Restoration of the structural and aggregate composition of grey forest soil when transferred to a fallow state

The study was conducted to assess the influence of vegetation and fallow age on the structural state of grey forest soil in the subtaiga of the Trans-Urals. The work was carried out from 2020 to 2024 in the Tyumen Region. The objects of the study were virgin, arable, and fallow plots, the soil cover of which was represented by grey forest soil. Soil structure was determined using the sieve method, and water stability was determined using the Baksheev apparatus. Virgin soil was characterised by excellent structural condition (structural coefficient of 1.4-5.4), water retention varies from 22 to 48% and decreases consistently with depth. On arable land, the structural coefficient was 54 % lower than on virgin soil, with a water stability of 33% in the 0-20 cm layer, increasing to 45% in the 20-40 cm layer. In deeper layers (60-100 cm), the impact of agricultural activity was not recorded. The conversion of old-arable grey forest soil to a fallow land and the development of herbaceous vegetation on it for 15 years had a favourable effect on the structural-aggregate composition. The structural coefficient during overgrowing with deciduous trees varied from 3.3 to 1.1 units, and with coniferous species – from 2.9 to 2.0 units. In the fallow area, the water resistance coefficient in the 0-20 cm layer increased to 43%, which leads to a qualitative improvement in the structural-aggregate composition. After 30 years, in the area with deciduous trees, the structural-aggregate state was restored to the level of the virgin plot. The structural coefficient in the 0-20 cm layer was 11.6 units, and the water resistance was 49 %. In the fallow area with coniferous trees, where the species composition of herbaceous vegetation changed, the values of these indicators were at the level of 3.6 units and 39 %, respectively, which offsets the positive impact on the structure formation of herbaceous vegetation in the first 15 years.