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Full-Range Calibrated Water Potential Sensor

  • Model: E-240-TEROS-21 GEN 2
  • Manufactured by: Meter (formerly Decagon / UMS)

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Product Description:

Better than ever

The TEROS 21 Gen 2 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—finally making it a true full range water potential sensor. TEROS 21 Gen 2 is part of a complete system of sensors, loggers, and software designed to reduce your workload.

What’s new with TEROS 21 Gen 2?

TEROS 21 Gen 2 Improvements

Higher quality circuit with less temperature sensitivity
−5 to −100,000 kPa makes it a true full range sensor
Improved microprocessor means less possibility of firmware corruption


  • Easy to use
  • Improved accuracy comes from the six-point factory calibration
  • Tough, long-lasting body
  • No recalibration
  • Low salt sensitivity
  • Affordability
  • Excellent range (sensitivity from -9 kPa all the way to air dry [-100,000 kPa])
  • Onboard temperature measurement
  • Plug and play capability
  • Use with the ZL6 for remote access to data on the cloud
  • SDI-12 compatible

Do not settle for less

When it comes to measuring water potential (or soil suction), it’s difficult to find a device that will meet your every need. You’re either forced to deal with lowered accuracy or high-maintenance hassles (not to mention getting soaked on cost). You wouldn’t think taking such a simple reading would be so challenging.

Highly accurate. Yet 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, 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, especially when you consider it measures across a wide range, including dry values.

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 matric 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.

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.

Coverage—Get the maximum for the minimum

This is where you may expect to see a high price point for all of the extra value we engineered into TEROS 21. Instead, we offer them at a low cost so you don’t have to spend more money to get the measurement coverage you need. Not only do more sensors for the money make more sense, but because they use less energy and include a temperature sensor, you’ll also be getting more value for your money. And it’s all backed by 15 years of research.

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.

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