Peat is still widely used as a growing medium because of its favorable properties, but it is also a major source of carbon emissions when extracted and consumed. As a result, there is currently a widespread search for other, more sustainable substrate materials. These alternatives can be composed of waste streams such as coconut fiber.
To quantify the water content in a substrate, the 'Volumetric Water Content' (VWC) is often used: the volume of water divided by the substrate volume. The VWC can be determined via electrical measurement, by measuring the permittivity of the substrate. However, the relationship between the VWC and permittivity, especially for low VWCs, strongly depends on the substrate used. Therefore, when using peat calibrated moisture sensors in alternative substrates, a relatively large measurement deviation can occur.
To address this problem, Quantified Sensor Technology has developed a calibration method for soil moisture sensors, which, for any substrate, can quickly relate the values measured by the soil moisture sensor to the VWC. "By performing an accelerated wet/dry cycle, a complete calibration is obtained fully automatically and within one to two days. Thereby, the measured sensor values from completely dry to field capacity are linked to actual VWCs obtained by weight measurement of the respective substrate. This calibration curve allows the grower to measure reliable VWC values even in new substrates."
Automatic calibration routine of a WET sensor in an osmocote/potting soil substrate
Calibration is offered as a service for Quantified customers and can be performed for both existing and new sensors and substrates.
For more information: 
Quantified Sensor Technology
Langegracht 70 - PLNT
2312 NV Leiden
[email protected]
www.quantified.eu