Runoff of E. coli and other fecal indicator bacteria from grazing lands has been identified as a significant source of bacterial contamination in need of reductions to improve water quality. Improved management of creek pastures and implementation of on-farm best management practices to address these bacterial issues is critical to the success of watershed restoration efforts. To address this, the impacts of grazing management and providing alternative off-stream water in creek pastures were evaluated to assess their effectiveness for reducing E. coli loading.
Study results showed that there was no difference in runoff E. coli concentrations from ungrazed, properly grazed and heavily grazed pastures and no correlation between stocking rate and E. coli concentrations. It is suspected that the observed rapid decline in E. coli concentrations following rotation and significant contributions by wildlife resulted in this lack of correlation. However, rotational grazing, when timed appropriately, was found to be a very effective practice for reducing E. coli concentrations in runoff. As a result of these findings, it was recommended that, where feasible, creek pastures and other hydrologically connected pastures be grazed during periods when runoff is less likely and that upland sites be grazed during rainy seasons when runoff is more likely to occur.
The study also found that when alternative off-stream water was provided, cattle spent 43% less time in the creek. Despite this significant reduction in the amount of time cattle spent in the creek, the study was not able to document statistically significant E. coli loading reductions from providing alternative water. Nevertheless, providing off-stream water in creek pastures was highly recommended practice for improving water quality due to the reduction in the amount of time cattle spend in the creek documented by this study and the finding of other studies demonstrating reductions in sediment, nutrients and bacteria.
Kevin Wagner, Texas Water Resources Institute, Texas A&M University firstname.lastname@example.org
Terry Gentry, Ph.D., Texas A&M University, Soil and Crop Sciences Department; Larry Redmon, Ph.D., Texas A&M University, Soil and Crop Sciences Department; R. Daren Harmel, Ph.D., USDA-ARS, Grassland Soil and Water Research Laboratory; Jamie Foster, Ph.D., Texas A&M University, Soil and Crop Sciences Department; Robert Knight, Ph.D., Texas A&M University, Ecosystem Science and Management Department; C. Allan Jones, Texas A&M University, Spatial Sciences Laboratory
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