Measurement and modelling of organic matter’s altering effect on dielectric behavior of soil in the region of 200 MHz to 14 GHz

Organic matter (OM) is one of the parameters which is commonly ignored while studying the properties of soil but it strongly affects and alters soil’s behavior and characteristics. The presented study analyzes the properties of soil like bulk density, and dielectric properties (ε′ and ε″), penetration depth, emissivity, and conductivity as a function of OM (0.78–17.28% of total soil mass), moisture content (15–25% volumetric basis), and frequency (200 MHz–14 GHz). The properties have been investigated using a vector network analyzer (VNA), and an open-ended coaxial probe (85070E, Agilent Technologies). The observed results showed that in addition to moisture content and frequency, the amount of OM present in soil strongly affects the properties of soil. The OM present in soil improves soil structure as well as binding forces in soil water molecules. Third-order Response surface method (RSM) regression models are generated to estimate soil’s properties as a function of OM, frequency, and moisture content. These models show a R2 score of 0.9754, 0.9964, 0.9204, 0.9962, 0.9827, 0.9859 for bulk density, ε′, ε″, penetration depth, conductivity, and emissivity, respectively. These models can be helpful for fast and accurate prediction of properties of soil under the effect of OM, moisture content, and frequency.