Utilization Efficiency of Chemical Fertilizers among Different Counties of China
中国化肥利用率的区域分异

According to the grain yield response to fertilizers, China's fertilizer application rate can be classified into 3 typical regions: (1) the maximum fertilizer input region including 11 Eastern provinces (ER region); (2) the middle fertilizer input region covering mainly 10 Middle provinces (including Xinjiang and Gansu) (MR region); and (3) the low fertilizer input region consisting of 9 Western provinces (WR region). The average fertilizer application rate per ha cultivated land (sowing area) in 674 counties of ER region was 329 kg/ha, the average rate in the 973 counties of MR region was 231 kg/ha and that in the 709 counties of WR region was 231 kg/ha (Fig.1). The maximum application rate in some counties of China was found to be as high as 2,241 kg/ha which was nearly 10 folds of the average of whole China, i.e., 238 kg/ha. According to the response of grain yield to fertilizers, there were 11.9% excessive-fertilized counties which should reduce their fertilizer application rate and 14.6% counties which were not necessary to increase fertilizer application rate in China.