Comprehensive Evaluation Of Cultivated Land Natural Quality Based On Agricultural Land Classification And Geochemical Survey

This study based on food security and cultivated land protection, takes Kaifengcity in Henan province for example, according to the result of agricultural landclassification and the geochemical survey, combining the reality of the study area,selects S, B, Mo, Mn as beneficial elements and As, Cd, Pb, Hg, Cr as harmfulelements, through the evaluation of the selected elements to evaluate the cultivatedland comprehensive quality. The main conclusions are As follows:The average content of B, Mo and Mn elements is under the national averagelevels. Spatial variation of beneficial elements generally presents the characteristics ofhigh in the west and low in the east. The average contents of harmful elements areless than its natural background value. More than95%of the soil is level1land, andthe level2land mainly distributed in the southeast of Kaifeng.The average values of single pollution index of harmful elements are less than0.7. The highest average values of single pollution index is As,0.465. Cd, As and Pb,whose maximum value of single pollution index are greater than1. With the Cdelement has the highest maximum of single pollution index,11.142. Based on theresults of harmful elements comprehensive evaluation, only0.63%of the soil inkaifeng were polluted,0.45%of the soil in the warning level,98.92%of the soil in thesecurity level. The mainly pollution elements were Cd, Pb, and As. The polluted soilmainly distribute in the southeast of Kaifeng city. From an overall perspective, thesoil in Kaifeng is generally clean and suitable for crop growth.The average values of single enrichment index of beneficial elements are greaterthan0.7. The highest average value of single enrichment index is S,1.109. Themaximum values of single enrichment index of beneficial elements are greater than1,The highest maximum value of single enrichment index is S,4.85. Statisticalindicators of element B are the lowest. Based on the results of beneficial elementscomprehensive evaluation,17.31%of soil is lack of beneficial elements,53.99%forthe right amount, only28.69%is rich in content. Four kinds of beneficial elements are lacking in the west of Kaifeng country and northwest of Weishi country.This paper put forward soil comprehensive pollution index as a limiting factor,then according to the regional comprehensive enrichment index to evaluate the qualityof cultivated land. Eventually, the classification range of cultivated land change isdivided into four levels: decreased to grade0, reduced1, unchanged and increased1.According to the comprehensive evaluation results of cultivated land quality, thecultivated land of Kaifeng can be divided into eight grades(grade0,9-15grade).compared with the previous agricultural land classification, it is found grade0incomprehensive evaluation results, covered an area of1880.87hectares; the gradewhich reduce1of the cultivated land area is77384.23hectares; the grade which notchange of the cultivated land area is225796.39hectares; the grade which rise1of thecultivated land area is126172.11hectares. The proportion of the low quality ofcultivated land (grade0, grade9to grade11) is increased, but the high quality ofcultivated land was reduced.This study discuss the integration method of agricultural land classification andgeochemical survey’s outcome. It provides a scientific basis for regional landresources management. The result can be used for land resources quantity, quality andecological protection, environmental pollution control programs and cultivated landprotection.