Effects Of Reduction Of N Fertilizer Application Rates Plus Rice Straw Return On Soil Nutrient And Rice Yield Of Double Cropping Rice

In recent years,the utilization rate of straw resource is low.By the way,the phenomenon of the excessive use of chemical fertilizer is very common.On one hand,this situation will cause waste of resources,on the other hand,it will affect the ecological environment and food safety.At present,there are many researches on straw returning to the field and fertilizer use both at home and abroad,but there are few researches on straw returning to the field and N-fertilizer reduction and application,especially the lack of orientation test.The experiment was started in July 2016 in ShangGao experimental field of JiangXi Province.There are nine treatments of four treatments and nitrogen free area experiment are set up in all,i.e.early rice Tan LiangYou 39,late rice YongYou 538 as test rice varieties,with double rice straw returning to the field in full amount(even returning to the field),early rice returning to the field in late rice(round returning to the field 1),early rice returning to the field in late rice(round returning to the field 2),early rice returning to the field in late rice(no returning to the field,control,CK).In 2018,half of the straw of early rice and late rice was returned to the field,totaling nine treatments,and the nitrogen reduction experiment was also increased.Six treatments were set for early rice and late rice according to different nitrogen application.Rice plant samples and soil samples were taken at the critical growth stages of rice,such as flowering stage and maturity stage.This paper studies the straw resources and the decomposition characteristics of straw returned to the field in Jiangxi Province,and clarifies the influence of straw returning to the field on rice growth,yield and soil physical and chemical properties,so as to provide ideas for the rational and effective application of straw returning with chemical fertilizer in agricultural production.The main results are as follows:1.The growth of double cropping rice in central JiangXi is better than that in other areas of JiangXi.The nutrient content of double cropping rice straw was higher in northern Jiangxi.According to the rice yield of double season rice in JiangXi in 2016,it can be estimated that the amount of straw of double season rice in JiangXi is one thousand seven hundred and eleven point two Million tons.The nutrient content of double cropping rice straw in JiangXi is huge.2.The decomposition rate of Conventional Indica rice straw was higher than that of Japonica hybrid rice straw,and that of double cropping rice straw was faster in the soil surface.After 30 days of straw returning to the field,the release rate of straw nitrogen in the surface layer of the soil was higher than that in the lower layer of the soil,which may be related to the process of absorbing and fixing nitrogen in the early stage of rice growth.Different depth of burying had no significant effect on the carbon release rate of double cropping rice straw.3.The combination of straw returning and nitrogen reduction can effectively increase the leaf area of the upper three leaves of rice and improve the nitrogen level in the later growth stage of rice.By the way,the combination of straw returning and nitrogen reduction can increase the chlorophyll content in the later leaves of rice and enhance the photosynthetic capacity of the upper three leaves in order to obtain higher yield and reduce production cost.For early rice,10%reduction of N application by straw returning can increase rice yield and 30%reduction of N application is the highest yield;for late rice,10%reduction of N application has no effect on yield.4.The content of soil total nitrogen and organic matter was increased by straw returning.Straw returning to the field is beneficial to increase the content of available N and P in the soil.Returning straw to the field in the current season can improve the content of alkali hydrolyzed nitrogen in the soil surface.Under the treatment of straw returning,reducing nitrogen fertilizer can maintain or even improve the content of total nitrogen and available nitrogen,phosphorus and potassium.Under the treatment of straw returning to the field,no application of nitrogen fertilizer was beneficial to the increase of soil available potassium content.