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This article in SSSAJ

  1. Vol. 66 No. 2, p. 347-351
    Received: Jan 31, 2001

    * Corresponding author(s): wangz@mail.cr.edu


Visualizing Preferential Flow Paths using Ammonium Carbonate and a pH Indicator

  1. Zhi Wang *a,
  2. Jianhang Lua,
  3. Laosheng Wua,
  4. Thomas Harterb and
  5. William A. Jurya
  1. a Dep. of Environmental Sciences, Univ. of California, Riverside, CA 92521
    b Dep. of Land, Air, and Water Resources, Univ. of California, Davis, CA 95616


Despite their negative charge, anionic dyes are less-than-ideal tracers of water flow in soil. A new method is presented here for detecting flow patterns faithfully representing the movement of water flow paths in structured and nonstructured soils. The method is based on application of ammonium carbonate during infiltration, which displays a unique color signature when sprayed with a pH indicator after excavation and exposure of the soil profile along a trench face. We compare its performance with that of the popular Brilliant Blue in a laboratory study, and show that it is a more conservative tracer of the water front. We also illustrate its use in a field experiment to detect preferential flow. In contrast to other methods, ammonium carbonate is inexpensive, nontoxic, and leaves negligible residue.

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Copyright © 2002. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.66:347–351.