Fig. 3 Relative permittivity as a function of water content. In (a) is the apparent relative permittivity estimated directly from time domain reflectometry based on Eq. 3. In (b) are the real (filled symbols) and imaginary (open symbols) components of the relative permittivity estimated from the use of Eq. [4] and [5]. In the legends, the first letter indicates the soil horizon (A or B), the next symbol(s) indicate the wetting solution (W = water, S1 = KCl solution once and S2 = KCl solution twice). The dotted curve was given by Topp et al. (1980). The solid curve assumes the water in soil has a relative permittivity of 80
