Simultaneous Mapping of the Soil Electrical Conductivity and Dielectric Permittivity using a Medium Frequency EM Device

Electrical conductivity and dielectric permittivity are two useful tools to characterize the soil state parameters such as its water or clay content. A new EM device working in the medium frequency range has been developed to simultaneously measure these parameters. The prototype, working between 1 and 5 MHz with an inter-coil spacing of 1.2m has been tested on a clay loam plot at INRA Estrée-Mons (ORE-ACBB) during the spring dry period. As only half of the plot was covered with growing wheat, significant water content variations were expected. The prototype detected these variations and electrical conductivity and dielectric permittivity were mapped. These first results are in good agreement with the spatial distribution observed by d.c. electrical profiling and by mass water content direct measurements.