Veterinary Antibiotic Sorption to Agroforestry Buffer, Grass Buffer and Cropland Soils.

Veterinary antibiotics are widely used to treat infectious animal diseases and enhance animal growth.  Use of antibiotics in these capacities has, however, resulted in the distribution of antibiotics in soil and natural waters.  In Missouri, the increased growth of confined animal feeding operations (CAFOs) and the need to dispose of large quantities of manure generated by these operations is known to be problematic from a nutrient management standpoint.  However, land-application of manure is also problematic due to co-application of antibiotics contained within the manure, which may then migrate to natural waters via runoff and leaching.  In claypan or claypan-like soils, surface runoff events are rather common, thus there is a need to develop and evaluate management techniques to mitigate antibiotic transport to surface water bodies.
Agroforestry is a management program that intersperses trees within cropping systems, pastures, or grass buffers to provide economic benefits and ecosystem services.  Previous studies have shown that agroforestry buffers can help reduce surface runoff, and sediment, nutrient and pesticide loss from row-crop agriculture.  However, the potential of these buffers to mitigate antibiotic transport has yet to be investigated.  Therefore, the goal of this research is to investigate the potential effects that agroforestry buffers may have for mitigating antibiotic transport from agroecosystems.  The initial phase of this research involves investigating the sorption and desorption of oxytetracycline (tetracycline class), and sulfadimethozine (sulfonamide class) to soils collected tree-grass buffers, grass buffers, and cropland.  Results from adsorption/desorption isotherms, isotherm modeling, and correlation of isotherm model parameters with soil physical properties will be presented and discussed.