Effects of Irrigation and Nitrogen Fertilization on Ammonia Volatilization in Paddy Field

Controlling the ammonia(NH 3)volatilization from nitrogen(N)fertilization could be a good strategy to reduce N loss in crop growing season.The interaction of irrigation and N fertilization NH 3 volatilization were conducted in an experiment of pool culture within rainproof shelter in paddy field.Data were collected during the growing season of 2009 and 2010 from treatments under controlled and conventional irrigation receiving N application of 90 kg·hm-2,180 kg·hm-2,and 270 kg·hm-2.The NH 3 volatilization was determined by the venting method.Results showed that the total amounts of NH 3 volatilization in the whole growth period ranged from 31.67 kg·hm-2 to 69.70 kg·hm-2 among the treatments,accounting for 17.95%～28.64% of N applied.The peak of ammonia volatilization appeared in 1～3 days after each N application,regardless of treatments.The NH 3 volatilization during the whole growing season was in order:returning green stagejointing-booting stagetillering stageheading-flowering stagemilky stage.Irrigation and N fertilization significantly influenced on NH 3 volatilization.Total amounts and loss rate of NH 3 were lower in controlled irrigation compared with conventional irrigation.With the increment of N application rates,NH 3 volatilization significantly increased.The loss rate of NH 3 volatilization(17.59%)was lowest under controlled irrigation with N application of 180 kg·hm-2.We concluded that combining controlled irrigation and reducing N fertilization can reduce NH 3 volatilization in the Paddy field.