Series: Sensors for growing blueberries in pots.
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Sentec Drill and Drop (not used in substrate)
The Australian company Sentec’s Drill & Drop sensor is one of the best sensors in the world. It measures the water content WVC%, electrical conductivity EC and temperature T in the soil. Moreover, a signal measuring all three quantities comes from every 10 centimeters of its length.
According to the manufacturer of the Sentec Drill and Drop sensor, its use in the substrate is not recommended. This is due to the fact that there are air bubbles in the substrate, which are not allowed to be around this sensor. It is installed in a hole made in the soil, where an aqueous solution of the soil is poured to expel the air.
With complex calibration techniques, it is possible to see the trend of water content WVC% change with this sensor, but we still cannot achieve accuracy. However, electrical conductivity, EC calibration is not performed at all. See link
For this reason, such a high-tech sensor (and expensive) is not used in the substrate, i.e. in pots, when growing blueberries.
There are other sensors whose measuring mechanism does not depend on whether there are air bubbles around or not. The next two sensors presented are just such sensors.