Dynamics of Mobile Phosphorus and Potassium in the Soils of Agricultural Lands of Kostanay Region

Abstract

Soil phosphorus deficiency is a growing constraint on crop productivity in the agricultural lands of the Kostanay Region, Republic of Kazakhstan, yet systematic data on the spatial dynamics of mobile phosphorus and potassium across soil types remain limited. This study assessed the availability of mobile forms of phosphorus and potassium, alongside key physicochemical properties, including soil pH and cation exchange capacity, in Chernozem and chestnut soils of agricultural enterprises across the Kostanay Region. Soil samples were collected from arable fields and analyzed using standard agrochemical methods. Results revealed a widespread deficiency of available phosphorus in arable soils across most surveyed enterprises, with concentrations ranging from 25 to 80 mg/kg, in contrast to consistently high mobile potassium levels of 200-450 mg/kg. In flat, poorly drained areas of steppe plains and low-relief zones, Chernozem and chestnut soils were frequently subject to salinization and alkalinization, exhibiting elevated soil pH values that further constrain nutrient availability and overall fertility. These conditions underscore the need for targeted phosphorus fertilization, optimized crop rotation planning, and soil amelioration measures in affected areas. Continued monitoring of soil degradation and desertification processes on agricultural lands is recommended to support sustainable land management in the Kostanay Region.