Geochemical Evalution Of Land Quality In Cangwu County,Guangxi

This thesis focuses on the soil geochemical survey in Cangwu County,Guangxi.Atmospheric,irrigation water and crop geochemical surveys are conducted at the same time.These researches determine the geochemical grades of the soil nutrient,soil environment,soil quality,atmospheric and irrigation water.On the basis of the comprehensive geochemical grade of soil quality,with the environmental geochemical comprehensive grade of atmospheric and irrigation water,the assessment of geochemical grade of land quality was completed.The results indicate that the comprehensive condition of soil nutrient behaves worse in the study area.The geochemical comprehensive grades of soil nutrient rank 3 and 4 mainly,amounting to 45.10% and 43.02%,which shows the lack of soil nutrient that consists of nitrogen,phosphorus and potassium in the topsoil of the whole study area.It is recommended that the amount of phosphate and potash should be increased appropriately in the study area.The soil environment in the study area is in good condition,with major of the geochemical comprehensive grades of soil environmental ranking 1 and 2,accounting for 90.66% and 7.39% respectively.The soil quality in the study area is good as well,with major of the geochemical comprehensive grades of soil quality ranking 2 and 3,accounting for 38.96% and 48.32% respectively,while grades 1 only accounts for 7.90%.The geochemical assement grades of land quality rank 2 and 3 in the study area,which account for 38.97% and 48.32% respectively.There is little difference between the grade 1 and grade 4,accounting for 7.90% and 4.37% respectively.The distribution of grade 5 is less.As a whole,the geochemical assessment grade of land quality in the north east of the study area is superior to that in the south west region.According to the distribution characteristics of the excellent selenium-rich land in the study area,combined with the comprehensive quality grade of crops and the development status of the local agriculture,especially the se-enriched industry,four excellent selenium-rich planning areas were divided.Some suggestions on the suitability planning of the selenium-rich industry in the planning areas were given meanwhile.Based on the status of the use of three major land,according to the characteristics and influencing factors of each land use type,specific plans and utilization suggestions for each land use type are proposed from the perspective of geochemistry.Social economic benefits were estimated from the perspective of the development of selenium-rich agricultural products.