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Title: Nitrogen source and placement effects on soil nitrous oxide emissions from no-till corn

Author
item Halvorson, Ardell
item Del Grosso, Stephen - Steve

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2012
Publication Date: 5/25/2012
Citation: Halvorson, A.D., Del Grosso, S.J. 2012. Nitrogen source and placement effects on soil nitrous oxide emissions from no-till corn. Journal of Environmental Quality. 41: 1349-1360.

Interpretive Summary: Nitrogen (N) application generally increases nitrous oxide (N2O) emissions from cropland. Commercially available controlled-release N fertilizers were evaluated for their potential to reduce N2O emissions from a clay loam soil compared to conventionally used granular urea and liquid urea-ammonium nitrate (UAN) fertilizers under irrigated irrigated no-till corn production. Controlled-release N fertilizers evaluated were: a polymer-coated urea (ESN), stabilized urea (SuperU), and UAN+AgrotainPlus. Each N source was surface band applied at 202 kg N ha-1 near the corn row at emergence. All N sources reduced growing season N2O emissions when compared to urea (0.7% of applied N), with UAN+AgrotainPlus (0.2% of applied N) and ESN (0.3% of applied N) having lower emissions than UAN (0.4% of applied N). Compared to granular urea, UAN+AgrotainPlus reduced N2O-N emissions 62%, ESN 57%, SuperU 46%, UAN 41%, and ESNssb 13%. Compared to liquid UAN, UAN+AgrotainPlus reduced N2O-N emissions 37%, ESN 27%, and SuperU 9%. Similar trends were observed when Expressing N2O emissions on a grain yield showed similar reductions per unit of grain yield. Corn grain yields did not vary with N source. Selection of N fertilizer source can be a mitigation practice for reducing N2O emissions in NT, irrigated corn in semi-arid areas.

Technical Abstract: Nitrogen (N) application generally results in increased nitrous oxide (N2O) emissions from cropland. Commercially available controlled-release N fertilizers were evaluated for their potential to reduce N2O emissions from a clay loam soil compared to conventionally used granular urea and urea-ammonium nitrate (UAN) fertilizers in an irrigated no-till (NT) corn (Zea mays L.) production system. Controlled-release N fertilizers evaluated were: a polymer-coated urea (ESN), stabilized urea (SuperU), and UAN+AgrotainPlus (contains nitrification and urease inhibitors). Each N source was surface band applied (202 kg N ha-1) near the corn row at emergence and watered into the soil the next day. A subsurface band ESN treatment (ESNssb) was included. Nitrous oxide fluxes were measured during two growing seasons and after harvest using static, vented chambers. All N sources had significantly lower growing season N2O emissions than granular urea (0.7% of applied N), with UAN+AgrotainPlus (0.2% of applied N) and ESN (0.3% of applied N) having lower emissions than UAN (0.4% of applied N). Similar trends were observed when expressing N2O emissions on a grain yield and N uptake basis. Corn grain yields were not different among N sources, but greater than the check with no N applied. Selection of N fertilizer source can be a mitigation practice for reducing N2O emissions in NT, irrigated corn in semi-arid areas.