Many users inquire about sensors capable of measuring "pore water" electrical conductivity (EC). However, it's important to clarify that current sensor technology cannot directly measure this property.
Why is it so difficult?
Pore Space Inaccessibility: Soil pore water resides within the intricate network of spaces between soil particles. Existing sensor technologies lack the ability to directly access and measure the EC within these microscopic pores.
What Sensors Actually Measure: Bulk EC
Soil EC Sensors: These sensors measure the electrical conductivity of the bulk soil, which encompasses the soil matrix (solids), water, and air.
Impact of Soil Disturbance: Bulk EC is influenced by soil compaction and disturbance. Pore water EC, on the other hand, remains unaffected by these factors.
The Relationship Between Bulk and Pore Water EC
Indirect Estimation: While direct measurement is not feasible, researchers have developed mathematical models and empirical relationships to estimate pore water EC from measured bulk EC values.
Saturation Extract EC: These models can also be used to estimate the EC of the saturation extract, another important parameter in soil science.
For Further Exploration:
For a deeper dive into the relationship between bulk EC and pore water EC, refer to this comprehensive resource:
Dennis L. Corwin and Kevin Yemoto, Salinity: Electrical Conductivity and Total Dissolved Solids.* Soil Science Society of America. https://www.ars.usda.gov/arsuserfiles/20361500/pdf_pubs/P2558.pdf
Key Takeaway:
While sensors cannot directly measure pore water EC, they provide valuable bulk EC data that can be used in conjunction with established models to estimate this crucial soil property.
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