IRRIGATION AND MINERAL FERTILIZER EFFECTS ON PHYSICAL PROPERTIES OF LIGHT CHESTNUT SOIL USED IN THE CULTIVATION OF SUGAR BEET (BETA VULGARIS L.)

This work studied the effect of irrigation and mineral fertilizers on the physical properties of light chestnut soil used in cultivating sugar beet (Beta vulgaris L.). The experiment happened in 2021 on an irrigated field with an area of 2 ha in the territory of the Kazakh Research Institute of Agriculture and Plant Growing, District Karasai, Almaty region, Kazakhstan. A sugar beet hybrid (obtained from domestic selection 'Aksu' and foreign selection 'Yampol') cultivation used four levels of mineral fertilizers, i.e., 0:0:0 (control), 90:90:60, 120:120:90, and 150:150:120 NPK kg ha-1. During the sugar beet growing season, all periods of observations recorded an increase in the bulk density in the upper, middle, and lower soil layers, from 1.14-1.27 g/cm3 to 1.31-1.48 g/cm3. The content of agronomically valuable aggregates in 0-10 cm, 10-20 cm, and 20-30 cm soil layers decreased from the germination phase to harvesting of sugar beet in extensive technology (10.0%-15.7%) and intensive technologies (2.3%-13.1%). In these soil layers, the number of water-stable aggregates decreased from the beginning of renewal to the end of the growing season of sugar beet in technology without the use of fertilizers (2.9%-6.4%) and in technologies with the application of mineral fertilizers (1.6%-7.6%). In the soil layers, the noted highest content of productive moisture occurred in the phase of closing the leaves in the rows with the extensive technology of sugar beet cultivation (51.5-213.2 mm). Irrigation during the sugar beet growing season reduces the content of agronomically-valuable and water-stable aggregates in soil layers to the minimum values for harvesting in technology without the use of fertilizers (50.5%-54.4% and 12.9%-14.2%) and technology with the use of mineral fertilizers (52.3%-54.4% and 10.9%-13.5%), respectively.