Field tests by University of Missouri scientists confirm laboratory research showing that buffer strips of grass and other plants reduce herbicide and antibiotic levels in surface runoff from farmland.

Vegetative buffer strips have already proven effective in limiting erosion and reducing sediment and nutrients in runoff.

The new findings come as concerns surface about the potential of antibiotics fed to livestock in surface water leading to the development of antibiotic-resistant bacteria. The antibiotics can enter the environment through manure from confined animal feeding operations and from crops fertilized with manure.

“Vegetative buffer systems are recognized as one of the most effective approaches to mitigate surface water runoff from agroecosystems, and we think that such systems also have the utility for reducing veterinary antibiotic loss,” says Bob Lerch, USDA soil scientist and adjunct University of Missouri adjunct professor.

Researchers compared the impact of three grass buffer treatments for effectiveness in reducing the transport of herbicides and veterinary antibiotics in surface runoff. Plant species used were tall fescue, switchgrass and native warm-season grasses, mainly eastern gamagrass.

In the study, researchers applied three herbicides and three antibiotics, then generated surface water runoff using a rotating-boom rainfall simulator to create uniform soil moisture content. Water and suspended sediment samples were collected and measured.

All vegetative buffers greatly reduced the transport of herbicides and veterinary antibiotics. Grass buffers of 13 to 26 ft. reduced more than 70% of antibiotics in runoff surface water, says Chung Ho Lin, research assistant professor with the University of Missouri Center for Agroforestry and Department of Forestry.

Antibiotics tested included tylosin, sulfamethazine and enrofloxacin.

Filter strips provide an opportunity to use an accepted practice in a manner people have not used before, says Keith Goyne, University of Missouri assistant professor of environmental soil chemistry.