Determination of potassium sorption characteristics of soils derived from three diverse parent materials in Akwa Ibom State

Abstract

This study was carried out to determine the potassium sorption characteristics of soils of three (3) parent materials in Akwa Ibom State. The soils for the study were formed from alluvium, shale, and sandstone. The physical and chemical properties of the soils were determined. The sorption isotherm was determined by equilibrating 5g of the soils sample with five levels of K at various concentration of 0,5,10, 15 and 20 K prepared from KCl was added, and three drops of toluene were added, shaken twice daily for 30 minutes. The K was determined and the sorption data calculated were fitted to Freundlich, Langmuir and Temkin equation. The results revealed that soils were moderately acidic and high in nutrients. Percentage K sorped was in the order of Shale > Alluvium > Sandstone. The amount sorped increased with increasing K addition. Maximum sorption capacity were in this order: 0.72mgkg^-1(sandstone) < 0.81mgkg^-1(Alluvium) < 0.87mgkg^-1(Shale). Bonding energy were 0.49mgkg^-1 (Alluvium) > 0.46 mgkg^-1 (Shale) > 0.36 mgkg^-1 (Sandstone). Buffering capacity were 0.94 mgkg^-1 (Shale) >0.41mgkg^-1 (Alluvium) > 0.30 mgkg^-1(Sandstone). The sorption data were fitted to Freundlich, Langmuir and Temkin equation shows a significant difference in the results. Langmuir equation described K sorption characteristics better than the two other equations as evidenced by a higher coefficient of determination (R2 ) (0.901 in shale to 0.968 in sandstone). Therefore Langmuir equation is recommended to be used for these soils.