AGROCHEMICAL PROPERTIES AND PARTICLE-SIZE DISTRIBUTION OF SOILS IN THE YURYUZAN RIVER VALLEY (REPUBLIC OF BASHKORTOSTAN)

Abstract

This article presents the results of studies on the soil cover of the Yuryuzan River Valley in the Republic of Bashkortostan. Floodplain soils, acting as a biogeochemical barrier, a regulator of the water regime, and an accumulator of flood sediments, represent valuable highly productive agricultural lands and serve as an indicator of the intensity of anthropogenic impact. This underscores the particular importance of their comprehensive study. During fieldwork, 7 soil pits were established: 5 in the central floodplain under meadow vegetation and on pastures, and 2 on the right native bank under coniferous-broadleaf forests. The study focuses on the analysis of the agrochemical and morphological characteristics of the soils, taking into account the influence of natural and climatic factors on their formation and development. It was established that the meadow-alluvial soils of the central floodplain, influenced by floodwaters, exhibit a significant organic carbon content (up to 9.9%) and a sandy particle-size distribution. The supply of available phosphorus in the studied soils ranges from low to moderate (22–70 mg/kg), potassium from moderate to high (50–198 mg/kg), and alkaline-hydrolyzable nitrogen is high (140–405 mg/kg). In addition to analyzing the current state of the soils, the study revealed a significant influence of anthropogenic factors (intensive grazing and recreational pressure) in the central floodplain, which is manifested in a decrease in the content of organic matter and nutrients. Fundamentally different conditions are found on the right native bank of the river, where underdeveloped mountain-forest gray soils have formed on eluvial-deluvial deposits under coniferous-broadleaf forest. These soils are characterized by a low organic matter content (not exceeding 2.4%). The content of available phosphorus and potassium corresponds to very low and low supply levels. Thus, the conducted research revealed significant differences in the morphological and agrochemical properties of the soils of the floodplain and the native bank of the Yuryuzan River, demonstrating the determining role of azonal factors (alluvial processes, floodplain inundation, and groundwater level) in the genesis and spatial differentiation of the soil cover of the Yuryuzan River.