Impact of Vegetative Filter Strips on Herbicide Loss in Runoff from Soybean (Glycine max)
Metolachlor and metribuzin loss in runoff was determined in three soybean tillage systems with and without a 4 by 2 m tall fescue vegetative filter strip. Soil erosion plots were 4 by 22 m with 3% slope. Regression analysis was used to describe herbicide concentration in runoff, and to determine if vegetative filter strips reduced herbicide concentration. Analysis of covariance indicated no difference in concentration of metolachlor or metribuzin in runoff from the three tillage systems within any vegetative filter strip treatment. Metolachlor loss in 1991 was highest from the no-till monocrop without a vegetative filter strip, and it was 65g ha−1 or approximately 2% of the amount applied. In 1992 and 1993, the no-till doublecrop had a total loss of 120 and 147 g ha−1, respectively, approximately 4% of the amount applied. Similar results were noted with metribuzin, but total loss was as high as 46 g ha−1 or 11 % of the amount applied in 1993 from a no-till doublecrop system without a vegetative filter strip. When a vegetative filter strip was present, losses of metribuzin and metolachlor were reduced over 85% in 1993, and totaled 1.2 and 0.5%, respectively, of the amount applied. The vegetative filter strip reduced herbicide and suspended solids from runoff produced by a conventional-till production system to levels equal to or lower than a no-till doublecrop system.