Very often, we get this question:
"Do you carry a sensor that can measure pore water EC?"
This is usually right after they realize that the HITA E0 electrical conductivity sensor from EnviTronics Lab is advertised as a “bulk” EC sensor and not a so called “pore” water EC.
The short answer is, no we don’t carry such sensor. The matter of the fact is that nobody does! Such sensor is not invented yet and there’s a good reason for that.
Soil pore water EC, also known as apparent soil electrical conductivity in the scientific world, is the electrical conductivity of the water in the pore spaces of the soil or any other substrate of interest. These pores cannot be accessed by sensor technologies that exist today and therefore pore water EC is very difficult to measure directly.
The bulk soil electrical conductivity, on the other hand, is the EC of the undisturbed bulk soil (soil, water, and air) and is the parameter that soil sensors report. This means if you disturb the soil or compact it, the bulk EC changes, but pore water EC does not.
The good news is there is a relationship between the two and researchers have developed a variety of empirical and theoretical mathematical equations that can be used to estimate pore water EC (as well as saturation extract EC, which is another story for another day) from measured bulk EC values.
I don’t want to get into the math here so I will just share an paper for those who are interested to learn more about this:
Dennis L. Corwin* and Kevin Yemoto, Salinity: Electrical Conductivity and Total Dissolved Solids. Soil Science Society of America. URL: https://www.ars.usda.gov/arsuserfiles/20361500/pdf_pubs/P2558.pdf
Comments