|Franklin, Dorcas - Dory|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2005
Publication Date: 11/7/2005
Citation: Byers, H.L., Cabrera, M.L., Matthews, M.K., Franklin, D.H., Andrae, J.G., Radcliffe, D.E., Mccann, M.A., Kuykendall, H.A., Hoveland, C.S., Calvert, V.H. 2005. Phosphorus, sediment, and e. coli loads in unfenced streams of the Georgia Piedmont, USA. Journal of Environmental Quality. 34:2293-2300.
Interpretive Summary: Contamination of unfenced streams with phosphorus, sediments, and potentially harmful bacteria from cattle activity may be affected by the availability of shade and alternative water sources. This cooperative study evaluated water quality in two streams draining tall fescue/common bermudagrass pastures with different shade distributions and with alternating water sources (streams and watering troughs away from streams). Phosphorus (soluble and total) and sediments were measured during storm flow and normal stream flow (base flow) conditions and fecal bacteria (E. Coli) was measured every 14 days during base flow for two years in the Piedmont region of Georgia. Cooperation was between USDA-ARS J.Phil Campbell, Sr. Natural Resource Conservation Center, University of Georgia College of Agricultural and Environmental Sciences, and USDA Natural Resource Conservation Service. We found that providing cattle shade away from the streams reduced phosphorus and sediment contamination of streams. Providing water troughs away from streams reduced phosphorus by 50%, sediment by 60% and E. Coli bacteria by 85%, in streams during base flow. These results indicate that installation of alternative water sources near shade sources located away from streams (non-riparian shade) can improve water quality without the added cost of fencing streams. This information can be used by State Cooperative Extension Systems, USDA-NRCS, environmental consultants, State and federal environmental agencies and agricultural producers developing stream nutrient criteria and management plans for conservation of financial and environmental resources. Georgia has approximately 3000 miles of unfenced rivers and streams in pastures. Fencing costs could conservatively range between 1 and 2 dollars a foot depending on fence. Cattlemen in Georgia could save between 30 and 60 million dollars if fencing of rivers and streams were not necessary to improve water quality.
Technical Abstract: Contamination of unfenced streams with phosphorus, sediments, and pathogenic bacteria from cattle activity may be affected by the availability of shade and alternative water sources. The objectives of this study were to evaluate water quality in two streams draining tall fescue (Festuca arundinacea Schreb.)/ common bermudagrass (Cynodon dactylon L.) pastures with different shade distributions, and to quantify the effects of alternative water sources on stream water quality. Loads of dissolved reactive phosphorus (DRP), total phosphorus (TP), and total suspended sediments (TSS) were measured during storm flow, and loads of DRP, TP, TSS, and E.coli were measured every 14 d during base flow in two streams located in the Piedmont region of Georgia. Our results showed that grazing cattle in pastures with unfenced streams contributed significant loads of DRP, TP, TSS, and E. coli to surface waters (p<0.01). Although storm flow was similar in both streams, loads of DRP, TP, and TSS were larger (p< 0.08) in the pasture with the smaller amount of non-riparian shade. Water trough availability decreased (p< 0.08) base flow loads of TSS and E. coli in both streams. Our results indicate that possible best management practices to reduce P, sediment, and E. coli contamination from beef-cattle-grazed pastures would be to develop or encourage non-riparian shade and to provide cattle with an alternative water source away from the stream.