The four-electrode probe method was tested on a Crowley silt loam soil in which salt type, salt content, and water content were varied. Theory associated with this technique of assessing soil salinity was verified. Equations were developed which quantified the relationships between soil electrical conductivity obtained by the four-electrode probe technique (EC), saturation extract (EC1), and 1:2 soil to water extract (EC2).
Sriotai, K. and Gilmour, John T.
"Soil Salinity Measurement by the Four-Electrode Probe Technique,"
Journal of the Arkansas Academy of Science: Vol. 30, Article 33.
Available at: https://scholarworks.uark.edu/jaas/vol30/iss1/33