Submitted to: American Chemical Society Symposium Series
Publication Type: Book / Chapter
Publication Acceptance Date: April 27, 1999
Publication Date: N/A
Herbicides are often transported through subsurface drainage to surface waters from corn-growing areas of the USA and Canada. Herbicide losses are highly variable, typically ranging from less than 0.01 to 10 g/ha. The magnitude of herbicide loss results from precipitation patterns, herbicide interactions with the soil, and farming practices. This report reviews existing literature and presents new research on the effects of farming practices on herbicide losses in drainage water. Conservation tillage practices that increase infiltration tend to increase herbicide losses in drainage. Increasing intensity of drainage and increased frequency and rate of herbicide use tend to increase herbicide losses. Banding consistently reduced annual losses and average concentrations of atrazine compared to broadcast applications, which is consistent with the lower application rate. Metolachlor losses were reduced by banding, but the effect was only statistically significant in continuous corn systems.