Soil Selenium Speciation in Cropland of Western Ankang and the Characteristics of Crop Selenium Enrichment

On the basis of geochemical investigation and evaluation of the soil in western Ankang,Shaanxi province,this paper studies the soil selenium content, soil selenium speciation, and the characteristics of crop selenium enrichment in cropland of Ziyang and Hanyin County. The average content of selenium in soil of crop root is 1.24-2.27×10^-6, 2.1 to 4.7 times higher than the standard for natural selenium-enriched land (DD-2019-10).The proportion of selenium speciation in soil from high to low is residual fraction (0.891×10^-6)>humic acid compound (0.255×10^-6)>strong organic combined fraction (0.217×10^-6)>soluble fraction (0.015×10^-6) ≥ carbonate bound fraction (0.015×10^-6)>ion exchanged fraction (0.012×10^-6)>Fe-Mn oxidized fraction (0.008×10^-6).Selenium contents in the edible parts of 8 kinds of crops have met the standard of selenium-enriched agricultural products.The crop selenium enrichment coefficient from high to low is rape(1.03) > rice (0.47)>garlic (0.36)>tea (0.20)>corn (0.13)>sweet potato (0.11), konjak (0.10)>potato (0.08).It is suggested that the agricultural production should take full advantage of selenium resource and make reasonable plan for planting according to crop selenium enrichment.