Effect of the Slow-Release Nitrogen Fertilizer Oxamide on Ammonia Volatilization and Nitrogen Use Efficiency in Paddy Soil

The effects of a single basal fertilization with oxamide compared with those of a split application of urea on ammonia volatilization, rice yield, nitrogen (N) accumulation, and N use efficiency were investigated in a field experiment over 2 years. The study consisted of two N fertilizers (oxamide and urea) applied at 157.5 and 225 kg N ha(-1) and a no-N Control. Compared with urea, the single application of oxamide produced similar rice yields and reduced approximately 38.3% to 62.7% of the N lost through ammonia volatilization in 2013 and 2014. Oxamide applied at a rate of 225 kg N ha(-1) resulted in greater aboveground accumulation of N by rice than the other treatments in both years, and oxamide fertilization resulted in the accumulation of an additional 15.2 kg N ha(-1) and 15.3 kg N ha(-1) compared to the amounts accumulated under the urea treatments at the same N application rates. N use efficiency was higher under oxamide than under urea treatment. In conclusion, the use of oxamide as a fertilizer can reduce N loss via ammonia volatilization, increase N use efficiency, and maintain a steady rice grain yield.