, but there are commercial sensors available,” says Dewhurst.

Cameras are also improving the detection of threats to cow health. The inflammatory condition mastitis — often the result of a bacterial infection — is one of the biggest costs to the dairy industry, causing declines in milk production or even death. Thermal-imaging cameras installed in cow sheds can spot hot, inflamed udders, allowing animals to be treated early.

Carol-Anne Duthie, an animal scientist at SRUC, is using 3D cameras to film cattle at water troughs to estimate the carcass grade (an assessment of the quality of a culled cow) and animal weight. These criteria determine the price producers are paid. Knowing the optimum time to sell would maximize profit and provide abattoirs with more-consistent animals. “This has knock on effects in terms of overall efficiency of the entire supply chain, reducing

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the animals which are out of specification reaching the abattoir,” Duthie explains.

And researchers in Belgium have developed a camera system to monitor broiler chickens in sheds. Three cameras continually track the movements of thousands of individual birds to spot problems quickly. “Analysing the behaviour of broilers can give an early warning for over 90% of problems,” says bioengineer Daniel Berckmans at the University of Leuven. The behaviour-monitoring system is being sold by Fancom, a livestock-husbandry firm in Panningen, the Netherlands. The Leuven researchers have also launched a cough monitor to flag respiratory problems in pigs, through a spin-off company called SoundTalks. This can give a warning 12 days earlier than farmers or vets would normally be able to detect a problem, says Berckmans. The microphone, which is positioned above animals in their pen, identifies sick individuals so that treatment can be targeted. “The idea was to reduce the use of antibiotics,” says Berckmans.

Berckmans is now working on downsizing a stress monitor designed for people so that it will attach to a cow’s ear tag. “The more you stress an animal, the less energy is available from food for growth,” he says. The monitor takes 200 physiological measurements a second, alerting farmers through a smartphone when there is a problem.

SILICON SOIL SAVIOURS The richest resource for arable farmers is soil. But large harvesters damage and compact soil, and overuse of agrichemicals such as nitrogen fertilizer are bad for both the environment and a farmer’s bottom line. Robotics and autonomous machines could help.

Data from drones are being used for smarter application of nitrogen fertilizer. “Healthy vegetation reflects more near-infrared light than unhealthy vegetation,” explains Barton. The ratio of red to near-infrared bands on a multispectral image can be used to estimate chlorophyll concentration and, therefore, to map biomass and see where interventions such as fertilization are needed after weather or pest damage, for example. When French agricultural technology company Airinov, which offers this type of drone survey, partnered with a French farming coopera-tive, they found that over a period of 3 years, in 627 fields of oilseed rape (Brassica napus), farmers used on average 34 kilograms less nitrogen fertilizer per hectare than they would without the survey data. This saved on average €107 (US$115) per hectare per year.

Bonirob (pictured) — a car-sized robot originally developed by a team of scientists including those at Osnabrück University of Applied Sciences in Ger-many — can measure other indicators of soil quality using various sensors and modules, including a moisture sensor and a penetrometer, which is used to assess soil compaction. According to Arno Ruckelshausen, an agricultural technolo-gist at Osnabrück, Bonirob can take a sample of soil, liquidize it and analyse it to precisely map in real time characteristics such as pH and phosphorous levels. The University of Sydney’s smaller RIPPA robot can also detect soil characteristics that affect crop production, by measuring soil conductivity.

Soil mapping opens the door to sowing different crop varieties in one field to better match shifting soil properties such as water availability. “You could differentially seed a field, for example, planting deep-rooting barley or wheat vari-eties in more sandy parts,” says Maurice Moloney, chief executive of the Global Institute for Food Secu-rity in Saskatoon, Canada. Growing multiple crops together could also lead to smarter use of agrichemi-cals. “Nature is strongly against monoculture, which is one reason we have to use massive amounts of her-bicide and pesticides,” says van Henten. “It is about making the best use of resources.”

Mixed sowing would challenge an accepted pillar of agricultural wisdom: that economies of scale and the bulkiness of farm machinery mean vast fields of a single crop is the most-efficient way to farm, and the bigger the machine, the more-efficient the process. Some of the heaviest harvesters weigh 60 tonnes, cost more than a top-end sports car and leave a trail of soil compaction in their wake that can last for years.

But if there is no need for the farmer to drive the machine, then one large vehicle that covers as much area as possible is no longer needed. “As soon as you remove the human component, size is irrelevant,” says van Henten. Small, autonomous robots make mixed planting feasible and would not crush the soil.

In April, researchers at Harpers Adams began a proof-of-concept experiment with a hectare of bar-ley. “We plan to grow and harvest the entire crop from start to finish with no humans entering the field,” says Green. The experiment will use existing machinery, such as tractors, that have been made autonomous, rather than new robots, but their goal is to use the software developed during this trial as the brains of purpose-built robots in the future. “Robots can facilitate a new way of doing agricul-ture,” says van Henten. Many of these disruptive technologies may not be ready for the prime time just yet, but the revolution is coming. ■

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36 | North CaroliNa agriCulture

TECH North Carolina growers

make use of top-of-the-line ag technologies

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 Farmers across North Carolina are embracing advanced technologies designed to improve yields

while making their operations more sustainable and efficient.

In addition, new technologies are in the works that may continue to positively transform the state’s agriculture industry, making it easier than ever for growers to conserve natural resources as they enhance and refine their operations.

Drone TechnologyBased in Raleigh, PrecisionHawk

produces easy-to-operate unmanned

aerial vehicles – commonly referred to as drones – which include sensors that capture aerial images at sub-inch per pixel resolution and can detect hundreds of bands of light, exposing problem areas not visible to the human eye.

PrecisionHawk’s software gives drones the ability to fly autonomously as well as collect, process and analyze images that provide important information.

“This data gives our customers valuable, actionable information they can use to make management decisions,” says Dr. Bobby Vick, an agriculture enterprise solutions

executive for PrecisionHawk who holds a Ph.D. in agricultural engineering. “For example, our vegetative analytics produce a grid of polygons across a field with information about what’s in each polygon, giving farmers an in-depth look at how their field is responding. The farmer can then combine his or her knowledge with the data, create a prescription and apply the correct input, such as fertilizer or water, to the area that needs it. This saves farmers an incredible amount of time.”

Dr. Vick says PrecisionHawk’s software can also analyze the yield

Savvy

North Carolina farmers take advantage of new technologies including drones, GPS and high-tech irrigation systems to help with efficiency.

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potential of a field and count existing plants, helping growers determine if they should replant crops in specific areas after instances of flooding or disease.

“There are scenarios in which a farmer needs to assess damage for insurance claim purposes, and we’re able to provide a much more objective and quantified assessment of the extent of the damage or stress in an area than traditional field scouting allows,” Dr. Vick says.

New TechnologiesAgricultural technology

is continuing to advance, and Dr. Raju Vatsavai, an associate professor in the computer science department at NC State University in Raleigh, predicts farmers will soon have access to new tools and technologies.

Dr. Vatsavai points to recent advances in sensing technologies coupled with big-data analytics, which are helping farm technology companies make farming more efficient and environmentally sustainable.

For example, he says ground sensors combined with thermal-sensor data from remote sensors can monitor and predict soil moisture, helping large-scale farmers schedule irrigation systems at the right time and location.

Additionally, emerging agricultural technology companies are experimenting with robots and artificial intelligence. Startups across the U.S. are developing image recognition algorithms that can detect and classify plant pests and disease more accurately than humans, for example, as well as creating machine vision systems to measure crop populations and detect weeds.

“Unfortunately, we can’t increase the land for agriculture, and that leaves us with the only option of increasing agricultural productivity by reducing energy and water footprints,” Dr. Vatsavai says. “Modern sensors, drone

technologies and big-data analytics by utilizing modern artificial intelligence technologies provides great opportunities for farmers to improve their productivity. Digital agriculture, which combines these

technologies for precision farming, holds the promise of increased productivity for farmers as well as a better environment and produce that’s higher in quality and cheaper for consumers.”

– Jessica Walker Boehm

“This data gives our customers valuable, actionable information they can use to make management decisions.” Dr. Bobby Vick, PrecisionHawk