Effect Of Optimized Fertilization And Straw Returning On The Nitrogen/Phosphorus Utilizaition And Runoff Losses In Dryland Crops

In the production process of crops,there is often an unreasonable phenomenon of fertilization,which in turn causes a decrease in fertilizer production efficiency and nutrient utilization efficiency,as well as a negative impact on the environmental,ecological and economic benefits.Therefore,based on the wheat-corn rotation system in the ancient Yellow River area and the wheat-sweet potato rotation system in the Yangtze River Basin,this study started from the following four aspects:（1）showed that the farmland nitrogen（N）and phosphorus（P）accumulation,the fertilizer use efficiency,and the N and P leaching loss control technologies of,and establishes a comprehensive technology system for the farmland fertilizer runoff optimization and the runoff and leaching nonpoint source pollution prevention and control.First,in the wheat-corn rotation system in the ancient Yellow River area of Yancheng,Northern Jiangsu,the following three aspects were studied:（1）Effect of annual optimized nitrogen/phosphorus management on the N and P runoff losses under the wheat-corn rotation agroecosystem;（2）Effect of the technological innovation of controlledrelease fertilizer on the N and P runoff losses under the wheat-corn rotation agroecosystem;（3）Effect of different fertilization on the N and P of runoff and leaching losses under the wheat-sweet potato rotation agroecosystem;（4）Effect of inoculating with earthworms following straw returning on the N and P runoff losses under the wheat-corn rotation agroecosystem.The main results show that:Compared with the farmer fertilization practice treatment,the annual optimized nitrogen/phosphorus management treatment did not reduce the yield of wheat and corn under the condition of the reduced application of 150 kg N · hm^-2 and 60 kg P·hm^-2 throughout the year.Meanwhile,the annual optimized nitrogen/phosphorus management treatment significantly improved the above-ground N absorption of wheat and corn,but significantly reduced the soil alkaline N content,total N content and runoff losses of nitrate N and total P content.Compared with farmer fertilization practice treatment,the technological innovation of controlled-release fertilizer（PCU）and the controlled-release fertilizer with urea（BBF）treatment significantly improved the N and P utilization efficiency.Meanwhile,PCU treatment have significantly decreased the nitrate N of runoff losses,while BBF treatment has no significant effect on the N and P of runoff losses.In the wheat-sweet potato rotation agroecosystem,reduced fertilization treatment did not significantly affect the wheat and sweet potato yield and fertilizer utilization efficiency.However,significantly reduced the loss of the nitrate N,ammonium N,and total N in the runoff losses throughout the year.At the same time,straw returning treatment significantly increased the yield of sweet potato by 5.91%and had no significant effect on the wheat yield and the annual N and P content of leaching losses.Compared with farmer fertilization practice treatment,inoculating with earthworms following straw returning treatment increased the yield of wheat and corn to a certain extent.Moreover,inoculating with earthworms following straw returning treatment have significantly reduced the runoff losses of the ammonium N,nitrate N and total N content by 29.0%,44.6%and 41.3%,respectively.However,the risk of total P runoff losses was still increased to a certain extent.This study showed that the annual optimized nitrogen/phosphorus management,inoculating with earthworms following straw returning and reduced fertilization have effectively reduced the N and P runoff losses in the agriculture,which also provides basic data and theoretical basis for proposing scientific fertilization measures and decisions.