A Novel Frequency Domain Impedance Sensor with a Perforated Cylinder Coaxial Design for In-Situ Measuring Soil Matric Potential

Abstract

Soil matric potential is an important parameter for agricultural and environmental research and applications. In this study, we developed a novel sensor to determine fast and in-situ the soil matric potential. The probe of the soil matric potential sensor comprises a perforated coaxial stainless steel cylinder filled with a porous material (gypsum). With a pre-determined gypsum water retention curve, the probe can determine the gypsum matric potential through measuring its water content. The matric potential of soil surrounding the probe is inferred by the reading of the sensor after the soil reaches a hydraulic equilibrium with the gypsum. The sensor was calibrated by determining the gypsum water retention curve using a pressure plate method and tested in three soil samples with different textures. The results showed that the novel sensor can determine the water retention curves of the three soil samples from saturated to dry when combined with a soil water content sensor. The novel sensor can respond fast to the changes of the soil matric potential due to its small volume. Future research could explore the application for agriculture field crop irrigation.

Robust Soil Water Potential Sensor to Optimize Irrigation in Agriculture

“…In addition to the mentioned commercially available sensors, Whalley [13][14][15] developed a porous matrix sensor that shows a measuring range from 500 hPa to 3000 hPa. Recently, a few new sensors have been introduced in the literature, which could market-launch in the near future [16][17][18][19][20][21][22][23][24][25]. EQ3 Equitensiometer Delta-T Devices Ltd. (Burwell, Cambridge, UK) 0 to 10,000 hPa 800 € [28] Tensiomark (0-7) EcoTech Umwelt-Meßsysteme GmbH (Bonn, Germany) 1 to 10,000,000 hPa 650 €…”