Sustainable nutrient management and agricultural productivity in chernozem soils of the Kostanay Region, Kazakhstan

Chernozem soils, known for their high organic matter and fertility, are crucial for agricultural productivity in northern Kazakhstan's Kostanay region. This study evaluated the physical, chemical, and biological properties of these soils to assess their suitability for crop production and propose sustainable management practices. Soil samples were collected from 0-20 cm depths across various locations to represent the region's main nutrient profile. Physical analyses included texture determination, while chemical analyses measured pH, electrical conductivity (EC), organic matter, and nutrient levels (N, P, K, Ca, Mg, Fe, Cu, Zn, and Mn) using standard methods. Biological assessments focused on microbial biomass carbon (Cmic), basal soil respiration (BSR), dehydrogenase and catalase activities, as well as Cmic: Corg and metabolic quotient (qCO₂) ratios. Results indicated high organic matter content (mean 4.49%), sufficient total nitrogen (>0.25%), and high levels of potassium and calcium. However, phosphorus levels were low (