Nitrogen Source Effects on Nitrous Oxide Emissions from Irrigated No‐Till Corn

Nitrogen fertilization is essential for optimizing crop yields; however, it may potentially increase nitrous oxide (N2O) emissions. The study objective was to assess the ability of commercially available enhanced‐efficiency N fertilizers to reduce N2O emissions following their application in comparison with conventional dry granular urea and liquid urea‐ammonium nitrate (UAN) fertilizers in an irrigated no‐till (NT) corn (Zea maysL.) production system. Four enhanced‐efficiency fertilizers were evaluated: two polymer‐coated urea products (ESN and Duration III) and two fertilizers containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus). Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Enhanced‐efficiency fertilizers significantly reduced growing‐season N2O‐N emissions in comparison with urea, including UAN. SuperU and UAN+AgrotainPlus had significantly lower N2O‐N emissions than UAN. Compared with urea, SuperU reduced N2O‐N emissions 48%, ESN 34%, Duration III 31%, UAN 27%, and UAN+AgrotainPlus 53% averaged over 2 yr. Compared with UAN, UAN+AgrotainPlus reduced N2O emissions 35% and SuperU 29% averaged over 2 yr. The N2O‐N loss as a percentage of N applied was 0.3% for urea, with all other N sources having significantly lower losses. Grain production was not reduced by the use of alternative N sources. This work shows that enhanced‐efficiency N fertilizers can potentially reduce N2O‐N emissions without affecting yields from irrigated NT corn systems in the semiarid central Great Plains.