Selenium content and distribution in various Japanese soils

The Se contents of Japanese mountain soil profiles, surface soils of grasslanc and paddy lands were measured. The average total Se content of grassland soils was 0.89 ppm (N=25), about two times as high as that of surface mountain (0.57 ppm, N=6) and paddy soils (0.46 ppm, N=44). The Se distribution patterns of six mountain soil profiles were investigated. The soils derived from a homogeneous parent material showed a high Se content in the surface organic horizon. However in the soils which had undergone some changes in their profiles such as the addition of other materials, the Se distribution pattern was affected by the Se content and the extent of influence of the additional material. The water-soluble Se contents of grassland and paddy soils were 14.2 and 14.4 ppb, respectively, corresponding to 2.30 and 3.85% of the respective total Se content. The total Se contents of various Japanese soils were comparable to, or even slightly higher, than those reported from other countries. However, the water-soluble Se content was slightly lower especially in grassland soils.