| Wuchuan County is one of the two autonomous counties with Gelao and Miao as the main ethnic groups in China,and belongs to the demonstration county of regional development and poverty alleviation in Wuling Mountain area.Cultivated land is the basic material material for human survival,but with the development of society,the cultivated land resources are decreasing day by day,so to ensure the sustainable development of agriculture,we must ensure the quality and quantity of cultivated land.This paper takes Wuchuan County as the research area,and conducts geochemical investigation and research on cultivated land soil in this area.On the basis of identifying the spatial distribution pattern of nutrient elements and heavy metal elements in the area,according to the Code for Geochemical Evaluation of Land Quality(DZ/T 0295—2016),taking the national soil environmental standards as a reference,and then comparing the characteristics of soil environment in the study area,the comprehensive evaluation of soil environmental quality was carried out,which provided scientific basis for the utilization and protect of cultivated land resources as well as the development and utilization of cultivated land with distinctive characteristics.This paper mainly obtains the following results:1.the results of soil nutrient quality evaluation in the area show that microelement of F,V,Mn,Zn,B,Mo and Co are relatively abundant,and all were dominated by the first class.The soil in the area is mainly divided into two classes:medium nutrient(the third class)and rich nutrient(the second class),accounting for94.59% of the total area;nutrient deficient(the fifth grade)soil area is 400 mu,0.03%of the total area.The main deficiency area is P deficiency,followed by K deficiency.2.The results of soil physical and chemical indexes evaluation indicate that the acid soil accounts for the largest proportion in the study area,mainly distributed in towns and villages of this county,accounting for 70.69%;and then the neutral soil isaccounting for 23.37% of the county;alkaline soil and strong acid soil have a small proportion;there is no strong alkaline soil in the area.The p H value in this area ranges from 4.31 to 8.34,with an average value of 6.17.3.The evaluation results of soil environmental quality evaluation in the study area manifest that the comprehensive grade of environmental geochemistry in the study area is Class I and Class II,covering an area of 1,152,000 mu whichaccounts for98.21% of the total area.The comprehensive grade of soil environmental geochemistry is Class III,covering an area of 21,000 mu whichholds 1.79% of the total area.The severely over-standard elements include Mercury(Hg),Cadmium(Cd)and Arsenic(As),among which Mercury has the largest over-standard area.4.The results of comprehensive evaluation of soil quality in the study area demonstate that the soil is predominantly third-class medium,with an area of1,022,300 mu,accounting for 87.15% of the total area.The total area of the fourth-class poor soil and the fifth-class inferiorsoil is 21,200 mu,accounting for1.81% of the total area.The soil quality of this area is generally good. |
