Effect Of Fertilization On Yield Increase And Nutrient Use Efficiency Of Grain Crops In Different Agro-ecological Regions Of China

As an important agricultural production material, extraordinary contributions of fertilizers application to the crops production in China have been made. However, with the rapid increase of fertilizer consumption, problems such as unreasonable application, low fertilizer use efficiency and the resulted serious environmental pollution have become more evident. Therefore, the effects on yield-increases, nutrient use efficiency and its historical development under such fertilization condition have become a global concern. Based on the dataset by National project of formulated fertilization by soil testing, Chinese agricultural statistical data and literatures released recently, the Chinese agricultural area were separated into 10 agri-ecological districts including Northeast (NEC), Huanghuaihai Plain (HHH), Upland of North China (NCU), Northwest China (NWC), the Middle and Lower reaches of Yangtze river (MLY), Upland of South China (SCU), Plain and upland of Southeast China (SEC), Sichuan basin (SB), Southwest China (SWC) and Tibet Plateau (TP), respectively. The effects on yield-increase, nutrients use efficiency and the historical development of wheat, corn and rice production within these agri-ecological districts was analyzed to be aware of how to further increase food crops yields and nutrients using efficiency in China. The main research outcome is summarized as follows:1. During 2005 to 2008, the fertilization rates in each district were increased by 44.7%-131.0% for wheat, 65.7%-162.6% for maize and 25.4%-224.3% for rice production, respectively in comparison with 1980s. Of these districts, the increases of nutrients input during wheat production in HHH and MLY districts were greater than NCU and NWC districts; while for maize production, the increase of nutrients input in NWC was much greater than other districts; as for rice production, the increases of nutrients input in SCU and SEU were higher than SB ,NEC and MLY. Of the increase of fertilization rates of N, P and K, N application is with the greatest increase.2. Significant effects of fertilization on yield increases were observed in all ecological districts and the respective yield increase of wheat, maize and rice production were 34.7%-77.3%, 28.5%-43.0% and 25.5%-59.0%, and the contributions of fertilizers to wheat, maize and rice yields were 25.8%-43.6%, 22.2%-30.1% and 20.3%-37.1%, respectively. Great differences in yield responses to fertilization and fertilizers contribution to yields among different agri-ecological districts were observed, where, for wheat production, the yield increase of fertilization in NEC and MLY were higher than HHH and NCU; for corn production, it was much higher in NEC and NWC than in MLY and NCU; while for rice production, the yield increase of fertilization in NEC and MLY were higher than other districts. In contrast to 1980s, the yield-increase effects of fertilization for wheat in NWC and MLY and for rice in NEC and MLY were improved obviously. However, no significant difference on the yield increases by fertilization for maize production in NEC and NWC were found in contrast to 1980s.3. There was no uniform trend of fertilizer use efficiency for the main cropping systems in China in comparison with 1980s and large variations among these districts were observed. For example, the PFP for wheat production in HHH and MLY were lower than NWC and NCU; the PFP for maize production in NCU and NWC were higher than HHH and NWC; for rice production, the NEC and MLY had greater PFP than SCU and SEC. The AE of wheat production in NWC and MLY were higher than other areas, while for maize and rice, it's much higher in NEC than other areas. In addition, comparing with 1980s, the AEN for wheat production in MLY and NWC were increased with 21.6% and 5.6%, yet decreased with 46% and 12.4% in HHH and NCU, respectively; the AEN of maize production in NCU was improved by 52.0%, however it was lowered from 7.9% to 43.3% in other areas; The AEN for rice production in NEC and MLY were improved by 24.3% and 9.4%, yet decreased by 42.9% in SB and 22.9% in SEC and 10.4% in SCU, respectively. Furthermore, the REN (Recovery Efficiency of Nitrogen) for wheat in HHH and MLY were higher than that NCU and NWC, while for maize production, it was higher in NWC and HHH than NEC and NCU areas, and for rice production, the MLY, SCU and SEC had greater AEN than NEC and SB. This study also indicates that the fertilizer use efficiency of recommendation-based crop production was higher than conventional crop production.