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Georgia Water Resources Conference
Georgia Water Resources Conference
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ItemMechanical Aeration to Reduce P Export from Manured Grasslands(Georgia Institute of Technology, 2007-03) Butler, David M. ; Franklin, Dorcas H. ; Cabrera, Miguel L. ; Tasistro, Armando S. ; Xia, KangThe poultry industry is an important component of agricultural production in the Southern Piedmont of Georgia. Associated manures are typically surface-applied to pastures as a fertilizer for forages. However, this surface application of manures allows phosphorus (P) to accumulate at the soil surface and runoff to become contaminated with P and to transport it to surface waters. As such, a study was conducted to examine the conservation potential of mechanical aeration of grasslands. Mechanical aeration has potential to reduce P transport by partially incorporating applied manures, allowing for more P adsorption by the soil, increasing infiltration by breaking the soil surface, and by slowing runoff flow by increasing the roughness of the landscape. We examined the effects of four aeration treatments (aeration with cores, “no-till” disk aeration perpendicular to the slope, aeration with spikes, and no aeration treatment) on the export of dissolved reactive P (DRP) in surface runoff from grasslands with two nutrient treatments (broiler litter and a control of no manure). Plots (0.75 x 2 m) were established on a Cecil soil series with mixed tall fescue/bermudagrass vegetation on 8 to 12% slopes. Plots were then aerated and manures applied at a rate of 30 kg P ha-1, prior to simulated rainfall at a rate of 75 mm h-1. While aeration had minimal impact on volume of runoff, core aeration decreased DRP loads (P < 0.05) from applied broiler litter by 61%. Given that Cecil soil is common in pastures receiving broiler litter in the Southern Piedmont, these results suggest that core aeration could have a widespread impact on water quality in the Southern Piedmont region.
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ItemPhosphorus, sediment, and e. Coli loads in unfenced streams of the Georgia Piedmont, USA(Georgia Institute of Technology, 2005-04) Byers, Harris L. ; Cabrera, Miguel L. ; Matthews, Monte K. ; Franklin, Dorcas H. ; Andrae, John G. ; Radcliffe, David E. ; McCann, Mark A. ; Kuykendall, Holli A. ; Hoveland, Carl S. ; Calvert, Vaughn H., IIContamination 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/ bermudagrass pastures with different shade distributions, and to quantify the effects of alternative water sources on stream water quality. Loads of DRP, TP, and 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 significantly decreased (p< 0.08) base flow loads of TSS and E. coli in both streams. Our results indicate that possible BMPs to reduce P, sediment, and E. coli contamination from beef-cattle-grazed pastures may be to develop or encourage non-riparian shade and to provide cattle with an alternative water supply away from the stream.
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ItemWatershed assessment through ecological research/farmers active in research(Georgia Institute of Technology, 2003-04) Franklin, Dorcas H. ; Cabrera, Miguel L. ; Steiner, Jean L. ; Risse, Larry A. ; Risse, L. Mark ; Hibbs, Henry E.Producers in the Southern Piedmont graze and manage their lands in a variety of ways across watersheds and across individual farms. These land management practices may have an impact on the nitrogen (N) and phosphorus (P) concentrations in stream base flow and storm flow. A group of producers, researchers and educators (WATER/FAIR) pulled together to assess stream nutrient concentrations relative to land management practices in two typical Southern Piedmont watersheds. The objective of this paper is to increase awareness of participatory monitoring and of the spatial and temporal distribution of stream nutrients (N & P) at watershed and farm levels. Results showed that dissolved reactive P (DRP) concentrations were highly variable depending on the management system. Stream base flow nitrate concentrations were lower leaving farms than going into farms more than more than 75 percent of the time and were 16 percent lower in 2000 than in 1999. These lower concentrations coming out of farms could suggest that these management systems are not losing nutrients to aquatic systems but rather utilizing them on the farm.
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ItemThe Effects of Stream Fencing and Water Troughs on Cattle Movement Patterns and Stream Water Quality(Georgia Institute of Technology, 2003-04) Matthews, Monte K. ; Cabrera, Miguel L. ; Franklin, Dorcas H. ; Radcliffe, David E. ; Andrae, John G. ; Calvert, Vaughn H., IIInformation about cattle impact on streams is limited in the southeastern United States. This study is being conducted to determine the effects of stream fencing and use of water troughs on stream water quality in the Georgia Piedmont. Base flow and storm flow samples are taken and analyzed for N, P, E. coli, total sediments, turbidity, dissolved oxygen, and temperature. Global Positioning System collars are used to track cattle and determine the amount of time spent within the stream riparian area. Results from the first year of the study showed that the amount of time cattle spent in riparian areas (over 10%) was positively correlated with daily maximum air temperature (r2 =0.92). Additional results reveal that the concentration of E. coli in base flow samples was higher in unfenced than in fenced streams, and also showed a positive relationship with the time cattle spent in riparian areas. Maximum dissolved reactive P concentrations in storm flow were higher in unfenced than in fenced streams. Removing water troughs from the pasture resulted in an immediate increase in the amount of time cattle spent near the streams.