Study on the Nitrous Oxide Emission and Denitrification Losses from Loess Plateau under Different Water Regimes and Nitrogen Fertilizer Rates

A middle- term laboratory research was performed by monitoring three types of loess soils of NH⁴⁺ and NO_3- dynamics and N₂O production and denitrification. Results showed that there were no significant differences in the total amount of N₂O production and denitrification loss over 22 day between fertilized and unfertilized soils. This study also indicated that soil moisture had significant effect on N₂O production and denitrification loss. From 80% to 110% WFPS, the amounts of N₂O production and denitrification loss increased by 16-41 and 17-22 folds, respectively. The maximum N₂O emission rates and denitrification rates from all treatments occurred after rewetting of dry soil. The peaks maintained transitorily in the two clay loess soils, however, the higher fluxes remained for several days in sandy loess soil. The total N₂O production and denitrification from the sandy loess soil were significantly higher than that from clay loess soils. Soil moisture could be the most important factor controlling N₂O emissions and denitrification loss when a rich N supply existed in soil.