Mini-TDR probe

TDR Soil Moisture SensorThe shortest TDR manufactured in the world is ideal for soil moisture measurements in scientific and engineering experiments such as soil columns. The low cost of the sensor allows scientists to increase replication and improve statistical analysis.

The Mini-TDR measurement rods are 6cm in length, making these sensors ideal for scientific experiments in the glasshouse or in soil columns. The Mini-TDR can also be installed in the field for long-term, continuous measurements of soil volumetric water content.


related products


  • The Mini-TDR’s short wave guides make this sensor superior for salty soils or high clay content. 
  • Easily interfaces with CSI TDR100 in combination with CSI data loggers. Connect to your existing loggers or Edaphic Scientific provides full support in connecting to CSI data loggers.
  • Each probe comes with a certificate of calibration and a calculated probe constant.
  • Low cost, high reliability and ideal for scientists.



Available in two head designs: Model T3R-round head 22mm in diameter and Model T3F with a flat head. Handle is 25 x 13 x 13 mm long.

  • 3-needle balanced design
  • Needle length: 6 cm
  • Needle diameter: 1.4 mm
  • Spacing between needles: 6 mm
  • Needle composition: 304 Stainless Steel
  • Cable: 50 Ohm RG-58A/U
  • Standard cable length: 2m
  • Maximum cable length: 10m
  • Maximum Soil EC: 6 dS/m
  • TDR100 required.


measure in high saline soils

The Mini-TDR is able to measure in soils with salinity up to 6 dS/m. Beyond this level of salinity, the propagation signal is attenuated and cannot be measured. The Mini-TDR is also able to measure soil bulk electrical conductivity, or bulk soil salinity.

Mini-TDR Theory and How to Measure in High Saline Soils


data logger requirements

Campbell Scientific TDR100The Mini-TDR requires the CSI TDR100 for accurate measurements. The TDR100 is used to accurately determine soil volumetric water content, soil bulk electrical conductivity, rock mass deformation, or user-specific time-domain measurement. Up to 16 TDR100s can be controlled using a single Campbell Scientific data logger. PC-TDR software is used with our TDR100-based systems during system set-up and troubleshooting. Compatible with CR800, CR850, CR1000, and CR3000 data loggers.

Edaphic Scientific can assist in connecting the Mini-TDR Soil Moisture Sensors to the TDR100 and data logging system. We can also support in connecting these sensors to your existing CSI logging platform.


further information