THE INFLUENCE OF pH ON THE CATION EXCHANGE CAPABILITY AND EXCHANGEABLE CATIONS OF GEHEKU CLAY, KOGI STATE.

ABSTRACT

The study explored the influence of pH on the cation exchange capability (CEC) and exchangeable cations(EC) of two (2) samples of Geheku clay (A and B) obtained from Geheku, Kogi State. For Geheku clay sample A, the result obtained shows that exchangeable cations (EC) for Mg⁺² had its optimum value at pH 4 (0.194±0.022) and its least value at pH 7(0.125±0.034). Ca⁺² had its optimum values (1.042±0.031) at the neutral pH (pH 7) slightly higher than pH 5 (1.042±0.024). Whereas the least value were obtained at pH 4 (0.800±0.041). Mg⁺² had its optimum value at pH 4 (0.194±0.022) and its least value at pH 7(0.125±0.034). K⁺ had its optimum value at (1.864±0.425) and its least value at pH 9 (0.278±0.076).Na⁺² had its optimum value at pH 9 (3.573±0.091). CEC had its optimum value at pH 7 (11.424±1.117).

For Geheku clay sample B, exchangeable (EC) cations result shows that Mg⁺² had its optimum value at pH 5 (0.139±0.020) and least value at pH 9 (0.069±0.020). Ca⁺² had its optimum value at pH (2.242±0.226) and its least value at pH 9 (1.409±0.083). K⁺ had its optimum value at pH 4 (1.863±0.324) and least value at pH 9 (0.517±0.054). Na⁺ had its optimum value at pH 9 (3.377±0.161) and its least value at pH 4 (0.616±0.010). From the results obtained, it shows that pH is an important soil parameter because when the soil was treated at different pH the values of the cations (Ca, Mg, Na and K) were affected. I.e. they have different values when subjected to different pH. Generally, the values of ECs increase irregularly from acidic media to alkaline media. More cations were obtained in the acidic media than the neutral and alkaline media; indicating that soil is easily leached in the acidic media. The CEC values obtained from the result shows that pH is positively correlated to CEC. It shows that the higher the pH the more negative charges which in turns leads to a higher corresponding CEC value. In essence, the CEC values increases down from the acidic media to the neutral media and then decreases down from the neutral to alkaline media in both Geheku sample A and B: indicating that soil can hold more cations at higher pH.