Measures the moisture content of the soil. The Davis Instruments sensor measures on a scale of 0 (fully wet) to 200 (fully dry) centibars. Other soil moisture sensors measure on a various scales of 0 (fully dry) to up to 100% (fully wet) of volumetric water content (VWC). They are used to help manage efficient watering of crops. The Davis soil moisture sensor measures the vacuum created in the soil by the lack of moisture. Other soil moisture sensors measure reflected microwave radiation to determine the content of moisture in the soil.