Change of Forest-Steppe Chernozems under the Influence of Shelterbelts in the South of the Central Russian Upland

The results of a comprehensive study of soils under a 30-m-wide five-row oak shelterbelt of meridional orientation and on the adjacent arable fields of the agroforestry landscape in typical forest-steppe of Belgorod oblast are discussed. Background soils are medium-deep light clayey leached chernozems (Luvic Chernozems) on calcareous loesslike heavy loam. As a result of tree growth during the past 50 years (age of the shelterbelt), certain changes in the intensity and direction of soil-forming processes have taken place in soils of both the shelterbelt and the adjacent arable land. Data on the contents and stocks of the clay (<0.001 mm) and fine silt (<0.005-0.01 mm) fractions in the soil profile under the shelterbelt attest to the development of its textural differentiation. The accumulation of sodium and magnesium in soil water extracts is detected in the deep (200-400 cm) layer of this soil. Adjacent arable soils contain less carbonates than soils under the shelterbelt; the removal of carbonates from the layers of 0-200 and 0-300 cm is estimated at 57 and 84 t/ha, respectively. The topsoil (0-20 cm) under the shelterbelt significantly differs from the topsoil of the adjacent arable land in a lower bulk density, lower stocks of clay (<0.001 mm) and physical clay (<0.01 mm), and higher stocks of C-org. The influence of the shelterbelt on the properties of adjacent arable soils can be traced to a distance of 50-60 m from the shelterbelt edges. The significant quantitative differences are seen in the clay stocks.