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Effects of low-external-input and conventional rice cultivation on indicator and pathogenic bacteria presence
Proceedings of the 2020 Mississippi Water Resources Conference
Year: 2020 Authors: Firth A., Baker B., Brooks J., Davis J.B., Iglay R., Smith R.
Over 800,000 ha of rice is planted in the Mississippi Alluvial Valley (MAV), making it a significant economic crop of the region. Additionally, recognized under the North American Waterfowl Management Plan and the Lower Mississippi Valley Joint Venture, winter-flooded rice fields provide critical habitat for migratory waterbirds. However, wintering waterbird use of flooded rice fields could facilitate pathogen transport in a low-external-input-sustainable-agriculture (LEISA) rice system in the MAV. This study compared two rice farms with different management histories during the winter (conventional and LEISA). Each farm selected for study and received two treatments: 1) unflooded or 2) winter flooded fields. Fecal indicator bacteria (Enterococci, Clostridium perfringens, Salmonella, Campylobacter and Escherichia coli.) were quantified in soil before and after winter flooding and bird fecal matter estimated. Water samples collected from winter flooded fields were tested for Enterococci, C. perfringens and E.coli before fields were drained. Soil analysis results indicated LEISA flooded fields had significantly greater detections of C. perfringens than non-flooded fields. No significant differences were detected between fields in water samples. All observed pathogen rates among treatment were also less than U.S. EPA standards. Results suggest that long-term waterbird stopovers can influence pathogen indicators in soil, however, not at a significant level to pose threat to human and environmental health standards. Nevertheless, because the study was only conducted over one season, it limits the conclusions drawn about wintering bird's potential to contaminate rice fields. Future studies should focus on long-term monitoring of rice fields that harbor wintering birds.