Delta-T Devices Ltd.

- Model WET-2 - Soil Moisture Sensor

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The WET Sensor has crucial applications in precision horticulture and soil science research and is usable in both soils and growing substrates. It is exceptional in its ability to measure pore water conductivity (ECp), the EC of the water that is available to the plant.

Rapid checks on growing conditions

The sensor is easily inserted into substrates, composts and most soils. It takes less than 5 seconds to measure water content (%), pore water conductivity (ECp) and temperature – all being important indictors of root zone health.

Pore water conductivity

The WET Sensor is able to calculate pore water conductivity (ECp) which is the EC of the water available to plant roots. The ECp calculation is derived from an approximate relationship between dielectric properties. This applies particularly well to WET Sensor readings, which are taken at the same frequency within the same defined region of soil/substrate. The approximation is valid in most soils and is particularly accurate in mineral wool and other artificial substrates media.

Fertigation and hydroponics

Where plants are grown in artificial substrates using hydroponic or fertigation systems, nutrients are routinely supplied in irrigation water. Nutrient levels are controlled by monitoring the water content and conductivity (EC) and adjusting the injection of liquid fertiliser into the irrigation water. The Delta-T Devices WET Sensor excels in monitoring this crucial information.

Container-grown shrubs and trees

Nutrients are sometimes provided by fertigation but are often provided by Controlled Release Fertilisers (CRF). The rate at which these are taken up depends on several factors, including the weather conditions and irrigation regime.
The Delta-T Devices WET Sensor can be used to measure the EC within the growing media and so take much of the guesswork out of this process.

Soil salinity

If the irrigation water is recycled or abstracted from rivers and aquifers with high levels of dissolved salts, over time there can be a build up of soil salinity. Soil salinisation will eventually reduce crop yields. The WET Sensor is fast and efficient for sampling soil salinity, ensuring that farmers have the essential information they need to take remedial action as quickly as possible.

WET Kit

WET Sensors are normally ordered as a complete kit that includes a WET Sensor, an HH2 Moisture Meter and a handy carry case. There are three types of Kit – each with a different set of substrate calibrations. Please download our Soil Moisture Measurement catalogue for further details.

Readout and data logging

For portable applications, readout and data storage are handled by the HH2 Moisture Meter. Alternatively, the WET Sensor can be connected to the GP1 Data Logger or GP2 Data Logger and Controller, making it possible to monitor growing conditions over a period of hours, days or longer. The smart relay capability in these data loggers allows them to control water content in response to EC or temperature.

WET Sensors used aboard China’s Tiangong-2 Space Station

The WET Sensor has been used by Chinese astronauts to conduct horticultural experiments in space. find out more.

Soil and horticultural substrate calibrations

The WET Sensor is supplied with calibrations for generic mineral, organic, sand and clay soils. Special substrate calibrations can be ordered as a set for a variety of horticultural substrates which are factory installed at Delta-T Devices.

  • WET-GH-1 for coir (coco fibre), peat based potting mixes, greenhouse ‘mineral’ soils
  • WET-ST-1 for Stonewool artificial mineral wool substrate (vertical and horizontal measurement)