Tylosin is a veterinary antibiotic commonly used in swine production for growth promotion and disease prevention. Swine excrete this drug in urine and feces, and tylosin enters the environment via manure application. This study proposes to investigate the mobility and degradation of tylosin, as well as the survival and movement of microorganisms in the presence of tylosin. Waters leaching from intact soil columns will be examined for tylosin, for total Escherichia coli and for tylosin-resistant E. coli. Following the completion of the study, soil will be evaluated for the mobility of tylosin and presence of metabolites, as well as for survival and movement of microorganisms. The experimental design will allow us to determine if tylosin causes increased levels of tylosin-resistant E. coli in soil or if tylosin increases survival and movement of tylosin-resistant E. coli in manure.