The Watermark Soil Moisture Sensor (granular matrix sensor) is an indirect method of measuring soil water. It is an electrical resistance sensor read by our Moisture Meter or Moisture Meter Datalogger. It provides the input needed by the Moisture Meter to report soil moisture, but it does not directly report soil moisture itself, and cannot be used independently. This is the same sensor as the Davis 6440 Soil Moisture Sensor.
This sensor has been the subject of scientific investigation by plant and soil science since the mid-1980's, and has demonstrated itself to be an affordable and practical substitute for tensiometric measurement in most agricultural and landscape irrigation environments.