Influence of Land Use on the Physical Properties of Chernozems in the Forest-Steppe Zone of Western Siberia

The land use type and agricultural practices significantly affect the aggregate state and many physical properties of soils. In this study, we provide a comparative assessment of the bulk density, water holding capacity of disturbed samples (WHC), and structural state (dry sieving method) of Luvic Greyzemic Chernozems under different land uses (long-used arable land, newly developed arable land, 27-yr-old abandoned land, and virgin steppe) in the Cis-Altai forest-steppe soil province of Western Siberia. At each site, three mixed samples were taken from the layers of 0-5, 5-10, 10-20, and 20-30 cm of the humus horizon. The influence of land use on the bulk density was only seen for the upper 5-cm layer, in which the decompaction after 27 years of abandonment was statistically significant. Differences in the bulk density between the two croplands and between the abandoned and virgin lands were insignificant. Changes in the WHC under the impact of land use were manifested for the upper 20-cm layer. In six years of using the previously abandoned land for growing cereals, the aggregate-size distribution of the soil became almost identical to that in the old-arable soil. Judging the amount of agronomically valuable aggregates and the structural coefficient value, the aggregate state of all the studied soils can be assessed as excellent. Thus, Luvic Greyzemic Chernozems of the forest-steppe zone in Western Siberia are characterized by the high tolerance towards agrogenic impact and retain their natural crumb-granular structure for a long time of their using for crop production.