Michigan farmer Myron Ortner knows that regulations are coming on farm fertilizer use, so he collaborated with scientists on a system where corn farmers can earn voluntary credits for reducing nitrogen application rates.
All nitrogen fertilizers and manure emit potent greenhouse gases. Nitrous oxide (N2O), is a greenhouse gas with about 300 times the global warming potential of carbon dioxide, according to EPA.
One of Ortner’s 40-acre corn/soybean fields was used by Michigan State University scientists to measure how much nitrous oxide (N2O, a gas) wafts invisibly into the air at various nitrogen-application rates, under different weather conditions and under various other environmental conditions (see http://bit.ly/N2OMethodology). A research summary, translated to a voluntary credit protocol, predicted that a 12-15% nitrogen-rate reduction within the profitable nitrogen-rate range for corn can generate significant nitrous-oxide reductions without affecting yields. If widely adopted, the nitrogen rate protocol “could reduce nitrous oxide from fertilized row-crop agriculture by more than 50%.”
The new Delta Nitrogen Credit Program will pay qualified Corn Belt corn farmers who reduce their documented nitrogen rates. These credits will be purchased by industries mandated to reduce or offset their greenhouse-gas emissions, in this cap-and-trade-style program. Delta is reaching out to farmers through partner organizations, including American Farmland Trust, Conservation Technology Information Center, Environmental Defense Fund and agricultural retailers.
The program began as an NRCS Conservation Innovation Grant.
Fertilizer nitrogen formulation, timing, and placement do not correlate as strongly with nitrous oxide emissions as the N rate does, says Michigan State University Senior Research Associate Neville Millar, who co-developed the formula translating N fertilizer to credit.
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“All forms of nitrogen fertilizers change to ammonium nitrogen form (NH4) to be plant-available, but that same ammonium is also what gets lost via nitrous oxide (N2O) by air or nitrates (NO3) in water,” Millar adds. “Of all the 4R nitrogen variables (source, timing, placement and rate), the nitrogen rate has the most scientifically reliable correlation with nitrous-oxide release and is what we’ve chosen for the N2O credit formula.”
Ortner uses 70% ESN polymer-coated stabilizer and 30% urea incorporated immediately at planting. He recently reduced his nitrogen rates by 15% without cutting corn yields, but could only earn an N2O credit for the rate reduction, although the management changes undoubtedly improve his N efficiency.
Besides reducing greenhouse gases, reduced nitrogen-fertilizer rates can reduce nitrate leaching into water tables.