Stevens Hydraprobe
Robust proven soil moisture sensor for the continuous and accurate measurement of soil moisture, temperature, and salinity.
Robust soil moisture sensor for the continuous and accurate measurement of soil moisture, temperature, and salinity.
The Hydraprobe is a robust sensor for the continuous and accurate measurement of soil moisture, temperature, and salinity.
- Robust and reliable, used to ground truth NASA satellite measurements
- Uses Coaxial Impedance Dielectric Reflectometry
- SDI-12, RS485, or Modbus output options
Stevens Hydraprobe
Technical Specifications
Measurement 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 | Up to 0.5 to 1.0 S/m (5 to 10 dS/m)*** | 0.001 |
| Pore Water EC | N/A | must have > 0.10 wfv | 0.001 |
| Temperature | ± 0.3°C | -40°C to +75°C | 0.1°C |
| Inter-sensor variability | ± 0.012 WFV (θ m3 m-3) | n/a | n/a |
Electrical And Communication
| SDI-12 | RS-485 | Modbus | |
| Power supply | 9-16 VDC | 9-16 VDC | 9-16 VDC |
| Power consumption | 1 mA idle / 25 mA active | 2.5 mA idle / 25 mA active | 2.5 mA idle / 25 mA active |
| Cable | 3-wire: power, ground, data | 4-wire: power, ground, com+, com- | 4-wire: power, ground, A, B |
| Max. cable length | 60 m | 1,219 m Non-spliced: 304.8 m |
1,219 m Non-spliced: 304.8 m |
| Baud Rate | 1200 | 9600 | 1200-115200 9600 (default) |
| Communication protocol | SDI-12 Standard v. 1.2 | Custom or open spec | Modbus RTU |
Environmental
| Operating temperature range | -40°C to +75°C** |
| Storage temperature range | -40°C to +75°C |
| Water resistance | Tolerates continuous full immersion |
| Cable | 18 gauge (SDI-12) / 22 gauge (RS-485 and Modbus), UV resistant, direct burial |
| Vibration and shock resistance | Excellent; potted components in PVC housing and 304 grade stainless steel tines |
| * Accuracy may vary with some soil textures. ** Temperature Test Certificate from -40°C to 75°C available |
Physical Dimensions
| Length | 124 mm |
| Diameter | 42 mm |
| Weight | 200 g Optional slim housing version available: 184 g |
| Cable weight | 80g/m |
| Sensing volume | Length: 5.7 cm Cylindrical region: 3.0 cm diameter |
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Case Studies
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