Submitted to: Water Resources Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/8/2005
Publication Date: 12/20/2005
Citation: Western, A., and Seyfried, M.S. 2005. Calibration and temperature correction of a capacitance-based soil-moisture sensor. Hydrological Processes 19:3785-3795. Interpretive Summary: Numerous new electronic soil moisture sensors have been developed in recent years. These sensors are relatively inexpensive and are potentially useful for both research and commercial applications (irrigation scheduling, for example). A problem is that, in general, these sensors have not been tested over a range of conditions and the necessary calibrations have not been developed. In this paper we develop and test calibration procedures for the Campbell Scientific CS615 Water Content Reflectometer. We use data collected from soils with highly variable properties in Australia and the USA. The result is a calibration procedure that requires the use of one soil measurement. The calibration incorporates constant soil properties, like the clay content, and changing properties, like the temperature.
Technical Abstract: Calibration is required for most soil moisture sensors if accurate measurements are to be obtained. This can be time consuming and costly, especially if field calibration is undertaken, but can be facilitated by a good understanding of the behaviour of the particular sensor being calibrated. In this paper, generalised temperature correction and calibration relationships for sensors are developed. The temperature correction is estimated as a function of the raw sensor measurement. The calibration relationship requires one soil related parameter to be set. These relationships facilitate field calibration of these sensors to acceptable accuracies with only a small number of samples.