Gumbo” is soil composed of fine-grain clays. When wet, the soil is highly plastic, very sticky, and has a soapy appearance. When dried, is develops large shrinkage cracks.
The resistivity of soil is primarily determined by the soil's electrolyte contents. Electrolytes consist of moisture, minerals, and dissolved salts. In general, soil resistivity decreases (improves) as electrolytes increase. Figure B-1 shows soil resistivity changes as a function of soil moisture content. The resistivity of the soil decreases rapidly as the moisture content increases from very little moisture to approximately 20 percent moisture.