Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 11/7/2011
Publication Date: 12/5/2011
Citation: Gish, T.J., Prueger, J.H., Kustas, W.P., Hatfield, J.L., Mckee, L.G., Russ, A.L. 2011. Herbicide off-site transport. Soil Science. Intech. p. 229-252.
Technical Abstract: Herbicides are an important part of modern agriculture as they control weeds that would otherwise reduce yields by competing for water and nutrients. In the future herbicides will play an increasing role as agriculture strives to meet food, fuel, and fiber requirements of a growing global population. Unfortunately, herbicides can be toxic to humans and other forms of life at low concentrations, so determining herbicide off-site transport is important in developing sustainable agricultural systems. This chapter summarizes the three major loss pathways governing herbicide off-site transport: 1) surface runoff; 2) groundwater leaching; and 3) volatilization. This review shows that annual herbicide runoff losses are typically less than 1% of that applied, with the largest portion of this loss occurring near the time of application. However, a worst case scenario can generate herbicide runoff losses greater than 5% of that applied. Field-scale herbicide leaching losses in non-tile-drained fields is difficult to quantify due to soil heterogeneity, but estimates of herbicide leaching are generally <1% of that applied, and in a worst case scenario herbicide leaching losses are probably << 5% of that applied. The third loss pathway, volatilization, is of major environmental concern with herbicide losses commonly exceeding 5% of that applied, and worst case scenario’s generating herbicide losses exceeding 60% of that applied. This chapter summarizes the critical processes governing field-scale herbicide behavior and provides several managerial options to mitigate off-site transport.