Spot spraying reduces herbicide concentrations in runoff

Journal Publication ResearchOnline@JCU
Melland, Alice R.;Silburn, D. Mark;McHugh, Allen D.;Fillols, Emilie;Rojas-Ponce, Samuel;Baillie, Craig;Lewis, Stephen
Abstract

Rainfall simulator trials were conducted on sugar cane paddocks across dry-tropical and subtropical Queensland, Australia, to examine the potential for spot spraying to reduce herbicide losses in runoff. Recommended rates of the herbicides glyphosate, 2,4-D, fluoroxypyr, atrazine, and diuron were sprayed onto 0, 20, 40, 50, 70, or 100% of the area of runoff plots. Simulated rainfall was applied 2 days after spraying to induce runoff at one plant cane and three ratoon crop sites. Over 50% of all herbicides were transported in the dissolved phase of runoff, regardless of the herbicide’s sediment–water partition coefficient. For most sites and herbicides, runoff herbicide concentrations decreased with decreasing spray coverage and with decreasing herbicide load in the soil and cane residues. Importantly, sites with higher infiltration prior to runoff and lower total runoff had lower runoff herbicide concentrations.

Journal

Journal of Agricultural and Food Chemistry

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Volume

60

ISBN/ISSN

1520-5118

Edition

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Issue

20

Pages Count

12

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Publisher

American Chemical Society

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EISSN

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DOI

10.1021/acs.jafc.5b03688