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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. 

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