Evaluation of Some Chemical Properties of Geheku Clay Deposit in Kogi State, Nigeria for Possible Application as Soil Blends

Abstract

Geheku clay deposit in Kogi State, Nigeria was evaluated for its nutrient content in order to mitigate the problem of the decline in arable land which has been amplified by increase in population and urbanization in Nigeria. Exchangeable cations (EC), cation exchange capacity (CEC), exchangeable acidity (EA) and percent base saturation which are indices of soil fertility were evaluated for the top (L₁) and bottom levels (L2) of Geheku clay at different pH levels. These parameters were evaluated against pH 4, 6, 7 and 9 to establish the best pH where the essential nutrients will be available for plant uptake. Exchangeable Na+ cations had the highest value at pH 9 for both levels recording values of 3.57± 0.09 cmol/kg and 3.38± 0.16 cmol/kg for L₁ and L₂ respectively. Exchangeable K+ ion was highest at pH 4 in both cases while Mg²⁺ was highest at pH 4 and 5 for L₁ and L₂ respectively. Ca²⁺ cations were highest at pH 4 and pH 7 for L₁ and L₂ respectively. The Ca/Mg ratio was greater than 4 for both layers indicating that the clay is well-structured. The fertile nature of the clay material was evident from the high values of CEC obtained at each pH with the highest values of 11.42± 1.12 and 12.73± 0.72 cmol/kg obtained at pH 7 for L₁ and L₂ respectively. However, the percent base saturation was highest at the acidic pH5 for both layers and also reasonably high at the alkaline pH of 9. Thus, depending on crop tolerance to acidity or alkalinity, a blend of Geheku clay at either pH 5 or 9 with nutrient improvised soil is recommended for optimum nutrient availability for plant uptake and effective soil management.