Figure 6-10. Soil Electrical Resistivity
A towed electrode-array (six coulter-electrodes) soil ECa mapping system behind a utility vehicle in a field of corn stubble.
Soil electrical resistivity represents the capacity of soil materials to resist the flow of electrical current. Methods that calculate the apparent electrical resistivity use Ohm’s law and the measured injected current, the measured potential difference, and a geometric factor. The geometric factor is a function of the electrode spacing or configuration (Samouёlian et al., 2005). The apparent resistivity is a complex function of the composition and arrangement of solid soil constituents, porosity, porewater saturation, pore-water conductivity, and temperature (Samouёlian et al., 2005). Electrical resistivity methods can be divided into those that inject currents into the ground through direct coupling and those that inject through capacitively induced coupling. Typically, both types of methods measure the apparent electrical resistivity, which is subsequently converted to its inverse, the apparent electrical conductivity of the soil.
Highly mobile, continuously recording, towed-array ER systems have been developed to expedite fieldwork and facilitate the collection of spatially dense data sets at field scales. In the United States, towed electrode-array ER systems have been used in precision agriculture and soil research.
Soil Survey Manual, Ag. Handbook 18, 2017, (p. 373).
Figure 6-10. Soil Electrical Resistivity
A towed electrode-array (six coulter-electrodes) soil ECa mapping system behind a utility vehicle in a field of corn stubble.
Soil electrical resistivity represents the capacity of soil materials to resist the flow of electrical current. Methods that calculate the apparent electrical resistivity use Ohm’s law and the measured injected current, the measured potential difference, and a geometric factor. The geometric factor is a function of the electrode spacing or configuration (Samouёlian et al., 2005). The apparent resistivity is a complex function of the composition and arrangement of solid soil constituents, porosity, porewater saturation, pore-water conductivity, and temperature (Samouёlian et al., 2005). Electrical resistivity methods can be divided into those that inject currents into the ground through direct coupling and those that inject through capacitively induced coupling. Typically, both types of methods measure the apparent electrical resistivity, which is subsequently converted to its inverse, the apparent electrical conductivity of the soil.
Highly mobile, continuously recording, towed-array ER systems have been developed to expedite fieldwork and facilitate the collection of spatially dense data sets at field scales. In the United States, towed electrode-array ER systems have been used in precision agriculture and soil research.
Soil Survey Manual, Ag. Handbook 18, 2017, (p. 373).