Soil Moisture and Salinity Sensor - HydraProbe

• MEASUREMENT: Soil moisture for inorganic & mineral soil
± 0.01 WFV for most soils
± ≤0.03 max for fine textured soils
• RANGE: From completely dry to fully saturated (from 0% to 100% of saturation)

  • Model Number: HydraProbe
  • Data Sheet: Date Sheet File
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  • Soil Moisture and Salinity Sensor
  • Soil Moisture and Salinity Sensor
  • Soil Moisture and Salinity Sensor
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Product Specification

HydraProbe Soil Moisture and Salinity Sensor Description
HydraProbe is a rugged soil sensor with patented technology that provides continual, consistent accuracy measuring 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, NASA, leading irrigation companies, and many universities for over 20 years. It’s been engineered to be exceptionally rugged and will provide data that you can trust year after year.

HydraProbe to Go
The HydraProbe Field Portable puts the power of HydraProbe in the palm of your hand.
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.

HydraProbe Soil Moisture and Salinity Sensor TECHNICAL SPECIFICATIONS
Real dielectric permittivity
< ± 0.5% or ± 0.2 dielectric units
1 to 80 where 1 = air,
80 = distilled water
Soil moisture for inorganic
& mineral soil
± 0.01 WFV for most soils
± ≤0.03 max for fine textured soils*
From completely dry to fully saturated
(from 0% to 100% of saturation)
Bulk electrical conductivity
± 2.0% or 0.02 S/m whichever is 
typically greater*

0 to 1.5 S/m
± 0.3° C
-10°C to +60° C
Inter-sensor variability
± 0.012 WFV (θ m3 m-3 )

* Accuracy may vary with some soil textures. 
** Extended temperature range sensor (down to -40° C) available

Electrical and Communication

Power supply
9-20 VDC
9-20 VDC
Power consumption
<1 mA idle / 10 mA active
<1 mA idle / 30 mA active
3-wire: power, ground, data
4-wire: power, ground, com+, com-
Max. cable length
60 m (197 ft.)
1,219 m (4,000 ft.)
Non-spliced: 304.8 m (1,000 ft.)
Baud Rate
1200 9600

SDI-12 Standard v. 1.2
Custom or open spec
Serial; allows multiple sensors to be connected to any RS485 or SDI-12 data logger via a single cable.

Operating Temperatures
• In soils: freezing to +60° C
• Standard temperature probe range: -10° C to +60° C
• Extended temperature probe range: -40° C to +60° C*
Storage Temperatures
-40° C to +60° C
Water Resistance
Tolerates continuous full immersion
18 gauge (20 gauge for RS-485/analog), UV resistant, direct burial
Vibration and shock resistance
Excellent; potted components in PVC housing and 304 grade 
stainless steel tines

4.9” (124 mm)
1.6” (42 mm). Optional slim housing version available: 1.4” (35.8 mm)
7 oz. (200 g). Optional slim housing version available: 6.5 oz. (184 g)
Cable weight
0.86 oz/ft (80g/m)
Sensing volume (cylindrical region)
Length: 2.2” (5.7 cm)
Diameter: 1.2” (3.0 cm)
* ”Extended Temperature Range” version available, which can measure down to -40° F (-40° C) for research, cold-climate, high-altitude, arctic applications or any ot her measurement situation where there will be significant below-freezing ground temperatures.

HydraProbe Soil Moisture and Salinity Sensor ORDERING INFORMATION
93640-025 / 63646-025
HydraProbe with 25’ (7.62 m) cable, SDI-12 / RS485
93640-050 / 63646-050
HydraProbe with 50’ (15.24 m) of cable, SDI-12 / RS485
93640-100 / 63646-100
HydraProbe with 100’ (30.48 m) of cable, SDI-12 / RS485
HydraProbe Field Portable

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