Soil Sensors

Moisture, EC (Salinity), Temperature

Stevens HydraProbe

HydraProbe is a rugged soil sensor with patented technology that provides continual, consistent accuracy measuring a number of parameters including the three most significant soil parameters simultaneously— moisture, salinity and temperature.

As the most scientifically researched soil sensor available, it has been depended on by the USDA, NOAA, leading irrigation companies, and many universities for over 10 years. HydraProbe has been engineered to be exceptionally rugged and will provide data you can trust year after year.

  • RELIABLE: Continual, long-term data without calibration.
  • RUGGED: Durable stainless steel tines, fully potted components, compact sealed design and a 5-year warranty.
  • SIMPLE: Set it and forget it.
  • ACCURATE: Consistent research-grade accuracy every season, every location.

Available in SDI-12 and analog versions.

HydraProbe Field Portable

Take soil measurements anywhere, without the effort or expense of setting up a permanent soil monitoring system. Your smartphone communicates wirelessly with the HydraProbe using an ad-hoc wi-fi network created by the HydraProbe Field Portable.

Simply insert the probe into the soil, and tap on the “Sample” button in the app. The location of each measurement is recorded along with the soil measurement data. All data can be saved and emailed as a .CSV for analysis in Excel.

Hydra Data Reader

The Stevens Hydra Data Reader acquires, displays, and logs data directly from the analog HydraProbe Sensor. The Hydra Data Reader converts raw HydraProbe voltages directly into soil moisture, salinity, and temperature readings without requiring any further processing or calibration. Data can then be logged, stored and downloaded to a PC for analysis, or the unit may be put in direct read only mode.


The patented HydraProbe sensor is also available integrated with a pro-quality GPS in a portable, rechargeable package. POGO is ideal for golf and sports turf applications for instantaneous measurement of soil moisture, salinity (EC) and temperature. Data is logged is displayed in real-time on a free app for smartphones or tablets, and can be synchronized with the cloud-based POGO Turf Pro software, which provides consultant-level, detailed analysis of data, reports, and alerts.

Matric Potential


The TensioMark measures the soil water potential or matric potential. The soil matric potential is the pressure it takes to pull water out of the soil and is an indicator of stress to plants and crops, can be used to determine soil water fluxes and available water held in the soil. Water equilibrates with the ceramic tip portion of the sensor where the heat capacitance is measured. The matric potential is then calculated from the thermal storage properties of the soil, based on a sensor specific calibration.

Because the TensioMark bases its measurements on the thermal properties of the soil, it does not need to be calibrated by the user, does not need to be filled with water, has excellent accuracy and stability, and a much larger range than any conventional tensiometer.

  • Can have ranges that can capture very dry conditions.
  • Quick response to changes on soil moisture.
  • Low inner sensor hydrological hysteresis and variability.
  • Not sensitive to soil salinity.
  • Quick equilibration time.
  • Not damaged by frost.
  • Maintenance-free (no filling required).
  • No calibration needed.