Abstract: A soil probe, comprising, in one form, a cylindrical member of insulating material having a pair of metal, electrically conductive, ring electrodes mounted a short distance above a conical portion at the lower end of the probe, these ring electrodes lie flush with the outer surface of the cylindrical member and are spaced apart from each other by the insulating material. An electrical-electronic measuring system is connected to the electrodes by conductors providing identical line impedance for each ring. The system has an initial electronic portion inside the cylindrical member and close to the electrodes and has a second portion distant from the cylindrical member. A plurality of different frequencies of radio-frequency current is applied to the electrodes, for accurate determination of capacitance at the different frequencies. Therefrom are determined the dielectric dispersion characteristics of the soil.

Abstract: A method and implementing apparatus for measuring in situ the electrical capacitance and resistance of soils and determining therefrom the density and fabric thereof. The apparatus includes a self-contained probe adapted to be driven into the soil to be measured. The probe has a soil sensor element and a measuring circuit such as a capacitance and resistance bridge. The measuring circuit employs radiofrequency current to enable direct measurement at the probe of the resistance and capacitance of the soil sample and of the pore liquid. A remote indicator and control unit in communication with the probe is provided with indicators such as meters or displays which provide direct readout of measured resistance and capacitance, and which may also enable the bridge in the probe to become balanced. Alternatively, the probe may include a computer for automatically balancing the bridge and calculating critical soil properties.