Study of acid-alkaline conditions of different-age arable soils of landscape catens of Central Forest-Steppe

Fertility of soils is largely determined by their physical and chemical properties. Response of soil environment is a mobile indicator of soil fertility. Direction and intensity of almost all soil processes that provide nitrogen, phosphorus and potassi- um regimes of soils, as well as availability of macro- and microelements for plants, depend on it. The paper presents the result of a field study of acid-alkaline conditions of profiles of black soil of typical and leached different terms of agricultural use of soil cat- ens of the meadow-steppe section of the Belgorod region in 2019. The research object was different-age arable areas with an age of agricultural development of 140 and 240 years, respectively. The steepness of surface in areas corresponding to the meadow-steppe zonal landscape of the forest-steppe did not exceed 4-6 °. As a result of field studies, 32 incisions were studied in the mead- ow-steppe section (6 incisions on background catens and 12 incisions on open catens). Each incision was provided with layered values of morphometric indicators of soil horizons. For background steppe soils, shade slopes are characterized by more alkaline conditions, in comparison with southern slopes. For 140-year-old arable land, the situation is opposite: shadow slopes have a more acidic reaction of the medium, in comparison with insoluble ones; for 240-year-old arable land, alkaline-acid conditions on the slopes of opposite expositions did not differ significantly. In the first 140 years of plowing, acidification of the soil profile occurs; the difference in the pH value between the background and arable land values of 140 years of age on the slope of the northern ex- position reaches 1.6 on the surface, gradually decreasing to 0.2 at depth. Further plowing leads to alkalization of the soil profile by 0.6-0.9 pH units. The research results can be used in development of agricultural systems in crop industries.