Microbial Pathogen and Indicator Survival In Fescue Soils with Livestock Amendments.

Although the majority of bacteria associated with manures are beneficial and/or innocuous, the potential for contamination of agricultural environments, livestock and crops with manure-borne pathogens necessitates greater knowledge of their persistence. Data that fill gaps in knowledge about important microbial indicators and pathogens in field-scale studies are needed to improve decision support tools, development of on-the-farm best management practices (BMPs) and the predictability of mathematical models. The objective of this study was to determine die-off rates of bacterial pathogens and indicators associated with poultry and dairy manures after addition to tall fescue soils.  A field experiment with four replicates was established to investigate the survival of microbial pathogens and indicators in fescue soils amended with dairy manure (DM), poultry litter (PL) or un-amendmened (C) under conventional or no-till management. Initial concentrations of Campylobacter jejuni in poultry litter were 5.4 ±3.2 X 10⁶ cells per gram of soil, while enterococci averaged 5.4 ±0.7 X 10⁶ cells per gram of soil. Salmonella spp. could not be detected in initial manures, but was enriched sporadically from manured soil samples suggesting that pathogens may be intermittently occurring in response to chemical and/or environmental factors. The common fecal indicator organism Escherichia coli only occurred in low concentrations in PL or DM samples and could not be detected in field soils. These results suggest that enterococci may be better indicators of fecal contamination from field applied manures.