Influence of economic activities of land users on the state of soil fertility of agricultural lands in the southern forest-steppe of the Omsk region

The research was carried out in order to obtain information on the state and dynamics of soil fertility of agricultural land and to identify negative results of economic activities of land users in the Lyubinsky district of the Omsk region. The soil cover of arable land in the surveyed territories is represented by ordinary chernozems and meadow-chernozem soils. Hayfields and pastures are located on solonetzes, alluvial and partially meadow-chernozem soils. In the period from 1965 to 2001, a decrease in the amount of humus and a reduction in the area of soils with an increased (6.1-8.0%), and in some land uses with an average (4.1-6.0%) content of humus by 2-6 times. By 2020, the area of soils with a high and medium content of mobile phosphorus has decreased. Its amount decreased by 25-39% in relation to the initial level (1965-1987). The redistribution of the arable land area according to the content of potassium has been established. The area of soils with its high supply for plants increased by 2-4 times, while the weighted average value of the element remained very high (more than 180 mg/kg of soil). Throughout all the rounds of the survey in the soils of land use, the reaction of the environment in the soils was established in the neutral and close to neutral range and amounted to 6.1-6.6 units pH. Analysis of soil fertility for each field separately indicated a decrease in the level of soil fertility in one or several indicators. The soils of the arable land had an average degree of cultivation. Their culture index varied from 0.72 to 0.77 units. In general, the soils in the surveyed area were not contaminated with heavy metals, their value did not exceed the APC and MPC.