SENSITIVITY ANALYSIS ON THE COMPARISON BETWEEN THE GAPON AND VANSELOW EXCHANGE COEFFICIENTS

The traditional nonthermodynamic Gapon exchange selectivity coefficient (K//G) for Na-Ca exchange has previously been shown in the literature to be in close agreement with the Vanselow coefficient (K//V) for Na equivalent fractions (N//N//a) in the exchange of less than 0. 20. Furthermore, it has previously been shown for a heterogeneous group of soils that the traditional empirical ESP-SAR relation (ESP equals N//N//a multiplied by 100; ESP equals exchangeable sodium percentage and SAR equals sodium adsorption ratio) is indistinguishable from the ESP-SAR relation predicted by the Vanselow equation for N//N//a less than 0. 40. This study is a sensitivity analysis of the comparison between the K//V and K//G for Na** plus replacing Ca**2** plus in the exchange phase. It is carried out by mathematically deriving and graphically demonstrating the interrelationships between K//V and K//G.