Exchange Capacity of Calcium and Sodium Soils as Determined by Different Replacing Cations

Abstract Experimentally determined CEC values are dependent on the nature of the initially adsorbed cation and the replacing one. Cation exchange capacities of Na‐saturated and Ca‐saturated soils were determined using monovalent and divalent cations. In the exchange of initially adsorbed Na or Ca by monovalent cations, the magnitude of CEC increases with increasing ionic radius or polarizability of the replacing cation. The Na soil shows a greater CEC than the Ca soils. The Na soil and Ca soil behave differently with respect to the exchange by divalent cations. While the CEC of a soil initially saturated with Ca increases as the ionic radius of the replacing cation is larger, the magnitude of CEC of a Na soil decreases.