Effects of soil tillage on the microwave emission of soilsIn order to understand the interactions of soil properties and microwave emission better, a series of field experiments were conducted in 1984. Small plots were measured with a truck-mounted passive microwave radiometer operating at 1.4 GHz. These data were collected concurrent with ground observations of soil moisture and bulk density. Treatment effects studied included different soil moisture contents and bulk densities. Evaluations of the data have shown that commonly used models of the dielectric properties of wet soils do not explain the observations obtained in these experiments. This conclusion was based on the fact that the roughness parameters determined through optimization were significantly larger than those observed in similar investigations. These discrepancies are most likely due to the soil structure. Commonly used models assume a homogeneous three phase mixture of soil solids, air and water. Under tilled conditions the soil is actually a two phase mixture of aggregates and voids. Appropriate dielectric models for this tilled condition were evaluated and found to explain the observations. These results indicate that previous conclusions concerning the effects of surface roughness in tilled fields may be incorrect, and they may explain some of the inconsistencies encountered in roughness modeling.
Document ID
19860048842
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Jackson, T. J. (Department of Agriculture Beltsville, MD, United States)
Koopman, G. J. (USDA, Hydrology Laboratory, Beltsville MD, United States)
Oneill, P. E. (Department of Agriculture Beltsville, MD, United States)
Wang, J. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)