Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: October 7, 1999
Publication Date: N/A
Technical Abstract: The effects of crop management systems including tillage, rate of application, and type of application on the transport of herbicides in surface runoff were studied on three field-size watersheds located in the claypan soil region of north-central Missouri. Water samples were collected from the drainage areas for atrazine, alachlor, and metolachlor analysis during each runoff event from 1993-1997. Herbicide concentrations in runof were extremely high for the events that occurred within a few days of application. Atrazine loss to surface runoff accounted for 9.5 and 2.0% of the total application to no-till and minimum-till systems, respectively. More than 90% of the total loss occurred within 4 weeks of application. The study showed that a small decrease in herbicide rate had no effect on the amount of loss to surface runoff. Atrazine and alachlor/metolachlor runoff losses from a no-till system where herbicides were surface applied and not incorporated increased by 63 and 30% respectively, compared to a minimum-till system where herbicides were surface applied and incorporated.