EVALUATION OF GRANULOMETRIC AND AGGREGATE COMPOSITION OF DARK CHESTNUT SOIL IRRIGATED WITH LIMITEDLY AVAILABLE WATER

Purpose: to assess the impact of irrigation with limitedly available water on the granulometric and aggregate composition of dark chestnut soil. Materials and methods. The studies were conducted in 2023–2024 on two irrigated pilot plots (the first with drip irrigation, the second with sprinkling irrigation) and a rainfed field located in the Pervomaysky district. The sources of irrigation water for the first pilot plot were wells no. 1 (2023) and no. 2 (2024), and for the second, the North Crimean Canal (NCC) system (first ten-day period of 2023) and the Vorontsovka River (second – fourth ten-day periods of 2023 and 2024). During the studies, the chemical composition of the irrigation water was determined and its quality was assessed based on the calculation of the sodium adsorption ratio. The granulometric composition of soil was determined and analyzed by pipette method and aggregate composition of soil was determined and analyzed by wet sieving under irrigated and rainfed conditions. Results. According to the data obtained during the chemical analysis of the selected water samples, excess of maximum allowable concentrations (MAC) of pollutants in water was recorded at the following sources: wells no. 1 (sulfates, chlorides, magnesium, sodium) and no. 2 (sodium), the Vorontsovka river (chlorides, magnesium, sodium). The North Crimean Canal system and water intake well no. 2 are characterized by the best water component composition. At the time of the survey, the upper soil layer contained 0.001 mm fractions (silt) under drip irrigation and sprinkling, respectively, than under rainfed conditions, by 1.5 and 1.8 times. According to the aggregate composition in the 0–20 cm soil layer, the average content of water-stable aggregates larger than 0.25 mm in irrigated conditions was 57.7 %, while in rainfed conditions it was 49.8 %. Conclusions. The use of limitedly available water for irrigation of dark chestnut soil in combination with other natural, climatic and anthropogenic factors led to a change in the granulometric composition of the upper 40-cm soil layer and did not have a negative impact on the content of water-stable aggregates.