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This article in SSSAJ

  1. Vol. 76 No. 5, p. 1529-1535
    Received: Jan 30, 2012
    Published: September 12, 2012

    * Corresponding author(s): wuravnakka@yahoo.com
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Estimation of Soil Clay Content from Hygroscopic Water Content Measurements

  1. Mark N. Wuddivira *a,
  2. David A. Robinsonb,
  3. Inma Lebronb,
  4. Laëtitia Bréchetc,
  5. Melissa Atwelld,
  6. Sunshine De Cairesd,
  7. Michael Oathame,
  8. Scott B. Jonesf,
  9. Hiruy Abduf,
  10. Aditya K. Vermag and
  11. Markus Tullerg
  1. a Dep. of Food Production the Univ. of the West Indies St. Augustine, Trinidad and Tobago
    b Centre for Ecology and Hydrology Environment Centre Wales, Deiniol Road, Bangor, Gwynedd, UK
    c Soil Team, Environmental Dynamics and Spatial Organizations, UMR INRA-AgroParisTech, Environnement et Grandes Cultures, Thiverval- Grignon, France and Dep. of Life Sciences the Univ. of the West Indies, St Augustine, Trinidad and Tobago
    d Dep. of Food Production the Univ. of the West Indies, St. Augustine, Trinidad and Tobago
    e Dep. of Life Sciences the Univ. of the West Indies, St Augustine, Trinidad and Tobago
    f Dep. of Plants Soils and Climate, Utah State Univ. Logan, UT 84322
    g Dep. of Soil, Water and Environmental Science, The Univ. of Arizona, Tucson, AZ 85721


Soil texture and the soil water characteristic are key properties used to estimate flow and transport parameters. Determination of clay content is therefore critical for understanding of plot-scale soil heterogeneity. With increasing interest in proximal soil sensing, there is the need to relate obtained signals to soil properties of interest. Inference of soil texture, especially clay mineral content, from instrument response from electromagnetic induction and radiometric methods is of substantial interest. However, the cost of soil sampling and analysis required to link proximal measurements and soil properties, for example, clay mineral content, can sometimes outweigh the benefits of using a fast proximal technique. In this paper, we propose that determination of a soil’s hygroscopic water content at 50% atmospheric relative humidity (RH50), which is time and cost efficient, and particularly suitable for developing countries, can act as a useful surrogate for clay content in interpreting soil spatial patterns based on proximal signals. We used standard clays such as kaolinite, illite, and montmorillonite to determine the water release characteristic as a function of hygroscopic water content. We also determined clay content of soils from temperate (Arizona, United States) and tropical (Trinidad) regions using the hydrometer method and hygroscopic water content for soils equilibrated at RH50. We found linear dependence of clay percentage and RH50 for a range of soil mineralogies. Hygroscopic water measurements offer an inexpensive and simple way to estimate site-specific clay mineral content that in turn can be used to interpret geophysical signal data in reconnaissance surveys.

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Copyright © 2012. Copyright © by the Soil Science Society of America, Inc.