An analysis of the contribution of organic matter and clay to cation exchange capacity of some philippine soils

Simple and multiple regression analyses was used to examine the relationships between cation exchange capacity (CEC) and organic matter, and clay content of 40 surface Philippine soils to determine the contributions of organic matter and clay to CEC. CEC was significantly correlated to organic matter (r = 0.512**) and clay (r = 0.580**) contents. Multiple regression analysis showed that on average organic matter and clay fractions contributed 37.6 and 62.4% respectively to the CEC of the soils. It was also found that 60% variation in CEC could be solely attributed to the variation in organic matter and clay contents together.