G.N. Cherkassov, M.N. Masyutenko, A.V. Kuznetsov
SSI All-Russia Research Institute of Arable Farming and Soil Erosion Control, RAAS
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Summary. The paper presents the results of studying the dynamics of productive moisture and soil hardness, structural-aggregate state of typical chernozem soil in the multifactor field stationary experiment of VNIIZiZPE which was laid out in 1984 (Kursk region). The research was conducted in 2011-2012 on watershed plateau, northern and southern slopes in the 7th cycle of the grain crops-grass and grain crop–fallow-row crop rotations with moldboard and subsurface tillage. It was found that the stocks of productive moisture in the layers of 0-20 and 0-100 cm of typical chernozem soil in the years studied from May to June decreased in bare fallow, under perennial grasses and winter wheat, and further by September the nature and directivity of their dynamics were different depending on slope exposure, a crop rotation type and a tillage system. The estimation of available soil moisture reserves was carried out. The experimental data confirmed the moisture accumulation function of bare fallow. In the grain crop-grass crop rotation excellent water stability of the soil structure was revealed on all the slope exposures in the top and subsurface layers, in the grain crop–fallow-row crop rotation it was good on the watershed plateau and the northern slope in the layer of 0-20 cm. On the southern slope in the grain crop-fallow-row crop rotation the water stability of the soil structure depended on its tillage, i.e. it was satisfactory when moldboard tillage was used, if subsurface tillage was used it was good. The microbial biomass accumulation was revealed in the agronomically valuable fractions of the typical chernozem soil with a diameter of 3-1 mm 1.5-2.1 times more in comparison with the total soil sample. Moreover, in the grain crop–fallow-row crop rotation with subsurface tillage on the watershed plateau and the northern slope the process was more pronounced than when the soil was processed with a moldboard plow. The dynamics character of the soil hardness and its value depended on soil depth, a rotation, slope exposure, a tillage system. Its high spatial (K var = 11...219 %) and temporal variability (K var = 25.7...129.4%) was established.
Keywords: typical chernozem soil, productive moisture, dynamics, structural-aggregate composition, structure water stability, microbial biomass, soil density, soil hardness, crop rotation, tillage system, slope exposure.