Study on complex dielectric properties of saline soils

Using the Vector Microwave Network Analyzer in broad band (from 0.2 to 18 GHz), a controlled laboratory experiment was conducted on artificially prepared wet saline soil samples. The complex dielectric constants of soil samples in a wide range of moisture and salinity contents were measured and the relationship to the moisture and salinity of the soils were analyzed. The experiment results shows that the imaginary part of the dielectric constant of wet soil is more sensitive to the salinity of soils at low frequency range (f<5 GHz). It indicates that L band or P band SAR can be more effective in soil salinity detection. Secondly, 41 soil samples were collected along a profile from a dried salt lake in late April of 2001. Their moisture and salinity vary along the profile differently. The Vector Microwave Network Analyzer measured the complex dielectric constants of the collected soil samples in laboratory. C band, HH polarization RADARSAT data were simultaneously acquired on April 23, 2001. The backscatter intensity taken from RADARSAT image correlates with the complex dielectric constant. The correlation coefficient between the backscatter intensity and the real part of the complex dielectric constant is 0.23, and the imagine part of the complex dielectric constant is 0.66. This result shows that SAR will contribute to salinity monitoring program.