No-till, rotation can limit greenhouse gas emissions from farm fields
WEST LAFAYETTE, Ind. - 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."
Using a corn-soybean rotation instead of continuous corn decreased nitrous oxide emissions by 20 percent in the three-year study. Vyn said the reduction could be even greater, though, 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 receive 20 percent less nitrogen.
Vyn said finding ways to reduce nitrous oxide emissions is important because food production accounts for about 58 percent of all emissions of the gas in the United States. Of that, about 38 percent is coming from the soil.
"There is more nitrous oxide emission coming from agriculture than the tailpipes of cars and trucks," Vyn said. "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.
The next step in Vyn's research is to develop integrated management practices to reduce nitrous oxide emissions even more. He's also studying additives that slow the conversion of nitrogen-based fertilizers to chemicals that can emit nitrous oxide.
A U.S. Department of Agriculture grant to the Consortium for Agricultural Soil Mitigation of Greenhouse Gases at Kansas State University funded the research. The Indiana Corn Marketing Council and Dow AgroSciences are funding his present on-farm studies of integrated management practices to reduce nitrous oxide emissions.
Writer: Brian Wallheimer, 765-496-2050, email@example.com
Source: Tony Vyn, 765-496-3757, firstname.lastname@example.org
Ag Communications: (765) 494-2722;
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Agriculture News Page
Soil Nitrous Oxide Emissions in Corn Following
Three Decades of Tillage and Rotation Treatments
Rex A. Omonode, Doug R. Smith, Anita Gál, Tony J. Vyn
Few experiments have directly compared the long-term effects of moldboard, chisel, and no-till tillage practices on N2O emissions from the predominant crop rotation systems in the Midwestern United States. This study was conducted from 2004 to 2006 on a tillage and rotation experiment initiated in 1975 on a Chalmers silty clay loam (a Typic Endoaquoll) in west-central Indiana. Our objectives were to assess (i) long-term tillage (chisel [CP], moldboard plow [MP], and no-till [NT]), rotation (continuous corn [Zea mays L.] and corn–soybean [Glycine max (L.) Merr.]), and rotation tillage interaction effects on soil N2O emission, and (ii) how soil N2O emission is related to environmental factors during corn production under identical N fertilizer management. Seasonal N2O emissions were measured at intervals ranging from a few days to biweekly for up to 14 sampling dates in each growing season for corn. Nitrous oxide emissions during the growing season were significantly affected by tillage and rotation but not their interaction; however, 50% of total emissions occurred shortly after N application regardless of tillage or rotation practices. Seasonal cumulative emissions were significantly lower under NT but not statistically different for CP and MP. Overall, emissions under NT were about 40% lower relative to MP and 57% lower relative to CP. Rotation corn lowered N2O emissions by 20% relative to continuous corn. Higher N2O emission under MP and CP appeared to be driven by soil organic C decomposition associated with higher levels of soil–residue mixing and higher soil temperatures.