Soils electrical resistance probe

Sample tests in the field. These include coupons, stressed samples, electrical-resistance probes exposed to the plant corroding medium, or samples exposed to the atmosphere, to soils, or to fresh, brackish, or sahne waters. 

An alternate method exists to determine in situ bulk density usually only in very shallow water such as bays and estuaries, without the necessity of using radioactive isotopes. To accomplish the electrical resistivity of the soil and also of the pore water (to correct for variations in salinity) is measured using two probes (Rietsema and Viergever, 1979). This is a convenient measurement, although the equipment may be somewhat complicated to use because of having to use two separate probes to obtain one measurement in addition, the laboratory calibration procedure is not simple. What appears to be a more versatile device has been described by Bennett et al. (1983). 

An electrical resistance (ER) probe is designed to measure corrosion in soil, without the necessity to be dug up for examination. This is an advantage over the coupons. The ER of the probe, made of the same metal as the structure, will change its value because of loss of metal, due to conversion to corrosion products on the metal surface. The ER probe also gives indirect information about the soil corrosivity and its changes with time. 

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