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Testimonials
Lecturer in Physical Geography
University of Newcastle
Choosing equipment that you have complete trust in to record the data you need, and, importantly, technical backup when challenges arise, were fundamental requirements for us. When you are running out of time (and daylight) in a remote banana field it was reassuring that someone at Delta-T was responding so quickly to our technical questions.
The Delta-T devices kit has been first class – it has not missed a beat since we installed the equipment. We now plan to leave the SM150T sensors in-situ after the project to continue developing our understanding of the soil-water fluxes under banana crops." Prof Jerry Knox
Cranfield Water Science Institute,
Cranfield University, UK
Bern University of Applied Sciences
York University, Toronto
Stable and accurate (± 3%) - Robust and buriable with 5 year warranty*
- Accurate substrate moisture monitoring
- Ideal for precision irrigation
The SM150T is an affordable soil moisture and temperature sensor that is ideal for system integrators
SM150 Sensor – a versatile sensor for growers and system integrators
The SM150T is the perfect sensor for a wide range of applications in horticulture and agriculture. It can be used in both soils and substrates and is buriable. In addition, the SM150T offers excellent salinity and temperature stability.
The SM150T is a reliable and cost-effective solution for system integrators, who appreciate its ease of installation and simple interface (0 – 1 V DC output).
SM150 Kit – for instant readings
The SM150 Kit combines the SM150T Sensor with a handy readout meter, providing growers with a low cost, portable, and easy to use tool for obtaining instant accurate moisture measurements. Find out more about the SM150 Kit.
NB: When used in portable mode the SM150T Sensor does not provide temperature indication. To record temperature the sensor must be fully buried and connected to a suitable data logger.
Easy installation
The SM150T’s sharp pins minimise soil disturbance, preserving the original soil structure around the measurement rods, and making the probe easy to insert and install. For burial at depth the cylindrical shape facilitates installation in augered holes. Optional extension tubes assist with placement and removal (50 cm and 100 cm lengths, connectable).
Applications
Horticulture – In kit form (see SM150 Kit) the SM150T Sensor comes with calibrations for mineral, peat mix, coir, mineral wool and perlite (plus also provides raw voltage output) – providing a simple, effective, rugged solution to checking the uniformity of growing conditions for many types of growing media.
Precision Irrigation – Accuracy and ease of use make SM150T Soil Moisture Sensors well suited to precision irrigation applications. The SM150T’s compact size (143mm total length – rods 51mm long) allows it to be easily installed in plant pots or grow bags. Readings can be used to optimise irrigation scheduling, or the SM150T can be installed as part of an automatic irrigation system.
System integration – The SM150Ts accurate and stable measurement (± 3% for 0-70% VWC** range), simple 0-1 V output (moisture), and low power (18 mA for 1 second) makes it the ideal sensor for system integrators.
Patented sensor electronics produce research-grade accuracy performance alongside exceptional salinity and temperature stability – an essential combination for critical control and precision irrigation decisions.
Industrial rated, UV resistant cable fitted with a waterproof IP68 connector allows the sensor to be buried indefinitely, whilst still permitting easy cable exchange or extension if necessary.
More information is available in the SM150T System Integrator Data Sheet.
Data logging
The SM150T is compatible with all Delta-T Devices Data Loggers and its 0 to 1 V DC output can be handled by most other types of data logger. Temperature measurement (10 K thermistor) requires burial of the probe.
Product history
The new SM150T replaces both the SM300 and SM150 Sensors, combining their strengths and offering great value.
* Extended 5 year warranty requires online registration.
**Volumetric water content
Specification
| Measurement | Volumetric water content and soil temperature |
| Accuracy | ± 0.03 m3.m-3 (3%) With soil-specific calibration |
| ± 0.5°C (0 to 40°C for temp sensor) ± 0.75°C (-20 to +60°C for temp sensor) | |
| Soil moisture measurement range | Full accuracy over: 0 to 0.7 m3.m-3 |
| Full range : 0 to 1.0 m3.m-3 | |
| Salinity range | 50 to 500 mS.m-1 |
| Salinity errors < 0.035 m3.m-3 from 0.05 to 0.4 m3.m-3. Can be calibrated up to 2000 mS.m-1 | |
| Temperature range | Full accuracy over: 0 to 40°C |
| Output | 0 to 1.0 V differential Corresponding to 0 to ~0.6 m3.m-3 |
| Resistance 5.8Ω to 28Ω for temp sensor | |
| Power requirement | 5-14 V, ~18 mA for 1s |
| Minimum 5 V with 100 m cable | |
| Environmental | IP68 (-40 to +70°C) |
| Sample volume | ~55 x 70 mm diameter |
| Sample volume is weighted towards soil immediately surrounding the rods | |
| Dimensions and weight | Overall: 143 x 40 mm diameter Rods: 51 mm x 2.5 mm diameter Weight: 0.1 kg (exc. cable) |
| 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
- SM150T System Integrator Data Sheet 3 MB
Filename: SM150T_System_Integrator_data_sheet_v.1
Case Studies
- Cranfield University - Using SM150T to improve banana irrigation management in ColombiaDownloadFilename: →
- SM150T Soil Sensor used by Rothamsted Research for major experiment 3 MBDownloadFilename: Case_Study_Delta-T_Rothamsted_2021
- NIAB EMR's WET Centre uses Delta-T soil moisture sensors to achieve record yields 3 MBDownloadFilename: NIAB_EMR_WET_Centre_Case_Study_ver_20_02_2021
- Seven brief Delta-T Devices soil moisture sensor case studiesDownloadFilename: →
- Newcastle University uses SM150T in Iceland erosion research - case study 3 MBDownloadFilename: SM150T_Iceland_erosion_case_study_Newcastle_Uni_v.1
Videos
Manuals
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. - How do I use the SM150T Soil Moisture Sensor for side insertion into small growing pots?
Question
How do I use the SM150T Soil Moisture Sensor for side insertion into small growing pots?
Answer
The SM150T sensors are well suited to this application as their pins are thinner and sharper than those of the Delta-T ML3 Sensor. It is often possible to push the pins through the sides of a pot and into the media.
You need to take great care when doing this to:- Minimise compression of the soil. A soft container could mean you squash the sides and deform the soil, which then has an altered bulk density, resulting in the volumetric water content reading being changed.
- Minimise movement of the pins inside the container; this can disturb the media, creating air spaces around the pins
If in doubt, pierce the pots before you start (with a small drill, for example).
As an alternative approach for spot-checking, some growers remove the plant, root ball and soil from the pot and then insert the sensor exactly where they want – the sharp pins make this easy. (Once a plant is established, the whole pot contents come out together). - Are Delta-T soil moisture sensors waterproof? Can they be buried? (SM150T ML3 ThetaProbe)
Question
I see that the environmental protection rating for Delta-T soil moisture sensors is IP68. In practical terms what does this mean for the performance of the sensors and their cable connections, and can they be buried?
Answer
The IP68 Standard
The IP standard defines the degree of protection against the entry of water and dust that an instrument has. The first digit corresponds to performance for dust protection, the second figure for the level of water resistance. A rating of IP68 means that a device is completely sealed against dust and that it can withstand complete and continuous submersion in water. More information on the standard can be found here: https://en.wikipedia.org/wiki/IP_Code.
When Delta-T develop products for use in the field, we not only aim to meet the requirements of relevant IP standards, but, where possible, to surpass them. Our product design and testing aims to establish the highest performance we can achieve for the sensor and the cable connection.Sensor sealing
During the design of the *SM150, SM150T, *SM300 and ML3 sensors, extensive water resistance tests were performed with reference to IP68 standards. Thermal shock tests were also carried out, which involved continuously monitoring the humidity inside the sensor as it was subjected to temperatures above 100OC before being plunged into ice cold water. It was demonstrated that, even under these harsh ‘shock’ regimes, the sensors showed no signs of water ingress.M12 connector sealing
During the design stage of the ML3 ThetaProbe (our most recently released sensor) we completed a comprehensive range of tests on the M12 cable connector (also fitted to several other Delta-T soil moisture sensors) to ensure satisfactory water resistance when submerged in water at depth.These tests will continue and results made available. Test results so far indicate that the M12 connection with the soil sensor can withstand burial to a depth of 2m – providing care is taken to ensure the connectors are clean and dry when assembled, and that they are hand-tightened securely.Routine production testing
*SM300s, *SM150, SM150T and ML3 sensors are batch tested using the hot water leak test – which involves submerging a proportion of sensors from a manufacturing batch in a 60°C water bath for a fixed time whilst checking for bubbles emerging from the sensor or connector. In terms of pressure, this treatment is comparable to an immersion in 1.4m depth of water. We have determined that this an acceptable test to discover assembly errors.
5 year warranty
All Delta-T products will benefit from a 2 year warranty. However, for additional peace of mind, once you have registered your SM150T or ML3 soil moisture sensor with us, the warranty increases from 2 years to 5 years.*SM300 and SM150 are now discontinued
Regulatory Information
- SM150_2004_108_EC_certificate 59 KBDownloadFilename: sm150_2004_108_ec_certificate