The Dynamics of Crop Yields under Different Fertilization Systems in Drab Fluvo-aquic Soil

The study on dynamics of crop yields,sustainable yield index(SYI) and agronomic efficiency of fertilizer under different fertilization systems including the treatments of N,NP,NK,PK,NPK,NPK+M(manure),NPK+S(crop straw) and CK(no fertilizer) were carried out based on 14 years' long term fertilizer experiment in Drab Fluvo-aquic soil in Beijing.The results showed that N and P were two crucial limited nutrients of crop yield in Drab Fluvo-aquic Soil.In NPK treatment yield of wheat was increased by 459%,386%,280%,205%,and corn by 154%,108%,87%,78%,respectively,compared with these in CK,N,NK,PK treatments.The yield of NPK+M treatment was more 12% than that of NPK treatment.However,the yield of NPK+S was similar to that of the NPK treatment.The sustainable yield indexes of NPK,NPK+M and NPK+S treatments were greater than those of other treatments.The output of yields per unit fertilizer(i.e.agronomic efficiency of fertilizer,AEF) was varied considerably with different crops and combinations of fertilizers applied.The AEF of N for wheat and corn by single use of N fertilizer was reduced,while that of NPK treatment was 16 kg/kg N for wheat and 14 kg/kg N for corn and had an increase tendency during the experiment period.The AEF of P in wheat was greater than that in corn,further more,the AEF of P was 4.57.0 times higher than that at the beginning of the experiment 10 years ago.The AEF of K was negative in NK treatment,while increased rapidly in NPK treatment after 10-year crop cultivation;K was also one of critical limited nutrients for crop yield.The AEF of farmyard manure(FYM) in NPK +M treatment was 21 kg/t of wheat and 25 kg/t for corn,while the AEF of crop straw in NPK+S treatment was negative for wheat and 37 kg/t for corn.Soil O.M.,total N,P and available N,P,K content were increased in NPK treatment.The accumulations of soil O.M.and N,P,K nutrients were accelerated in NPK+M and NPK+S treatments.On the contrary,total N,total P were exhausted in the treatments without N,P fertilizer.Available P,K had the same variation trend in the treatments without P,K fertilizer.