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This article in JEQ

  1. Vol. 33 No. 6, p. 2149-2156
     
    Received: Feb 19, 2004


    * Corresponding author(s): mingxin.guo@ucr.edu
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doi:10.2134/jeq2004.2149

Distribution and Leaching of Methyl Iodide in Soil following Emulated Shank and Drip Application

  1. Mingxin Guo *a,
  2. Wei Zhenga,
  3. Sharon K. Papiernikb and
  4. Scott R. Yatesc
  1. a Department of Environmental Sciences, University of California, Riverside, CA 92521
    b USDA-ARS, North Central Soil Conservation Research Laboratory, Morris, MN 56267
    c USDA-ARS, U.S. Salinity Laboratory, 450 West Big Springs Road, Riverside, CA 92507

Abstract

Methyl iodide (MeI) is a promising alternative to methyl bromide in soil fumigation. The pest-control efficacy and ground water contamination risks of MeI as a fumigant are highly related to its gas-phase distribution and leaching after soil application. In this study, the distribution and leaching of MeI in soil following shank injection and subsurface drip application were investigated. Methyl iodide (200 kg ha−1) was directly injected or drip-applied at a 20-cm depth into Arlington sandy loam (coarse-loamy, mixed, thermic Haplic Durixeralfs) columns (12-cm i.d., 70-cm height) tarped with virtually impermeable film. Concentration profiles of MeI in the soil air were monitored for 7 d. Methyl iodide diffused rapidly after soil application, and reached a 70-cm depth within 2 h. Relative to shank injection, drip application inhibited diffusion, resulting in significantly lower concentration profiles in the soil air. Seven days after MeI application, fumigated soil was uncapped, aerated for 7 d, and leached with water. Leaching of MeI was significant from the soil columns under both application methods, with concentrations of >10 μg L−1 in the early leachate. The leaching was greater following shank injection than drip application, with an overall potential of 33 g ha−1 for shank injection and 19 g ha−1 for drip application. Persistent residues of MeI remaining in soils after leaching were 50 to 240 ng kg−1, and the contents were slightly higher following shank injection than drip application. The results suggest that fumigation with MeI may pose a risk of ground water contamination in vulnerable areas.

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Copyright © 2004. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA