Agriculture and Forestry Sector: Nitrogen Reduction
~ Iowa

Reducing Nitrogen Fertilizer Use

Iowa's extensive programs to reduce pesticide and fertilizer use were born
out of a desire to reduce groundwater contamination but grew to include
the protection of all waters. Streams in Iowa have among the highest nitro-
gen and phosphorous levels in the country and may contribute one-fourth
of all the nitrates washed into the Gulf of Mexico each year. Beginning in
1982, a series of research and demonstration programs have encouraged
farmers to reduce their fertilizer use to improve profit margins and help the
environment. In 1987, these programs, developed by numerous organiza-
tions, were expanded into the statewide Integrated Farm Management
Demonstration Project and the Model Farms Demonstration Project. Funding for these programs expired in 1993,
but they continue to have a profound effect on fertilization practices in Iowa. Collectively known as the Iowa
Agricultural-Energy-Environmental Initiative, these programs succeeded in reducing the 1998 nitrogen application
rate on corn by 12.5% over the 1985 application rate. In addition to reducing groundwater contamination, farmers
achieved lower production costs. It was estimated that every dollar invested in the project returned more than
fifteen dollars in savings.

Reduction of nitrogen fertilizer application acts in two ways to reduce greenhouse gas emissions. First, a small
percentage of the nitrogen applied to the soil gets directly converted to nitrous oxide (N20), a powerful green-
house gas. Second, fertilizers and pesticides derived from fossil fuels make up 75% of the energy inputs in Iowa
corn production. By reducing the amount of fertilizer applied, Iowa farmers reduce the amount of energy used to
manufacture, ship, and spread fertilizer to their fields each year.

Results:

In 1998, 12.5 million acres of corn were planted in Iowa. Of
this area, 96% was treated with commercial nitrogen-based
fertilizers. The average fertilizer application rate was 127 lbs
nitrogen (N) per acre, down from 145 lbs N per acre in 1985 (a
12% reduction). This rate is 18% less than the rate in surround-
ing Corn Belt states, which applied an average of 154 lbs N per
acre. Despite this drop in nitrogen application, corn yields in Iowa were higher than those in the surrounding
states. In 1998, Iowa averaged a corn yield of 145 bushels per acre while other Corn Belt states averaged a yield
of 136 bushels per acre.

The lower application rate translates to a savings of 216 million lbs of nitrogen. This is equivalent to a N20
savings of 1,900 metric tons* of N20 or in terms of C02 equivalents a savings of 597,000 metric tons* (163,000
MTCE*). At a fertilizer price of 15 cents per lb N, the lower application rate saved $32.4 million. Although it is
difficult to quantify the energy savings associated with the application of less fertilizer, best estimates indicate
that the energy required to manufacture, transport, store, and apply five pounds of nitrogen is equivalent of one
gallon of diesel fuel (based on Btu equivalency). Thus, in 1998, lower application rates saved the equivalent of
43.2 million gallons of diesel fuels**.

Principal Actors:

The Iowa State University Agronomy Department developed the programs through the Agricultural Energy
Management Program. The initiative was financed primarily through oil overcharge funds and the Iowa Ground-
water Protection Act funds administered by the Iowa Department of Natural Resources. Many other organizations
collaborated in implementing these programs and contributed to their success.

! Cost Savings

Greenhouse



Gas Reductions

j $32.4 million

163,000 MTCE*/yr j


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Additional Information:

Craig Stark, Program Planner, Iowa Department of Natural Resources, 515-281-4739, cstark@max.state.ia.us.

This case study is based on information provided by Craig Stark, Iowa Department of Natural Resources and downloaded from
the Iowa State University Department of Agronomy website: http://extension.aaron.iastate.edu/soils/nuse.html.

~Original data have been converted from tons nitrogen applied to metric tons of carbon equivalent (MTCE) based on conver-
sion formulas from the 1999 Emission Inventory Improvement Program Volume XIII as follows:

, , 0.0125 tons N emitted 44 tonsNiO 310 tons COi equiv 12 tons C

tons N applied x	x	x	x	

tons N applied 28 tons N emitted	tons NiO	44 tons COi

**This energy data has not been converted to C02 savings because it represents estimated energy savings from a variety of
different fuels based on BTUs (British thermal units). Because carbon intensity per Btu varies significantly between fuel types,
it is difficult to obtain a meaningful value of C02 savings from this type of estimate. It is included as an indication that the
agricultural management programs have achieved significant energy savings as well as nitrogen savings.


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