The purpose of the research is to determine the impact of mechanical activity on runoff of melting waters considering changes in physical and water-physical properties of top soil layer (0–30 cm) of plowed fields for various crops. The object of research is ordinary chernozem (warm short-freezing northern-pryazovian). The study of physical and water-physical soil properties was conducted by the methods standard for soil science and agriculture. The determination of melting water runoff was done at the fixed runoff sites. It is established that depending on the method of mechanical activity with soil, agricultural lands divide by two main categories: loose (tilth) and compacted (fields of winter crops, permanent grasses, surface and zero tillage, and the fields won’t been plowed last autumn) arable lands. The greatest impact on soil density has mechanical treatment in autumn period. For example, if the field is preparing for winter crops sowing, then three operations (cultivation, sowing, and cultivation) are made. As a result of these operations, the value of soil density in arable layer is differed by 0.10–0.23 t/m³ in average from the value after sowing of winter crops. For loose soil at a density of 0.98–1.02 t/m³, the infiltration rate of precipitations into the soil is 5.14 mm per minute, for compacted (1.14–1.24 t/m³) – 1.82 mm per minute. In the period of snow-melting, the rate is 1.26 and 0.10 mm per minute respectively. The value of water permeability at plowed lands in 4–5 times higher than at the fields of winter wheat and permanent grasses. The depth of surface runoff for 46-year observation period at ordinary chernozem in the Rostov region was in average 16.9 mm for compacted arable lands, and 7.3 mm for loose arable lands.
Keywords: loose arable lands, compacted arable lands, soil density, water permeability, depth of surface runoff.
