INFLUENCE OF GRAIN CROPS AND THE BACKGROUND OF MINERAL FOOD ON PHYSICAL INDICATORS OF SOIL
The article presents the results of studying the influence of grain of the I group (wheat, oats, barley, triticale) and the background of mineral nutrition on the development of the root system of plants, density, and structural state of dark gray forest soil. The experiments were carried out on the experimental field of the Irkutsk Research Institute of Agriculture, located in the forest-steppe zone of the Irkutsk region. The forest-steppe zone is considered the most agriculturally developed region of the region. It is characterized by favorable weather conditions for most crops. The methods included field (stationary) and laboratory studies. The predecessor to cereals was pure fallow. The generally accepted technology of soil preparation for sowing for the forest-steppe zone of the Baikal region was applied. Observations, accounting and data processing were carried out according to generally accepted methods. Variants of the experiment were studied without fertilizers, with the introduction of nitrogen and complex mineral fertilizers in doses of 45 kg of the active substance. The area of one experimental plot was 45m<sup>2</sup>. Soil samples were taken at the end of the growing season, in the first decade of September, before harvesting crops. Soil samples and plant material were analyzed in the laboratory of the Department of Agriculture and Crop Production. In the course of the research, it was established that the breads of group I and the background of mineral nutrition have different effects on the physical properties of the soil. The development of the root system of plants depended on the background of mineral nutrition. In the variants of the experiment with the complex application of mineral fertilizers, the root system developed better. The optimum soil density was in the variants of the experiment using N<sub>45</sub> and N<sub>45</sub>P<sub>45</sub>K<sub>45</sub>. The content of agronomically valuable aggregates in the soil with sizes from 1 to 5 mm, depending on the variants of the experiment, varied from 34.6 to 51.7%.