Effect of pH on the Sodium-Calcium Exchange Equilibria in Soils1
- P. F. Pratt,
- L. D. Whittig and
- B. L. Grover2
The Na-Ca exchange equilibria in 10 acid soils were measured at pH values of 5, 6, 7 and 8 and the results related to a theoretical ion exchange equation based on the Poisson-Boltzmann differential equation of the electrical double-layer. The theoretical equation satisfactorily predicted the relative change in ratio of adsorbed Na to adsorbed Ca as the pH of the equilibrium solutions decreased. The actual values of ratios of adsorbed Na to adsorbed Ca agreed with the theory when the surface charge densities for each soil were multiplied by an appropriate factor. This factor varied from 1.0 to 2.1 but was the same for all pH values for a given soil.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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