More no-till benefit
No-till and a corn-soybean rotation can significantly cut field emissions of the greenhouse gas nitrous oxide, a Purdue University study shows.
Agronomist Tony Vyn says no-till reduces nitrous oxide emissions by 57% over chisel plowing and 40% over moldboard plowing.
“There was a dramatic reduction simply because of the no-till,” says Vyn, whose findings were published in the Soil Science Society of America Journal. “We think the soil disturbance and residue placement impacts of chisel plowing and moldboard plowing modify the soil physical and microbial environments such that more nitrous oxide is created and released.”
During early-season nitrogen fertilizer applications on corn, no-till may actually reduce nitrous oxide emissions from other forms of nitrogen present in, or resulting from, that fertilizer.
Nitrous oxide is the third most abundant greenhouse gas in the atmosphere, but it has about 310 times more heat-trapping power than carbon dioxide, in part, due to its 120-year life span.
“This suggests there is another benefit to no-till beyond soil conservation and improving water quality,” Vyn says.
Using a corn-soybean rotation instead of continuous corn decreased nitrous oxide emissions by 20% in the three-year study. Vyn says the reduction could be even greater because for the long-term experiment, both continuous corn and rotation crops were fertilized based on the needs of continuous corn. A rotation cornfield would normally get 20% less nitrogen.
Vyn says finding ways to reduce nitrous oxide emissions is important because food production accounts for about 58% of all emissions of the gas in the U.S. Of that, about 38% comes from the soil.
“There is more nitrous oxide emission coming from agriculture than the tailpipes of cars and trucks,” Vyn says. “And there is likely to be more nitrous oxide emission if we increase nitrogen application rates to increase cereal yields.”
The study took place on a consistently managed 30-year-old rotation/tillage experiment near Purdue. A USDA grant to the Consortium for Agricultural Soil Mitigation of Greenhouse Gases at Kansas State University funded the research. Vyn’s next goal is developing integrated management practices to reduce nitrous oxide emissions even more.