Analysis And Evaluation For Soil Quality On Small Area

Due to negative impacts of land degradation,soil pollution and other soil problems,soil quality arouses more and more concerns.Soil quality includes soil environmental quality,soil fertility quality,soil health quality according to soil functions.Soil quality assessment can quantitatively assess the status of soil quality and provide a scientific basis for the government's agricultural sector to make plans for agricultural development.In this thesis,we made assessment of five heavy metals-chromium,cadmium,arsenic,lead,and mercury in soil,which are of great concerns,and their risk.We also assessed five essential elements-calcium,magnesium,iron,zinc,and copper.At the same time,we assessed soil fertility based on ten physical and chemical properties-pH,organic matter,soil texture,zinc,copper,iron,total nitrogen,total phosphorus,available phosphorus and cation exchange capacity.Finally,we obtain the following results:(1)The concentration of Ca,Mg,Fe,Zn,and Cu decreases from northwest to southeast in the study area.Compared with the geochemical reference value of carbonate rock in Zhejiang Province,the soil is rich in Ca and Zn in the study area,while the average content of Mg and Fe is lower than the reference value.As to the comprehensive fertility,about 97%of the study areas is at level II.(2)There exits heavy metal pollution in the study area,especially Cd and Pb pollution.Heavy metal pollution shows a decreasing trend from northwest to southeast,which may result from industrial activities.The total noncarcinogenic risk index for heavy metals in the study area is less than 1,which is acceptable.(3)It is recommended to plant rice,vegetables and other crops in the southeast area;plant rice,upland crops,fruit trees,and other trees for non-timber products in the central area;plant trees for non-timber products such as Camellia oleifera and Camellia sinensis and avoid rice cropping and vegetables farming in the northwest area.We also suggest calcium-rich,zinc-rich crops cultivation and animal products development in local area.