ML3 ThetaKit

Class leading ± 1% soil moisture accuracyComplete kit with readout unit & caseThe ML3 ThetaKit provides researchers with a portable tool for highly accurate, near instantaneous measurement of mois

  • Product Name:ML3 ThetaKit
  • Model:ML3
  • Maunufactor:Delta-T
  • Country:UK
  • 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.

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

Measurement             Volumetric water content and soil temperature


± 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


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


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