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Aged Manures as Sources of Pathogens in Agricultural Runoff
Citation:
Molina, M., G. Whelan, C. Fitzgerald, AND C. Stevens. Aged Manures as Sources of Pathogens in Agricultural Runoff. Presented at American Society for Microbiology, Denver, CO, May 18 - 21, 2013.
Impact/Purpose:
Presented at ASM Annual if the American Society for Microbiology. Denver, CO May 18-21,2013
Description:
Overland runoff from fields with applied manure may carry a variety of chemical and microbial contaminants that compromise water quality and increase the human health risk of exposure to pathogenic microorganisms. A series of rainfall simulation experiments were designed and implemented to understand and compare microbial release, fate, and transport mechanisms of fecal pathogens and indicators from animal-derived sources during runoff-producing rainfall events. A set of four rainfall simulations were conducted over different seasons on a field containing 36 plots (0.75 x 2 m each), in which chicken litter, liquid swine manure, and solid cattle manure were applied to all individual plots the first week of the experiment. A constant rate of simulated rainfall was then applied and was continued for an additional 60 minutes after initiation of runoff. One-third of the plots each contained manure that was aged in the field 0, 1, and 2 weeks, respectively. Plot-scale monitoring of runoff was conducted at various time intervals throughout the rainfall application. Runoff was analyzed for E. coli 0157, Salmonella, Giardia, Cryptosporidium, enterococci and culturable E. coli. Results indicated that most of the Giardia was recovered during the first day after application, with negligible amounts recovered one and two weeks after application. Depending on the season, 40% of the applied E. coli 0157 and 50% of the applied Cryptosporidium were recovered up to two weeks after application. Salmonella was also recovered up to two weeks after application but only from plots fertilized with chicken litter. Larger amounts of E. coli originated from poultry litter than cattle and swine, while larger amounts of enterococci originated from swine manure than poultry or cattle. This study revealed that aged manures can be a considerable source of fecal indicators and pathogen contamination to surface waters. The type of pathogen surviving in aged manures and transported in runoff depends on the type of livestock manure used as fertilizer and the season when application occurs.
