How optimizing application of coated controlled-release urea affects crop yield in China

Abstract

Application of coated controlled-release urea (CRU) has been widely recognized as an effective measure to improve crop yield while alleviating N fertilizer–induced environmental consequences. However, the overall effect of CRU on crop yield across field sites remains uncertain, especially for CRU applied at a reduced rate and frequency or blended with urea. Here, we applied a meta-analysis approach to address these issues. Our results indicated that applying CRU at an equal N rate significantly increased crop yield by 9.2% compared with conventional urea. The increase in crop yield was positively correlated with soil organic matter content and with the N release period of CRU but negatively correlated with mean annual temperature. However, reducing CRU application times brought a smaller yield increase (7.0%), although it could save labor and mechanical cost. Moreover, lowering CRU-N application rate had no significant effect on crop yield, mainly due to the reduced application frequency. This effect can be further weakened with the decreasing CRU-N application rate. In contrast, one-time application of a CRU-urea blend still exhibited superior efficiency, with a 9.8% increase in crop yield. Our findings showed that there existed a trade-off between the saving of CRU input cost and crop yield gain. However, a win-win scenario that attains more yield increase while saving input cost can be achieved through one-time application of a CRU-urea blend.