Microwave dielectric behavior of MoistSalt soil - Experimental observations and improved dielectric models

Some progress has been made in recent years in the development of microwave remote sensing for the salinity of soil. In order to further understand the influences of salinity on the dielectric properties of soil, soils with different texture are collected and made into samples with different salinity and moisture content In this paper, we describe the use of open-ended coaxial probes for the measurement of dielectric properties of soil samples. We evaluate the microwave dielectric behavior of moist soil-salinity mixtures as a function of salinity, water content, and soil textural compositions, using the dielectric measurements of five soils ranging from sandy loam to silty clay at frequencies between 0.2GHz and 20GHz at room temperature. For solution of salt soil, especially at lower frequencies dielectric loss depends on the salinity. Furthermore, salinity has influence on static dielectric constant and relaxation time of soil solution. The real part of dielectric constant slowly declines with the increment of salinity. Therefore we cannot neglect the influences of salinity on microwave dielectric behavior of moist salt soil at P, L, C-band of microwave remote sensing. We add salinity factor into the Dobson semiempirical soil mixing model. The improved models yields values that correlate well with the results of dielectric measurement.