Reducing greenhouse gases with agriculture
By Dennis O'Brien USDA-ARS
Apr. 1, 2013 - U.S. Department of Agriculture (USDA) scientists and their partners are providing guidance to growers in Montana and the Dakotas on how they can use some tried-and-true agricultural practices to reduce their climate change footprint.
Upendra Sainju and his colleagues with the Agricultural Research Service (ARS) in Sidney, Mont., have been studying how no-till systems, crop rotation and other approaches can reduce greenhouse gas emissions, sustain crop yields and cut back on the use of nitrogen fertilizer that pollutes the air and water. ARS is USDA's principal intramural scientific research agency, and this research supports the USDA priority of responding to climate change.
Agriculture contributes about 25 percent of the carbon dioxide produced by humans and 70 percent of the similarly produced nitrous oxide being released into the atmosphere. Tillage, cropping sequences, crop-fallow management practices, and the use of nitrogen fertilizers all play significant roles in those emissions.
The researchers evaluated the effects of irrigation, tillage, cropping systems, and nitrogen fertilization on greenhouse gas emissions from five cropping systems in sandy loam soil in western North Dakota, where growers can irrigate fields.
They also studied three cropping systems in loam soil in eastern Montana where irrigation is not usually an option. They raised conventionally tilled malt barley with and without nitrogen fertilizer, no-till malt barley with and without fertilizer, and a no-till malt barley-pea rotation with and without fertilizer. Some systems were irrigated and others were not, and the researchers tracked soil temperatures and soil water content, measured plant biomass, and used static, vented chambers to measure greenhouse gases.
Their results, described in papers in the Journal of Environmental Quality and the Soil Science Society of America Journal, showed that regardless of whether the field was irrigated, the no-till malt barley-pea rotation with reduced nitrogen fertilizer rates was the most effective system for reducing greenhouse gas emissions and sustaining yields. They also found that the no-till barley-pea rotation reduced the need for fertilizers with no effect on yields.
The study is part of a comprehensive effort to examine the effects of irrigation and different management scenarios on greenhouse gas emissions in the northern Great Plains. Growers have known for decades that no-till improves soil quality and that rotating crops reduces weeds, diseases, and pests. But the study and others like it are prompting growers to adopt no-till, rotate crops and use less fertilizer.
Read more about this research in the March 2013 issue of Agricultural Research magazine.