ku-pF Unsaturated Hydraulic Conductivity Apparatus DT 04-01 UGT 

Principle:  The ku-pF Apparatus measures the hydraulic conductivity (ku) and the pF curve of samples in the unsaturated range based the evaporation method. Samples get fully saturated in the sample ring and then sealed at the base. The free surface is exposed to evaporation, and the gradient of the resulting water movement is recorded with a data logger. Water movement, i.e. the amount of water which per time interval passes through the sample surface, gets weighed, and the gradient of water tension is measured in each sample ring by two tensiometers spaced at a distance of 3 cm. The tensiometer values are recorded with the time pulse of weighing. The hydraulic conductivity of the samples is calculated according to DARCY’s equation, assuming quasi-stationary flow.​


Capabilities: Using the ku-pF Apparatus, up to ten soil samples can be analyzed simultaneously. For this, the sample rings are put onto a star-shaped sample changer and put periodically, with a suitable time interval, onto a scale.

Pressure Plate Extractor  Apparatus SoilMoisture® 0700CG23 manifold ​

Principle: Used for the determination of soil (or other materials’) water retention at an imposed matric potential. The technique involves placing a saturated soil sample on a porous ceramic plate inside a pressure chamber. The underside of the ceramic plate is maintained at atmospheric pressure while the soil samples are pressurized, thus creating a hydraulic gradient and subsequent flow of water from the samples through the saturated ceramic plate. In theory, flow ceases once the soil samples reach equilibrium with the imposed pressure. The characteristic curves that relate the soil suction (matric potential), at which moisture is held by the soil to its moisture (water = soil solution) content can be developed. These curves are known by various names such as water retention curvewater characteristic curvewater content–matric potential curve, and capillary pressure–saturation relation. ​


Capabilities: Can be set to constant preset pressures ranging from 10- to 1500-kPa (0.1 to 15 bars or 100 to 15000 cm H2O) using Pressure Plate Extractor System Apparatus comprising SoilMoisture® 0700CG23 manifold with 1500G1 (15-bar) and 1600G1 (5-bar) Pressure Plate Extractors and a 2 MPa (300 psi) air compressor (source of pressure).​

Department of Ecosystem Science and Management


117 Forest Resources Building
University Park, PA 16802