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


"We have ThetaProbe sensors installed at another site, some of them have been running for 8 years now and we've found them very reliable, so we'd like to use Delta-T Devices sensors again." Anu Riikonen, PHD Student
Department of Forest Ecology, University of Helsinki
  • Class leading ± 1% soil moisture accuracy
  • Complete kit with readout unit & case

The ML3 ThetaKit provides researchers with a portable tool for highly accurate, near instantaneous measurement of moisture levels in soils and substrates. 

The ThetaKit is easy to use. Simply switch the connected HH2 Moisture Meter on, insert the probe pins fully into the soil, and press the HH2’s “read” button to display the moisture measurement. Readings can then be stored with a single button press (if required) – and downloaded to PC later.

The kit comprises an ML3 ThetaProbe Soil Moisture Sensor, an HH2 Moisture Meter (readout unit), replacement sensor rods, and a carry case.

Click here for details on the ML3 Sensor

NB: Other moisture measurement kits are available if lower cost or EC measurements are required.


Measurement Volumetric 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 range Full accuracy over:
0 to 0.5 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 5.5 V with 100 m cable
Environmental IP68 (-40 to +70°C)
Sample volume ~60 x 30 mm diameter
Sample volume is weighted towards soil immediately surrounding the rods
Dimensions and weight Overall: 158 x 40 mm diameter
Rods: 60 mm x 3.2 mm diameter
(Rods are replaceable)
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

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




Main components and software

Mountings and enclosures

Installation accessories

Cables and networks

GPRS remote comms

Spares and consumables

Power options


Product Resources

Data Sheets



Regulatory Information