A method of fixed- site field was adopted in the present experiment for study of different N, P and K applications on effects
of summer maize yield,fertilizer utilization ratio and economic fertilizer application rate.The results indicated that grain yields of summer maize had significant difference among the different N,P and K
fertilization treatments.The treatment with N 195 kg· hm- 2, P2O5 78 kg· hm- 2, and K2O 78 kg· hm- 2 (N∶ P2O5∶ K2O with 1∶ 0.4∶ 0.4) showed the highest grain yields,with maximum economic benefits and higher fertilizer comprehensive utilization efficiency. The yield regression analysis showed that when N, P2O5, K2O application rates were 262.5 kg· hm- 2, 180 kg· hm- 2 and 262.55 kg· hm- 2 in the winter wheat, reasonable P and K application rates were 68.25～ 87.75 kg· hm- 2 (N∶ P2O5=1∶ 0.4± 0.05) and 78～ 97.5 kg· hm- 2 (N∶ K2O=1∶ 0.4～ 0.5)
respectively, in the summer maize with N application at the rate of 262.5 kg· hm- 2, equivalent to P and K in the fixed formulation 39± 9.75 kg· hm- 2 and 19.5～ 39kg· hm- 2 , with the proportions 0.2± 0.05 and 0.1～ 0.2, respectively.