Volumetric Measuring Instruments determine the Water Content in Soils, and inform the user about the amount of water, which is presently contained in soil. The shown amount of water in soil includes the non plant available part. Common measurement units are Vol% or mm water per liter or m³ soil.

These Sensors are ideal to answer the question how much water needs to be applied, to fill the rooted soil-profile from the presently measured state to a defined volumetric percentage of field capacity (for example to 90% field capacity). On the other hand, data interpretation of volumetric sensors does require a deeper knowledge of specific soil properties on site, since the measured amount of water always includes the non plant available part of soil water.


  • information about the amount of water in soil
  • very accurate technique
  • immediate reaction on changing soil moistures
  • maintenance free and frost proof sensors


TDR Fieldscouts are fully mobile measuring instruments for volumetric soil water content. No permanent sensor installation necessary, no valuable equipment remains in field. Multiple field points or a multitude of different fields can be measured. One measurement takes only seconds: prick measurement rods fully in ground, push button to take the measurement, go to next measuring point!

Working Principle

TDR (Time Domain Reflectometry) Sensors determine the soil water content by measuring the dielectric properties of the soil between two (or more) measuring rods. The travel time of an electromagnetic impulse emitted by the instrument is determined by the dielectric properties of soil , and thus it's water content. The measurement shows the average water content of the measured soil profile, which equals the length of the measuring rods presently in use. The measuring rods are exchangeable, available length are 3,8 cm, 7,5 cm, 12 cm and 20 cm.


Three calibrations already programmed in the firmware of the instrument: Standard (for most soils), sand and high clay (for soils with clay contents of 30% or more).

Irrigation Mode

TDR-Fieldscouts additionally offer pre-programmed irrigation mode. In this mode it is possible to set the full and the refill point for two specific soils via the included software. In irrigation mode, the instrument shows the amount of water necessary (in mm) to fill the profile from the presently measured state to the full point.