Metolachlor and metribuzin losses in runoff as affected by width of vegetative filter strips

Tall fescue vegetative filter strips 0.5 to 4.0 m wide were evaluated for their ability to reduce losses of metolachlor, metribuzin, and runoff (water and sediment) in conventionally tilled soybean. Differences in the parameters studied were significant between filter and no filter strips, regardless of filter strip width. Two days after treatment, metribuzin concentration in runoff from the unfiltered treatment was 231 ng ml−1; filter strips reduced this amount to 119 ng ml−1or less. Similar trends were observed with metolachlor, with concentrations of 1,009 ng ml−1from the unfiltered, whereas filter strips of any width reduced this to 523 ng ml−1or less. Metribuzin loss during the growing season was 41 g ai ha−1, or 9.8% of the amount applied when no filter strip was present. The addition of a filter strip, regardless of width, reduced cumulative metribuzin losses to 11 g ha−1or less. Similar results were noted with metolachlor. Filter strips, regardless of width, reduced cumulative runoff and sediment loss at least 46 and 83%, respectively.