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Vadose Zone Journal Abstract - Original Research

Leaching of Glyphosate and Aminomethylphosphonic Acid from an Agricultural Field over a Twelve-Year Period

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This article in VZJ

  1. Vol. 13 No. 10
    Received: May 15, 2014
    Published: October 14, 2014

    * Corresponding author(s): trine.norgaard@agrsci.dk
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  1. Trine Norgaard a,
  2. Per Moldrupb,
  3. Ty P.A. Ferréc,
  4. Preben Olsena,
  5. Annette E. Rosenbomd and
  6. Lis W. de Jongea
  1. a Dep. of Agroecology, Faculty of Sciences and Technology, Aarhus Univ., Blichers Allé 20, P.O. Box 50, DK-8830 Tjele, Denmark
    b Dep. of Civil Engineering, Aalborg Univ., Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark
    c Dep. of Hydrology and Water Resources, Arizona Univ., 1133 E. James E. Rogers Way, P.O. Box 210011, Tucson, AZ 85721-0011
    d Geological Survey of Denmark and Greenland, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark


The study presents a unique 12-yr leaching series of glyphosate and its most frequently detected metabolite aminomethylphosphonic acid (AMPA) from a field-scale study. The leaching of glyphosate, AMPA, and soil particles were studied in a shallow drainage system beneath a 1.26-ha field after five annual glyphosate applications with different autumn application dates.

The globally used herbicide glyphosate [N-(phosphonomethyl)glycine] and its most frequently detected metabolite, aminomethylphosphonic acid (AMPA), were studied in a unique 12-yr field-scale monitoring program. The leaching of glyphosate, AMPA, and soil particles was studied in a shallow drainage system beneath a 1.26- ha field. Five annual glyphosate applications were applied with different autumn application dates. Solute mass flux from the drain system following the five glyphosate applications were compared to determine how different factors affect the leaching of glyphosate, AMPA, and particles. Glyphosate and AMPA leaching were highly event driven, controlled by the time and intensity of the first rainfall event after glyphosate application. A high similarity in cumulative drainage and leached pesticide masses with time suggests near-constant drainage and leaching rates. There was no clear relationship between particle-facilitated transport and the transport of glyphosate or AMPA. However, soil particles, glyphosate, and AMPA all showed distinct, simultaneous concentration curves, indicating common dominant transport mechanisms. Also, soil-water content at the time of application and the level of the groundwater table relative to the drain depth exerted clear controls on detection of solutes in the drainage water. To summarize our findings, we present a leaching risk chart to illustrate the dependence of glyphosate, AMPA, and soil particle leaching based on rainfall intensity and the timing of rainfall events after glyphosate application.

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