Advances in Determining Soil Matric Potential Using an Engineered Porous Ceramic and Dielectric Permittivity.
Colin Campbell, Gaylon Campbell, Douglas Cobos, and Lauren Bissey. Decagon Devices, Inc., Decagon Devices Inc, 2365 NE Hopkins Ct., Pullman, WA 99163-5601
Soil water potential is a key parameter for determining water availability for plant growth, water flow, and soil stability. Although an in situ measurement of matric potential has been the focus of considerable research over the years, existing solutions still have many drawbacks such as high maintenance, limited longevity, individual calibration requirements, high cost, and small measurement range. The objective of this research was to develop a sensor that could be used in the field to accurately measure soil matric potential without the limitations noted above. The sensor, which consisted of a dielectric sensor sandwiched between porous ceramic, was tested over a range soil types, electrical conduct ivies, and temperatures to calibrate and characterize its output. Data show consistent calibration curves between sensor output and actual soil matric potential. Although temperature showed a slight effect on sensor output, it did not appear to be enough to affect sensor readings. Likewise, salt effects were not visible in the evaluated soils. Data suggest the sensor will be an effective and robust tool to determine in situ matric potential.