Effects of Combined Application of Organic Manure and Chemical Fertilizer on Maize Yield and Nitrogen Utilization under Equal Nitrogen Rates

Based on a long-term fertilizer experiment in black soil which was established in 1989,the effects of combined application of organic manure and chemical fertilizer on maize yield and nitrogen utilization efficiency under equal nitrogen rates were studied.The results showed that NPK and NPK combined organic manure(cow manure + NPK,straw+ NPK) could improve maize yield,contrast to CK,increased 192.0%,218.3% and 192.6%,respectively. N agronomic efficiency and N partial factor productivity of NPK,cowmanure + NPK and straw+ NPK treatments were higher than N treatment.Compared with the beginning of the trial,the three treatments all could increase soil organic matter,total N and available N contents were increased in NPK,cowmanure + NPK and straw+ NPK treatment,with the best effect in cow manure + NPK treatments,soil organic matter,total N and available N contents increased 46.6%,28.6% and 36.8%,respectively.Soil pH had no significant change in cowmanure and strawtreatments during different years,but decreased in the applications of chemical nitrogen treatments.