Nitrous Oxide Emissions In Medium and Coarse Textured Soils From Corn Production Under Conventional and Alternative Fertilizer Treatments.

Nitrogen (N) fertilizers applied in corn production cause soil-to-atmosphere direct emission of nitrous oxide (N₂O), a major greenhouse gas. Some of the added N that leaches into groundwater as nitrate (NO₃^-) can subsequently be transformed to N₂O, which represents an indirect source of N₂O emissions. Different N fertilizers applied in diverse agronomic practices may have varied impacts on N₂O emission, which, if properly understood, will help to improve management practices to reduce N₂O emissions. The objective of this study was to compare N₂O emissions from corn production under various N fertilizers combined with different management practices. We conducted experiments at two sites, Becker and Rosemount, MN. In this study, we compared conventionally-applied anhydrous ammonia (d-AA, d for deep), a shallow applied anhydrous ammonia (s-AA, s for shallow), conventional granular urea (U), polymer coated urea, and urea amended with urease and nitrification inhibitors. We also studied impacts of tillage, irrigation, and lime application. Direct N₂O emissions were measured using static chambers. Indirect N₂O emissions were estimated based on measurement of NO₃^- concentration in soil water collected using ceramic cup lysimeters combined with water-balance estimates of water leaching rates, and published emission factors for estimating the fraction of leached NO₃^- that is eventually converted to N₂O. Direct N₂O emission following s-AA was significantly greater than that following d-AA and U. Compared with non-limed plots, direct N₂O emissions from lime treated plots increased by 15 and 80 % following d-AA and urea respectively while it decreased by 20% following s-AA. Results indicate that the interactions between N fertilizers and different management practices are important to understand in our effort to reduce N₂O emissions from corn production.