Measurement of the Dielectric Properties of Soils Using Electromagnetic Sensors.

Accurate soil water content estimates are important for agricultural water management, ecosystem studies, and climate research. Electromagnetic techniques for measuring soil water content are fast, safe, non-destructive, and easily automated. The relationship between the measured dielectric properties of the soil and the soil water content depends on the frequency of the applied stimulus, soil structure, soil texture, clay mineralogy, and the ion composition of the soil water. In this work the dielectric properties of different soil horizons are examined by combining Hydra impedance probe 50 MHz real and imaginary permittivity with Time Domain Reflectometry dc ionic conductivity measurements. It is shown how the measured dielectric properties can be used to determine soil horizon-specific permittivity-soil water content calibrations.