Effect Of Corn Straw Return Depth On Its Decomposition Characteristics In Different Agricultural Areas Of Heilongjian

The correct way of corn straw returning is benefit to the improvement of soil fertility and crop production.In order to understand the influence of returning depth on the decomposition of corn straw in different agricultural planting areas in Heilongjiang Province,our study selected the method of crushing and burying of straw and set up five treatments(no returning,0cm surface covering and returning,10 cm burying and returning,20 cm burying and returning and30 cm burying and returning)to study the impacts of different straw returning depth on the decomposition characteristics of corn straw,the release law of straw nutrients,the change of soil enzyme activity,the emissions of soil greenhouse gas and the contents of soil organic acids.1.The results showed that the straw decomposition and decomposition rates both presented fast in the early stage and slow in the late stage.In terms of different depths,10 cm burying and returning to the field > 20 cm burying and returning to the field > 30 cm burying and returning to the field > 0cm surface covering and returning.So,the effects of 10-20 cm returning depth were best for the straw decomposition.2.The decomposition results of straw cellulose,hemicellulose and lignin also showed that the effects of 10-20 cm returning depth were the best on the decomposition of cellulose and hemicellulose,and the effect of surface mulching was the best on the decomposition of lignin.Under different returning depths,the decomposition rates of cellulose,hemicellulose and lignin were different.3.The results of straw nutrient release showed that 100 days after returning,the carbon release rates of corn straw of all burying and returning were higher than that of the 0cm surface covering and returning.The nitrogen and potassium release rate was the highest at the returning depth of 10-20 cm,and the phosphorus release rate was basically the same at each returning depth,indicating unaffected by the returning depth.4.Straw returning significantly improved the activities of soil α-Glucosidase,β-Xylosidase,β-Cellobiosidase,β-Glucosidase,Acetylglucosaminidase,Leucineaminopeptidase and phosphatase.After 30-60 days returning,the activities of these soil enzyme increased significantly,and the enzyme activities in the soil were significantly higher in 10-20 cm returning depth than in other returning depths.Similarly,the content of soil organic acids increased significantly after 30-60 days returning,and gradually decreased after 60 days.5.In addition,after straw returning,CO2 emission increases and NH3 emission decreases in soil greenhouse gas emissions.From our results,the 10-20 cm returning depth of corn straw was better for promoting straw decomposition,nutrient release and soil enzyme activity.