Potassium Release Kinetics as Influenced by Time and Parent Materials in Parts of Akwa Ibom State, Nigeria

Abstract

The goal of the study was to evaluate potassium (K) release in soils derived from three parent materials (shale, sandstone, and alluvium  soils), and to identify the best-fitting equations to describe K release to 0.01M CaCl₂ extraction over the course of 1–128 hours at various  concentrations of added K ranging from (0, 50, 100, 150, 200mgL1K). Two gram (2g) soil suspended in 20 ml of 0.01M CaCl₂ was shaken at  25^oC on a reciprocating shaker and subsequently centrifuged. The K concentration in the supernatant was determined. Potassium  release with time was modeled using zero and first order equations. The results revealed a sharp increase in K release from 0mgL^-1 to  50mgL^-1 in the soils. The highest concentration was found in alluvial soil, while the lowest concentration was found in shale soil. In zero  order equations, the trends were Alluvium 146.3 > sand stone 108 > shale 72.27 mgkg^-1 and in first order equations, Alluvium 5.308 >  sand stone 4.983 > shale 4.557mgkg^-1. The concentration of K released in the soil increased as time passed in the soils. The results also  revealed that the zero order equation adequately described the K release reactions, with the highest mean R² values of 0.997.