Affordable scientific accuracy

TEROS 12

Advanced Soil Moisture Sensor + Temperature and EC

Make large sensor networks simpler, longer-lasting, and more affordable with the ultra-dependable TEROS 12 soil moisture, temperature, and EC sensor. The TEROS 12 soil moisture sensor calibration procedure maximizes accuracy and minimizes sensor-to-sensor variability while keeping the cost reasonable, so you can install more sensors with confidence that each will read exactly like the next one.

  • Measure more with a 1010 mL volume of influence
  • Minimize salinity and textural effects using 70 MHz frequency capacitance technology
  • Plug and play with METER ZL6 data loggers, or easily integrate with third-party data logging systems
  • Get peace of mind with a 3-year long-life guarantee
  • Visualize data remotely on your PC or phone using and ZENTRA Cloud

Better accuracy—verified

The TEROS 12 soil moisture sensor uses a completely new calibration procedure that maximizes accuracy and minimizes sensor-to-sensor variability while keeping the cost reasonable. So you can be confident that every sensor you install is going to read exactly like the next one. Unlike other sensors on the market which spec an unverifiable  ±1.0% VWC accuracy, the TEROS 12 was rigorously tested by our soil physicists across a challenging range of soil types and EC levels so you can be confident in the accuracy of your data.

Plus, TEROS sensor repeatability can be checked with an accuracy verification standard. No other soil moisture sensor has this ability. Just slide the verification clip onto a sensor and plug it into a logger. If it reads within the right range, your sensor is good to go.

Small soil moisture sensor lets you think bigger

The TEROS 12 delivers the best volume of influence to sensor size on the market so you’re less susceptible to soil variability errors. We’ve optimized the circuitry in this 9.4-cm sensor to deliver an incredible one-liter volume of influence (versus the 200 mL typical for most sensors). Most soil sensors that measure this much volume are 20 cm or longer, causing installation headaches. Not only that, you can cut your installation time in half or more when you install with the new Borehole Installation tool. The tool mistake-proofs installation, eliminating common errors that cause uncertainty in the data—like air gaps, or preferential flow. And the TEROS 12 is plug and play with the cloud-connected ZL6 logger. No programming required. See your data instantly in real time, wherever you are.

With you for the long haul—guaranteed

The culmination of our new TEROS water content line, the plug-and-play TEROS 12 soil moisture, temperature, and electrical conductivity sensor makes your life easier with a large volume of influence, reduced sensor-to-sensor variability, and a near-bulletproof form factor—which lasts up to 10 years in the field. These innovations, along with our well-published capacitance technology, an accuracy verification standard, real time, remote data visualization with ZENTRA Cloud, and a blazing fast installation tool have combined to generate our most accurate, easy-to-use, highly durable—yet still economical—soil moisture sensor. We’re so confident about the long life of our TEROS sensor line, we’ve increased our standard warranty from one to three years.

Legendary technology—long-lasting performance

Backed by over 20 years of soil moisture research, the TEROS 12 soil moisture sensor combines METER’s trademark 70 MHz circuitry with an extremely ruggedized epoxy fill and securely attached, sharpened stainless steel needles that easily slip into the soil and are resistant to salts, so you can worry less about sensor deterioration. Very low power consumption and a high resolution provide increased precision over a longer period of time. If you’re planning a long-term large sensor network and want long-lasting performance for less work and less of your research budget, then choose the TEROS 12.

Volumetric Water Content

Range

Mineral Soil Calibration: 0.00–0.70 m3/m3

Soilless Media Calibration: 0.0–1.0 m3/m3

Apparent Dielectric Permittivity (εa): 1 (air) to 80 (water)

NOTE: The VWC range is dependent on the media the sensor is calibrated to. A custom calibration will accommodate the necessary ranges for most substrates.

Resolution

0.0010 m3/m3

Accuracy

Generic Calibration: ±0.03 m3/m3 (±3.00% VWC) typical in mineral soils that have solution EC

Medium Specific Calibration: ±0.01–0.02 m3/m3 in any porous medium

Apparent Dielectric Permittivity (εa): 1–40 (soil range), ±1 εa (unitless) 40–80, 15% of measurement

Measurement Specifications

Temperature

Range: –40 to +60 °C

Resolution: 0.10 °C

Accuracy: ±0.5 °C from –40 to 0 °C
Accuracy: ±0.3 °C from 0 to +60 °C

Dielectric Measurement Frequency

70 MHz

Bulk Electrical Conductivity (EC)

Range: 0–20,000 μS/cm (bulk)

Resolution: 1 μS/cm

Accuracy: +/- (5% + 10 μS/cm) from 0–10,000 μS/cm
+/- 8% from 10,000–20,000 μS/cm

Measurement Volume

Max Volume: 1010 mL
See our comparison article

Communication Specifications

Output

DDI serial or SDI-12 communications protocol

Data Logger Compatibility

METER ZL6, EM60, and Em50 data loggers or any data acquisition system capable of 4.0- to 15-VDC power and serial or SDI-12 communication

Physical Specifications

Dimensions

Length: 9.4 cm (3.70 in)

Width: 2.4 cm (0.95 in)

Height: 7.5 cm (2.95 in)

Needle Length

5.5 cm (2.17 in)

Operating Temperature Range

Minimum: -40.00 °C

Typical: NA

Maximum: 60.00 °C

NOTE: Sensors may be used at higher temperatures under certain conditions; Contact Customer Support for assistance.

Cable Length

5 m (standard)

75 m (maximum custom cable length)

NOTE: Contact Customer Support if a nonstandard cable length is needed.

Cable Diameter

0.165 ± .004 (4.20 ± .10 mm) with min. jacket of .030 (.76 mm)

Connector Types

3.5-mm stereo plug connector or stripped and tinned wires

Stereo Plug Connector Diameter

3.5 mm

Conductor Gauge

22 AWG/24 AWG drain wire

Electrical and Timing Characteristics

Supply Voltage (VCC to GND)

Minimum: 4.0 VDC

Typical: NA

Maximum: 15.0 VDC

Digital Input Voltage (Logic High)

Minimum: 2.8 V

Typical: 3.6 V

Maximum: 5.0 V

Digital Input Voltage (Logic Low)

Minimum: –0.3 V

Typical: 0.0 V

Maximum: 0.8 V

Digital Output Voltage (Logic High)

Minimum: NA

Typical: 3.6 V

Maximum: NA

Power Line Slew Rate

Minimum: 1.0 V/ms

Typical: NA

Maximum: NA

Current Drain (During 25-ms Measurement)

Minimum: 3.0 mA

Typical: 3.6 mA

Maximum: 16.0 mA

Current Drain (While Asleep)

Minimum: NA

Typical: 0.0 mA

Maximum: NA

Power Up Time (DDI Serial)

Minimum: 80 ms

Typical: NA

Maximum: 100 ms

Power Up Time (SDI-12)

Minimum: NA

Typical: 245 ms

Maximum: NA

Power Up Time (SDI-12, DDI Serial Disabled)

Minimum: 145 ms

Typical: 155 ms

Maximum: 165 ms

Measurement Duration

Minimum: 25 ms

Typical: NA

Maximum: 150 ms

Other

Compliance

EM ISO/IEC 17050:2010 (CE Mark)

2014/30/EU 2011/65/EU

EN61326-1:2013 EN55022/CISPR 22

EN 55011:2016/A1:2017 (GROUP 1, CLASS A-RCM mark)

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