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Title: Nitrogen fertilizer source and placement effects on nitrous oxide emissions

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

Submitted to: Proceedings of Great Plains Soil Fertility Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/9/2012
Publication Date: 3/6/2012
Citation: Halvorson, A.D., Del Grosso, S.J. 2012. Nitrogen fertilizer source and placement effects on nitrous oxide emissions. Proceedings of Great Plains Soil Fertility Conference. 14:8-14.

Interpretive Summary: Nitrogen source and placement effects on nitrous oxide (N2O) emissions from strip-till (ST) and no-till (NT), irrigated continuous corn fields were evaluated for two growing seasons. Emissions were monitored from plots receiving commonly used urea and UAN and four enhanced-efficiency N fertilizers (ESN®, SuperU®, UAN+Nfusion®, UAN+AgrotainPlus®,) at a rate of 202 kg N/ha surface band applied near the corn row. A subsurface band application of ESN was also included, as well as, a no N applied treatment. Nitrogen placement treatments included surface band and surface broadcast urea, ESN, and SuperU. All enhanced-efficiency N sources and UAN had significantly lower growing season N2O emissions than granular urea, with ESN, UAN+Nfusion and UAN+AgrotainPlus having lower emissions than UAN in ST and NT, irrigated corn. Corn grain yields did not differ among N sources. Growing season N2O emissions were lower with surface broadcast placement than with surface band N applications. The study shows that N source selection and placement are important management decisions for reducing N2O emissions from Central Great Plains’ cropping systems.

Technical Abstract: Nitrogen (N) source and placement effects on nitrous oxide (N2O) emissions from strip-till (ST) and no-till (NT), irrigated continuous corn fields were evaluated from 2009-2011 near Fort Collins, CO. Emissions were monitored from plots receiving commonly used urea and UAN and four enhanced-efficiency N fertilizers (ESN®1, SuperU®, UAN+AgrotainPlus®, UAN+Nfusion®) at a rate of 202 kg N/ha surface band applied near the corn row and watered (19 mm irrigation water) into the soil the day after application. A subsurface band application of ESN was also included, as well as, plots with no N applied. Nitrogen placement treatments included surface band and surface broadcast urea, ESN, and SuperU. Nitrous oxide fluxes were measured during the growing season using static, vented chambers for gas sample collection, about three times per week, and analyzed with a gas chromatograph. Cumulative increases in daily N2O fluxes were more rapid for urea and UAN than the other N sources following N fertilizer application. All enhanced-efficiency N sources and UAN had significantly lower growing season N2O emissions than granular urea, with ESN, UAN+AgrotainPlus, and UAN+Nfusion having lower emissions than UAN in ST and NT, irrigated corn. Similar trends were observed when expressing N2O emissions on a grain yield and N uptake basis. Corn grain yields did not differ among N sources. Growing season N2O emissions were lower with surface broadcast placement than with surface band N applications. The study shows that N source selection and placement are important management decisions for reducing N2O emissions from Central Great Plains’ cropping systems.