Comprehensive Evaluation Of Cultivated Land Quality In Xiantao City Based On Soil Geochemistry

Cultivated land is one of the most valuable resources in China.With the rapid development of urbanization,The contradiction between the urban expansion,arable land reduction,land reclamation,soil heavy metal pollution and the current food security,cultivated land protection are becoming more and more serious.Carrying out the evaluation of cultivated land quality and improving the production capacity of cultivated land have become the focus of attention.The candidate selected Xiliuhe Town,Pengchang Town and Yanglinwei Town of Xiantao City,Hubei Province as the study area,systematically collected samples of soil,irrigation water and crops,and analyzed its geochemical characteristics and spatial distribution.Combining soil survey,agricultural land classification and other data,carry out comprehensive evaluation of cultivated land quality and research work on selenium-enriched arable land.The results were listed as follows:?1?The topsoils of the study area is dominated by alkaline,followed by neutral soil.Compared with the average level of Chinese topsoil,it has higher concentrations of B,Cd,Co,Cr,Cu,Zn,Ni,Mn,V,Se,K₂O and lower Mo,soil organic matter.It show relatively higher concentrations of Cd,Cu,Zn,Ni,Se and K₂O content than the average level in Hubei Province topsoil and Jianghan Basin topsoil.According to the latest soil environmental quality standards in China,the rate of soil heavy metal exceeding the standard in the study area is:Cd>Cu>As>Ni>Zn=Hg=Pb=Cr,the main reason is that the Cd element exhibits a low concentration exceeding the standard.?2?Multivariate statistical analysis showed that the accumulation of heavy metal elements Cd,Hg and nutrient elements P and Mn in soil was mainly caused by random factors and human activities,while As,Pb,Cr,Cu,Zn and Ni were mainly affected by natural factors.N,Se and soil organic matter all showed strong correlation and variation characteristics,and were affected by natural structural factors and random human activity factors,while pH was mainly affected by soil parent material in the region.?3?Based on existing achievements in the evaluation of cultivated land quality,the evaluation system and evaluation method of cultivated land quality in the study area were constructed from three aspects:cultivated land natural quality,farming conditions and health status.The natural quality of cultivated land was used as the background value of cultivated land quality,farming conditions and health status as a restrictive dimension.Obtained the evaluation index and grade of cultivated land quality by using an integrated algorithm.The results showed that the cultivated land quality index in the study area was mainly distributed between 50.49 and 94.17,and the superior land was 13343.66 hectares,accounting for 49.32%.The second-class cultivated land is 13712.63 hectares,accounting for 50.68%.There is no medium or low land.The superior cultivated land is mainly distributed in the east of Xiliuhe Town,the eastern and southwest of Pengchang Town,and the middle of Yanglinwei Town.In general,the quality of cultivated land in Pengchang Town is better than that of Xiliuhe Town and Yanglinwei Town.?4?On the basis of comprehensive evaluation of cultivated land quality,according to factors such as soil selenium,soil nutrients,soil environmental quality,and selenium-enriched characteristics of crops,the ecological agriculture division was carried out on the study of selenium-enriched cultivated land,and five selenium-rich industrial bases were drawn.The planned area is 9882 hectares and the cultivated area is 5770 hectares,it provides scientific guidance for the development of local selenium-rich land and specialty agricultural products.