DETERMINATION OF SOIL TROPHICITY BY ELECTROPHYSICAL METHOD. MESSAGE 1. DEVICE AND LABORATORY TECHNIQUE

The purpose of this work was to develop a device and technique for determining the soil trophiсity using the electrophysical method based on the measurement of the soil specific resistivity (SR). In the proposed device the F. Wenner installation is used as a sensor. The device has a modular design and includes a voltage boosting module, a PWM generator of rectangular pulses, a rectangular signal inverter and an H-bridge that switches the polarity of the power supply in order to prevent polarization of the electrodes. The metrological characteristics of the specific resistivity measurement as well as the influence of the electrodes immersion depth in the substrate studied are determined. Its significant influence and nonlinear character which was well approximated by the power function were established. The simplest equations for bringing the measured values of the RS to a certain depth of the electrodes in the object studied are proposed.