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分别采集了张家口克山病区非病村4个砂土样品和重病村6个草甸土、褐土样品．用连续提取程序分离出水溶态硒、离子交换态硒、有机态硒、酸溶态硒、硫化物态硒和残余态硒。水溶态硒容易被植物吸收。交换态硒也能被植物吸收，但受到吸附环境和pH值的影响。有机结合态硒只有在碱性条件下其中的富啡酸态硒才能被植物吸收。酸溶态硒是铁锰氧化物和碳酸盐类矿物醚性淋溶作用的结果，酸性条件下硒容易流失，碱性条件下硒被原矿物固定，因此都难被植物吸收利用。硫化物态硒和残余态硒是最难溶的，基本上不被植物吸收。张家口地区重病村土《铁锰氧化物和腐殖质含量高，呈中-微酸性，而非病村正好与之相反。因此，重病村土壤虽然水溶性硒+交换态盾+有机态硒高于非病村，但这三种硒形态所反映的土壤植物有效性反而低于非病村。这可能是病村粮食比非病村低硒的原因。
Four sand samples of non-disease village and 6 meadow soil and cinnamon soil samples were collected from Zhangjiakou Keshan Ward. Separation of water-soluble selenium, ion-exchanged selenium, organic selenium, acid-soluble selenium, sulfide selenium and residual selenium is carried out using a continuous extraction procedure. Water soluble selenium easily absorbed by plants. Exchangeable selenium can also be absorbed by plants, but by the adsorption environment and pH. Organic Selenium Selenium is only absorbed by plants under alkaline conditions. Acid soluble selenium is the result of ether leaching of Fe-Mn oxides and carbonate minerals. Selenium is easily lost under acidic conditions. Selenium is immobilized on raw minerals under alkaline conditions and therefore it is difficult for plants to absorb and utilize them. Sulfide and residual selenium are the least soluble and are not substantially absorbed by the plant. Zhangjiakou area seriously ill village soil "iron and manganese oxide and humus content is high, was medium - slightly acidic, but non-sick village just the opposite. Therefore, although seriously soluble disease of soil soluble selenium + exchange shield + organic selenium higher than the non-disease village, but these three selenium forms reflect the effectiveness of the soil plant but lower than the non-disease village. This may be the reason why the grain in the diseased village is lower than that in the non-diseased village.