Effect Of Straw Returning On The Properties Of Chernozem And Fertility Of Chernozem Overview

In order to solve the problems that chernozem is prone to wind erosion in spring,water erosion in summer and artificial soil nutrient reduction,this paper takes the conservation tillage research and development base of Shenyang Institute of Applied Ecology,Chinese Academy of Sciences as the experimental platform.Four kinds of straw returning methods were adopted to improve the quality of soil fertility.The four returning methods were as follows: conventional ridge cultivation,no-ploughing mulching,dislocation rotation and full deep turning.In order to evaluate which type of soil fertility has the highest comprehensive fertility quality,the soil physical fertility indexes(soil bulk density,soil temperature,soil water content,aggregate structure,total porosity,firmness)and chemical fertility index were measured in this paper,and the soil physical fertility index(soil bulk density,soil temperature,soil water content,aggregate structure,total porosity,firmness)and chemical fertility index were measured respectively.(total carbon,total nitrogen,total phosphorus,organic carbon,microbial biomass carbon,ammonium nitrogen,nitrate nitrogen,microbial biomass nitrogen,available phosphorus,organic phosphorus,soil pH),biological fertility index(C mineralization enzyme,N mineralization enzyme,P mineralization enzyme,The effects of four kinds of straw returning methods on them were analyzed.Principal component analysis,sensitivity analysis and discriminant analysis were used to evaluate the comprehensive fertility quality of the four straw returning methods.The best straw returning method of chernozem was determined,and the most suitable index for fertility quality evaluation of chernozem was selected.The results show that:1.For soil physical indexes,straw returning to the field can improve the aggregate structure and soil firmness of the soil,and reduce the soil temperature,and the bulk density and aggregate structure of the soil can not be the highest in the treatment of ploughing and mulching,and the soil bulk density and aggregate structure are the highest in the treatment of ploughing and mulching.The soil water content was the highest in the full amount of deep inversion treatment,but the change of soil total porosity was not obvious in the four treatments.2.For soil chemical indexes,straw returning to the field improved the pH,of soil,especially the dislocation wheel and the full amount of deep inversion were the most obvious.There are great differences in the effect of straw returning to the field onorganic carbon: no-tillage mulching reduces the content of organic carbon,while the content of organic carbon is increased when the total amount of straw is deep turned over.Straw returning to the field decreased the content of available phosphorus in the soil,especially in the dislocation wheel and the full amount of deep conversion,and the contents of ammonium nitrogen and nitrate nitrogen were the highest in order to avoid ploughing and mulching,and the content of ammonium nitrogen and nitrate nitrogen was the highest in order to avoid ploughing and mulching.The content of organic phosphorus was the highest in the way of dislocation rotation,but the content of total carbon,total nitrogen,total phosphorus and microbial biomass nitrogen did not change significantly.3.For soil biological indexes,straw returning increased soil glucosidase activity,?-glucosidase activity,cellobiose hydrolase activity,xylosidase activity and peroxide activity.The activities of protease,dehydrogenase and peroxide decreased when straw was returned to the field.The effects of straw returning to the field on the activities of acid phosphatase,alkaline phosphatase,phosphodiesterase,NAG enzyme and amylase were basically the same,that is to say,the enzyme activity of returning to the field was the highest in order to avoid ploughing and mulching.The urease activity of the four returning methods did not change significantly.4.For physical fertility quality and biological fertility quality,no-tillage mulching treatment had the highest comprehensive score and fertility quality,while conventional ridge planting treatment had the highest comprehensive score and the highest fertility quality as far as chemical fertility quality was concerned.For the evaluation of soil comprehensive fertility quality,whether it is simplified index comprehensive evaluation or all index comprehensive evaluation,the result is that the comprehensive score of no-tillage mulching treatment is the highest,and the fertility quality is the highest.5.Through principal component analysis and sensitivity analysis of 32 indexes related to soil fertility quality,12 key indexes suitable for fertility quality evaluation of black calcium soil were selected by discriminant analysis,which were as follows:aggregate structure,available phosphorus,Nitrate nitrogen,soil pH,organic carbon,peroxide,glucosidase,NAG enzyme,amylase,acid phosphatase,alkaline phosphatase,phosphodiesterase.