Abstract
About 50 cultivated soils collected at Kameoka basin, Kyoto, were used for the determination of total, water-soluble, and hot-water soluble selenium in the soils. Soluble Se was extracted with water (soil: water=1:10) at room temperature for 24h or in a boiling water bath for 30 min. 1) The average Se contents of plow and second layer soils were 0.288 (0.64-0.16, n=51) and 0.323 (0.56-0.11, n=21) ppm, respectively. Although the mean content of second layer was a little higher than that of plow layer, Se leaching from surface horizon to under layer did not appear. In addition, there was no relation between the Se content of the soils and that of mountain soils surrounding the Kameoka basin. 2) On particle-size fractionation, Se contents of each fraction (coarse sand, fine sand, silt, and clay) showed 0.0n ppm order. this indicated that most Se in soil was in an easily soluble state. 3) Water-soluble and hot-water soluble Se were 8.9 and 20.4 ppb, which amounts to 3.1% and 7.2% of total and these soluble Se were also significantly high. Moreover , the correlation between increased Se and amino acid in hot water as compared to water (hot water soluble-water soluble) was significant. From these results, it was considered that the proteinaceous fraction of soil humus was decomposed on heating, and Se dissolved as low molecular compounds, such as Se-amino acids.
