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Soil Science Society of America Journal Abstract - DIVISION S-1—SOIL PHYSICS

Evaluation of the OhmMapper Instrument for Soil Moisture Measurement


This article in SSSAJ

  1. Vol. 66 No. 3, p. 728-734
    Received: Nov 15, 2000

    * Corresponding author(s): j.walker@unimelb.edu.au
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  1. Jeffrey P. Walker *b and
  2. Paul R. Housera
  1. b Dep. of Civil and Environmental Engineering, Univ. of Melbourne, Parkville, Victoria 3010, Australia
    a Hydrological Sciences Branch, Lab. for Hydrospheric Processes, NASA's Goddard Space Flight Center, Greenbelt, MD 20771


An instrument for making rapid measurements of the soil moisture content in the root zone is an essential tool for many applications, including understanding of soil water dynamics, evaluation of agriculture water stress, and validation of soil moisture modeling. Studies have shown that electrical resistance measurements may be used to infer soil moisture content under special circumstances. In this paper, electrical resistivity (resistance multiplied by a geometric factor) measurements of the soil by the Geometrics Inc. OhmMapper instrument are compared with point measurements of soil moisture to a depth of 70 cm. It was found that the OhmMapper resistivity measurements could be used to infer soil moisture content with a coefficient of determination as high as 0.34 when a simple power law relationship was used. A more sophisticated analysis of the resistivity measurements could potentially lead to a greater coefficient of determination.

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Copyright © 2002. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.66:728–734.