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Soil Moisture Sensor

• Proven stable calibration
• Range of measurement from 0 to 239 cb (kPa)
• Fully solid-state
• Will not dissolve in soil
• Not affected by freezing temperatures
• Internally compensated for commonly found salinity levels
• Inexpensive, easy to install and use
• Compatible with AC or DC reading devices (specialized circuit required)
• NO maintenance required


In use since 1978, the patented WATERMARK sensor is a solid-state electrical resistance sensing device that is used to measure soil water tension. As the tension changes with water content the resistance changes as well. That resistance can be measured using the WATERMARK Sensor.
The sensor consists of a pair of highly corrosion resistant electrodes that are imbedded within a granular matrix. A current is applied to the WATERMARK to obtain a resistance value. The WATERMARK Meter or Monitor correlates the resistance to centibars (cb) or kilopascals (kPa) of soil water tension.
The WATERMARK is designed to be a permanent sensor, placed in the soil to be monitored and “read” as often as necessary with a portable or stationary device. Internally installed gypsum provides some buffering for the effect of salinity levels normally found in irrigated agricultural crops and landscapes


  •  Irrigation Scheduling
  • Water Table Monitoring
  • Leak Detection
  • Agronomy Research
  • Environmental Monitoring
  • Anywhere you need to know when or if the soil moisture status is changing

ABS plastic caps with stainless steel body over a hydrophilic fabric covered granular matrix.

Weight (mass)

.147 lb. (.067 kg) – with 5 ft. lead


Diameter: .875 in. (22 mm) Length: 3.25 in. (83 mm)