Fertility of arable and fallow meadow-chernozem soils of agricultural landscapes of the southern forest-steppe of the Omsk Irtysh region

The purpose of the work is to assess the current state of fertility of meadow-chernozem soils of agricultural landscapes of the southern forest-steppe of the Omsk region. The studies were carried out in 2014-2022 on the territory of the experimental fields of the Federal State Budgetary Educational Institution of Higher Education Omsk State Agrarian University in the Kamyshlovsky rural settlement of the Lyubinsk district. The object of study was meadow-chernozem soils that have been used for a long time in arable land and are in a fallow state. During the research, soil sections were laid, the morphology of profiles was studied, physical, physicochemical and chemical properties were determined, and soil quality scores were calculated. The soil cover of the surveyed areas is represented by meadow-chernozemic medium-deep and thin medium-humus and low-humus soils, predominantly heavy loamy, less often medium loamy granulometric composition. The thickness of the humus layer is 31-41 cm on arable land, 32-64 cm on fallow lands; the average humus content in the arable horizon is 5.79%, in the A horizon of fallow soil - 6.39%, with a significant decrease in it in the AB horizons by 1.5-2.3 times. The soils had favorable physicochemical properties: a close to neutral reaction environment, a high amount of exchangeable bases with a predominance of calcium, a small amount of sodium, but an increased proportion of magnesium relative to the optimum was observed. Comparison of the results with the data of a soil survey of the lands of the Kamyshlovsky educational farm in 1987 did not reveal a change in soil species in terms of the thickness of humus horizons and humus content. The soils had a good structural state in terms of the size of the aggregates (structural coefficients in horizons A and AB were 1.63 and 2.68 on fallow land, 2.3 and 1.45 on arable land). The water resistance of aggregates on arable land (36-61%) was significantly less compared to the fallow (78-88%). Meadow-chernozemic soils of the fallows were characterized by a higher density (1.19-1.28 g/cm3) and lower total porosity (48.2-50.6%) compared with arable land: 1.05-1.18 g/cm3 and 55.4-56.6%, respectively. According to the average quality scores (79 on fallow land, 85 on arable land), the soils belong to the categories of the best soils.