• Extended measurement range
  • Fast response
  • Maintenance free
  • Low power consumption

Full Range Tensiometer

Polymer Tensiometer
The Full Range Tensiometer by UGT covers the complete range of water potentials relevant for plants, even up to 1500 kPa depending on the model. Unlike other systems with an according measurement range the Full Range Tensiometer doesn‘t determine the tension as an indirect measurement derived from another measured parameter but as a direct pressure measurement. Changes in tension are transmitted very fast. A range of 1000 kPa is passed through within some minutes. Even after complete drying and leaving the measurement range the measurement is automatically continued as soon as the soil moisture increases again. Refilling is not necessary. Another advantage compared with other instruments for the complete plant relevant tension range is the low energy consumption (20 mA in operational mode). Therefore the Full Range Tensiometer is particularly suitable for remote measurement sites where regular maintenance and reliable supply of electricity cannot be ensured.The data transmission via RS485 allows communication even in environments with increased risk of electromagnetic interference and over greater distances.

Technical specifications

measurement range-100 up to +1500 kPa (pF 4,2)
operating temperature0 … + 40°C (soil temperature)
pH rangepH 2…pH 10
power supply20 mA/5…20 V
interface/ output signalRS485
connectionM12 sensor plug 4-pin
dimensionsØ 25 mm; L=150 mm
calibration range4-30 °C (at 100% water saturation)
relative error+/- 0,5% (relative to the entire measuring range)
ceramictip conical


  • Frost resistant
  • Reliable measurement
  • Maintenance free
  • Long lifetime
  • Fast response
  • Low influence of salinity and pH
  • Cost efficient


The SMT-100 combines the advantages of the low-cost FDR sensor system with the accuracy of a TDR system. Like a TDR, it measures the travel time of a signal to determine the relative permittivity εr of the soil. And like a FDR, it converts εr into an easy to measure frequency. The SMT-100 utilizes a ring oscillator to transform the signal’s travel time into a frequency. The resulting frequency (>100 MHz) is high enough to operate well even in clayey soils.

Compact, functional and robust: the PCB board based design allows for an economic design, and the blade shape facilitates installation. The casing and cable are water sealed. The SMT-100 is connected to a logger or handheld for data management. Different communication protocols are available (RS485 or SDI-12), as well as analogue output. It is bus capable and thus, multiple sensors can be connected to one logger.

The SMT-100 determines the volumetric water content and the soil temperature. It has a broad measurement range, it is maintenance free and frost resistant. With a short response time and low disturbance by salinity it is designed for a long-term observation. Additionally, it is possible to retrieve the relative Permittivity.

The SMT-100 sensor is supplied as standard with a reader for mobile measurement of volumetric soil moisture and soil temperature in a transport case.