Physical and chemical manipulation of urea fertiliser for reducing the emission of gaseous nitrogen species

摘要

Concerning environmental consequences, technological attempts to decrease reactive N species emitted by the application of urea fertiliser to agricultural soils are being continued. To find suitable mitigation options, urea size and placement depths as well as new inhibitors of various chemical origins were tested in loess soil cropped to spring wheat under greenhouse conditions. Relatively a larger urea granule (USG; <0.7 g) inhibited nitrification up to 7 weeks and reduced both NH3 and NOx emissions up to 94%. Under cropped conditions, the USG point-placed at 7.5 cm depth showed similar response to urea prills on N_2O emissions (0.20-0.21% of the added N) though increased to 0.53% at relatively higher soil moisture content. Urease inhibitor (substituted phosphoric acid triamide) decreased NH3 losses substantially (60%), and also N_2O (47%) when mixed into soil. Nitrification inhibitor (Dicyanamide plus triazole)-amended urea inhibited nitrification up to 5 weeks and reduced N_2O emission from 20to 60%. A combination of urease and nitrification inhibitors-included urea decreased both NH3 (60%) and N_2O (25-52%) losses. Results imply that both approaches could mitigate substantially the urea-induced emissions of reactive N species.