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Title: Nitrogen source effects on soil nitrous oxide emissions from strip-till corn

Author
item Halvorson, Ardell
item Del Grosso, Stephen - Steve
item JANTALIA, CLAUDIA - Embrapa National Research Center

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2011
Publication Date: 9/21/2011
Citation: Halvorson, A.D., Del Grosso, S.J., Jantalia, C.P. 2011. Nitrogen source effects on soil nitrous oxide emissions from strip-till corn. Journal of Environmental Quality. 40:1775-1786.

Interpretive Summary: Nitrogen (N) fertilizer application generally results in increased nitrous oxide (N2O) emissions. We compared N2O emissions resulting from the application of commercially available enhanced-efficiency N fertilizers compared with conventionally used granular urea and urea-ammonium nitrate (UAN) fertilizers in an irrigated strip-till (ST) corn system. The enhanced-efficiency N fertilizers evaluated were: a controlled release polymer-coated urea (ESN), stabilized urea and UAN products containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus), and UAN containing a slow release N source (Nfusion). Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. All the alternative N fertilizers had lower growing season N2O emissions than dry granular urea, with UAN+AgrotainPlus having lower emissions than UAN. Expressing N2O emissions on a grain yield and N uptake basis also showed the agronomic benefit of the enhanced efficiency fertilizers. Corn grain yields did not differ among N sources. Loss of N2O-N per kg of N applied was 0.8% for urea and <5% for all other N sources. Selection of N fertilizer source can be a mitigation practice for reducing N2O emissions in strip-till, irrigated corn in semi-arid areas.

Technical Abstract: Abstract: Nitrogen (N) application to crops generally results in increased nitrous oxide (N2O) emissions. Commercially available enhanced-efficiency 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 strip-till (ST) corn (Zea mays L.) production system. Enhanced-efficiency N fertilizers evaluated were: a controlled release polymer-coated urea (ESN), stabilized urea and UAN products containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus), and UAN containing a slow release N source (Nfusion). Each N source was surface band applied (202 kg N ha-1) at corn emergence and watered into the soil the next day. A subsurface band ESN treatment was included. Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. All N sources had significantly lower growing season N2O emissions than dry granular urea, with UAN+AgrotainPlus having lower emissions than UAN. Similar trends were observed when expressing N2O emissions on a grain yield and N uptake basis. Loss of N2O-N per kg of N applied was <0.8% for all N sources. Corn grain yields were not different among N sources, but greater than treatments with no N applied. Selection of N fertilizer source can be a mitigation practice for reducing N2O emissions in strip-till, irrigated corn in semi-arid areas.