Electrical impedance imaging of the root zone

P. Newill, D. Karadaglic, F. Podd, B.D. Grieve, M. Staerkle, J. Leipner, C. Screpanti, T.A. York

    Research output: Chapter in Book/Report/Conference proceedingConference contribution


    Exploration of electrical impedance measurements for imaging water transport in and around the roots of plants is described.
    The scientific aim is to use the images to inform phenotyping in crop breeding programmes. The present work considers
    preliminary measurements on a laboratory scale rhizotron fitted with 60 capacitively-coupled contactless conductivity (C4D)
    electrodes in a rectangular array. This reduces electrochemical effects by including an insulating layer on the surface of the
    electrodes. The resistance of the bulk material is deduced from spectroscopic considerations. Electrical impedance is
    measured between pairs of electrodes to build up a two-dimensional map. A modified electrical model of the electrodes is
    proposed which includes the resistive and reactive components of both the insulating layer and the bulk material. Using soil
    as the bulk material the effect of water content, compaction and temperature are explored. Moisture has the strongest
    influence particularly under dry conditions. Impedance measurements decrease by a factor of 1000 as soil moisture is
    increased from 5% to 30%. Compaction, up to a pressure of 0.21 kg/cm2, changes the impedance by up to 20%, under dry
    conditions. Measurements show a temperature sensitivity of about 2% / °C. Preliminary growth tests show changes in
    impedance as a root system develops and are compared to a control test with no plant.
    Original languageEnglish
    Title of host publication7th World Congress on Industrial Process Tomography
    Publisher International Society for Industrial Process Tomography
    Number of pages9
    ISBN (Print)978 0 853 16323 7
    Publication statusPublished - Sep 2013


    • capacitively-coupled contactless conductivity
    • ERT
    • root zone monitoring


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