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.