Ammonia volatilization and its influence factors of paddy field under water-saving irrigation

In order to study the characteristics of ammonia volatilization from paddy field under water-saving irrigation, ammonia volatilization under different irrigation techniques were measured through field experiment. Variations of ammonia volatilization rate and volatilization amount of paddy field during rice growing season were analyzed, as well as the relationships between ammonia volatilization rate and its influence factors. The results showed that the ammonia volatilization rate during rice growing season under controlled irrigation varied with the same pattern as that under flooding irrigation, and was lower than that under flooding irrigation in the most time after reaching the peak value of ammonia volatilization induced by tiller fertilizer. Volatilization amount during rice growing season was 125.27 kg/hm2 under controlled irrigation, and it was 145.64 kg/hm2 under flooding irrigation, account for 32.06% and 36.11% of the applied N respectively. In addition to fertilization, the ammonia volatilization from paddy field had close relationship with NH4+-N concentration in surface water or surface soil water, air temperature, wind speed, day light hours and the air humidity. Compared with flooding irrigation technique, controlled irrigation can reduce ammonia volatilization.