LEGUMINOUS PRECURSOR AGROTECHNICAL ASSESSMENT IN THE CROP ROTATION OF THE WESTERN SIBERIAN SOUTHERN FOREST-STEPPE
The purpose of research is to give a comparative assessment of the agricultural technologies of spring wheat in crop rotation without fallow after the leguminous predecessor in the forest-steppe zone of Western Siberia. Research objective: in the field crop rotation (soybean - spring wheat - rapeseed - spring wheat) to study the effectiveness of tillage systems and intensification means, including control and complex (fertilizers, herbicides, fungicides, retardants). The study was carried out in a stationary crop rotation (soybean - spring wheat - rapeseed - spring wheat) in the laboratory of resource-saving agricultural technologies of the Omsk ARC in 2011-2019. The climate of the forest-steppe is continental with a rainfall of 350-400 mm. Average long-term precipitation during the growing season is 200-210 mm, air temperature is 16.8 °C, HTC is 1.10. The soil is meadow-chernozem medium-thick with a humus content of up to 7-8 %. It has been established that in the crop rotation, the reduction in the intensity of tillage for wheat after the soybean predecessor from moldboard to shallow (to a depth of 10-14 cm) flat-cut reduces the yield by 0.43 t/ha (15.8 %). With complex chemicalization, there is a decrease in spring wheat water consumption to 70 mm per 1 ton of grain (by 2.3 times), an increase in crop biomass - up to 2843 g/m<sup>2</sup> (by 1.8 times), a decrease in the number and biomass of weeds (by 3.3-3.9 times), infection of plants with root rot (3.6-4.1 %), leaf and stem diseases, which contributes to an increase in crop yield by 0.73-1.86 t/ha, improvement of technological parameters of grain to the third quality class. In field crop rotations for grain production, the share of leguminous crops and predecessors, including soybeans, should be increased by 2.5-3 times.