Manure Consistency and Weathering Affect the Removal of Fecal Indicator Bacteria from Grass-Covered Soil
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Manure Consistency and Weathering Affect the Removal of Fecal Indicator Bacteria from Grass-Covered Soil M. D. Stocker & R. L. Hill & Y. A. Pachepsky
Received: 28 January 2020 / Accepted: 26 March 2020 / Published online: 22 April 2020 # This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2020
Abstract Animal manures contain bacteria which may be used to indicate the potential microbial pollution of irrigation and recreation water sources. The objective of this work was to research how the release of these indicators to runoff is affected by the concurrent influence of the manure consistency and the duration of manure weathering between rainfall events. Liquid and solid dairy manure was applied on grassed soil boxes. The percentage of manure-borne bacteria removed in runoff over 1 hour was determined after the initial rainfall immediately after manure application and after rainfalls that occurred 1 week and 2 weeks after the initial rainfall. The runoff delay was linearly related to the time between rainfalls and was significantly affected by both weathering duration and manure consistency (P = 0.017 and 0.038, respectively). The runoff delay was dependent on the antecedent gravimetric soil water content (R2 = 0.92 and 0.99 for liquid and solid manure treatments, respectively). Manure weathering caused a substantial decrease in the removal of fecal bacteria with runoff in the 2-week weathering compared with the 1Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11270-020-04556-4) contains supplementary material, which is available to authorized users. M. D. Stocker : Y. A. Pachepsky USDA-ARS Environmental Microbial and Food Safety Laboratory, 10300 Baltimore Avenue, Beltsville, MD 20705, USA M. D. Stocker (*) : R. L. Hill Environmental Science and Technology, University of Maryland, College Park, MD, USA e-mail: [email protected]
week weathering treatments for both of E. coli and enterococci (P = 0.063 and 0.049, respectively). Every day of weathering decreased the percentage of the released E. coli and enterococci by about 1.2 and 1.5 times, respectively, for both manure consistencies. Manure consistency was not found to significantly affect the percentages of E. coli or enterococci removed with runoff for any level of weathering. Results indicate the need of correcting existing manure bacteria removal models by accounting for manure consistency and weathering duration. Keywords E. coli . Enterococci . Runoff . Water quality . Runoff delay
1 Introduction Animal manures contain high concentrations of fecal microorganisms some of which may potentially pose significant harm to human health. During irrigation or rainfall events, microorganisms are released from manure and either move into soil with infiltrating water or are transported with overland runoff and can reach surface waters used for recreation or irrigation. To assess the fate and transport of manure-borne bacteria in the environment, co
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