Prediction of Cation Exchange Capacity from Clay and Organic Carbon of Some Smectite and Kaolinite-Rich Soils

With the object of predicting cation exchange capacity (CEC) from the contents of clay and organic carbon, soils were grouped into classes on the basis of their clay and organic carbon contents. In each class, multiple regression equations were worked out between organic carbon and clay and CEC. Using average· CEC, percentage of organic carbon and clay and partial regre~siort coefficients of the latter parameters, the relative contribution of clay and organic carbon to CEC was estimated; The CEC can be predicted with reasonable accuracy from the content of organic carbon and clay of the two groups of soils. Contribution of clay was more to CEC in the smectitic soils, whereas organic carbon contributed more in the kaolinitic soils. Irrespective of soils, the contribution of clay or organic carbon to CEC increased with their contents.