FORMATION OF CHERNOZEM SOIL THERMAL REGIME UNDER SEA BUCKTHORN IN THE ALTAI OB RIVER AREA
Soil temperature is the most important indicator of its thermo-physical condition. It is related to the rate of water and nutrients uptake by a plant, and the solvability of salts, oxygen and carbon dioxide. A meteorological factor renders the greatest effect on soil thermal regime. At the same time, soil genesis, vegetation and cultural practices also render their effects, though weaker, on heat distribution and accumulation in a soil profile. The main integral indicator of soil climate is daily cumulative temperatures at depths and through time. A thermal condition of chernozem during a growing season under sea buckthorn depends on planting density. Planting layout 4.0 × 2.0 m is heated up more intensively, while a denser layout (to 3.0 × 1.0 m) reduces daily soil temperature fluctuations and contributes to the formation of a more stable temperature background. The greatest variations in the depth of heat penetration in chernozem between the layout variants are observed in the upper humus horizons. The studied chernozem soil belongs to the category of the "warmest" soils. Effective temperature period lasts for about 5 months. Heating up to biologically favorable temperatures above 15°C in 1 m chernozem profile occurs from late June to mid August, and in the layer of maximum plant roots concentration for three months. The temperature regime of chernozem in winter, provided an early snow cover formation, is favorable for sea buckthorn overwintering.