A dual-probe heat pulse-based sensor that simultaneously determines soil thermal properties, soil water content and soil water matric potential

A dual-probe heat pulse (DPHP) sensor is a robust tool that can measure soil thermal properties and associated soil physical properties and processes. A new DPHP based sensor was developed to simultaneously measure soil thermal properties, soil water content and soil water matric potential. A series of experiments were performed to evaluate the sensor performance. The new sensor was able to measure each soil property with acceptable accuracy. The accuracy of the matric potential determinations was approximately 10% in log scale. The effective range for w measurements was -1000 to -2.5 m of water, and the accuracy of the w determinations was best between -350 and -2.5 m of water, which included values of field capacity and wilting point for most soils and crops. The sensor design included a single heater wire to provide simultaneous heat inputs to two different materials, i.e., the soil and the sensor porous medium. The single heater wire did not influence sensor accuracy as long as the soil and the sensor porous medium thermal conductivity values were not significantly different. The new DPHP based sensor effectively measured various soil properties, including soil water matric potential, soil water content, and soil thermal property values.