Soil dielectric spectroscopic parameters dependence on humus content

The purpose of this paper is to apply generalized refractive mixing dielectric model (GRMDM) based on the Debye relaxation formula to soils with various humus contents. With this approach, the soil types containing 6.6% and 0.6% of natural humus. Complex dielectric constant or complex refractive index were measured as a function of moisture at the frequencies of 0.55; 1.1; 1.8, 3.0, 11.5, 13.5 and 16.3 GHz with the temperature being of 20-24 °C. Using measured data only at 1.8, 3.0, 4.3 GHz, the GRMDM parameters - relaxation time, static dielectric constant, and conductivity for both types of water in soil were attained for both types of soil. Though variation in the relaxation parameters with humus content is moderate, this factor has to be taken into account when soil moisture remote sensing algorithms are being designed for agricultural areas. For this purpose, the GRMDM can be applied, with a soil humus content being one of its physical parameters.