IMPACT OF CONTROLLED-RELEASE NITROGEN FERTILIZERS ON AMMONIA VOLATILIZATION FROM PADDY FIELDS UNDER WATER-SAVING IRRIGATION

The impact of controlled-release nitrogen fertilizers (CRN) on ammonia volatilization from paddy fields under water-saving irrigation is investigated. The rice yield, nitrogen uptake, efficiency of water and nitrogen fertilizer use, and ammonia volatilization from paddy fields with CRN and water-saving irrigation were analyzed based on a two-year field experiment. The results show that the application of CRN reduced nitrogen fertilizer input by 29.77% and decreased nitrogen uptake by 4.43%, but it maintained rice yields and significantly increased nitrogen recovery by 27.78% of paddy fields under water saving irrigation. In addition, CRN substantially reduced the peak amounts and ammonia volatilization rates of paddy fields under water-saving irrigation. The ammonia volatilization rate of paddy fields in the entire growth stage was significantly lower compared with those of traditional water and nitrogen management (p<0.05). The slow-release characteristics of CRN prevented the weekly peaks of ammonia volatilization from paddy fields under water-saving irrigation and reduced total ammonia volatilization loss by 62.09% compared with those of the farmers' fertilization practice. The period of rapid increase of cumulative ammonia volatilization loss was within 30 days after transplanting when CRN management was implemented. The first-order kinetic equation can be used to predict the cumulative ammonia volatilization loss in paddy fields with different nitrogen fertilizer management scenarios under water saving irrigation. The overall findings show that CRN management is an effective technique for mitigating ammonia volatilization and maintaining rice yields of paddy fields under water-saving irrigation.