Field-Scale Metolachlor Volatilization Flux Estimates from Broadcast and Banded Application Methods in Central Iowa
- J. H. Prueger *,
- J. L. Hatfield and
- T. J. Sauer
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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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