Nutrient Pollution

The EPA drinking water standard is 10 ppm NO 3 -N 220 lbs of N / 4 million lbs of water = Nitrogen uptake by corn 55 ppm

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

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 ,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”

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 Rabalais, et al Rabalais, et al 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

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

N participates in many different processes Plant biomass Plant uptake Soil Microbial biomass red pathways = losses

Likely movement of nitrate when ~ 1 inch of water infiltrates 3 different textures of soil 6” 12”

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 O 2 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

?

NO 3 - NO 2 - NO N 2 O N 2 Denitrification Warm, anaerobic conditions + OM promote rapid denitrification

Agriculture Greenhouse gas & Ozone depleter Agriculture is main source

NOx N 2 O 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 s

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 ? Grain Meat

So what about phosphorus ???

P Saturated Dutch Soils Dutch 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:

use cover crops REDUCTION POTENTIAL

Annuals mg L corn corn – soybean rotation Perennials alfalfa--441 mixed grasses--410 Concentrations of NO 3 -N in tile drain water (Randall et al., 1997)

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

SPRING Summer annual cropping system water Evaporation Tile drain Fertilizers and pesticides Most fields used for annual cropping receive fertilizers and pesticides every year.

water SPRING Tile drain Runoff Evaporation and transpiration water Leaching Gulf of Mexico Summer annual cropping system

Nutrients and pesticides Soil Drainage water and run-off carries away sediment, nutrients and pesticides. SPRING Gulf of Mexico Summer annual cropping system

Gulf of Mexico SUMMER During the summer, crop uptake of water and nutrients is rapid and environmental losses are typically low. Summer annual cropping system

H2OH2O Nutrients and pesticides Soil After harvest, though, landscapes are once more left without plant cover to regulate ecosystem processes. FALL Evaporation Gulf of Mexico Summer annual cropping system

H2OH2O Nutrients and pesticides 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 Summer annual cropping system

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 Mexico

SPRING Fertilizers Soil and nutrients Soil, water and nutrient losses are greatly reduced resulting in reduced needs for costly inputs. The future of farming: perennial and diverse Gulf of Mexico

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. The future of farming: perennial and diverse Gulf of Mexico

The future of farming: perennial and diverse FALL After harvest, plant roots remain alive, ready to support regrowth the next spring. Gulf of Mexico

Perennial-based rotation systems Tree crops Permanent pasture systems Winter annual cover crops Green Lands, Blue Waters

Perennial biomass energy crops Perennial grain crops perennial wheatperennial sorghum perennial 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

No cover

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

McLean County, IL