No-till, rotations reduce greenhouse gases

Using no-till and corn-soybean rotation practices in farm fields can significantly reduce field emissions of the greenhouse gas nitrous oxide, according to a Purdue University study.

Tony Vyn, a professor of agronomy, found that no-till reduces nitrous oxide emissions by 57 percent over chisel tilling, which mixes crop residue into surface soil, and 40 percent over moldboard tilling, which completely inverts soil as well as the majority of surface residue. Chisel plowing is the most widely used form of tilling before planting corn in Indiana, he said.

"There was a dramatic reduction simply because of the no-till," said 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, according to the U.S. Environmental Protection Agency, has about 310 times more heat-trapping power than carbon dioxide in part because of its 120-year lifespan. 

"This suggests there is another benefit to no-till beyond soil conservation and improving water quality," Vyn said. "There is an air quality benefit as well."