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 (N(2)O) emissions. The study objective was to assess the ability of commercially available enhanced-efficiency N fertilizers to reduce N(2)O emissions following their application in comparison with conventional dry granular urea and liquid urea-ammonium nitrate (UAN) fertilizers in an irrigated no-rill (NT) corn (Zea mays L.) 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 N(2)O-N emissions in comparison with urea, including UAN. SuperU and UAN+AgrotainPlus had significantly lower N(2)O-N emissions than VAN. Compared with urea, SuperU reduced N(2)O-N emissions 48%, ESN 34%, Duration III 31%, UAN 27%, and UAN+AgrotainPlus 53% averaged over 2 yr. Compared with UAN, UAN+AgrotainPlus reduced N(2)O emissions 35% and SuperU 29% averaged over 2 yr. The N(2)O-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 N(2)O-N emissions without affecting yields from irrigated NT corn systems in the semiarid central Great Plains.