New Leads on Nitrous Oxide

ARS soil scientist Rodney Venterea (foreground) and technician Jason Leonard collect gas samples from chambers used to measure flux of nitrous oxide and other greenhouse gases from experiments in a corn field in Becker, Minnesota. Agricultural practices, particularly the use of nitrogen-based fertilizers, generate significant levels of the greenhouse gas nitrous oxide (N O). But the mechanisms behind these emissions are still nebulous, and some studies suggest that N O emissions may be underestimated by as much as 40 percent at some sites. “We need to know much more about how agricultural practices affect the production and consumption of greenhouse gases, including N O,” says microbiologist Tim Parkin, who works at the Air Quality of Agricultural Systems Research Unit in Ames, Iowa. Scientists already know that N O emissions rise as the applications of nitrogen-based fertilizers increase. Parkin and his Ames colleagues collaborated with scientists from AgCert International Limited under a cooperative research and development agreement to learn more about how different soils and fertilizers affect N The team used chamber studies to assess variation in the emissions of N O, carbon dioxide, and methane from a sandy loam mix and a clay soil. The fertilizers used were urea-ammonium nitrate (UAN) and a swine manure slurry. The researchers