Compact TEROS 11 soil moisture and temperature sensor is accurate, reliable and easy to use

Labcell, the UK distributor for METER Group (previously known as Decagon Devices), is introducing the METER TEROS 11 soil moisture and temperature sensor that benefits from a one-litre volume of influence, which is a substantial improvement over the 200 ml typical of most sensors. This remarkable performance is achieved despite the sensor measuring just 94mm long instead of the 200+ mm of alternatives. METER Group has more than 20 years’ experience of soil moisture instrumentation and, based on its experience and the TEROS 11’s superior design, the manufacturer expects the new sensor to operate for up to ten years.

Features that contribute to the TEROS 11’s longevity include stainless steel needles that can be easily inserted into any soil and are resistant to salts, and epoxy-encapsulated electronics that withstand extremes of temperature and moisture.

To improve ease of use and accuracy, a new calibration procedure has been developed; the sensor’s accuracy is checked by simply sliding a verification clip onto the needles. When the sensor is plugged into a data logger, the sensor’s accuracy is verified if the reading falls within the correct range. Sensor-to-sensor variability is therefore less than 1.5% VWC (volumetric water content). As with METER’s previous sensors, the TEROS 11 uses the proven 70 MHz frequency capacitance technology that enhances sensor accuracy by minimising the effects of soil texture and salinity. Furthermore, a ferrite core on the cable eliminates electrical noise.

The new TEROS 11 moisture and temperature sensor is fully compatible with METER Group’s ZENTRA Cloud system. With the plug-and-play sensor connected to a ZL6 data logger – which automatically detects the sensor type – users can access data in near-real-time from the ZENTRA Cloud via any web browser. As the TEROS 11 sensor uses the industry-standard SDI-12 digital data interface protocol, is can also be connected to other compatible data acquisition systems.

METER Group has made sensor installation easier, quicker and more reliable by developing the new TEROS Borehole Installation Tool. Using this, sensors can be quickly and accurately installed at precise depths, with the needles pushed smoothly into full contact with the soil. Because installation is via a small borehole, site disturbance is minimised. Integral lighting enables the sensor installation to be checked before the borehole is backfilled.

In mineral soils, the TEROS 11’s volumetric water content measurement range is 0.00 to 0.70 m3/m3 with a resolution of 0.001 m3/m3 and an accuracy of +/-0.03 m3/m3 or better, depending on soil type. The temperature measurement range is -40 to +60 °C with a resolution of 0.1 °C; accuracy is +/-1 °C below freezing point and +/-0.5 °C above.

Typical applications for the TEROS 11 sensor include research in the realms of biophysics, geophysics, agriculture and environmental sciences, as well as agriculture, horticulture, and the production, installation and maintenance of sports turf.

The TEROS 11 is suitable for integration within networks of soil and meteorological instrumentation, either singly or in multiples. To complement the TEROS 11, Labcell supplies and supports a comprehensive range of sensors and data loggers.

Labcell is the sole UK distributor for the METER range of instrumentation. Download detailed data sheets directly from Labcell’s website at or contact the company with specific enquiries or to request a demonstration by telephone on +44 (0)1420 568150 or email

For more information visit the website at, call Labcell on 01420 568150 or e-mail

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