Delta-T Devices Ltd.

- Model ML3 ThetaKit - Soil Moisture Measurement Kit


Supplied in a convenient carry case, the ThetaKit (based around the ML3 ThetaProbe Soil Moisture Sensor) contains everything you need to obtain accurate soil moisture measurements. The kit comes complete with a dedicated HH2 Moisture Meter for instant readout, an insertion tool for penetrating hard soils, and a set of spare replacement rods. With a proven reputation for reliability and robustness, the ML3 probe has extra features, improved performance and a new look. With class leading 1% accuracy it continues to set the standard for fast, easy soil moisture measurement.

  • Rapid, accurate measurement of water content in soil
  • Used by many of the world’s leading golf courses and sporting venues
  • Soil moisture with ± 1% accuracy


The leading international sports turf consultancy, STRI (Sports Turf Research Institute), provides independent advice to around 2,100 sports clubs and leisure facilities every year. Delta-T Devices has partnered with the STRI to produce a ThetaKit User Guide. This 8 page guide makes extensive use of photos and diagrams to help greenkeepers and other sports turf professionals make the most of their ThetaKit.


For over fifteen years the ThetaProbe Soil Moisture Sensor has gained a reputation among scientific researchers worldwide for its accuracy, stability, and robustness. This research grade performance is now available to turf managers – offering an unrivalled level of accuracy for the determination of soil water content.

With the ThetaKit it is possible to rapidly check irrigation uniformity and turf characteristics. Regular measurement of soil moisture content allows continual assessment of grass health – giving early warning of potential problems and enabling the turf manager to take preventative action – before damaging physical change in the turf has occurred.

  • Spot check soil moisture content quickly and easily
  • Identify areas too dry or too wet before turf problems become visible
  • Quantify background levels of water content that underpin good turf performance
  • Schedule optimised irrigation
  • Check the performance of automatic sprinklers and the uniformity of water application

Please note that although the ML3 has a built in temperature sensor, temperature can only be recorded if the probe is connected to a data logger (and the probe is fully buried). The HH2 Meter is unable to provide temperature indication.

Highly accurate yet very easy to use: With the ML3 ThetaProbe Soil Moisture Sensor it’s easy to make reliable, accurate soil moisture measurements. Simply insert the soil moisture probe into the soil, switch on the HH2 readout meter, and within seconds you can be logging soil moisture.

ML3 Soil Moisture Sensor

  • Water content
    • Accuracy: ±0.01 m3.m-3 (1%)
    • Range: 0 to 0.5 m3.m-3
    • Salinity range: 50 to 500 mS.m-1 < 0.035 m3.m-3
  • Output: 0 to 1.0V differential
  • Power: 5 to 14V, 18mA for 1s
  • Sample vol.: Approximately 60 x 30mm diameter
  • Overall size: 170 x 40mm diameter
  • Environmental: IP68, -40 to +70°C

[1] Figures apply to sensor only and exclude logger or cabling errors

  • HH2 Meter
  • Input connections: 1 water content sensor or 1 WET Sensor
  • Control outputs
  • Readings stored: 1,500
  • Recording rate
  • Configuration: By keypad
  • Communication options: RS232 / USB [1]
  • Sensor excitation: 1 switched battery
  • Power: 1 9V 6LR61 (PP3)alkaline
  • Battery life (dependent on usage): ~ 5,000 readings
  • Enclosure rating: IP54
  • Temperature range: 0 to +40°C
  • Display: 2 line x 16 character
  • Size: 125 x 80 x 45mm
  • Typical applications: Instantaneous reading of soil moisture / profiles/ WET Sensor