Advanced Soil Moisture, EC and Temperature Sensor TEROS-12


Meter Environment


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The Sensor measures: Soil Moisture/EC/D Perm./Temp
Cable Length: 5 meters

- Increased volume of influence (1010 mL)
- Easy installation with borehole installation tool (minimizes air gaps for cleaner readings)
- Dependable, long-life sensor
- Reduced sensor-to-sensor variability
- 3-year long-life guarantee
- Track solute and fertilizer movement with accurate EC measurement
- Check installation or troubleshoot with the ZSC Bluetooth sensor interface
- Repeatability can be checked with an accuracy verification standard
- Robust, epoxy body for tough field conditions
- Minimizes salinity and textural effects by using 70 MHz frequency capacitance technology
- Steel needles cut through the soil for better soil-sensor contact
- Easy-to-use SDI-12 communication for non-METER data loggers
- Ferrite core eliminates cable noise

Sensor longevity:
Soil can be highly variable in space, requiring numerous measurements and frustrating amounts of your research dollars.
Not to mention the extra cost and hassle of replacement sensors if you need long-term data.
Make long-term, large sensor networks simpler, longer-lasting, and more affordable with the ultra-dependable TEROS 12 soil moisture and temperature sensor. With you for the long haul, guaranteed

The culmination of TEROS water content line, the 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, and a blazing fast installation tool have combined to generate our most accurate, easy-to-use, highly durable, yet still economical, soil moisture sensor.
In fact, we’re so confident about the long life of our TEROS sensor line, we have increased our standard warranty from one to three years. Legendary technology and long lasting performance

Backed by more than 20 years of soil moisture research, the TEROS 12 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.

A small 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.

Better Accuracy:
TEROS 12 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.

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.

Near-instant data gratification:
Easy and reliable data collection is part of the TEROS experience. Combine the TEROS 12 with the new ZL6, where all data are connected and delivered in near-real time through the cloud. All you have to do is sit back and let the data flow.

Now you can have everything:
We created the TEROS line to eliminate barriers to good accuracy: installation inconsistency, sensor-to-sensor variability, and sensor verification. The TEROS 12 is a long-life, accurate, easy-to-install sensor that combines METER’s legendary technology with an ultra-rugged form and a new calibration procedure to deliver an unbeatable price-to-performance ratio. 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 (VWC)    

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.

0.001 m3/m3
Generic calibration: ±0.03 m3/m3 (±3.00% VWC) typical in mineral soils that have solution EC <8 dS/m
Medium specific calibration: ±0.01–0.02 m3/m3 (±1–2% VWC) in any porous medium
Apparent dielectric permittivity (εa): 1–40 (soil range) , ±1 εa (unitless) 40–80, 15% of measurement

Dielectric measurement frequency: 70 MHz

Range: −40 to 60 °C
Resolution: 0.1 °C
Accuracy: ±0.5 °C from −40 to 0 °C
±0.3 °C from 0 to +60 °C
Bulk electrical conductivity (ECb)    

Range: 0 to 20 dS/m (bulk)
Resolution: 0.001 dS/m
Accuracy: +/- (5% +0.01 dS/m) from 0 to 10 dS/m
+/- 8% from 10 to 20 dS/m
Measurement volume    



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 (see compatibility chart)


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)
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±.10mm) with min. jacket of .030 (.76mm)
Connector types    

3.5-mm stereo plug connector or stripped and tinned wires
Stereo plug connector diameter    

3.50 mm
Conductor gauge    

22 AWG/24 AWG drain wire


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: 3.9 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: 0.03 mA
Maximum: NA
Operating temperature range    

Minimum: –40 °C
Typical: NA
Maximum: +60 °C

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

Minimum: 145 ms
Typical: 155 ms
Maximum: 165 ms
Measurement duration    

Minimum: 25 ms
Typical: NA
Maximum: 150 ms

Manufactured under ISO 9001:2015
EM ISO/IEC 17050:2010 (CE Mark)
2014/30/EU and 2011/65/EU
EN61326-1:2013 and EN55022/CISPR 22

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