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223-L Soil Matric Potential Block for Multiplexer Use
Reliable Water Measurements
No maintenance required
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The 223, manufactured by Delmhorst, is a cylindrical gypsum block that estimates soil water potential from -10 to -1000 kPa. It connects to a datalogger via an AM16/32-series multiplexer.

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Benefits and Features

  • Compatible with AM16/32-series multiplexers, allowing measurement of multiple sensors
  • Multiplexer connection prevents electrolysis from prematurely destroying the probe
  • Measures a wide range of matric potential
  • Buffers salts in soil
  • No maintenance required
  • Compatible with most Campbell Scientific dataloggers

The "-L" on a product model indicates that the cable length is specified at the time of order.


Detailed Description

The 223 determines soil water potential by measuring electrical resistance. When the 223 is wet, electrical resistance is low. As the 223 dries, resistance increases.

The 223 cylindrical block is composed of gypsum cast around two concentric electrodes, which confine current flow to the interior of the block, greatly reducing potential ground loops. Gypsum located between the outer electrode and the soil creates a buffer against salts that may affect the electrical conductivity.

The 223 connects to a datalogger via an AM16/32-series multiplexer. Because the multiplexer contacts close only during measurement, electrical currents leading to premature degradation of the 223 are eliminated.

Campbell Scientific recommends removing the 223 during winter.


Material Gypsum
Measurement Range -10 to -1000 kPa
Calibration Individual calibrations are required for accurate measurements. Refer to the sensor manual for more information.
Operating Temperature Soil temperatures above freezing
Life Expectancy Two freeze-thaw cycles
Electrode Description Concentric cylinders
Center Electrode Excitation
Outer Electrode Ground
Cylinder Diameter ~2.25 cm (0.88 in.)
Cylinder Length ~2.86 cm (1.25 in.)
Weight 180 g (0.4 lb)



Multiplexers that can be used with the 223 include the AM16/32B, AM16/32A (retired), AM16/32 (retired), and AM416 (retired).

Datalogger Considerations

Two single-ended channels and one excitation channel per probe are required; the channels are shared by several probes when routed through an AM16/32-series multiplexer.

Compatible CRBasic Dataloggers

CR800/CR850 CR1000 CR3000 CR6 Series