Effects of different fertilizer application methods on ammonia volatilization and nitrogen fertilizer utilization rate in regenerating rice fields

【Objective】Investigated the effects of combined application of controlled-release urea and ordinary urea as well as one-time deep application of controlled-release urea on the ammonia volatilization loss and nitrogen fertilizer utilization rate in regenerated rice fields. In order to provide scientific guidance for the development of measures to increase production and reduce emissions in regenerating rice fields in China. 【Method】Rice cultivars Fengliangyouxiang No. 1 and Yongyou 4949 were used as experimental materials, and four treatments were set up: no nitrogen control(CK), conventional fractional application of ordinary urea(FFP), combination of ordinary urea with controlled-release urea(CRU+U) and one-time 10 cm deep application of controlled-release urea(CRUR) in the root zone. Determination of trends in ammonia volatilization,two-season yield and nitrogen fertilizer utilization rate in regenerated rice fields under different fertilization treatments were conducted. 【Result】Compared with FFP treatment, CRUR treatment and CRU+U treatment reduced the ammonia volatilization flux during the growth period of regenerated rice, the ammonia volatilization loss and ammonia volatilization loss rate of CRUR treatment were significantly reduced by 77.01%-78.10% and 92.17%-95.35%(P<0.05, the same below), the ammonia volatilization loss and ammonia volatilization loss rate of CRU+U treatment decreased by 53.60%-55.75% and 65.45%-66.72%. There was no significant difference in the average ammonia volatilization loss between Yongyou 4949 and Fengliangyouxiang No. 1(P>0.05). Compared with FFP treatment, CRUR treatment and CRU+U treatment significantly reduced the concentrations of ammonium nitrogen(NH₄⁺-N) and nitrate nitrogen(NO₃^--N) in field water; compared with FFP treatment, the yield of regenerated rice, yield in regeneration season and nitrogen fertilizer utilization rate increased by 30.00%-30.38%, 12.10%-20.28% and 84.31%-87.37%, CRU+U treatment increased the yield of regenerated rice in the first season, the yield in the regeneration season and the nitrogen fertilizer utilization rate increased by 10.00%-16.46%, 10.60%-18.84% and 35.14%-36.13%. The average yield of Yongyou 4949 in the first and regeneration seasons was 12.50% and 13.11% higher than that of Fengliangyouxiang No. 1. Correlation analysis indicated that the ammonia volatile flux of regenerated rice was extremely significantly positively correlated with the NH₄⁺-N concentration of field surface water(P<0.01). 【Conclusion】Compared with the conventional fractional application of common urea, combination of ordinary urea with controlled-release urea and one-time 10 cm deep application of controlled-release urea can significantly reduced the ammonia volatilization loss in paddy field, increase the yield of regenerated rice in two seasons,and improve nitrogen nitrogen fertilizer utilization rate. Moreover, the effect of one-time deep application of controlled release urea in root zone is better than that of ordinary urea combined with controlled release urea.