Grazing Effects on Bovine-Associated and Background Fecal Indicator Bacteria Levels in Edge-of-Field Runoff
1
Oklahoma Water Resources Center, Oklahoma State University, 139 Agricultural Hall, Stillwater, OK 74078, USA
2
Department of Soil and Crop Sciences, Texas A&M University, 370 Olsen Blvd., 2474 TAMU, College Station, TX 77843, USA
3
Center for Agricultural Resources Research, USDA—Agricultural Research Service, 2150 Centre Avenue, Fort Collins, CO 80526, USA
4
USDA—Natural Resources Conservation Service, 400 Community Park Boulevard, Dyersburg, TN 38024, USA
5
Texas A&M AgriLife Extension Service, Department of Soil and Crop Sciences, Texas A&M University, 370 Olsen Blvd., 2474 TAMU, College Station, TX 77843, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Hodon Ryu
Water 2021, 13(7), 928; https://doi.org/10.3390/w13070928
Received: 29 December 2020
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Revised: 9 March 2021
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Accepted: 25 March 2021
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Published: 29 March 2021
(This article belongs to the Section Water, Agriculture and Aquaculture)
Excessive levels of fecal indicator bacteria are a major cause of water quality impairment. Grazing and its management may significantly impact bacteria concentrations; however, other sources can contribute to water quality issues both in the presence and absence of cattle, thus confounding results. In this study, we utilize Bacteroides markers to evaluate bacteria loading from cattle versus background sources in runoff from rotationally grazed and ungrazed pastures and how grazing management, timing of runoff in relation to grazing events, and stocking rate affect Bacteroides marker (AllBac and BoBac) levels and ratios and their relation to E. coli concentrations in runoff at the small watershed scale. The data suggest that the AllBac and BoBac levels were not significantly impacted by grazing management or stocking rate; however, the timing of runoff events in relation to grazing events significantly impacted the levels of these markers found in runoff. Furthermore, the BoBac/AllBac ratio confirmed that fecal contamination present in runoff when sites were destocked for over two weeks largely originated from sources other than cattle. Thus, the magnitude and proportion of cattle impacts on fecal indicator bacteria in edge-of-field runoff were dramatically reduced shortly after de-stocking. However, background sources continued to contribute significant concentrations of E. coli.
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Keywords:
Bacteroides; AllBac; BoBac; E. coli; microbial source tracking; grazing; runoff; water quality; bacteria loading; cattle
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MDPI and ACS Style
Wagner, K.L.; Gentry, T.J.; Harmel, R.D.; Pope, E.C.; Redmon, L.A. Grazing Effects on Bovine-Associated and Background Fecal Indicator Bacteria Levels in Edge-of-Field Runoff. Water 2021, 13, 928. https://doi.org/10.3390/w13070928
AMA Style
Wagner KL, Gentry TJ, Harmel RD, Pope EC, Redmon LA. Grazing Effects on Bovine-Associated and Background Fecal Indicator Bacteria Levels in Edge-of-Field Runoff. Water. 2021; 13(7):928. https://doi.org/10.3390/w13070928
Chicago/Turabian StyleWagner, Kevin L., Terry J. Gentry, R. D. Harmel, Emily C. Pope, and Larry A. Redmon. 2021. "Grazing Effects on Bovine-Associated and Background Fecal Indicator Bacteria Levels in Edge-of-Field Runoff" Water 13, no. 7: 928. https://doi.org/10.3390/w13070928
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