Soils of Floodplain Landscapes of the River Selenga Basin

The factors of formation and patterns of spatial differentiation of soils within the floodplain landscapes of the River Selenga and its tributaries (on the territory of Mongolia and Russian Federation) depending on zonal–belt location are revealed. This factor has been established to significantly affect the genesis, structure, morphology, and properties of soils within river floodplains. Soil diversity is due to different types of synlithogenic trunk of the alluvial section and the trunk of primary soil formation of the department of underdeveloped soils. Soils of halomorphic section of the postlithogenic trunk are of a landscape significance in steppe and dry-steppe zones. Alluvial dark-humus soils are close to optimal in properties and regimes Alluvial humus–gley soils develop under excessive flood–ground moisture, the influence of the permafrost–thermal factor, and the low activity of soil microbiota. It is proposed to include the type of alluvial light-humus soils, which are quite widespread in the floodplain landscapes of the region, in the soil classification. These soils develop under conditions of sufficient heat supply, but severe moisture deficit and intensive mineralization of organic matter, and are characterized by low humus content. A comprehensive agrochemical assessment of the level of fertility of alluvial soils and hydromorphic solonchaks and the biological productivity of natural meadow communities is given.