CHEMICAL FORMS AND STABILITY OF SELENIUM IN SOIL

The chemical forms of selenium (Se) in soils derived from different pa rent rocks, and the stability of Se species in soils were investigated , Around 40% of the total Se occurred as organic Se on the average, To tal selenite content was higher than that of total selenate, The conte nt of organic Se decreased with heating of the soils at high temperatu res, and most of it disappeared at heating temperatures above 500 degr ees C, However, the results of incubation experiments indicated that S e species mere stable in soil, and that their chemical forms did not c hange appreciably with the variation of soil conditions. In soluble Se , organic Se accounted for about 50%, and in contrast to the total Se, the selenate content was higher than that of selenite.