Soil can be highly variable in space, requiring many 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 large sensor networks simpler, longer-lasting, and more affordable with the ultra-dependable TEROS 12 soil moisture, temperature, and EC sensor.
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.
3.0 % accuracy
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.
9.4 cm sensor
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 <8,000 μS/cm
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
±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
See 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
See compatibility chart
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 ±0.004 in (4.20 ± 0.10mm) with minimum jacket of 0.030 (0.760 mm)
Connector Types
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
