Electrical energy existing in the soil-water system plays an important role as discussed in Section 2.9 and illustrated by Figure 2.3. All other energy such as mechanical, thermal, or magnetic hinges on the characteristics of electric energy. Electrical characteristics in the soil-water system have multiphases due to the following reasons:

1. Both soil and water have inherited electrical characteristics as discussed in Chapters 4 and 5. 2. Electrical energy is closely related to thermal and magnetic energies, and difficult to sepa-

rate in the natural environment. 3. Electrical-chemical interaction in the soil-water system is sensitive to local environments

and, in many cases, these interactions are not clearly understood. The magnitude and behavior of electrical properties in the soil-water system cannot be measured effectively.