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This article in JEQ

  1. Vol. 28 No. 1, p. 75-81
    Received: Jan 23, 1998

    * Corresponding author(s): prueger@nstl.gov
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Field-Scale Metolachlor Volatilization Flux Estimates from Broadcast and Banded Application Methods in Central Iowa

  1. J. H. Prueger *,
  2. J. L. Hatfield and
  3. T. J. Sauer
  1. USDA-ARS, Biomass Research Center, Univ. of Arkansas, Fayetteville, AR 72701.



Volatilization of pesticides has been considered to be a large part of the loss from fields after application; however, there have been relatively few studies conducted to quantify the amount lost to the atmosphere. This study was designed to evaluate volatilization rates of a preemergent herbicide Dual [a.i. metolachlor 2.24 kg ha−1 (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide)] from two fields (175 and 45 ha) in central Iowa under contrasting tillage operations and pesticide application scenarios. Metolachlor vapor was trapped using polyurethane foam plugs at six heights on a profile mast. Average concentrations were measured at each height every 2 h for the first 4 d after application, then every 4 h thereafter. Volatilization rates were calculated with a flux-gradient technique using data from Bowen ratio and eddy correlation measurements. Flux profile concentrations of metolachlor were large during the first 24 h and quickly declined for the duration of the study. There was approximately a threefold greater cumulative volatilization loss of applied metolachlor from the broadcast (22%) treatment than from the banded treatment (6%) for the 10-d study period. Metolachlor volatilization was affected by residue cover, spatial concentration on the surface, and timing of precipitation.

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