Effects of Different Fertilization Systems on Ammonia Volatilization from Double-Rice Cropping Field in Red Soil Region

Ammonia volatilization from double-rice cropping field in red paddy soil was determined in a closed air-flow chamber under different fertilization systems.Ammonia volatilization under different fertilization systems exhibited a similar trend,with a peak 1-3 days after fertilization and a subsequent decline,and almost no emission after a week.Ammonia volatilization rate increased with fertilizer application rate.During the early rice growth,the accumulation of N loss via ammonia volatilization after fertilization was 1.6-3.6 kg/hm2 for basal fertilizer and 5.8-18.2 kg/hm2 for fertilizer topdressed at the tillering stage,and during the late rice growth,the accumulation of N loss via ammonia volatilization was 4.5-7.9 kg/hm2 for basal fertilizer,12.3-26.8 kg/hm2 for fertilizer todressed at the tillering stage and 1.4-2.4 kg/hm2 for fertilizer topdressed at the panicle initiation stage.The total accumulation in the early and the late rice growth period occupied 4.5%-15.3% and 16.9%-32.8% of the total of fertilizer application,respectively.Compared to the control,urea application could promote ammonia volatilization,and more N was lost through ammonia volatilization under the conditions of equal N application and zero P application.The supplement of more rice straw and green manure also showed a positive relationship with ammonia volatilization,so did NH4+-N concentration,water pH and climate conditions(light,temperature and rainfall etc.).