Effect of optimized nitrogen application on ammonia volatilization from paddy field under wheat-rice rotation system

A continuous airflow enclosure method was used to measure the ammonia volatilization (AV) from paddy field under the wheat-rice rotation system in Hubei Province. The results indicated that total amount of AV loss generally increased with the urea application rate. In wheat growing season, AV loss varied from N 11.37-17.05 kg/ha which accounted for 4.75 to 5.43 percent of applied N, the AV from fertilizer N lasted for 7-10 days and peak of AV occurred within 3-5 days after fertilization ; While in rice growing season, AV loss varied from N 32.50-62.82 kg/ha which ranged from 8.24 to 19.38 percent of applied N, the AV from fertilizer N lasted for 5-7 days and the peak occurred within 2-3 days after fertilizer was applied. Most of the AV loss occurred in the rice season, which ranged from 74.08% to 78.65% of total AV loss in the entire rotation system. Compared to farmer practice, optimizing N application associated with increasing ratios of dress N to base N fertilizer and times of split application based on plant N uptake at different growth stages could obviously reduce the AV loss under the rice-wheat rotation system.