Nitrogen Placement Effects On Soil Nitrous Oxide Emissions From Irrigated Corn.

Limited information is available on how N fertilizer placement affects soil nitrous oxide 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 nitrous oxide 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%) nitrous oxide emission than broadcast N averaged over three site yrs.  Nitrous oxide emissions for N source were in the order urea>polymer-coated urea=stabilized urea when averaged over site yrs.  The placement x N source interaction was not significant.  Grain yield and N uptake did not vary with placement or N source when averaged over site yrs.   The study shows that N placement and selection of N source are important management decisions for reducing nitrous oxide emissions in Central Great Plains cropping systems and potentially in the semi-arid western U.S.