In addition, an appropriate reduction in nitro-gen fertilizer rate also helps improve the efficiency of nitrogen utilization. Yi et al. (2010) investigated the effect of reduced nitro-gen applications in a rice–wheat rotation system and found that when nitrogen rates were reduced by 20–30%, the yields of rice and wheat did not decrease, whereas the nitrogen-use efficiency in the current season, AEN and PFPN were all increased; in addi-tion, when nitrogen was applied on multiple occasions, it enhanced grain yield and reduced fertilizer cost.