SDI12 sensor for matric potential (soil water tensions) and soil temperature pF-Meter


The new pF-meter measurement is based on the detection of the volumetric heat capacity. A ceramic membrane on the buried sensor equilibrates with the soil water tension. Inside the ceramic membrane a special sensor continuously measures the water content,which is converted to hydraulic potential. Thus the matrix potential can be measured actively and directly, similarly to a conventional water-filled tensiometer.

backround data
figures to the measurements
and resolution

  • large measuerement range (pF 0.0 to 7.0 = 1 to 10.000.000 hPa / mBar)
  • maintenance free
  • fast reaction (comparable to traditional water filled tensiometer)
  • simultan measurement of soil temperature (accuracy: ± 0.25°C)
  • directly and active measurement of matric potential (using ceramic membran)
  • measurements values not influenced by soil salinity
  • frost proof
  • output signal:(SDI-12) or analoge (0 to 7 volt = pF 0.0 to pF 7.0   / without temperature)

The pF-meter delivers digital data either in pF-value or in mbar (hPa). The modern, digital SDI12-concept prevents measurement errors so that cable lengths up to 50 m are applicable
Measurement networks with up to 24 pF-meters are realisable in connection with the network-compatible GPRS logger from GeoPrecision (i-log).