nutrient pollution

Nutrient Pollution

http://mckusicklake.org/wp-content/uploads/2008/04/2007_0327image0001.JPG

The EPA drinking water standard is 10 ppm NO3-N

220 lbs of N / 4 million lbs of water = 0.000055

Nitrogen uptake by corn

55 ppm

Why does so much N get into Illinois’ rivers ???

http://www.ars.usda.gov/SP2UserFiles/Place/36251500/TheExtentofFarmDrainageintheUnitedStates.pdf

Artificial drainage in the United States

% of land drained

Point source vs. non-point source pollution

Nutrient pollution(Eutrophication)Excess nutrients promote algal blooms in aquatic ecosystems creating unusually high biological oxygen demand when the algae dies and begins to decompose.

Conventional wisdom:Nitrogen is the most limiting nutrient in marine systems.

Phosphorus is the most limiting nutrient in freshwater ecosystems

Reality is more complex.

In 2002 5,549 miles (out of 15,491) of Illinois streams did not meet IEPA water quality standards.

Areas where nitrate levels are likely to harm amphibians

Understanding the “Dead Zone”

http://www.epa.gov/region5/water/npdestek/gulf_nutrients.pdf

Is the Hypoxic zone increasing in size ?

Yes… but not consistently.

The second largest hypoxic zone ever measured occurred in 2008

Extent of Hypoxia in the Gulf

Frequency of Occurrence 1985 - 1999Frequency of Occurrence 1985 - 1999

Rabalais, et alRabalais, et al.17

400 km

Distance Paris to London = 490 km

What is causing the hypoxic zone ?

“Geologic evidence shows that dead zones were not a naturally recurring event in the Chesapeake Bay or most

other estuarine ecosystems” says Diaz. "Dead zones were once rare. Now

they're commonplace”.

Why is nutrient pollution an expanding problem if…

A large survey of farming practices used in the Big Ditch Watershed in Champaign Co., IL was conducted

in 1995:

80% of the farmers interviewed regularly applied at least 20% more nitrogen fertilizer than recommended by the U of I.

How much N did the U of I recommend for corn in 1995?

1.2 lbs of N per bushel of expected yield

Relationship between optimal N rate and optimal corn yield in IL (72 site years)

Only 13 out of 72 site-years in IL required more than 1 lb of N per bushel

1 :1 line

Relationship between optimal N rate and optimal yield (81 site years)

Only 4 out of 81 sites in IA required more than 1 lb of N per bushelOnly 16 out of 81 sites in IA required more than 0.75 lb of N per bushel

http://www.fertilizer.org/ifa/publicat/PDF/2005_ag_frankfurt_lammel_slides.pdf

Weather often regulates crop productivity more than nutrient input rates in high productivity systems

N participates in many different processes

Plant biomass

Plant uptake

SoilM

icro

bial

bio

mas

s

red pathways = losses

Likely movement of nitrate when ~ 1 inch of water infiltrates 3 different textures of soil

6”

12”

http://res2.agr.ca/stjean/publication/bulletin/nitrogen-azote_e.pdf

Why is leaching is more likely in coarser textured soils ?

Fine textured soil

~ 14 % of wells in IL are contaminated

with excessive

nitrate

Why is nitrate such a slippery character ?

• Nitrate is an anion• Nitrate compounds are very soluble• Nitrate is next in line as an electron acceptor when O2 is not present

Work in Champaign County has shown that a significant amount of the N loss in very wet years like 1998 could be via leaching, but in years of less excess

water, the leaching loss is minor—less than 10 percent.

As a general rule of thumb, two-thirds of the N loss in Illinois soils occurs via the process of denitrification and the other one-third via

leaching.

N losses through tile lines

http://agronomyday.cropsci.uiuc.edu/2001/tours/n-fate/index.html

NO3- NO2

- NO N2O N2

Denitrification

Warm, anaerobic conditions + OM promote rapid denitrification

Agriculture

Greenhouse gas&

Ozone depleter

Agriculture is main source

NOxN2O are just one type of

Total Ammonia Emissions by County (1995)

Where is all this ammonia coming from ??

50 lbs N/acre

Deposition of reactive N

18601990s

Typical losses of N associated with consumption of grain and meat

What happens to the reactive N that doesn’t make to our dinner plates ?

Gra

inM

eat

So what about phosphorus ???

P SaturatedP Saturated Dutch SoilsDutch Soils

Long-term over-fertilization with P in animal manures,

biosolids, and fertilizers has “saturated” some soils to the point that “bio-available” and

soluble P losses in surface and subsurface runoff are

now of environmental concern

Emerging Issue:Emerging Issue:

use cover crops

REDUCTION POTENTIAL

1990

1991 1992 1993

Annuals ----- mg L-1 -----

corn 30 39 40 20

corn – soybean rotation

24 33 26 13

Perennials

alfalfa -- 4 4 1

mixed grasses -- 4 1 0

Concentrations of NO3-N in tile drain water

(Randall et al., 1997)

annual

Sept Dec March June

12 mos 21 mos

annual

Sept Dec March June

12 mos 21 mos

The perennial advantage

Roots of annual wheat and wheatgrass, a perennial relative of wheat, excavated at 4 different times of year.

http://www.greenlandsbluewaters.org/04_Glover.ppt

SPRING

Summer annual cropping system

. . . . . . . . . . . .

water

Evaporation

Tile drain

Fertilizers

and pesticidesMost fields used for annual cropping receive fertilizers and pesticides every year.


water

water

water

SPRING

Tile drain

Runoff

Evaporation and transpiration

water

Leaching

Gulf of Mexico



Nutrients and pesticides

Soil

Drainage water and run-off carries away sediment, nutrients and pesticides.

SPRING

Gulf of Mexico



Gulf of Mexico

SUMMERDuring the summer, crop uptake of water and nutrients is rapid and environmental losses are typically low.



H2 O


Soil

After harvest, though, landscapes are once more left without plant cover to regulate ecosystem processes.

FALL

Evaporation

Gulf of Mexico



H2 O


Soil

Fertilizers

More fertilizer must be applied to offset the season’s losses. Annual crops typically recover less than 50% of fertilizer nitrogen.

FALL

Gulf of Mexico



SPRING

Evaporation and transpiration

Regrowing from their roots, some perennial crops start growing earlier than summer annuals.

Runoff

The future of farming: perennial and diverse

Gulf of Mexicohttp://www.greenlandsbluewaters.org/04_Glover.ppt

SPRING

Fertilizers

Soil and nutrients

Soil, water and nutrient losses are greatly reduced resulting in reduced needs for costly inputs.



Soil and nutrients

SUMMER Perennial systems are more resilient in the face of environmental stress and yields are more stable from one year to the next.




FALL

After harvest, plant roots remain alive, ready to support regrowth the next spring.


Perennial-based rotation systems

Tree cropsPermanent pasture systems

Winter annual cover crops

Green Lands, Blue Waters

Perennial biomass energy crops

Perennial grain crops

perennial wheatperennial sorghumperennial sunflowers

perennial maize

Green Lands, Blue Waters

Scientific American, August 2007

Reality

Red counties had greater than 90% of

their cropland planted to corn and

soybeans in 2002

Upper Mississippi watershed

http://www.leopold.iastate.edu/research/eco_files/cover_030607.pdf

No cover

Singer, J.W., Nusser, S.M., Alf, C.J. 2007. Are Cover Crops Being Used in the US Corn Belt? Journal of Soil and Water Conservation. 62(5):353-358.

Interpretive Summary: The benefits of using cover crops are well established in the scientific literature, but adoption among end-users in agronomic farming systems is uncertain. The objectives of this study were to quantify cover crop use in the central western Corn Belt and the factors associated with their adoption. A mail survey was sent to 3500 producers in Illinois, Indiana, Iowa, and Minnesota in June of 2006 to survey farming practices and cover crop use. The survey response rate was 36%. An estimated 18% of producers in this region have ever used cover crops, 11% have used cover crops in the last five years, and 8% planted cover crops last fall. Crop diversity was the most consistent and important factor controlling the use of cover crops across the four states surveyed. Central western Corn Belt producers believe that cover crops are most effective at reducing erosion (96%) and increasing soil organic matter (74%). Approximately 56% of producers in this region indicated that they would plant cover crops if cost-sharing was available. The information collected in this survey will help educators and legislators identify critical impediments to inceasing cover crop adoption.

Traditional Cover Crop Planting Deadlines and Payment Schedule

• Plant by October 1, 2008: up to $85/acre. • Plant by October 15, 2008: up to $75/acre. • Plant by November 5, 2008: up to $70/acre.

• Fall certification with the soil conservation district must take place within one week after

the planting deadline. • Kill down/suppression may occur any time

after March 1, 2009, but no later than June 1, 2009.

Funding is available for ~ 50% of cropland in Maryland !!

Most comprehensive

reference on cover crops

available.

The entire book is

available on-line for free.

http://www.mccc.msu.edu/documents/ManagingCCProfitably.pdf

What is the future of agricultural drainage ?

Maximum conveyance

Subsurface bioreactors

Bioreactors provide many advantages:

They use proven technology They require no modification of current practices No land needs to be taken out of production There is no decrease in drainage effectiveness They require little or no maintenance They last for up to 20 years.

Water table management

Where are the drain lines ?Subsurface irrigation

http://dnr.state.il.us/oi/June_08_Site.pdf

McLean County, IL

nutrient pollution

Documents

n loss

optimal n rate

lbs of water

limiting nutrient

soluble nitrate

nitrate levels

ppm no3n220 lbs of n

optimal yield