Measurement principles



The method of thermal dissipation is analogous to sticking your finger in the soil and gauging the wetness from the sensation of coolness, due to the heat dissipated at your finger tip.



The actual method involves generating a precise heat pulse through a ceramic  disc and determining the moisture status of the surrounding medium from the signal picked up by a temperature sensor


The moisture signal is very strong and is readily converted to a soil moisture reading by the sensor electronics.




Embedding the sensor in a  porous ceramic material which absorbs moisture and  equilibrates with the soil when buried enables calibration of measurements against soil water tension  (matric potential) via a non-linear relationship.





These sensors show an excellent dynamic response.







A 'naked' sensor version is readily calibrated for volumetric moisture content and can be configured in different ways for different materials.