Ammonia volatilization of SN-labelled nitrogen fertilizer incorporated with soil as basal fertilizer for rice was investigated in a special designed closed enclosure. Results showed that (1) the rate of ammonia volatilization and its influence on the total loss of fertilizer N was enhanced with the increase of the flushing frequency of air passing over the standing water on the soil surface, and approached the maximum at the flushing frequency of 15-20 times/min.(2) in acidic soil, denitrification was the major pathway of ammonium sulfate and ura in cooler season, however,ammonia volatilization became important for the loss of urea in warmer season, and both denitrification and ammonia volatilization were the important pathways of N loss of ammionium bicarbonate;(3) while in calcareous soil, ammonia volatilization and denitrification both were the important pathways of N Ibss of ammonium sulfate and urea, and N loss of ammonium bicarbonate mainly resulted from ammonia volatilization.