Low N2O Emissions By Different N Fertilizer Sources from Cotton Field Under Plastic Mulched Drip Irrigation in Arid Xinjiang of China.

Few studies have examined the potential benefits of enhanced efficiency N fertilizers in reducing N₂O emissions from crop fields in arid Northwestern China. Field experiment was established near Urumqi of Xinjiang in 2015 with treatments of unfertilized control (CK), and application of 240 kg N ha^-1 of granular urea (U), polymer-coated urea (ESN), and stabilized urea with urease and nitrification inhibitors (U+I), to compare the N₂O emissions from cotton field under plastic mulch drip irrigation. All of the ESN was added at planting but the other treatments were added multiple times with drip irrigation during the growing season. Static chambers and gas analysis by chromatography were used to determine N₂O emissions at least bi-weekly during the growing season. The ESN increased soil cumulative N₂O emissions during the growing season by approximately 47%-70% than other treatments, likely due to the one-time application at planting resulted in high concentrations of soil ammonium and nitrate, and thus high N₂O emissions shortly after planting. The U+I treatment reduced emission by 9.9% in comparison with U, whereas the difference was not statistically significant. Growing season cumulative N₂O emissions ranged from 0.3 to 0.5 kg N ha^-1, generally lower than emissions reported for other agricultural systems. Such low emissions suggest drip irrigation successfully kept moisture conditions below levels for appreciable N₂O emissions. Multiple applications of N via drip irrigation was effective to reduce emissions than all N applied at planting. Further studies are undergoing to identify the key soil factors controlling N₂O production and emissions under plastic mulch drip irrigation.