Preservation and features of growth of forest crops on chalk-marl technogenic soils of the Kursk region

In the Kursk region, one of the agrotechnical techniques for conducting the mining stage of preparing the surface of the dump for forest reclamation, which consists in leveling its surface and applying a potentially more fertile reclamation layer with subsequent mechanized processing, has been tested on the chalk-marl dumps of the Shchigrovsky phosphorus mine. Three variants of artificial soil mixtures based on sand, loam, and humus were purposefully formed and cultures of Betula pendula Roth and Robinia pseudoacacia L. were created. For each variant of the soil mixture layer, in comparison with the control variant (fine marl soil without applying a reclamation layer), the dynamics of safety indicators, average gain, bonus, reserve, H/G1.3 ratio in the range of 5-30 years were studied. The safety of crops of R. pseudoacacia at the age of 30 years in the control variant is 36% (p < 0.05), with the application of a soil-improving layer, the safety reaches 70% (p < 0.05). The safety of the hanging birch (B. pendula) on chalk marl without improving forest growing conditions is 24% (p < 0.05), with the application of a reclamation layer in almost all three variants – 43-45%. B. pendula and R. pseudoacacia in a plantation created on chalk marl (control variant) showed the lowest tree height and diameter in the plantation at height 1.3 m, which corresponds to the IV site classes of the bonus. R. pseudoacacia plantings in the control variant at the age of 10 years have a maximum value of the growth stress index H/G1.3 ratio of 52.3 cm/cm2 and at the age of 30 years the indicator is 8.4 cm/cm2. The H/G1.3 ratio of B. pendula in the control variant reaches 130 cm/cm2 at the age of 15 years and decreases to 21.0 cm/cm2 by the age of 30 years of planting. At the age of 30, the indicator decreases in the variants: with a sandy layer by 4.4 times, with a loam layer – by 3.1, with a humus layer – by 2.4 times.