Measurement of Low Matric Potentials with Porous Matrix Sensors and Water-Filled Tensiometers

W.R. Whalley, G. Lock, M. Jenkins, T. Peloe, K. Burek, J. Balendonck, W.A. Take, Y. Tuzel

    Research output: Contribution to journalArticleAcademicpeer-review

    17 Citations (Scopus)

    Abstract

    Water-filled tensiometers are widely used to measure the matric potential of soil water. It is often assumed that, because these give a direct reading, they are accurate. With a series of laboratory tests with model laboratory systems of increasing complexity we show that the output of water-filled tensiometers can, particularly in drying soils, be in serious error. Specifically, we demonstrated that water-filled tensiometers can indicate a steady matric potential, typically between –60 and –90 kPa, when the soil is much drier. We demonstrate the use of water-filled tensiometers that can measure matric potentials smaller than –100 kPa in the laboratory and in the field. The physics of the failure of water-filled tensiometers is discussed. When the matric potential was greater than –60 kPa, in laboratory and field tests water-filled and porous matrix sensors were in good agreement. In the field environment the porous matrix sensor was useful because it allowed early detection of the failure of water-filled tensiometers. In dry soils (matric potential <–60 kPa) the porous matrix sensor was more reliable and accurate than the water-filled tensiometer.
    Original languageEnglish
    Pages (from-to)1796-1803
    JournalSoil Science Society of America Journal
    Volume73
    DOIs
    Publication statusPublished - 2009

    Keywords

    • hydraulic conductivity
    • soil suction
    • design
    • time

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