Agrochemical and Ecological Characteristics of Dry Steppe Carbonate Soils

Soil monitoring represents a key instrument for evaluating long-term changes in soil fertility and environmental safety under increasing climatic and anthropogenic pressures.This study provides a 30-year comparative assessment (1994-2025) of agrochemical and geochemical properties of dark chestnut carbonate soils in the Egindykol District, Akmola Region, Northern Kazakhstan.Field investigations and laboratory analyses were performed in accordance with International Organization for Standardization (ISO) procedures.The results indicate a moderate decline in humus content in the surface horizon from 3.48% (1994) to 3.0-3.2%(2024-2025), while the humus horizon thickness (25-30 cm) remained stable, confirming preservation of zonal soil characteristics.Soil reaction remained slightly alkaline (pH 7.6-8.2),reflecting carbonate buffering capacity.Concentrations of lead (Pb), cadmium (Cd), zinc (Zn), copper (Cu), cobalt (Co), nickel (Ni), iron (Fe), and manganese (Mn) were significantly below maximum permissible concentrations (MPC).Pollution Index (PI < 1) values across all horizons confirmed the absence of contamination risk and dominant lithogenic control of trace element distribution.The findings highlight gradual organic matter depletion as the primary long-term transformation trend and emphasize the importance of adaptive land management and continuous monitoring to maintain soil productivity and ecological stability in semi-arid steppe ecosystems.