Electrical resistivity measurement and conductive model of Dagang soil

The electrical resistivity of Dagang soil at different water content levels was measured by the means of DC four-electrode technology. The resistivity is lower at a higher water content level. During the measurement, the calculated value of resistivity is bigger at lower voltage grads; when the voltage grads increasing, it reduces and tends to a steady value, especially for low water content soil. A conductive model was presented, and soil conductivity was discussed by an equivalent circuit. At a lower water content level, the pathway of current flow is liquid phase pathway of pore water and solid-liquid phase pathway primarily via exchangeable ions. At higher water content the current passes mostly through pore water and the effect of exchangeable ions at the interface of solid-liquid phase can be ignored.