Co-Benefits of Yield and Nitrogen Use Efficiency Gains Through Combined Use of Controlled-Release Urea and Conventional Urea in Rice

Abstract

Combined use of controlled-release urea and conventional urea (CCU) is considered a practical strategy to simultaneously achieve the dual benefits of crop yield and nitrogen use efficiency (NUE). However, the overall impact of CCU on rice production is not well understood. A meta-analysis was conducted to determine the effect of CCU on rice yield and NUE in China. The results revealed that CCU increased rice yield by 6.22% and NUE by 16.5% compared with conventional urea. Significant yield and NUE gains from CCU were evident only when the ratio of controlled-release urea to total nitrogen input reached 0.6 or above. Rice yield and NUE were increased simultaneously at nitrogen rates ranging from 150 to 225 kg ha⁻¹, with no significant improvement in grain yield and NUE with nitrogen supply beyond 290 and 327 kg ha⁻¹, respectively. In addition, rice yield and NUE were significantly greater with split rather than single application of CCU. Also, rice yield and NUE were increased when mean annual temperature (MAT), mean annual precipitation (MAP) and soil available nitrogen (AN) were more than 10°C, 800 mm, and 50 mg kg⁻¹, respectively. Soil pH and organic matter content were significant determinants of rice yield and NUE gains with CCU. Our findings clearly demonstrate that the combined use of controlled-release urea and conventional urea will deliver significant gains in rice yield and NUE and that it should be proposed as an effective measure for sustainable rice production.