Effect Of Straw Application And Nitrogen Fertilizer On Crop Yield And Nitrogen Use Efficiency In Wheat And Maize

Crop straw is a kind of important organic resources in agricultural production,and fertilizer is a vital guarantee for national food security.In recent years,the irrational utilization situation of straw and fertilizer is to be on the acceleration,causing a series of resources waste and environmental pollution.Therefore,the rational utilization of straw and fertilizer resources has great significance to realize the sustainable development of agricultural production.Guanzhong Plain is an important grain producing region,meanwhile,the agricultural production in this area is facing sever challenges of the abuse of resources,which seriously affects the local agriculture development.This research was based on the local agricultural production actuality,choosing the local common“wheat and maize”cropping system as the research object.A split plot design was developed in the research,with three straw returning levels(full amount straw returning:S₁,half amount straw returning:S_0.5,no straw returning:S₀)as main treatments and three N fertilizer application(conventional N fertilization:N₁,reducing N fertilization:N_0.8,no N fertilization:N₀)as sub-treatments,summing to nine treatment combinations?S₀N₀ for CK treatment?.The research was conducted to systematic analysis the effects of straw returning in matching with nitrogen on crop yields,translocation of dry matter,water and nitrogen utilization in Guanzhong region,and provide theoretical basis and technical support to the realization of local crop yield increase and sustainable development of agriculture.The main results are as fallow.?1?The number of wheat spikes and the weight of corn kernels were significantly affected by straw application and nitrogen fertilizer.The yield of wheat and maize was increased with the increase of the amount of straw input and N.S₁N₁ treatment gained the highest wheat and maize yield,which were 44.4%-48.5%?wheat?and 29.4%-35.2%?maize?higher than CK.?2?The amount and rate of assimilate translocation and the contribution rate of assimilate to grain after anthesis of two crops were higher than that before anthesis.Straw returning matching with nitrogen fertilizer significantly increased the amount and rate of assimilate translocation before and after anthesis.Meanwhile,Straw returning combined with nitrogen fertilization also reduced the contribution rate of assimilate to grain before anthesis and increased it after anthesis significantly.Overall,S₁N₁ or S₁N_0.8 performed the best on the amount and rate of assimilate translocation and the contribution rate of assimilate to grain before and after anthesis,and the differences between the two treatments were not significant.?3?Straw returning combined with N application significantly increased 0-100 cm soil water storage before sowing and after harvesting of wheat and maize.Meanwhile,full amount straw returning combined with N fertilizer significantly increased the water use efficiency?WUE?of two crops.The WUE under S₁N_0.8 or S₁N₁ treatment was the highest in all treatments in 2014-2017,which was increased by 43.2%-53.5%in wheat and 25.2%-39.7%in maize compared with CK.?4?The amount of nitrogen accumulation in grain was about 57.0%-75.2%?wheat?and56.8%-63.9%?maize?of two crops above-ground part.The nitrogen accumulation in grain,stem and leaf of two crops under S₁N₁ treatment preformed best in three years,which was increased by 12.4%-14.9%respectively?wheat grain?and 26.6%-30.8%?wheat stem and leaf?,8.7%-16.9%?maize grain?and 8.4%-19.7%?maize stem and leaf?.The nitrogen utilization efficiency?NUE?,partial productivity?PEP_N?and agronomy efficiency?AE_N?of wheat and maize under S₁N_0.8 treatment reached the highest,increased by 43.7%-43.7%?wheat?,30.2%-33.9%?maize?,30.2%-36.3%?wheat?,31.3%-35.9%?maize?,and 35.8%-42.1%?wheat?,30.1%-39.1%?maize?compared with S₀N₁ treatment,respectively.On the whole,straw returning and nitrogen fertilization improved the crop yield;assimilate translocation,water and fertilizer utilization efficiency and economic benefits of wheat and maize.Compared with other treatments,S₁N_0.8 treatment ensured the crop yield in a high level,and also performed best on the water use efficiency,nitrogen fertilizer utilization,partial productivity and agriculture efficiency.Therefore,S₁N_0.8.8 treatment can effectively realize crop yield increase and the efficient utilization of resources in local agricultural production.