Can Vegetative Filter Strips Mitigate Veterinary Antibiotic Loss From Agroecosystems?.

Veterinary antibiotic (VA) presence in the environment, often associated with land application of manure, has generated significant interest in VA pollutant fate and transport in soil. These compounds have been subject to reconnaissance, column, macroscopic, and spectroscopic studies to elucidate VA presence and interactions in aquatic and soil environments. However, few studies have focused on land management practices that might mitigate VA loss to water resources. Our research group has and continues to evaluate the utility of vegetative filter strips (VFS) to serve in this capacity. Batch sorption experiments have illustrated significantly (p < 0.05) greater oxytetracycline and sulfadimethoxine sorption to VFS soils, relative to cropland soils. Sorption of oxytetracycline and sulfadimethoxine were found to be positively correlated with clay content (r² = 0.73) and pH (r² = 0.75), respectively. In a series of growth chamber studies, we have noted enhanced sulfamethazine dissipation in soils previously planted to vegetation commonly grown in VFS. Sulfamethazine dissipation was greatest in experiments associated with a hybrid poplar tree (half-life = 2.1 d), and the half-life was negatively correlated with soil microbial enzyme activity (fluorescein diacetate hydrolytic, glucosaminidase, and beta-glucosidase).  Recent plot trials conducted using a rainfall simulator demonstrated a > 70% reduction in aqueous phase concentrations for enrofloxacin, sulfamethazine, and tylosin after runoff passed through eight meters of any VFS design studied.  Results from these studies and ongoing research investigating (1) effects of dissolved organic matter on VA transport in VFS soils and (2) VA effects on soil microorganisms all suggest that VFS may be a practical land management practice to mitigate VA loss from agroecosystems.