The Feature of Selenium-rich Soil and Its Combined form in Eastern Qinghai

There is a larger area of selenium-rich soil in eastern Qinghai,and it mainly origined from red layer material of Paleogene-Neogene Xining Group.During the lake basin retreated,the material steadily deposited and formed the soil characterized by abundant and stable material source.The soil held high level of available selenium content and generally showed distinct alkalescence,which is propitious to absorption and utilization for crops.In soil,the contents of available selenium and total selenium have good relativity and showed linear relationship,making for the development of selenium industry.