Soil Quality Evaluation And Obstacle Factors Analysis Of Cotton Fields In Shaya County,Xinjiang

In this research,we took cotton fields and their salt spots in the main townships of Shaya County as the research objects and used technical methods such as field investigation,indoor analysis and computer technology.Seven soil physical and chemical indicators including soil organic matter,total nitrogen,alkaline-hydrolyzed nitrogen,available phosphorus,available potassium,total salt and bulk density were measured in cotton fields.Characteristics of soil physicochemical indicators and regional characteristics were analyzed in cotton fields.In addition,we used principal component analysis and combined the soil quality index method to quantitatively evaluate the soil quality of cotton fields in Shaya County.In the end,we established a regional soil quality classification system for cotton fields.We measured soil p H value,total salt content,cations(K⁺+Na⁺,Ca²⁺and Mg²⁺)and anions(Cl^-,SO₄^2-,HCO₃^-and CO₃^2-)in salt patch plots of cotton fields to analyze the main obstacle characteristics of cotton fields.Finally,we proposed general prevention countermeasures to provide useful suggestions for improving soil salinization.The main conclusions were as fallows.（1）According to the second national nutrient classification standard,we analyzed the content characteristics of soil physical and chemical indexes in cotton fields in Shaya county.The research showed that the contents of soil organic matter,total nitrogen,available phosphorus and available potassium were above the medium level in more than 70%of cotton fields,but the content of alkaline-hydrolyzed nitrogen was extremely deficient in the soil.Because soil bulk density value of the cotton field was 1.5 g/cm³and its indicator variation was small,the soil was too tight.The average total salt content was 4.16 g/kg in cotton field,and 43.55%of the sample plots showed different degrees of soil salinization.In addition,the salt index had great variability.（2）Except for alkali-hydrolyzed nitrogen and bulk density,the contents of soil organic matter,total nitrogen,available phosphorus and available potassium were in good condition in most cotton fields in the north of Hailou town,and most cotton fields were non-salinized,but the contents of soil organic matter,total nitrogen,available phosphorus and available potassium were lower in cotton fields in the northern part of Hongqi town.In addition,the soil of cotton fields was slight salinity in the northern part of Hongqi town.Analysis of variance was used to further reflect the regional status of soil physicochemical properties.The results showed that the difference of alkaline-hydrolyzed nitrogen and bulk density were not significant among the study regions,but most of the indicators of the cotton fields were in poor condition in Hongqi town and were significant differences with other town,especially the cotton fields in the northern part of Hongqi town.（3）The evaluation results showed that the contents of other nutrient indexes was moderate or above in the cotton fields of grades I to IV,but the content of alkaline-hydrolyzed nitrogen was very scarce,with an area ratio of 75.20%.However,except for the medium content of available potassium,the content of other nutrient indicators in grade V land was relatively lacking.The area of grade V land accounts for24.80%,which were distributed in Hongqi town.The lower the rating,the greater the soil salinization and the soil bulk density.Because most soil physicochemical indicators of cotton field showed a certain regional,the soil quality of cotton fields also was regional in Shaya County.The soil quality index of cotton fields was the lowest in the northern part of Hongqi town,which was significantly different from other towns.Because the northern part of Hailou town was dominated by cotton fields with higher soil quality,the soil quality was better.The results showed that the soil quality of the cotton fields were affected by regional factors to a certain extent in Shaya county.In addition,reed spot and sand spot were grade IV and grade V respectively,which was relatively consistent with the actual situation.（4）The salt spots of Cotton fields belonged to alkaline saline soils.The salt ions were mainly K⁺+Na⁺、Ca²⁺and SO₄^2-.Most salt ions showed medium variation,while soil p H value showed weak variability.The soil salinization type was mainly the chloride-sulfate that accounted for 53.33%.The correlation analysis showed that soil K⁺+Na⁺,Ca²⁺,Mg²⁺and Cl^-were the main impact attributes of salt spots.In order to control the soil salinization and the expansion of salt spots in cotton fields,we proposed some conventional prevention countermeasures to provide references.