Influence of the frequency of the electric signal on the measured specific resistance in the electrophysical approach to estimatе the properties of soils in the humid zone

Precision farming is recognized as a modern trend in crop production. Its basis is the application of fertilizers, depending on the variability of soil fertility. For the purpose of agrochemical evaluation that meets the requirements of efficiency and expression, the development of high-precision methods is necessary. The modern electrophysical method based on electrical resistance in soil analytical practice has become widespread. It has established itself as a convenient and rapid way to obtain a comprehensive characterization of soil properties. It is well known that in the zone of predominance of arid soils, electrical resistance is actively used, and its inverse is electrical conductivity, to assess salinity. Effective application of the method in humid zones is possible only after assessing the value of individual soil properties for resistance individually and in combination. It has been established that for the effective application of the electrophysical method for assessing the properties of soils of the humid zone by the method of an alternating electric field, it is necessary to take into account the influence of the frequency of the electric signal. A different effect of this factor on the obtained values of electrical resistivity was revealed on the example of ordinary chernozems, chernozems of solonetzic and sod-podzolic soil types. The effect of the frequency of the supplied signal on the measured electrical resistivity at various humidity levels is estimated. With an increase in frequency in the humidity range of 4-20%, for ordinary chernozems, alkaline chernozems, and for sod-podzolic chernozems in the range 4-16%, the resistivity decreases. In the range of 20-32% and 16-32%, respectively, to soil types, the soil is saturated with moisture, as a result, the resistance is practically independent of frequency.