Soil Moisture & Temperature Sensors

CWi Technical Ltd select sensors for inclusion in their systems based on quality, accuracy and reliability. If a sensor is in our list, it means we have the utmost confidence in its performance and reliability, and it fits the quality criteria for inclusion in datashare.

ML2 Theta Probe

The theta probe from delta-T devices is a world renowned soil moisture sensor which transmits volumetric soil water content using the well established method of responding to changes in apparent dielectric constant. These changes are converted to DC voltage and are virtually proportional to moisture content over a wide working range.

Soil moisture measurement is very sensitive to installation errors, and consequently, only soil moisture data provided by systems that we install and approve are valid on datashare.

The sensors come with 5m of cable and can be installed at any depth. extention rods are available to make deep installation easy. The sensors can be calibrated for soil specific conditions, but generally, in normal field conditions, we assume a minieral soil type and our loggers are programmed for this accordingly. If you need sensors for organic soils, a seperate program can be supplied. The reliability and accuracy is reflected in the cost, and we recommend that if you can afford the budget, you choose these sensors over others.

 
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SM300 Moisture & Temperature Probe

The SM300 sensor is a low cost soil moisture and temperature probe and is ideal for field studies where soil specific information is less critical. Its combination of moisture and temperature makes it a very cost effective sensor removing the need for an additional probe and making installation very efficient.

While the soil moisture status is good, with accuracy to 2.5% it does not match the performance of the theta probe. equally, the temperature specification is ±0.5°C and is only accurate over a 0-40C temperature range. that said, this is sufficient for most soil studies.

The sensor is rugged and weatherproof and can be buried and so is suitable for long term trials. Its cost makes it a "throw-away" item in the event of failure.

 

 
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SM150 Moisture Probe

The SM150 is a moisture only sensor developed by Delta-T devices as a low cost alternative to the SM300 and theta probes. It has a slightly lower accuracy over moisture than the SM300, and is ideal where soil temperature is not required, or where soil moisture and soil temperature are needed with differing levels of accuracy.

The sensor is rugged and can be buried, and access tubes are available for deep installations. It can be incorporated into any of our approved logger solutions.

 
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ST1 Temperature Probe

The ST1 Temperature probe is a thermistor beaded probe with a stainless steel sheath, with an accuracy of 0.1°C and a range of -20 to +60°C These sensors can be provided with large cable lengths, but we recommend no more than 20m. These sensors can be provided with a UKAS calibration certificate.

They are low cost, high accuracy and very relaible.

 
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