- Overview
- Specification
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Testimonials
Scientific Coordinator at the Jena Experiment, Germany
(DFG-funded Research Unit)
- Soil moisture content profiles down to 1m
- Dual purpose – installed and portable
- Uses access tubes for easy probe insertion and removal
- SDI-12 interface option available
No other soil moisture probe system enables you to monitor your soil water profiles with such ease and flexibility. Install an access tube into the soil, insert the PR2 Profile Probe and press the HH2 [Read] button to display an instantaneous reading, or connect the PR2 to a data logger (GP2 or DL6) and leave the system to record soil moisture changes over time.
Video – Introduction to PR2 Profile Probe
The PR2 soil moisture probe is built around patented sensing technology which provides unprecedented performance in all soil types, with minimal influence from either salinity or temperature. The PR2/4 model measures soil moisture at 4 depths down to 40 cm – the PR2/6 measures at 6 depths down to 100 cm.
Both analogue and SDI-12 interfaces are available for the PR2. Click here for information on SDI-12 Profile Probes.
- Highly reliable field-proven instrument
- Soil moisture content – not just trends
- Out of the box solution – supplied with calibrations for common soil types
- Portable meter option for multi-site measurement
The PR2 Profile Probe is available in two sizes to measure to a depth of 40 cm or 100 cm.
The PR2/4 has sensing elements at 10/20/30/40 cm
The PR2/6 has sensing elements at 10/20/30/40/60 and 100 cm
HH2 Meter
The HH2 is a versatile readout unit that provides an easy and convenient way to display and store readings from Profile Probes. With the HH2 and PR2 combination, a probe can be moved from access tube to access tube, enabling large amounts of soil moisture data to be collected at multiple sites.
Data Logging
Profile Probes are available with analogue or SDI-12 outputs.
For the analogue version, order PR2/4 or PR2/6.
For the SDI-12 interface version, order PR2/4-SDI-12 or PR2/6-SDI-12.
Please note that analogue and SDI‐12 probes cannot be mixed on the same cable system
Loggers for analogue Profile Probes
Delta-T offers a choice of two data suitable data loggers. Both have dedicated PR2 Profile Probe input channels and connectors:
The DL6 Data Logger can log one PR2/6 or one PR2/4 Profile Probe
The GP2 Data Logger can log up to two PR2/6s or three PR2/4s
Loggers for SDI-12 Profile Probes
The PR2 SDI‐12 is ideally matched to the SDI‐12 enabled GP2 Data Logger. Many SDI-12 Profile Probes can be connected to a single GP2 (actual number depends on cable length, power, and other considerations).
Further details of the PR2 SDI-12 can be found here.
Augering and Extraction Kits – for optimal Access Tube installation
Profile Probes are used within access tubes inserted into augered holes in the soil – correct installation is vital for accurate measurement of soil moisture profiles. The goal of installation is to produce optimal contact between the soil and the wall of the access tube. The augered holes should be straight, smooth sided and the correct diameter.
Delta-T augering kits help you achieve the best possible access tube installation in virtually any soil.
Click here for information about our augering equipment
Specification
For Analogue PR2 and SDI-12 PR2
| Measurement | Volumetric water content |
| Accuracy | ± 0.04 m3.m-3 (4%) With soil-specific calibration |
| Soil moisture measurement range | Full accuracy over: 0 to 0.4 m3.m-3 |
| Full range : 0 to 1.0 m3.m-3 | |
| Salinity range | 50 to 400 mS.m-1 |
| Salinity errors included in calibration | |
| Temperature range | Full accuracy over: 0 to 40°C |
| Output | (ANALOGUE) 0 to 1.0 V differential PR2/6: x6 outputs, PR2/4: x4 |
| (SDI-12) Digital | |
| Power requirement | (ANALOGUE) 5.5-15 V, PR2/6: ~120 mA for 1s PR2/4: ~80 mA for 1s __________________________ Minimum 7.5 V with 100 m cable |
| (SDI-12) Power consumption <60 mA at 12 V DC Sleep current <2 mA at 12 V DC | |
| Environmental | IP67 (when installed in access tube) |
| Sample volume | -95% sensitivity within a cylinder of diameter 200mm |
| Sample volume is weighted towards soil immediately surrounding the rods | |
| Dimensions and weight | PR2/6: length 1350 mm PR2/4: length 750 mm Both: 25.4 mm diameter PR2/6: weight 1.2 kg PR2/4: weight 0.8 kg |
| Sensor calibrations | Individual sensors are interchangeable Recalibration advised every 3 years (depending on use) |
| Soil calibrations | Generalised Mineral and Organic soil calibrations are supplied |
Accessories
Hardware
Main components and software
Mountings and enclosures
Installation accessories
Cables and networks
Remote communications
Spares and consumables
Power options
Other
Product Resources
Data Sheets
- PR2 Profile Probe SDI-12 Data Sheet 1 MB
Filename: PR2_SDI-12_v.2 - Soil Moisture Measurement Catalogue 14 MB
Filename: Soil_Moisture_Measurement_Catalogue_ver_5
Case Studies
- PR2 Futmon Case Study 638 KBDownloadFilename: pr2_futmon_case_study_ver_1
- The Jena Experiment - extensive use of PR2 Profile Probe in major ecosystem research project 4 MB
The Jena Experiment is a long‐term biodiversity focused research project funded by the German Research Foundation (DFG). The PR2 Profile Probe has been an important part of the Jena Experiment's sensor network for nearly the entirety of the long running project.
DownloadFilename: The_Jena_Experiment_case_study_PR2_Profile_Probe_10.02.21 - Seven brief Delta-T Devices soil moisture sensor case studiesDownloadFilename: →
- Cranfield University use the PR2 to explore how tillage affects water transport through the soil profile 2 MBDownloadFilename: PR2_Cranfield_tillage_research_case_study_version_1
Videos
Manuals
- PR2 Profile Probe User Manual ver 5.0 2 MB
PR2 Profile Probe User Manual v3.0 Jan 2008. Document Code: PR2-UM-3.0
DownloadFilename: PR2_user_manual_version_5.0
User Manual with specs, performance, installation and operating instructions. See also PR2 Augering Kits UM and QSG. - PR2 Profile Probe Quick Start Guide 3 MB
PR2 Profile Probe Quick Start Guide v2.0, 2008
DownloadFilename: pr2-profile-probe-qsg
Quick Start Guide. See also PR2 UM and PR2 Augering UM and Kits QSG. - PR2 SDI-12 User Manual 2 MBDownloadFilename: pr2_sdi-12-_user_manual_version_4_1
- PR2 Augering User Manual 3 MB
User Manual for Augering Kits for Profile Probe access tubes. The manual describes how to install short and long access tubes in most soils using the Delta-T range of augering tools and equipment. The information contains important and essential guidance on creating good installations, which applies to both PR2 and PR1 Profile Probes.
DownloadFilename: aug-augering-user-manual-v2-0 - PR2 Augering Quick Start Guide 4 MB
QSG forProfile Probe access tube Augering Kits. Briefly describes how to install short and long access tubes in most soils using the Delta-T range of augering tools and equipment.
DownloadFilename: aug-augering-quick-start-guide-v1-0 - Augering Health and Safety Sheet v1.0 47 KBDownloadFilename: augering-health-and-safety-sheet-v1-0
FAQs
- Setting up an M12 cable network to ensure a waterproof and secure connection.
Question
What is the best practice for setting up a M12 cable network to ensure a waterproof and secure connection..
Answer
It applies to:
GP2 for SDI-12 and logger networks.
Celora for SDI-12 networks.
All sensors with M12 connector cables.Examples of SDI-12 network and GP2 logger networks:
DO
When connecting multiple cables and T-piece together, it is essential that any M12 connector is tightened sufficiently:
• Ensure internal connector O-ring and opposite sealing face are free from dirt.
• Tighten the connector thumbscrews as much as you can by hand or use a torque driver set to 1Nm to be sure. See video:We recommend the Weidmuller “1900021000” torque driver:
• This will save lots of painstaking troubleshooting hours if you do have a loose connection and give you piece of mind that all connectors are correctly tightened.
• Untightened connectors can come undone and let water into the cable network which can damage wire cores and cause erroneous readings.
Connect in the office first and then transfer the network to the field. This way, you’re not trying to do it in unpleasant weather and the time pressures are off.
DON’T
Use duct tape. This will hold water against the connector. If tightened correctly, the connector will seal and hold. - What effect will air gaps around the PR2 Profile Probe Access Tube have?
Question
What effect will air gaps around the PR2 Profile Probe Access Tube have?
Answer
When installing access tubes, air gaps between the outside of the tube and the soil must be minimised for accurate readings.
The most important thing you can do to ensure accurate readings from the Profile Probe is to minimise air gaps around the access tube. Be careful when augering holes not to create a funnel-shaped hole by waggling the top of the auger, and be prepared to start again if you encounter avoidable stones or roots.
Air gaps can create serious errors in the readings. The Profile Probe is sensitive to the water content of the soil around its pairs of stainless steel rings. This sensitivity is biased towards the soil closest to the rings. Air gaps immediately around the access tube reduce the accuracy of the reading in two ways – firstly the sensors will measure some air instead of moist soil, but also the air gap reduces the penetration of the electromagnetic field into the surrounding soil.
It is virtually impossible to quantify the magnitude of errors from air gaps.
If air gaps are suspected, they can sometimes be diagnosed if the soil moisture content at a particular depth is anomalously low. Also, the reading at that depth may show a diminished range of variation in time, in relation to a known wetting event. However, if saturation and flooding of the soil around the tube occurs, the water content signal may exceed that at neighbouring depths.
After installation of the access tube, air gaps might be expected to close up with natural settlement of the loosened soil. However it is not easy to say how soon, or to what extent, this may occur.
- How do you insert large diameter cables (e.g. SPN1/BF5 cables) into the GP1/GP2/DL6 cable glands? – Video Guide
Question
How do you insert large diameter cables (e.g. SPN1/BF5 cables) into the GP1/DL6 cable glands? - Video Guide
Answer
The following video explains the best way that this can be done:
https://www.dropbox.com/s/lx9oyan70i75sgu/8%20way%20cable%20with%20sound.wmv?dl=0
Example in video is 8-way BF5 cable and GP1.
The GP2 logger has an optional expansion lid (GP2-G5-LID), which contains larger cable gland sizes to help with large diameter cables.
- How do I use the augering equipment and take measurements with a PR2 Profile Probe? – Video Guide
Question
How do I use the augering equipment and take measurements with a PR2 Profile Probe? - Video Guide
Answer
We would always recommend reading through the PR2 profile probe user manual and our augering user manual for the most up to date information on this topic. In addition, we have released this video to help:
- How can I create soil-specific calibrations for my PR2 Profile Probe?
Question
How can I create soil-specific calibrations for my PR2 Profile Probe?
Answer
The Profile Probe User Manual recommends that you use a Theta Probe (ML2x or ML2) to do a two-point soil-specific calibration.
You need to measure the moisture content of a wet sample of your soil, using the Theta Probe, and then oven-dry the sample and measure its water content once again.
The process is fully described in the Theta Probe User Manual and is also available in a detailed application note available from Delta-T. This should enable you to decide if the possible gain in accuracy is worth the additional effort of the calibration.
If you do not possess a Theta Probe, please contact your distributor or Delta-T for advice. The User Manual is available by email in electronic Acrobat pdf file format (and may be available for download from the Delta-T website).
Regulatory Information
- PR2 Profile Probe EC Declaration of Conformity 34 KBDownloadFilename: pr2-profile-probe-ec-declaration-of-conformity