Nitrous Oxide Emissions in a Coarse-Textured Soil Following Application of Conventional Nitrogen and Alternative Fertilizer Products for Irrigated and Rain-Fed Corn Production.

Urea based nitrogen (N) fertilizer products have been developed to provide N to crops at rates that closely mirror plant demand by adding a polymer controlled release coating or adding nitrification and urease inhibitors to urea. When compared to conventional urea (CU) fertilizer, the improved N use efficiency of these products has the potential to reduce soil to atmosphere emission losses through fertilizer conversion to the potent greenhouse gas nitrous oxide (N₂O). Alternative application methods of anhydrous ammonia (AA), including shallower injection with reduced soil disturbance, also aim to achieve similar N₂O emission reductions. The objective of this study was to quantify N₂O emissions and crop yields from irrigated and rain-fed corn production in a coarse textured soil over consecutive growing seasons after the application of 179 kg N ha^-1 as conventional and alternative N fertilizer products. Conventional includes treatments of CU or AA, both split applied, while alternative includes pre-plant applications of a polymer-coated urea product (ESN), a product containing nitrification and urease inhibitors (Super U), or a split application of AA applied at a shallower injection depth with less soil disturbance (AAlt). In the first season, only CU and ESN treatments were evaluated and dry conditions necessitated irrigation of the rain-fed treatments to alleviate severe water stress in the crop. Initial analysis suggested a slightly higher yield and N₂O emissions from CU then ESN (although the difference was much lower in the irrigated treatments then the rain-fed). Results from the current season, which includes the addition of the AA, AAlt, and Super U treatments, will also be presented.