Soils of pine-birch forests on high Pleistocene terraces in the Selenga delta region

The soils of pine-birch forests on Pleistocene lake-river terraces in the Selenga delta region were studied. These soils are characterized by their weak differentiation into genetic horizons, pale or light brown color, and the weak structure of their mineral horizons. The high base saturation, weakly acid or close to neutral reaction, and homogeneous bulk chemical composition evidence the absence of the eluvial-illuvial differentiation of the soil profiles. The humus is of the fulvate-humate type. Among the humic acids, the brown acids predominate; the content of black humic acids is slightly lower and that of the nonhydrolyzable residue is elevated. In the mineral horizons, the clay and iron-clay autochthonous formations on the primary mineral grains point to the weakly pronounced process of metamorphism. In the Bm horizon, the formation of crystallized iron compounds in the form of films and fine iron segregations is observed.