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Title: Nitrogen placement effects on soil nitrous oxide emissions from irrigated corn

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

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2012
Publication Date: 3/1/2013
Citation: Halvorson, A.D., Del Grosso, S.J. 2013. Nitrogen placement effects on soil nitrous oxide emissions from irrigated corn. Journal of Environmental Quality. 42:312-322.

Interpretive Summary: Information on how N fertilizer placement affects soil nitrous oxide (N2O) emissions under irrigated conditions in the semi-arid western U.S is limited. We evaluate the effects of surface banding and broadcasting of three N sources (urea, polymer-coated urea, and stabilized urea) on soil N2O emissions under irrigated corn production. The N fertilizers were applied at a rate of 202 kg N/ha to strip-till (2 years) and no-till (1 year) corn fields at crop emergence. Band applied N had a higher (45%) N2O emission than broadcast N averaged across N sources and all sites. Soil N2O emissions from the N sources were in the order: urea>polymer-coated urea=stabilized urea averaged across N placement and sites. Averaged across sites, grain yield and N uptake did not vary with placement or N source. Nitrous oxide emissions per unit of grain yield and N uptake were 47% greater with banded N fertilizer than with broadcast, as was the N2O loss per unit of N applied (59%). The study shows that N placement and selection of N source are important management decisions for reducing N2O emissions in irrigated cropping systems in the semi-arid western U.S. Nitrogen placement effects on N2O emissions needs to be evaluated further under other soil, cropping system, and climatic conditions to obtain a broader perspective on the effects of N placement on N2O emissions from agricultural systems.

Technical Abstract: Limited information is available on how N fertilizer placement affects soil nitrous oxide (N2O) emissions under irrigated conditions in the semi-arid western U.S. Our objective was to evaluate the effects of surface banding (applied near corn row) and broadcasting of three N sources (urea, polymer-coated urea, and stabilized urea) on soil N2O emissions from sprinkler irrigated corn fields. The N fertilizers were applied at a rate of 202 kg N/ha to strip-till (2010 and 2011) and no-till (2011) corn at crop emergence, and watered into the soil the day after application with ~19 mm irrigation water. Band applied N had a higher (45%) N2O emission than broadcast N averaged over N sources and three site yrs. Soil N2O emissions from the application of N sources were in the order of urea>polymer-coated urea=stabilized urea averaged over N placement and site yrs. The placement x N source interaction was not significant. Averaged across sites, grain yield and N uptake did not vary with N placement or N source. Nitrous oxide emissions per unit of grain yield and N uptake were 47% greater with banded N fertilizer than with broadcast, as was the N2O loss per unit of N applied (59%). The study shows that N placement and selection of N source are important management decisions for reducing N2O emissions in irrigated cropping systems in the semi-arid western U.S.