STM Soil Tension Meter

The STM Soil Tension Meter is a stand-alone logging instrument for the measurement of soil water potential.

  • Product Name:Soil Tension Meter
  • Maunufactor:ICT
  • Country:AU

The STM Soil Tension Meter is a stand-alone logging instrument for the measurement of soil water potential.

The STM Soil Tension Meter can support up to 5 pressure transducers. ICT International supplies 3 different types of pressure transducers which can measure in the ranges: ±7 kPa, ±100 kPa or -100 to +200 kPa. Tensiometers include designs for soil columns and field sites.

 The STM is a fully self-contained unit requiring power input from a 22W solar panel (field applications) or 24V power supply (laboratory applications). Communication is via a USB port or wireless connectivity. The STM is IP-65 rated and has a Windows and Mac compatible GUI for complete logging solutions including look-up tables, scripts and sensor calibration capabilities.


  •  Soil column testing

  •  Moisture retention curves

  • Geotechnical engineering

  • Soil water potential for irrigation monitoring

  • The continuous measurement of soil water potential in the field, glasshouse or soil columns.

  •  Precise measurements of soil matric potential

  • Live monitoring of sorption and desorption curves

  • Up to 5 sensor capacity


Analogue Channels

5 differential





Minimum Logging Interval

1 second

Delayed Start

Suspend Logging, Customised Intervals

Sampling Frequency




USB, Wireless Radio Frequency 2.4 GHz

Data Storage

MicroSD Card, SD, SDHC & SDXC Compatible (FAT32 format)

Software Compatibility

Windows 7, 8, 8.1 & 10. Mac OS X

Data Compatibility

FAT32 format for direct exchange of SD card with any PC

Data File Format

Comma Separated Values (CSV) for compatibility with all software programs

Memory Capacity

Up to 16GB, 4GB microSD card included.

Operating Conditions

Temperature Range

-40°C to +80°C

R/H Range



User Upgradeable firmware using USB boot strap loader function


Internal Battery Specifications

960mAh Lithium Polymer, 4.20 Volts fully charged

External Power Requirements

Bus Power

8-30 Volts DC, non-polarised, current draw is 190mA maximum at 17 volts per logger

USB Power

5 Volts DC

Internal Charge Rate

Bus Power

60mA – 200mA Variable internal charge rate, maximum charge rate of 200mA active when the external voltage rises above 16 Volts DC

USB Power

100mA fixed charge rate

Internal Power Management

Fully Charged Battery

4.20 Volts

Low Power Mode

3.60 Volts – Instrument ceases to take measurements

Discharged Battery

2.90 Volts – Instrument automatically switches off at and below this voltage when no external power connected.

Battery Life varies

Example A: With a recommended solar panel and/or recommended power source connected, operation can be continuous.

Example B: Power consumption is dependent on number and type of sensors connected, frequency of measurement and measurement duration.