Nutrient Pollution http://mckusicklake.org/wp-content/uploads/ 2008/04/2007_0327image0001.JPG
Jan 13, 2016
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.
http://www.greenlandsbluewaters.org/04_Glover.ppt
water
water
water
SPRING
Tile drain
Runoff
Evaporation and transpiration
water
Leaching
Gulf of Mexico
Summer annual cropping system
http://www.greenlandsbluewaters.org/04_Glover.ppt
Nutrients and pesticides
Soil
Drainage water and run-off carries away sediment, nutrients and pesticides.
SPRING
Gulf of Mexico
Summer annual cropping system
http://www.greenlandsbluewaters.org/04_Glover.ppt
Gulf of Mexico
SUMMERDuring the summer, crop uptake of water and nutrients is rapid and environmental losses are typically low.
Summer annual cropping system
http://www.greenlandsbluewaters.org/04_Glover.ppt
H2 O
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
http://www.greenlandsbluewaters.org/04_Glover.ppt
H2 O
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
http://www.greenlandsbluewaters.org/04_Glover.ppt
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.
The future of farming: perennial and diverse
Gulf of Mexicohttp://www.greenlandsbluewaters.org/04_Glover.ppt
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 Mexicohttp://www.greenlandsbluewaters.org/04_Glover.ppt
The future of farming: perennial and diverse
FALL
After harvest, plant roots remain alive, ready to support regrowth the next spring.
Gulf of Mexicohttp://www.greenlandsbluewaters.org/04_Glover.ppt
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