ABSTRACT
The cation exchange capacity (CEC) of three benchmark soils in the rain forest region of Southwestern Nigeria, were measured by three standard CEC methods. Results obtained were compared with a view to selecting the best suited CEC method for the soils. The study sites were the Teaching and Research Farm of Obafemi Awolowo University, Ile-Ife, and Itagunmodi settlement. Two representative soil profile pits each were established in soils developed in coarse-grained granite and gneiss, fine-grained biotite gneiss and schist, and the amphibolite. The three methods gave different CEC values in the order of CEC-pH 8.2 > CEC-pH 7 > ECEC. There was a significant correlation between soil organic matter (SOM) and the CEC obtained by each of the three methods (P ≤ 0.05), meanwhile, total clay showed no significant correlation. ECEC provided the best estimate of the CEC for the soils and adequate SOM management is crucial to enhance sustainable productivity of the soils.