Effects of Long-term Mixed Use of Organic Manure and Chemical Fertilizers on Crop Yield and Indigenous Soil Nutrients

Long-term fertilization experiment on indigenous soil of Hexi Oasis,Gansu Province indicated that 27 years' mixed use of organic manure and chemical fertilizers increased crop yield and its stability,especially for organic manure and NP or NPK fertilizers.Long-term use of organic manure and chemical fertilizers increased N,P and K investment to soil and nutrient output from soil as well as nutrient surplus.Soil organic matter,total N,total P,available N,available P and available K content increased by 10.0%~16.0%,58.1%~69.0%,13.4%~31.1%,45.7%~79.0%,172.2%~287.8%,21.4%~38.8%,respectively after 21~25 years' use of organic manure and chemical fertilizers,and were significantly higher than those of single use of chemical fertilizers and the contrast.The treatment of organic manure and NPK fertilizers was the best one in improving soil fertility.