Comparative agrochemical assessment of cultivated soils in East Kazakhstan: Implications for site-specific fertility management

Soil degradation driven by climate variability and unsustainable land use represents a growing challenge for agriculture in semi-arid and continental regions. This study presents a comparative agrochemical assessment of cultivated soils from two peasant farms—«Druzhba» (Ulansky District) and «Tamerlan & K» (Glubokovsky District)—in the East Kazakhstan Region. The objective was to evaluate site-specific fertility characteristics under contrasting climatic and landscape conditions and to provide practical recommendations for sustainable nutrient management. Composite soil samples were collected from three depth intervals (0–20, 20–40, and 40–60 cm) and analyzed for humus content, nitrate nitrogen, available phosphorus and potassium, sulfur, and pH using standardized GOST methodologies. The results revealed moderate fertility status in both farms, with humus levels ranging from 2.21% to 3.79%. Available nitrogen levels were relatively balanced; however, phosphorus availability was notably deficient in portions of the Tamerlan & K farm, posing potential constraints for phosphorus-demanding crops. Potassium and sulfur concentrations were generally adequate, while soil pH ranged from 7.00 to 7.47—slightly alkaline but within an acceptable range for most crops. Based on the agrochemical profiles and average nutrient uptake values, crop-specific fertilization strategies were developed. High-demand crops such as maize, sunflower, potato, and sugar beet require full NPK fertilization, while cereals like wheat and barley may be managed using NP fertilizers, supplemented with potassium every two to three years. The adoption of fertigation systems and the use of liquid organomineral fertilizers are recommended to enhance nutrient use efficiency and buffer heat and drought stress conditions. Furthermore, pH adjustment and organic matter restoration are critical to improve micronutrient availability and sustain long-term soil health. Overall, the study underscores the importance of adaptive, data-driven nutrient management approaches tailored to the agroecological diversity and evolving climate realities of East Kazakhstan.