Reactive Characteristics of Certain Soils from South Nigeria

Abstract Statistical relationships were determined between soil pH, effective cation exchange capacity (ECEC), surface area, and some other soil properties for selected soils of southern Nigeria. The soils were mostly hydromorphic with a pH range of 3.6 to 8.1. Exchange acidity was virtually due to exchangeable Al ( r = 0.99). Negative ΔpH values indicate a dominant silicate clay mineralogy. The ΔpH (pH KCl ‐pH H 2 O ) was correlated with exchangeable Na ( r = −0.56), sand content ( r = 0.51) and organic C ( r = 0.34). Effective cation exchange capacity was low, average of 7.1 cmol c kg −1 . No exchangeable Al was found above a soil pH (KCl) of about 4. A derived variable, ΔCEC (difference between CEC measured at pH 8.2 and ECEC), was used as a dependent variable to test pH dependence. The variability observed in ΔCEC values was found to be related to clay content ( r = 0.65), exchangeable K ( r = −0.11), and organic C ( r = 0.34). A regression analysis with BET‐N 2 (Brunauer, Emmett, and Teller) specific surface area as the dependent variable showed a strong relationship with clay content ( r = 0.96) and ΔpH ( r = −0.44) in the best regression equation.