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