Formation of erosion resistance of gray forest soils in the conditions of Carpathian region

Abstract

Aim. To study the impact of perennial grasses mixtures on the formation of erosion resistance of gray forest soils of different degradation degree and their unmodifi ed analogues in conditions of long-term permanent experiment. Methods. Field, laboratory, assessment and comparison. Results. It was established that lupine- cereal grass mixtures increased erosion resistance of slope soils considerably within fi fteen years. The sum of soil structural aggregates was improved from satisfactory into good category. There were positive changes in the number of water-resistant aggregates as well. The studies confi rmed a positive impact of legume-grasses on the density and porosity of soil. Soil density was the lowest when the slope was laid down in perennial lupine and its mixture with cereal grasses. The intensifi cation of soil erosion and the approximation of the illuvial horizon level to the surface resulted in the compaction of upper soil layers to 1.29–1.44 g/cc. General porosity of soil correlated with its density which did not exceed optimal values in poorly eroded soils in upper layers. The studies proved the impact of the ways of laying down the slope in grass and the level of soil degradation on its humidity and water permeability. In the experiment conditions, the increase in soil degradation led to the decrease in its moisture. The decrease in the content of humidity in crop fi eld took place at the expense of higher intensity of the growth and water consumption of lupine-cereal grasses in comparison with natural mixed herbs, especially in the periods with a small amount of precipitation. The difference in the upper soil layers was in the range of 0.2–0.5 %. It was established that the highest values of soil water permeability were formed on lupine-cereal grass mixtures in all the variants of degraded soils. Conclusions. Laying down slope lands in perennial lupine in combination with cereal grasses promotes the formation of their higher resistance to erosion processes and restoration of fertility. Perennial legume-cereal mixtures ensure the improvement of structural-aggregate state, total density and porosity of soil, enhance its water supply and water permeability.