HydraProbe – Soil Moisture Probe

The HydraProbe – Soil Moisture Probe from the Stevens Water range. A rugged soil moisture sensor with patented technology. Provides continual and consistent accuracy to measure the three most significant soil parameters simultaneously – soil moisture, salinity and temperature.


The HydraProbe is the most scientifically researched soil moisture sensor available. Several US Government agencies depend on it daily to deliver soil moisture data they can trust. In fact, every HydraProbe Soil Moisture Logger comes with a 5 or 10 year guarantee.


The HydraProbe is also ideal for remote monitoring with our Data Collection telemetry systems. This soil moisture logger is able to connect to any system that is RS485 or SDI-12 compatible. The HydraProbe, and other soil moisture sensors all link with our vanwaltDataHub and vanwaltDataSlave telemetry systems to deliver your soil moisture data directly to your desktop. Networks of soil moisture sensors can wirelessly feed into a central point, with data delivered to whoever needs to see it. A system continuously running without the need to go onsite to collect your readings.

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The most scientifically researched soil sensor on the market, it is used extensively by the United States Department of Agriculture (USDA), National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), many of the World’s leading irrigation companies and Universities for more than 20 years. It’s been engineered by Stevens Water to be exceptionally rugged and will provide data that you can trust year after year. We are so confident in the technology: every HydraProbe comes with a 5 or 10-year guarantee.

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HydraProbe – Soil Moisture Probe Equipment Options:


  • Agriculture
  • Soil health studies
  • Soil Research
  • Crop irrigation research & optimisation
  • Irrigation optimisation studies
  • Research into crop yields
  • Water conservation research
  • Water saving & water protection studies
  • Sports turf research
  • Soil erosion prediction models
  • Environmental modelling studies
  • Flood forecasting
  • Biofuel production
  • Reservoir recharge investigations
  • Soil carbon sequestration studies
  • Watershed hydrology studies
  • Landslide studies


HydraProbe Standard
HydraProbe Pro
HydraProbe Pro-ET
VWC (% Moisture)
Temperature (C / F)
VWC (% Moisture)
Soil Conductivity
Soil Conductivity (comp)
Real Permittivity
Real Permittivity (comp)
Imaginary Permittivity
Imaginary Permittivity (comp)
Temperature (C / F)
Pore Water EC
No Outputs
All Outputs
Soil Calibrations
Measurement Commands
Support aM and aC (but not aM# and aC#)
Support all aM# and aC#
Extended Commands
Not support aXM andaXW
Support all aXM andaXW
Conformance Certificate
Factory + NIST
5 Years
10 Years
Temperature Range
-10 to 60
-10 to 60
-30 to 65

Each HydraProbe is available with cable lengths of:

7.7 m (25 ft.)
15.25 m (50 ft.)
30.5 m (100 ft.)

Each HydraProbe is available with SDI-12 or RS485 Connectivity


Scientific Studies

Main Author
Publication Date
Journal Reference
Seyfried, M. S.
Seyfried, M. S., L. E. Grant, E. Du, and K. Humes, Dielectric Loss and Calibration of the Hydra Probe Soil Water Sensor, Vadose Zone Journal 4:1070–1079 (2005).
Derivation of the HydraProbe’s general soil moisture calibration
Schnur, M. T.
Ecological Informatics. doi:10.1016 / j.ecoinf.2010.05.001
Using HydraProbe soil sensor to assess regional effects on vegetation and root zone soil moisture in arid lands.
Zamora, R. J.
Journal of Atmospheric and Oceanic Technology, 28, 1129-1140. doi:10.1175 / 2010JTECHA1465.1
Using HydraProbe to forecast floods and assess flood risk.
Leao, T. P., E. P.
American Society of Agricultural and Biological Engineers, 58(1), 83-91. doi:10.13031 / trans.58.10720
Dielectric Mixing and dielectric permittivity of heterogeneous materials.
Brocca, L. C.
Advances in Hydro-Meteorological Monitoring, Special Issue of Water, 9(140). doi:10.3390 / w9020140
Soil Moisture and its effect on climate, drought and regional weather.
Bathiany, S. V.
Science Advances, 4(5). doi:10.1126 / sciadv.aar5809
Using soil moisture measurements to make improved climate models.


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