A Combined Frequency Domain and Tensiometer Sensor for Determining Soil Water Characteristic Curves

Abstract

There is increasing interest in the development of a technique that can simultaneously measure soil matric potential and water content for rapidly determining a soil water characteristic curve. In this study, we developed a new combined soil water content and potential sensor. The new sensor adapted the stainless steel tube of a conventional water‐filled tensiometer into a single sensing electrode for measuring soil water content. This novel design has the advantage of utilizing the whole length of the tensiometer without adding additional components to the sensor. To verify its feasibility, the sensor was tested on three soils (sand, sandy loam, and clay loam) while they were drying under laboratory conditions to produce the soil water characteristic curves in the matric potential range of 0 to −80 kPa. Water characteristic curves of the three soils were also obtained using standard laboratory techniques (tension table and pressure plate). The results show that water characteristic curves of the three soils from the new sensor are in good agreement with those obtained using the standard methods.