Equi-pf Automated Soil Moisture Release Curve Apparatus News

Oregon State University Validates Equi-pF Performance

Under the supervision of Professor Jeff McDonnell a team of his students at Oregon Sate University (Corvallis, Oregon) have validated the performance of Equi-pF using two methods:

  • Testing a number of grades of Accusand and comparing the Equi-pF results with published data on these Accusands.
  • Testing a number of soil cores taken from the HJ Andrews Experimental Forest and comparing the Equi-pF results with historical data from cores from the same site.

The result of the validation tests proved the suitability of Equi-pF for the generation of Soil Moisture Release Curves and also highlighted some significant extra features provided by the system which make it an even more useful tool for Equi-pF users.

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Lincoln University using Equi-pF

Under the supervision of Assoc. Prof. Graeme Buchan, PhD student Sam Carrick is using Equi-pF as part of his study of the modelling of infiltration and preferential flowpaths through layered soil columns

The project is centred on measurement of the hydraulic characteristics of four large lysimeters containing intact soil columns representative of extensive areas of the Canterbury Plains. The project focuses on the behaviour of the pore network at soil moisture conditions mainly above ‘field capacity’ (0 to -10kPa), where preferential flow paths are likely to be activated.

An experimental setup has been constructed to enable simultaneous measurements on two lysimeters, with the following parameters automatically measured by a datalogger at 1 minute intervals for each lysimeter:

  • Infiltration & drainage rates.
  • Soil water potential, using 30 tensiometers distributed over 4 depths.
  • Volumetric soil water content, using 4 TDR probes located at 4 depths.
  • Soil & air temperatures.

The Equi-pF machine is being used at this stage of the project, to test the accuracy of measurements of the water retention relationship obtained from standard suction tables. This aspect is critical, as the infiltration and early-stage redistribution of water in field soils are dominated by the larger drainage pores, whose characteristics can be revealed by the Equi-pF.

Papers on the Lincoln University work will be available soon.