Fertility models of agricultural soils in the northern forest steppe of the Omsk region

The aim of the research is to develop models of fertility of leached chernozems and gray forest soils, focused on obtaining high and stable yields of agricultural crops cultivated in the Omsk region. Fertility models of leached chernozems and gray forest soils were developed by studying and generalizing data on the characteristics of soils and plant productivity, obtained from 1976 to 2020 in the system of field experiments with grain and row crops by employees of the Siberian Research Institute of Agriculture and the departments of agrochemistry and soil sciences of Omsk SAU. The objects of study were leached chernozems and gray forest soils of the northern forest-steppe zone of the Omsk region. The optimum thickness of the arable layer should be 25-30 cm. In the aggregate composition, the agronomically valuable fraction (10-0.25 mm) should account for up to 60-70%, the lumpy fraction (>10 mm) - up to 20-40% with the amount of waterproof aggregates not less than 60-65%. Optimal regimes in leached chernozems will be formed when the content of physical clay is 35-50%, in gray forest soils at the level of 35-40%. The provision of soils with humus and nutrients make a significant contribution to the size of the yield. The optimal content of humus is set at 5.0-6.5%, mobile forms of phosphorus - 200-260, potassium - 120-260, nitrogen - 15-35 mg/kg of soil. Since the soils are poor in microelements, scales of their optimal supply with cobalt, copper, molybdenum, etc. have been developed. To a large extent, soils are subject to water erosion and deflation. A slight degree of soil erosion is allowed.