Sorption of Antibiotic Monensin to Pasture Soil Receiving Longterm Broiler Litter Application.

Monensin is one of the most commonly used antibiotic in broiler production against coccidiosis and may persist in broiler litter waste. In Georgia, where broiler production is the largest in the United States, continuous application of broiler litter as fertilizer to agricultural fields presents a potential threat for antibiotic contamination of surface waters and groundwater. The mobility of broiler litter-derived monensin depends not only on its nature, but also on its interactions with soil, and other relevant surfaces. In order to assess the impact of long-term surface application of broiler litter to pasture soils on its sorption capacity for monensin, a sorption study was conducted for this antibiotic between broiler litter- and non-broiler litter-amended soils of Northeast Georgia. The experiment was done using batch sorption technique and analysis of monensin’s parent compound as the sorbate using liquid chromatography mass spectrometry. Our findings showed that at its natural pH, the control soil has greater sorption affinity for monensin compared to the BL-amended soil. We also found monensin to sorb more at low than at high pHs for both soils. Differences observed in the partitioning coefficient of monensin between the two soils was found to be the effect of their native sorption pHs.