TEROS 22 Soil Water Potential Sensor

The complete picture
A water content sensor only shows the percentage of water within the soil but does not tell you how available that water is for uptake by the plants rooting in that soil. Combining water content measurements with the water potential measurements of TEROS 22 sensors provides the information needed to solve the puzzle of when to turn irrigation on and off. This soil moisture duo gives you control of exactly how stressed or well-watered your plants are at every stage throughout the season.

The power of potential
The TEROS 22 is a long-term monitoring solution you can trust. Each sensor is individually calibrated using a process that has been refined and perfected over the years. Save time and effort with the precalibrated TEROS 22. Taking these steps ahead of time saves you time and effort, making this sensor truly plug-and-play.

Installation without trenching required
Sometimes trenching is not an option in the location you’re hoping to measure soil water potential and with the TEROS 22 we say, “That’s ok!” While the TEROS 22 can easily be installed in the wall of a trench, it can also be installed with just an electric drill with a 16 mm (5/8 in) masonry drill bit and a level. Install however best fits your needs at angles ranging from 10-80°, depending on the installation depth. Whether your priority is minimal soil disturbance and easy sensor removal, or the greater depths achieved with trenching, the TEROS 22 has the flexibility to measure where you need it most.

Measure at various depths
We offer configurations that work best for your application. The TEROS 22 unit is 17 cm (7 in) or choose an extended sensor for depths of either 40 cm (16 in), 80 cm (31 in), or 120 cm (47 in). Need a different length? The base unit allows for your own tube of the desired length to be attached. This flexibility makes measuring water potential possible where other sensors cannot reach.

TECHNICAL SPECIFICATIONS

Measurement Specifications
Water Potential
Range: 0 to –100,000 kPa (1.70 to 6.00 pF)
Resolution: 0.1 kPa
Accuracy: ±(10% of reading + 2 kPa) from –100 to –5 kPa
NOTE: TEROS 22 can read up to 0 kPa when on a wetting path. The air entry of the soil limits the performance of the sensor to –5 kPa on the drying curve.
NOTE: TEROS 22 is not well calibrated beyond –100 kPa. For more information on using the TEROS 21 beyond this range, see Section 3.3.3 in the user manual

Dielectric Measurement Frequency: 70 MHz

Temperature
Range: –40.00 to +60.00 °C
Resolution: 0.10 °C
Accuracy: ±1.00 °C

Communication Specifications

Output: DDI serial or SDI-12 communication protocol

Data Logger Compatibility: METER ZL6 and EM60 data loggers or any data acquisition system capable of 4.0- to 15-VDC power and serial or SDI-12 communication

Physical Specifications
Dimensions:
Diameter: 1.7 cm (0.67 in)
Length: 17 cm (6.7 in)
Length with optional extensions: 40, 40, and 120 cm (15.7, 31.5, and 47.3 in)

Sensor Diameter: 1.7 cm (0.67 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.

Connector Types
Stereo plug connector or stripped and tinned wires
Connector Size: 3.50 mm
Conductor Gauge: 22-AWG \ 24-AWG ground 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

Required Supply Current
Minimum: 15 mA
Typical: NA
Maximum: NA

Power Line Slew Rate
Minimum: 1.0 V/ms
Typical: NA
Maximum: NA

Power Up Time (DDI Serial)
Minimum: NA
Typical: 100 ms
Maximum: 350 ms

Time before sensor is responsive to SDI-12 commands (DDI serial enabled)
Minimum: NA
Typical: 260 ms
Maximum: 500 ms

Time before sensor is responsive to SDI-12 commands (DDI serial disabled)
Minimum: NA
Typical: 170 ms
Maximum: NA

Measurement Duration
Minimum: NA
Typical: 50 ms
Maximum: NA

Other

Compliance:
EM ISO/IEC 17050:2010 (CE Mark)
EN 55011:2016 / A1:2017 (RCM Mark)
Prop 65 warning
EU Declaration of Conformity