HydraProbe
Meet the HydraProbe. A rugged soil sensor with patented technology to measure the three most significant soil parameters—moisture, electrical conductivity* and temperature. The HydraProbe is the most scientifically researched soil sensor available and is depended on by the USDA, NOAA, farmers, leading irrigation companies, and universities for over 25 years. It has been engineered to handle the terrain you want to measure and provides data you can trust year after year.
The Science Behind HydraProbe
HydraProbe was originally developed by the physics department at Dartmouth College. It’s “dielectric impedance” measurement principle differs from TDR, capacitance, and frequency soil sensors by taking into account the energy storage and energy loss across the soil area using a 50 MHz radio frequency wave.
Unlike other soil sensors, this unique, patented method separates the energy storage (real dielectric permittivity) from the energy losses (imaginary dielectric permittivity). Complex mathematical computations performed by an onboard microprocessor process the reflected signal measurements to accurately determine the soil’s dielectric permittivities—the key parameters behind the soil moisture and bulk EC measurement.
The HydraProbe’s detailed mathematical and signal characterization of the dielectric spectrum helps factor out errors in the soil moisture measurement such as temperature effects, errors due to salinity, and soil type. Low inner-sensor variability means there is no need for sensor-specific calibrations.
This method has passed the most rigorous scientific peer review from dozens of journals such as the Vadose Zone Journal, American Geophysical Union, and The Journal of Soil Science Society of America.
1.strong, non-bending, non-corrosive stainless steal tines
2.fully potted electronics-immersible in water
3.Durable 18 gauge, UV-resistant high-density polyethylene cable can remain buried or be exposed to the elemetes
Patented Sensor Technology
HydraProbe uses unique “Coaxial Impedance Dielectric Reflectometry” to provide consistent long-term accuracy of moisture, salinity and temperature in any soil type. This also provides low inter-sensor variability, so every sensor measures the same without the need to calibrate.
Reliable
Continual, long-term data without calibration.
1.Stable—no sensor drift, ensuring continual accuracy.
2.Patented technology that accurately measures moisture and electrical conductivity permits more accurate optimization of watering and fertilization than with just moisture.
3.Depended on by the USDA, NOAA, leading irrigation companies, and many universities for over 20 years. Used by NASA for ground truthing of satellite-based soil imaging.
4.Soil moisture calibration has been rigorously peer-reviewed, making it one of the most trusted soil sensors available.
Accurate
Consistent research-grade accuracy every season, every location.
1.Unparalleled spatial and temporal measurement consistency. No sensor-to-sensor variations across locations, seasons, soil types or moisture range.
2.Instant measurement of the 3 most significant soil parameters simultaneously—moisture, salinity and temperature.
3.Unlike most TDR or capacitance-based sensors, HydraProbe is less sensitive to changes in temperature, salinity, and soil mineralogy.
Simple
Forget calibrating, ignore the soil type. Just set it and forget it.
1.Repeatable accuracy and stability without the need for calibration in most soils.
2.Digital sensor using the SDI-12 protocol—no setup, just connect to data logger. Compatible with any SDI-12 capable data logger.
3.Zero maintenance required.
Rugged
Durable stainless steel tines, fully potted components and a 5-year warranty.
1.Can remain in-situ indefinitely, or relocated and redeployed without worry.
2.Ideal for remote locations, harsh environments and applications where data is critical.
3.Enables measurement of native (undisturbed) soil, even hard-packed clay.
4.Industry-leading 5-year warranty.
3 New Models
HydraProbe STANDARD
VWC (% Moisture)
Temperature
3 soil calibrations
5-year warranty
HydraProbe PROFESSIONAL
Everything the STANDARD model has plus:
Electrical Conductivity (EC)
Thermal compensation
Pore water EC
5 soil calibrations
10-year warranty
NIST Traceability
HydraProbe PROFESSIONAL
Everything the PROFESSIONAL model has plus:
Extended temperature range
Technical Specifications
MEASUREMENT | ACCURACY | RANGE | RESOLUTION |
---|---|---|---|
Real dielectric permittivity (isolated) | ± 0.5% or ± 0.2 dielectric units | 1 to 80 where 1 = air, 80 = distilled water | 0.001 |
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) | 0.001 |
Bulk electrical conductivity | ± 2.0% or 0.02 S/m whichever is typically greater | 0 to 1.5 S/m | 0.001 |
Temperature** | ± 0.3°C | -10°C to +60°C | 0.1°C |
Inter-sensor variability | ± 0.012 WFV (θ m3 m-3) | n/a | |
ELECTRICAL | |||
SDI-12 | RS-485 | ||
Power supply | 9-20 VDC | 9-20 VDC | |
Power consumption | 1 mA idle / 10 mA active for 2 seconds during duty cycle | 10 mA idle / 30 mA active | |
Cable | 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 | |
Communication protocol | SDI-12 Standard v. 1.2 | Custom or open spec | |
Addressing | Serial; allows multiple sensors to be connected to any RS485 or SDI-12 data logger via a single cable. | ||
ENVIRONMENTAL | |||
Operating temperature range |
| ||
Storage temperature range | -40°C to +65°C | ||
Water resistance | Tolerates continuous full immersion | ||
Cable | 18 gauge (22 gauge for RS-485 version), UV resistant, direct burial | ||
Vibration and shock resistance | Excellent; potted components in PVC housing and 304 grade stainless steel tines | ||
PHYSICAL | |||
Length | 4.9” (124 mm) | ||
Diameter | 1.6” (42 mm) Optional slim housing version available: 1.4" (35.8 mm) | ||
Weight | 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) | ||
MEASUREMENT PARAMETERS | |||
1 | Voltage 1 | ||
2 | Voltage 2 | ||
3 | Voltage 3 | ||
4 | Voltage 4 | ||
5 | Voltage 5 | ||
6 | Soil Temperature in Celsius | ||
7 | Soil Temperature in Fahrenheit | ||
8 | Water fraction by volume | ||
9 | Loss Tangent | ||
10 | Soil Conductivity (temperature corrected) in Siemens / meter | ||
11 | Real dialectric permittivity | ||
12 | Real dielectric permittivity (temperature corrected) | ||
13 | Imaginary dialectric permittivity | ||
13 | Imaginary dialectric permittivity (temperature corrected) | ||
15 | Soil conductivity in Seimens / meter | ||
16 | Diode Temperature in Celsius | ||
17 | Saved for future development | ||
18 | ADC Reading 1 | ||
19 | ADC Reading 2 | ||
20 | ADC Reading 3 | ||
21 | ADC Reading 4 | ||
22 | ADC Reading 5 |