Rock fraction effects on the interpretation of microwave emission from soils

The effect of the rock fraction of soil on emissivity is presently investigated through a combination of laboratory dielectric measurements and field observation of emissivity from soils with and without rocks. The rock fraction reduced the range of emissivity; beyond this, it appears to be important only in determining the moisture in the soil component. Data gathered at 6 cm indicate that the presence of rocks renders this and shorter wavelengths useless as soil-moisture sensors. Modeling of the 21-cm case suggest that rock-fraction effects on soil dielectric properties can be compensated for by the greater surface roughness.