ML3 ThetaKit

    How to Buy
ML3 ThetaKit - with accessories Zoom
ML3 ThetaKit – taking soil measurementsML3 ThetaKit – with carry caseML3 ThetaKit – including ThetaProbeML3 ThetaProbe metal rod layout


"After 32 years of greenkeeping I thought I had a handle on the moisture requirements of my surfaces. Like most greenkeepers, I relied on a combination of experience and on-site weather data to determine irrigation requirements. But when I started to measure soil moisture content with the ML3 ThetaKit and compared the figures against irrigation inputs, the numbers just didn’t add up. At times I was over-irrigating, even though experience was telling me I was spot on. Using the ThetaKit has enabled me to apply less water, more frequently, leading to potentials savings - with the added benefits of a drier rootzone. Simply put, being armed with accurate soil moisture information has allowed me to make better agronomic decisions." Paul Brown, Course Manager
Fulwell Golf Course, Middlesex
  • 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

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 plus class leading 1% accuracy, the ML3 continues to set the standard for fast, easy soil moisture measurement.

Video – Using the ThetaKit to optimise turf health and playing surface quality

Sports Turf User Guide – co-authored with the STRI ml3_kit_user_guide_ver_1-0-thumbnail

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.

Click here to download the guide.

ThetaKit – the ideal tool for turf professionals

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.

Use the ThetaKit to:

  • 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.







MeasurementVolumetric water content and soil temperature
Accuracy± 0.01 m3.m-3 (1%)
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 rangeFull accuracy over:
0 to 0.5 m3.m-3
Full range : 0 to 1.0 m3.m-3
Salinity range50 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 rangeFull accuracy over: 0 to 40°C
Output0 to 1.0 V differential
Corresponding to 0 to ~0.6 m3.m-3
Resistance 5.8Ω to 28Ω for temp sensor
Power requirement5-14 V, ~18 mA for 1s
Minimum 5.5 V with 100 m cable
EnvironmentalIP68 (-40 to +70°C)
Sample volume~60 x 30 mm diameter
Sample volume is weighted towards soil immediately surrounding the rods
Dimensions and weightOverall: 158 x 40 mm diameter
Rods: 60 mm x 3.2 mm diameter
(Rods are replaceable)
Weight: 0.1 kg (exc. cable)
Sensor calibrationsIndividual sensors are interchangeable
Recalibration advised every 3 years (depending on use)
Soil calibrationsGeneralised Mineral and Organic soil calibrations are supplied

HH2 Meter

Input connections1 water content sensor or 1 WET Sensor
Control outputs
Readings stored1,500
Recording rate
ConfigurationBy keypad
Communication optionsRS232 / USB [1]
Sensor excitation1 switched battery
Power1 9V 6LR61 (PP3)alkaline
Battery life (dependent on usage)~ 5,000 readings
Enclosure rating IP54
Temperature range0 to +40°C
Display2 line x 16 character
Size125 x 80 x 45mm
Typical applicationsInstantaneous reading of soil moisture / profiles/ WET Sensor



Main components and software

Mountings and enclosures

Installation accessories

Cables and networks

Remote communications

Spares and consumables

Power options


Product Resources

Data Sheets

Case Studies




Regulatory Information