Field tests and laboratory research conducted by University of Missouri (MU) scientists indicates that buffer strips of grass and other plants can reduce the amount of herbicide and veterinary antibiotics in surface runoff from farm plots.

Vegetative buffer strips have already proven effective in limiting erosion as well as reducing sediment and nutrients in runoff. The recent findings come amid concerns about the potential of veterinary antibiotics in surface water leading to the emergence of antibiotic-resistant bacteria. The antibiotics can enter the environment through manure from confined animal feeding operations (CAFOs) and from fields fertilized with manure, scientists explain.

Researchers compared the effectiveness of three grass buffer treatments in reducing the transport of herbicides and veterinary antibiotics in surface runoff. Plant species included tall fescue, switchgrass and native warm-season grasses, primarily eastern gamagrass. Cultivated fallow served as a control treatment.

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 buffer systems significantly reduced the transport of both dissolved and sediment-bound herbicides atrazine, metolachlor and glyphosate in surface runoff by 58 to 72%, reports Chung-Ho Lin, research assistant professor with the MU Center for Agroforestry and Department of Forestry.

Similar outcomes applied to veterinary antibiotics. Grass buffers, 13 to 26 ft. wide, reduced more than 70% of veterinary antibiotics in runoff surface water, Lin says. Using certain species such as hybrid poplar can further enhance degradation of deposited antibiotics. Antibiotics in the trials included Tylan, used in swine feed to promote growth and prevent disease; sulfamethazine, used in swine feed with other antibiotics, and Baytril 100, used for swine and cattle for respiratory illnesses.

A goal of the research was to provide practical guidelines that agencies, land managers and agroforestry practitioners can use to design effective buffer strips.