Hello Uwe,

 

This procedure basically measures ground rod effectiveness more than the soil conductivity, although fairly good conductivity can be inferred from the result.

 

If you are trying to measure earth conductivity in mS/m for RF propagation purposes, however, the technique is not very helpful.  In fact, there is no easy way to measure this property directly at RF.  From a practical engineering standpoint, we generally do it by measuring the attenuation of a groundwave radio signal traversing a given distance of the soil in question.

 

John