The Disc
The CSIRO disc permeameter of Perroux and White (1988) (not patented) comprises a nylon mesh supply membrane (with a very small diameter around 10-40 mm), a water reservoir and a bubbling tower. The bubbling tower is connected to the reservoir and is open to air. The bubbling tower controls the potential h0 applied to the membrane by adjusting the water height in the air-inlet tube. So essentially the soil pores need to have energy equivalent to h0 to overcome water that is held under tension in the reservoir. It can be used to supply potential ranging -200 mm to 0 mm, effectively excluding pores with diameter bigger than 0.075 mm.
Many different designs have evolved, including:
- automated recording tension infiltrometer (Ankeny, Kaspar & Horton, 1988), patented by the Iowa State University (Soil Moisture Measurement http://www.soilmeasurement.com/tension_infil.html)
- mini-disc infiltrometer (Decagon Devices, http://www.decagon.com/products/lysimeters-and-infiltrometers/mini-disk-tension-infiltrometer)
- hood infiltrometer (Umwelt-Geräte-Technik, http://www.ugt-online.de)
Read more about this topic: Disc Permeameter
Famous quotes containing the word disc:
“Soundless as dots—on a Disc of Snow—”
—Emily Dickinson (1830–1886)
“Perhaps all music, even the newest, is not so much something discovered as something that re-emerges from where it lay buried in the memory, inaudible as a melody cut in a disc of flesh. A composer lets me hear a song that has always been shut up silent within me.”
—Jean Genet (1910–1986)