Grazing Effects on Bovine-Associated and Background Fecal Indicator Bacteria Levels in Edge-of-Field Runoff

Excessive levels of fecal indicator bacteria are a major cause water quality impairment. Grazing and its management may significantly impact concentrations; however, other sources can contribute to issues both in the presence absence cattle, thus confounding results. In this study, we utilize Bacteroides markers evaluate loading from cattle versus background runoff rotationally grazed ungrazed pastures how grazing management, timing relation events, stocking rate affect marker (AllBac BoBac) ratios their E. coli concentrations at small watershed scale. The data suggest that AllBac BoBac were not impacted by or rate; events these found runoff. Furthermore, BoBac/AllBac ratio confirmed contamination present when sites destocked for over two weeks largely originated than cattle. Thus, magnitude proportion impacts on edge-of-field dramatically reduced shortly after de-stocking. However, continued significant coli.