Природные условия и основные факторы почвообразования в долине реки Аган

Soil types are identified on the basis of the relationship between soil-forming factors. The major soil formation factors, including lithology, topography, soil temperature, groundwater level, and vegetation, were described during fieldworks at the valley of the Agan River. During these fieldworks the researcher has studied and described the morphological characteristics of soils, given the definition of the mechanical composition of the rocks, studied the basic topography characteristics (such as altitude, exposure and steepness of slopes), identified the groundwater level in the summer-autumn period, produced geobotanical description, and made measurements of soil temperature using a route probe to measure the temperature of the soil horizons. The soils of the Agan River valley are of heterogeneous types, which is primarily due to the lithological and geomorphological conditions associated with the geological history of the territory. Loamy sediments of the Middle Pleistocene period in the left bank of the Agan River valley, together with prolonged low temperatures and vapor in the air create conditions for cryogenic processes in the soil horizons. Cryogenic processes are the main factors shaping so-called “light soils”, which were not identified as a separate soil type in the handbook on “Soil Classification” (1977). These soils could be earlier defined as podzolic, gley-podzolic, or eluvial-gley soils. The soils on sandy sediments of the Upper Pleistocene period dominating along the tributaries of the right bank of the Agan River valley under eluviation were formed as soil alfehumic type, such as illuvial-ferruginous podzols, illuvial-humus podzols, peat-podzolic soils. The right bank of the Agan River valley was formed mainly by lacustrine-alluvial sands, as during the Upper Pleistocene period this bank used to be a water body, therefore during the modern Holocene period the territory is formed by vast expanses of oligotrophic bogs with numerous lakes, which created the conditions for the development of oligotrophic peat soils with peat thickness up to 5 m.