Electromagnetic Detection of Soil Moisture: Progress Report I

Abstract

The remote determination of soil moisture content requires a remotely detectable physical property of soils which is primarily dependent on moisture content. One physical property which holds promise of satisfying these conditions is the complex dielectric constant of the soil in the frequency band 10⁷ to 10⁹ Hz. Laboratory and field experiments employing time domain reflectometry (TDR) methods indicate the following: that the dielectric constant depends strongly on soil moisture and weakly on soil type, and density; that variations of several hundred per cent in the dielectric constant occur as moisture content varies for the range of moisture content normally encountered in the field; that an empirical relationship between dielectric constant and soil moisture exists.