Fig. 1. Comparison of the data and equation of Rhoades et al. (1976) and a percolation-based formulation. The two equations produce similar curves when plotted with (a) linear axes; differences are clearer in (b) logarithmic space. (, volumetric water content; _c, critical water content; , electrical conductivity; _b, bulk solution electrical conductivity; µ, universal scaling exponent for conductivity.)