Soil Physicochemical Characteristics And Comprehensive Evaluation Of Xilingol Grassland

Soil physical and chemical properties are an important evaluation index in soil fertility and one of the important basis for soil quality evaluation.The study of soil quality grades in different regions is of great significance to guide vegetation growth and soil sustainability.Inner Mongolia Xilingol grassland is one of the four major grasslands in the country.Affected by water and heat conditions,the Xilingol grassland has formed three distinct grassland types: meadow grassland,typical grassland,and desert grassland.The physical and chemical properties and distribution characteristics of soil in different grassland types are different,which will have important theoretical and practical significance for soil health and species research in Xilingol grassland.In this study,based on the natural grassland of Xilingol,the physical and chemical characteristics and soil quality evaluation of different grassland types were carried out.The evaluation indicators were available nitrogen(AN),available phosphorus(AP),available potassium(AK),and total nitrogen(TN).,total phosphorus(TP),total potassium(TK),soil organic matter(SOM),soil water content(SMC),soil salt content(SSC)and p H and other 10 indicators,using statistical analysis method,Moran index,Principal component analysis method,correlation analysis method,membership function method and other methods were used to conduct indepth analysis and evaluation of the three main grassland types from the basic content,spatial distribution and soil health,and the following results were obtained.(1)There are similarities and differences in soil physical and chemical indicators in different grassland types in the study area.The 10 physical and chemical indexes showed moderate variability in each steppe except for p H with weak variability.The average content is ranked as meadow steppe > typical steppe > desert steppe.There are seven indicators: AP,AN,SOM,TN,TP,SSC,and SMC.The indicators showing the opposite change characteristics are p H,and TK and AK show the typical steppe has the highest content,and the lowest content is meadow steppe and desert steppe,respectively.The variation coefficient and mean content of the ecostoichiometric ratio of carbon,nitrogen and phosphorus had the same variation characteristics as TN,TP,and SOM.(2)The spatial distribution of each index at different soil depths is different.AN,AP,AK,SOM,SMC,and TK all show high-low-low spatial aggregation types at different depths.Except for 40-50 cm in TN,which is a low-low-high-high isolated type,the other soil layers show a positive spatial correlation between high-high-low-low,and SSC shows an opposite spatial relationship in each layer.Except for 10-20 cm,TP belongs to positive spatial correlation,and the rest belongs to negative spatial correlation,that is,the distribution characteristics of isolated type.Soil p H appears at the inflection point at 20 cm.Above 20 cm,soil p H has a highlow aggregation type,and below 20 cm is the opposite.(3)The spatial distribution of each soil index is different in different grassland types.In the vertical direction,the contents of AN,AP,TN,TP,SOM,and SMC in each layer are in the order of meadow steppe>typical steppe>desert steppe.The TK content is typical steppe > meadow steppe >desert steppe.The soil p H layers in the profile direction belonged to desert steppe > typical steppe > meadow steppe.Soil AK and SSC had no obvious regularity at the depth of 0-50 cm.It can be seen that all physical and chemical indicators show a small floating range in the vertical distribution of the desert steppe region.(4)In the evaluation of soil fertility of different grassland types,the explanatory power of each index in the three grassland types is above 80%,which can comprehensively evaluate the soil fertility of the region.In the transition zone of different grassland subtypes,the comprehensive soil fertility is relatively better than other regions.Among them,SOM plays an important role in meadow steppe and typical steppe,while potassium plays an important role in desert steppe.(5)The soil quality of meadow steppe and typical steppe was generally better than that of desert steppe.The soil quality in the study area was13.33%,and the average and good grassland accounted for 36.67%,which was suitable for the growth and development of vegetation.The grades in the middle and poor grades account for 50% of the total,indicating that the Xilingol grassland is mainly dominated by medium-level land.