Manure and irrigation water contaminated with salmonella may cause long-term contamination in soil and root vegetables say researchers from Georgia, Maryland and South Carolina. Their findings appear in the April 2004 issue of the journal Applied and Environmental Microbiology.

"Although manure is an obvious source of pathogens, two additional sources of pathogens that contaminate soil, water, crops, animals, and humans are runoff water from manure fields and irrigation water containing manure."

In the study, three manure compounds and irrigation water were contaminated with a nonpathogenic strain of Salmonella enterica to determine the life span of the bacteria in soils fertilized with the compounds as well as the water, and carrots and radishes grown in the contaminated soil. Researchers determined the bacteria stayed in soil samples for 203 to 231 days and for 84 to 203 days after radish and carrot seeds were planted.

"It is remarkable that a one-time application of contaminated irrigation water or compost can result in pathogen contamination of radishes and carrots well beyond their growing cycle," say the researches. "Our results indicate that contaminated irrigation water or manure compost may play an important role in contaminating vegetables and the soil in which they grow."

(M. Islam, J. Morgan, M.P. Doyle, S.C. Phatak, P. Millner, X. Jiang. 2004. Fate of Salmonella enterica serovar typhimurium on carrots and radishes grown in fields treated with contaminated manure composts and irrigation water. Applied and Environmental Microbiology, 70. 4: 2497-2502.)

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Contact: Jim Sliwa
jsliwa@asmusa.org
202-942-9297
American Society for Microbiology
16-Apr-2004