Measurements: Water Potential

Applications: Water Balance Studies

Typical Applications

  • Field measurements
  • Water balance, leaching, transport studies, model calibration
  • Ecological impact studies
  • Agricultural or forestal studies
  • In-situ retention curves
  • Data logger applications
  • Spot your readings in with the INFIELD7b



  • Reliable outdoor tensiometer
  • Solid construction
  • Year-round operation when installed deeper than 30 cm
  • T4e can be refilled or emptied without removing it from the soil.



  • Not for dry soils
  • Installation angle between 20° and 70°. At vertical and horizontal installation an air bubble will remain in the cup.

Part number 45201


High-strength special ceramic with homogeneous porosity

Length: 60 mm

Diameter: 24 mm


Temperature-compensated, typical shift 0.5% FS over 20K

Stability typical shift < 0.5% p.a.


Various lengths available (standard 300 mm)

Diameter: 25 mm

Material: acrylglass 19/25 mm

**Please indicate shaft length on your order!**


Piezoresistive pressure-transducer

Max. overpressure: ± 3000 hPa


-100 kPa = -100 ± 3 mV

0 kPa = 0 ± 3 mV

85 kPa = 85 ± 3 mV

Galvanic sensor insulated from soil water, signals analog and continuous

Accurate values according to the calibration certificate.

Impedance: ~.5 kOhm

MEASURING PRINCIPLE Soil water tension, transmitted via ceramic cup into the tensiometer, onto the water and pressure transducer, giving a continuous analog signal
ELECTRONIC PRINCIPLE Asymm. Wheatstone full bridge
POWER SUPPLY 10.6 VDC (5 - 15 VDC), stabilized
RANGE +100 to -85 kPa
ACCURACY ± 0.5 kPa
DATALOGGER COMPATIBILITY Campbell Scientific, Infield 7
CABLE 1.5 m: 4-pin plug M12
UMS uses UV-resistant, durable materials for long-term field studies. Seals and screw connectors are watertight according to IP 68.


  MPS-6 MPS-2 T5/T5x* T4 T8 TS1
COST $$ $ $$$ $$$ $$$$ $$$$$
ACCURACY ± 10% of reading + 2 kPa from -9 to -100 kPa ± 25% of reading + 2 kPa from -9 to -100 kPa ±0.5 kPa ±0.5 kPa ±0.5 kPa ±0.5 kPa
RANGE -9 to -100,000 kPa -9 to -100,000 kPa +100 kPa to -85 kPa (-200 kPa*) +100 kPa to -85 kPa +100 kPa to -85 kPa +100 kPa to -85 kPa
POWER REQUIREMENTS 3.6-15 V, 10 mA 3.6-15 V, 10 mA 5-15 VDC 5-15 VDC 3.6 V-15 VDC 5-15 VDC
MEASUREMENT OUTPUT Digital SDI-12 Digital SDI-12 Analog Analog Digital SDI-12, RS-485 Digital SDI-12, RS-485
METHOD USED FOR DETERMINING WATER POTENTIAL Capacitance of a ceramic matrix, 6 point calibration Capacitance of a ceramic matrix, 2 point calibration Piezoelectric pressure sensor, Wheatstone full bridge

- Long term research studies

- Natural environment monitoring

- Low cost irrigation monitoring

- Column & Spot Measurements in the Laboratory

- Small point measurements

- Long term field studies

- Vadose zone hydrology

- Long term field studies

- Vadose zone hydrology

- Long term field studies

- Vadose zone hydrology

- Monitoring in remote sites


Auger Kits for Pore Water Samplers and Tensiometer

The cutting edge of the auger has a tapered tip similar to the shape of a Tensiometer or pore water sampler.  Thus, the bore hole is large enough to insert the shaft, but the cup will have a tight and perfect fit to the soil.

The not recommendable slurrying of the cup with quartz clay can be avoided.

A divisible auger set includes:

  • Cutting edge with tapered tip
  • Handle with hammering head

Parts have threaded connection and can be extended with one or more 100 cm extension rods.


  • Simplifies installation of shafts
  • Avoids slurrying
  • Multipart - divisible - extendable
  TB-20 TB-25
  • Cutting Edge
22 mm dia. x 50 cm 26 mm dia. x 50 cm
  • Tip
20 mm dia. x 5.6 cm 24 mm dia. x 5.6 cm
  • Total length
1.25 m 1.5 m
  • For shafts with
20 mm dia. 24 mm dia.
Part no. TB-20/125 TB-25/150
Extension rod Part no. TBE-100  


Infield 7

The INFIELD7 is a multi-functional handheld read-out unit for all UMS tensiometers. Download readings to PC with accessory USB converter


  • Memory for 250 readings
  • Vertical water column compensation for Tensiometers
  • T8 and TS1 configuration
  • Carrying case
  • 4 AA batteries

Looking for a data logger for long-term installations? Contact Decagon support at 1-800-755-2751.


Lab Refill Kit for Tensiometers

Lab refill kit for tensiometers (includes T4 and T8), includes stand with clamps, adapter that fits sensor body, 500 mL bottle, pressure gauge, tubes, beaker, and refilling syringe.

Refill Kit for External Refillable Tensiometers

Refill kit for external refillable tensiometers (includes T4e and T8), includes hand-operated vacuum pump, 500 mL bottle, refill syringe, tubes and valves.

Request Support

​Email: support@decagon.com
Phone: 509-332-2756
Fax: 509-332-5158