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TEROS 21 Soil Water Potential Sensor(MPS-6 Upgrade)

Updated:2025-03-13

Brand: METER
Model: TEROS 21
Description: When it comes to measuringwater potential(or soil suction), it’s hard to find a sensor that meetsyour every need. You're either forced to deal with lowered accuracy or high-maintenance hassles (plus g
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Product Details

TEROS 21 Soil Water Potential Sensor Description：

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Broad soil applications. Dependable accuracy.

To say TEROS 21 is more accurate than competitor sensors doesn't do it justice. That’s because unlike competitor models, we calibrate each and every sensor for you. To do this, we use a chamber system that allows the TEROS 21 water potential sensor to come to a fixed water potential. We put sensors in silica flour, and by controlling the water potential, we’re able to set calibration points from -10 kPa to -80 kPa. The result: a long-term monitoring solution you can finally trust.

A true full-range water potential sensor that’s low maintenance and low cost

The TEROS 21 water potential sensor is incredibly easy to use. It requires no maintenance, and it’s accurate enough for most applications. In fact, the TEROS 21 provides an even more accurate soil moisture picture than measuring water content alone. A water content sensor only shows the percentage of water in the soil, but add a TEROS 21 water potential sensor, and you’ll know if that water is available to plants and where it will move. Plus, unlike water content, matric potential isn’t dependent on soil type, so you can compare moisture between different sites. Not only that, the TEROS 21 is surprisingly affordable, and the new Gen 2 version boasts an improved circuit, a more robust microprocessor, and an improved measurement range. It now measures all the way from near saturation to air dry (?5 to ?100,000 kPa) making it the world’s first true full range water potential sensor.

Coverage — Get the maximum for the minimum

Expecting to see a high price point for the extra value we engineered into TEROS 21? No way. We offer them at a low cost so you don't have to spend more money to get the coverage you need.And, because they use less energy and include a temperature sensor, you get even more value. Plus it's all backed by 15 years of research.

The only worry-free soil water potential sensor

Ease of use isn’t something you normally associate with water potential measurement devices. Until now. That’s because TEROS 21 is plug and play in a number of ways. First, once it’s in the ground, the durable epoxy coating ensures long-lasting usage. Second, no maintenance is involved. That means no refilling. And no worrying about frozen conditions. Lastly, the TEROS 21 water potential sensor is also easy to integrate into systems (SDI-12 compatible) so it can be used with third-party loggers. All this adds up to saving you time and a lot of unnecessary labor.

Soil water measuring that’s immeasurable in value

Accurate. Easy to use. Affordable. The TEROS 21 water potential sensor outperforms in every aspect because we specifically designed it to save you time, hassle and money.

Function：

Easy to use

Improved accuracy comes from the six-point factory calibration

Tough,long-lasting body

No recalibration

Low salt sensitivity

Affordability

Excellentrange(sensitivity from -5 kPa all the way to air dry[-100,000kPa])

Onboard temperature measurement

Plug and play capability

Use with the ZL6 for remote access to data on the cloud

SDI-12 compatible

TEROS 21 Soil Water Potential Sensor Specification：

Measurement Specifications	Water Potential	Range:-5 to -100,000 kPa(1.70 to 6.00 pF)
		Resolution:0 kPa
		Accuracy: ±(10% of reading + 2 kPa)from -100 to -5 kPa
		NOTE:TEROS 21 Gen 2 can read up to 0 kPa when on a wetting path.The air entrvofthe soillimits the performance of the sensor to -5 kPa on the drying curve.
	Temperature	Range:-40.00-60.00°C
		Resolution:0.10°C
		Accuracy:±1.00°C
	Dielectric Measurement Frequency	70 MHz
Communication Specifications	Output	DDI serial or SDI-12 communication protocol
Communication Specifications	Data Logger Compatibility	METERZL6,EM60,and Em50 data loggers or any data acquisition system capable of 3.6-to 15-VDC power and serial or SDI-12 communication
Physical Specifications	Dimensions	Length:9.6 cm (3.8 in) Width:3.5 cm (1.4 in) Height: 1.5 cm (0.6 in)
	Sensor Diameter	3.2 cm (1.3 in)
	Operating Temperature Range	Minimum:-40.00°℃ 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)
	Connector Types	3.5-mm stereo plug connector or stripped and tinned wires
Electrical and Timing Characteristics	Supply Voltage (VCC to GND)	Minimum: 3.6 VDC 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
	Power Line Slew Rate	Minimum:1.0 V/ms
	Current Drain (During Measurement)	Minimum:3.0 mA Typical:5.0 mA Maximum:16.0 mA
	Current Drain (While Asleep)	Minimum:0.0 mA
	Power Up Time (DDI Serial)	Maximum:50 ms
	Power Up Time(SDI-12)	Typical:175 ms
	Measurement Duration	Typical:175 ms
Other	Compliance	Manufactured under ISO 9001:2015 EM ISO/IEC 17050:2010 (CE Mark)