Soil Resistivity

[sewerratt]

How do I test for soil resistivity to determine how hot a local soil is? I have copper water laterals corroding in a certain location at an accelerated rate. Is this something I can do with easily available equipment or do I need to obtain some stuff or get a pro?

 

[kenvlach]

It takes some equipment, so consider hiring a pro and learning the procedure from him.

Two common methods:
The soil box, which is packed with soil to its original density. The dimensions of the box and the probes spacing are such as to give a direct resistivity reading in ohm-cm.
A link for this procedure is in the following thread
pH, resistivity measurement of soil
thread193-45981

Another method is the Wenner Four-Pin Method. ASTM G57-95a(2001) Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method gives the details. Four steel pins are driven into the ground, equally spaced in a straight line. AC or periodically reversed DC is passed through the outermost pins, the voltage is measured between the inner 2 pins with a) current on and b) current off.

Practical handbook of Corrosion Controls in Soils, S. A. Bradford, chap. 3, ‘Corrosivity of Soils’ (2000) describes the preceding and several more methods. Worth mentioning is the Shepard rods method, which uses only 2 probes, and seems suited for multiple measurements over a distance.

 

[eijkelkamp]

search the web for SOIL-mct a sensor that measures and logs soil moisture, temperature and conductivity