Rock fraction effects on the interpretation of microwave emission from soils

The effects of the rock fraction were investigated through a combination of laboratory dielectric measurements and field observation of emissivity. A series of field measurements were conducted which included soils with (35% by volume) and without rocks. Analysis focused on the use of a 21-cm wavelength, although some field observations at 6 cm were also made. For the rock samples, the average values of the dielectric constant were 4.7 and 0.07 for the real and imaginary parts, respectively. The effects of rock fraction are not significant in estimating the sample soil moisture when 21-cm data are used, for the rock fraction examined. Data collected at 6 cm clearly showed that the presence of rocks will make this and shorter wavelengths useless as soil moisture sensors