Surface Complexation Model of Cation Adsorption on Humic Soils

Open Access
Publisher Website
Google Scholar
Abstract
We evaluated the ability of a new surface complexation model “multi-layer model” of Nakahara and Wada (1995: Soil Sci. Plant Nutr., 41, 659-669) to predict the K+-Ca2+ exchange equilibria on a humic Andisol. Under the assumption that the relative permittivity of the interfacial region is constant at any points, we could calculate the K+-Ca2+ exchange equilibrium conditions using the four parameters previously obtained from K+ and Ca2+ adsorption data. The model predicted the variation of the exchange selectivity coefficient of Van-selow (K V) and the pH of the bathing solutions as a function of the equivalent fraction of adsorbed K+ satisfactory. We concluded that our model can be used for the calculation of the chemical equilibria of soil solutions of humic soils.