title: Rainfall simulation in greenhouse microcosms to assess bacterial-associated runoff from land-applied poultry litter.
abstract: Runoff water following a rain event is one possible source of environmental contamination after a manure application. This greenhouse study used a rainfall simulator to determine bacterial-associated runoff from troughs of common bermudagrass [Cynodon dactylon (L.) Pers.] that were treated with P-based, N-based, and N plus lime rates of poultry (Gallus gallus) litter, recommended inorganic fertilizer, and control. Total heterotrophic plate count (HPC) bacteria, total and thermotolerant coliforms, enterococci, staphylococci, Clostridium perfringens, Salmonella, and Campylobacter, as well as antibiotic resistance profiles for the staphylococci and enterococci isolates were all monitored in runoff waters. Analysis following five rainfall events indicated that staphylococci, enterococci, and clostridia levels were related to manure application rate. Runoff release of staphylococci, enterococci, and C. perfringens were approximately 3 to 6 log10 greater in litter vs. control treatment. In addition, traditional indicators such as thermotolerant and total coliforms performed poorly as fecal indicators. Some isolated enterococci demonstrated increased antibiotic resistance to polymixin b and/or select aminoglyocosides, while many staphylococci were susceptible to most antimicrobials tested. Results indicated poultry litter application can lead to microbial runoff following simulated rain events. Future studies should focus on the use of staphylococci, enterococci, and C. perfringens as indicators.
authors.affiliation: USDA-ARS, Waste Management and Forage Research Unit, P.O. Box 5367, Mississippi State, MS 39762, USA. john.brooks@ars.usda.gov
authors.forename: John P
authors.initials: JP
authors.lastname: Brooks
authors.forename: Ardeshir
authors.initials: A
authors.lastname: Adeli
authors.forename: John J
authors.initials: JJ
authors.lastname: Read
authors.forename: Michael R
authors.initials: MR
authors.lastname: McLaughlin
mesh_terms: D000818:Animals; D002645:Chickens; D003016:Clostridium perfringens / Q000302:isolation & purification; D024881:Drug Resistance, Bacterial; D016983:Enterococcus / Q000302:isolation & purification; D005308:Fertilizers / Q000382:microbiology*; D008372:Manure / Q000382:microbiology*; D011891:Rain; D013210:Staphylococcus / Q000302:isolation & purification; D014876:Water Pollution / Q000032:analysis*
chemical_list: D005308:Fertilizers; D008372:Manure