Abstract
Simultaneous measurement of volumetric soil water content (θw) and soil solution electrical conductivity (ECw) was made for dune sand soil using Time Domain Reflectometry (TDR). The best relationship between TDR dielectric constant (Ka) and Ow, and that for bulk soil electrical conductivity (ECb) and ECw were defined for dune sand soil and assessed in a dune sand field. The salinity of soil solution showed no effect on Ka and consequent θw. The commonly used linear relation between TDR transmission coefficient (T) and 6w was inaccurate for dune sand soil when θw was in the range of soil water holding capacity. A polynomial equation was suggested for expressing the relation between T and θw, with less variation than a power relation. Based on field assessment, there was a better agreement between θw)recorded by TDR and that from soil sampling than a similar relation for ECw. The relative error (RE) between TDR measured and soil sampling was 4.97% and 10.67% for Ow and ECw, respectively.
