Effect Of Different Annual Straw Return Rates On Soil Physical And Chemical Properties And Crop Yield In Winter Wheat-Summer Sorghum Cropping System

In order to solve the problems of crops straw burning and degradation of soil,the present study mainly analyzed the effects of crops straw return rates on changes in soil physical and chemical properties,and their impact on crop yields,and evaluated the soil physical and chemical properties and crop yields were related to each other,in order to find the best straw return rates measures for winter wheat-summer sorghum cropping system.The experiment was set up in 2015 and included four treatments of straw not returning(CK),straw returning of 50%(HR),straw returning of 100%(WR),and straw returning of 100%+ organic fertilizer(WRO).This article is mainly based on the experimental data from 2016 to 2017.The main results are as follows:(1)Compared with the CK treatment,the WR treatment showed that the soil bulk density of 0-10 cm profile significantly decreased by 8.5-10.3%,the soil water content and three-phase deviation(R)of 0-20 profile also decreased significantly,while the soil porosity and field maximum water holding rate increased significantly.The WR treatment significantly increased the geometric mean diameter(GMD)of the water-stable aggregates in the 0-10 cm profile and significantly reduced the fractal dimension(D)(P<0.05).Straw returning treatment can significantly increase soil organic matter(SOM),available nitrogen,phosphorus and potassium,and total nitrogen,phosphorus and potassium contents in the 0-30 cm profile,and gradually decrease with the deepening of soil depth,but increased with the augment of the amount of straw returning in the 0-20 cm profile.(2)Compared with WR treatment,WRO treatment can significantly increased SOM content of the topsoil(0-30 cm),increased soil moisture content and nitrogen and phosphorus content,and reduced soil R and D values,but it negatively affected the soil potassium content.The soil physical properties of the 20-30 cm profile between different stalk return treatments were differed from year to year.(3)Compared with CK and WR treatments,annual yield of wheat and sorghum significantly increased about 10.6-14.1%and 8.9-18.0%,respectively,and WRO treatment significantly increased 9.3-19.1%compared with WR treatment.Among them,there was a significantly positive correlation between grain yield and the soil moisture content and available nitrogen content of 0-10 cm,and the available potassium content of 0-30cm,but the soil R,D value of 0-10 cm and the soil SOM,water content,capillary porosity and D value showed a significantly negative correlation with the yield.It can be concluded that the treatment of WRO treatment can significantly improve the soil physical,chemical properties and crops yields in winter wheat-summer sorghum cropping system and it is suitable for promotion of Jinzhong area.