Soil Matric Potential / Water Retention Curve

pF-Meter™
Installation work for a comparison of pF-meters and tensiometers as well as of TDR- and ERT-Probes, Forschungszentrum Jülich

pF-Meter™

Application

Measurement of soil matric potential in the range of pF 0 ... pF 7 (1 ... 10.000.000 hPa); maintenance-free and frost-resistant.

Principles of operation

The patented pF-meter measures heat capacity in a porous equilibrium body. The changes of soil humidity lead to increases or decreases of the heat capacity of the sensor head. The correlation of matric potential values and the measured heat capacity is achieved by a sensor-specific calibration curve.

Advantages

Six reference systems for soil matric potential have been in operation of the Geologic Survey of Northrhine-Westfalia since May 2007. With daily transmission of 1200 measuring values into the Internet telephone costs were less than 5 Euros annually!

Technical Data
Range pF 0 ... pF 7, - 40 ... 80 °C
Signal Digital (SDI-12), optional analogue
Dimensions L = 100 mm, D = 20 mm
Cable length 5 m, others as desired
Case Stainless steel


Options and accessories

Monitoring

Left figure: Measurements of a pF-Meter compared to four Tensiometers in the same depth Forschungsanstalt für Waldökologie und Forstwirtschaft SDG Süd, Trippstadt, 2008
Left figure: pF-Meter measurements of the Geological Survey Northrhine-Westfalia as reference probes for the soil matric potential; Site Kleve (of six sites in NRW);

Bars = daily precipitation, curves = measurements of pF-Meters (red: 30 cm, green: 40 cm, blue: 60 cm depth), July, 12th to Sept. 12th 2007