Building and Maintaining Soil Fertility:

Organic Practices for Cut Flower Growers

Association of Specialty Cut Flower Growers: Growers’ Intensive, March 23, 2015

• Defining Soil Quality and Why Its Important

Soil Quality and Soil Health Defined: Visible, Physical, Chemical and Biological Components

Indicators of Soil Health and Sound Soil Fertility Management: Soil Organic Matter, Microbial Population, Structure/Tilth,

Nutrient Availability, Near Neutral pH, Low Salinity

Practices That Promote Soil Quality, Soil Fertility and Crop Health: Compost Application, Cover Cropping, Crop Rotation, Crop Diversity, Timely &

Reduced Tillage, Continuous Soil Coverage, Careful Irrigation Management, Soil Analysis, Nutrient Budgeting

Typical Soil Food Web in Sustainably Managed Soils: diversity and abundance of microbial population and macroorganisms as a strong indicator of soil quality

Typical Numbers of Soil Organisms in Healthy Ecosystems: the living soil community that is responsible for mineralization of plant

nutrients, soil respiration, and a major contributor to the formation and stability of soil aggregates.

Ag Land Prairie Forest

Organisms per gram (teaspoon) of soil

Bacteria 100 mil. -1 bil. 100 mil. -1 bil. 100 mil. -1 bil.

Fungi Several yards 10s – 100’s of

yds

1-40 miles

(in conifers)

Protozoa 1000’s 1000’s 100,000’s

Nematodes 10-20 10’s – 100’s 100’s

Organisms per square foot

Arthropods < 100 500-2000 10,000-25,000

Earthworms 5-30 10-50 10-50

(0 in conifers)

Components of Soil Organic Matter

Detritus :Decomposing

Organic Matter

(active fraction)

33% - 50%

Humus:

Stabilized

Organic

Matter

33% - 50%

Fresh

residue

<10%

Living

organisms

<5%

Practices and Management Tools to improve soil quality, build fertility, enhance crop health and increase crop productivity, while simultaneously reducing environmental degradation and human health risks associated with conventional soil management strategies

Practices That Promote Soil Quality, Soil Fertility and Crop Health: Compost Application, Cover Cropping, Crop Rotation, Crop Diversity, Timely &

Reduced Tillage, Continuous Soil Coverage, Careful Irrigation Management, Soil Analysis, Nutrient Budgeting

Surface soil compaction can lead to poor infiltration, runoff and soil erosion

A Fundamental Tool for building and maintaining soil health and nutrient availability

Cover Crops for Healthy Soils: Legume/Bacteria and N fixation

Capture and cycling of existing nutrients to prevent leaching Root structures can break up plow pans, build aggregates, create macropores Provides soil surface coverage to limit erosion, crusting, compaction Add organic matter as fuel for biological community, mineralization, aggregation Provide weed suppression, beneficial insect habitat and suppress pests & disesases

Nitrogen-fixing Bacteria, in association with Leguminous Cover Crops, convert atmospheric

Nitrogen-N2 into Ammonium-NH4+, for use by the

Legume and by subsequent crops through the ongoing mineralization

•Nodules formed where Rhizobium bacteria infected soybean roots.

Mulching: Provides continuous soil cover Protects against erosion Builds soil organic matter Improves soil structure, prevents crusting and protects soil aggregates Suppresses weed growth Aids in moisture conservation Reduces soil temperatures An approved NRCS cost share practice

Rainfall landing directly on bare soil can lead to soil aggregate destruction, soil crusting, surface erosion, reduced infiltration, and poor soil aeration.

Soil Aggregates and Soil Crusting via aggregate destruction

Soil Aggregate Stability Test: Same Soil Type with Different Management History

Fungi and Soil Quality

– Decompose carbon compounds

– Improve OM accumulation

– Retain nutrients in the soil

– Bind soil particles

– Food for the rest of the food web

– Mycorrhizal fungi

– Compete with plant pathogens

Regular Compost Application in your Soil Provides: a stable nutrient supply, increased soil organic matter, an enhanced biological community, strengthened aggregation and tilth, better aeration, infiltration & drainage, buffering of pH, and improved water holding capacity.

Compost and increased soil organic matter act as buffering agents, such that soils perform closer to neutral pH values, thus optimizing nutrient availability

Tillage and Cultivation Operations: Timely operations driven by ideal soil moisture benefit soil structure, prevent compaction and protect soil aggregates. Time biomass incorporation and nutrient release to meet needs of subsequent crops. Minimize tillage operations to conserve soil organic matter

Strip Till and No Till Systems: like mulching, these practices maintain continuous soil coverage, protect against erosion, improve soil structure and build the biological community

Transpiration (water loss from the plant leaves)

Evaporation (water loss from the soil surface)

Transpiration + Evaporation = Evapotranspiration (Et)

Careful Management of Irrigation is critical to meet changing plant needs, deliver nutrients in the soil solution, prevent leaching, compaction, runoff, and crusting. Know your local ET rates to help determine proper timing and quantity of water deliveries. Water conservation can be aided by drip irrigation, but especially in arid zones, this can lead to salt accumulation on the soil surface. Drought Tolerance & Resilience as management goals

Crop & Soil Health through Crop Rotation: to balance nutrient demands and limit pest and disease issues

Soil Testing and Plant Tissue Sampling: provide benchmarks to current assess needs, track trends over time and adjust practices accordingly. A critical tool to prevent nutrient deficiencies

and over-application of expensive fertility inputs

Web Resources for Soil Health and Fertility Management:

Soil Health Assessment Training Manual: Cornell University http://soilhealth.cals.cornell.edu/extension/manual/manual.pdf Web Soil Survey: USDA Natural Resources Conservation Service http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm Soil Health: USDA Natural Resources Conservation Service http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/ Sustainable Soil Management, Drought Resistant Soils and many more resources on organic management practice: NCAT ATTRA https://attra.ncat.org/soils.html The Biology of Soil Compaction: Ohio State University http://ohioline.osu.edu/sag-fact/pdf/0010.pdf Assessing Soil Quality in Organic Agriculture: The Organic Center https://www.organic-center.org/reportfiles/SoilQualityReport.pdf

Print Resources for Soil Health and Fertility Management: Building Soils for Better Crops: Sustainable Soil Management, 3RD Edition F. Magdoff & H. Van Es, SARE, 2010 Crop Rotation on Organic Farms: A Planning Manual C. Mohler & S. E. Johnson, NRAES, 2009 Soil Biology Primer E. Ingham, Soil & Water Conservation Society/USDA NRCS, 2000 Managing Cover Crops Profitably, 3RD Edition A. Clark, SARE, 2007 Teaming With Microbes: The Organic Gardener’s Guide to the Soil Food Web

J. Lowenfels, Timber Press, 2010 Teaming With Nutrients: The Organic Gardener’s Guide to Optimizing Plant

Nutrition J. Lowenfels, Timber Press, 2013 The Nature and Property of Soils, 14TH Edition N. Brady & R. Weil, Prentice Hall, 2007