Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 13, 1999
Publication Date: N/A
Technical Abstract: Cover crops, such as hairy vetch, are increasingly being used in no-till corn production systems. At corn planting, these cover crops produce a dense mat of vegetation that intercepts nearly all of the applied herbicides. The effect of hairy vetch on herbicide distribution in soil and loss to runoff is largely unknown and difficult to measure under field conditions. This laboratory study was designed to simulate similar field conditions in terms of the time and intensity of the rain events after herbicides application. Sixteen chambers (100 x 35 x 25 cm) were packed with soil, hairy vetch was planted on half of the chambers, and corn stover was spread uniformly on the surface of all chambers to simulate crop residue conditions. After atrazine and metolachlor were applied to all chambers, runoff experiments were conducted to simulate 5 and 20 day time periods between herbicide application and the first rainfall/runoff event. Runoff losses of atrazine and metolachlor was about 1.9 and 1.4 times higher from vetch than non vetch treatments, respectively at 5 days after application. Losses were 1.3 to 4 times higher at 5 than at 20 days after application. Amounts recovered in crop residue, soil and in leachate will be discussed.