Abstract: The N_(2)O emission flux on the rice fields by long-term different fertilization treatments was continuously observed at Wangcheng County of Hunan Province in 2004,by using the static chamber-GC theory with manual method.N_(2)O emissions from rice field had obvious seasonal variations.The N_(2)O emission flux was larger after drainage than that during early and middle growing periods.There existed the differences between early and late rice.There was no significant difference among the different fertilization treatments for the early rice fields,while the differences were extremely significant(p<0.01) for the late rice fields.The maximum(N_(2)O) emission flux with 1.48 kg/ha occurred in the early rice fields by NPK treatment,while the maximum value with 1.40 kg/ha was by NPKS treatment in the late rice fields.Being the organic fertilization with chemical fertilization treatment,no significant differences among the treatments were observed in early rice fields.However,N_(2)O emission from NPKS treatment was larger than NKM treatment,and there was significant difference(p<0.05) between them.The seasonal variation of N_(2)O emission flux was significantly determined by water situation of rice fields.The N_(2)O emission flux was larger during drainage than flooding.

Key words: Long-term fertilization, Long-term fertilization, Rice field, N_(2)O emission, Effect factor