Field Methods for Determination of Soluble Salts and Percent Sodium from Extract for Identifying Dispersive Clay Soils

This paper presents field test procedures for determining the total dissolved salts and the percent sodium in the saturation pore water extract for the purpose of identifying dispersive clay soils. Soluble salts were determined by two methods. The first method used a sodium electrode and chemical reagents, while the second method used a wheatstone bridge. Plots of data and geometric regression analyses were used to determine the relationship between the soluble salts obtained by the two field techniques versus the soluble salts by atomic absorption. The percent sodium was calculated three separate ways using data from the sodium electrode, chemical reagents, and bridge. Plots of data and linear regression analyses were made of the percent sodium by the three methods versus the percent sodium by atomic absorption. In all plots of soluble salts and percent sodium, the atomic absorption data were used as the independent variable.