A combination of sensors to measure the heat flux entering the soil:
Use of these sensors is described here and installation documentation here.
Gsoil sensors are calibrated by the manufacturer.
Soil moisture sensors use a generic calibration from the manufacturer, but are checked in the field using manual gravimetric measurements (that also measure the soil bulk density). Occasionally, the calibration is adjusted in post-processing based on these manual measurements.
The thermal properties sensors are calibrated in the laboratory at one point by inserting in a preparation of agar gel.
Tsoil sensors are calibrated in the EOL oil bath. Coefficients are loaded into and applied by EOL's front-end microprocessor for each sensor.
