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dc.contributor.authorRomeis, James Joshua
dc.description.abstractFew watershed-scale studies have evaluated how phosphorus (P) source and hydrologic transport factors in watersheds managed by poultry operations translate into in-stream P loading. In this study, a combination of continuous (5-minute) streamflow and mixed-frequency water quality data sets were used to estimate total P (TP) loads in three forested (FORS) and nine agricultural (poultry-pasture) (AG) headwater streams (2.4 – 44 ha) in the upper Etowah River basin of Georgia. Specific P source (soil P) and transport (watershed land cover and physical characteristics) factors were also investigated. The data collection duration at study sites ranged between 18 and 22 months. A total of 1,603 water quality samples were collected from the study sites. Significant (P < 0.1) inverse relationships were detected between extreme flow response variables (i.e. Q0.1) and drainage area and percentage of forest cover. Order-of-magnitude differences in TP and dissolved reactive P (DRP) concentration were observed between AG and FORS sites and among AG sites specifically. At AG sites, stormflow TP concentrations depended on streamflow, but the concentration-flow relationships were strongest on a storm-event basis. At most AG sites, stormflow TP concentrations appeared to reach supply-limited concentrations that were independent of streamflow rate. A documented exception was at an AG site where a storm event was sampled soon after poultry litter application. Three load estimators were examined in the study—planning level, flow-duration rating curves (FDRC), and log-transformed regression models with and without bias-correction techniques. Based on FDRCs, FORS site TP yields ranged between 0.01 and 0.1 kg-P ha-1. At AG sites, the yields ranged 0.031 to 3.17 kg-P ha-1. With confidence intervals factored in, AG site yields ranged 0.025 to 13.1 kg-P ha-1. Total P yields were significantly related (P < 0.005) to area-weighted Mehlich-1 soil test P (AWSTP) concentrations. Dissolved reactive P concentrations observed during non-storm flow conditions were significantly related (P < 0.05) to AWSTP and P yield. Results suggest that water quality sampling during non-stormflow conditions may be a useful screening tool for watershed scale P risk-based management.
dc.subjectwatershed, hydrologic response, phosphorus, load, land cover
dc.titlePhosphorus loading in agricultural and forested headwater streams in the upper Etowah River basin, Georgia
dc.description.departmentDaniel B. Warnell School of Forestry and Natural Resources
dc.description.majorForest Resources
dc.description.advisorC. Rhett Jackson
dc.description.committeeC. Rhett Jackson
dc.description.committeeMiguel Cabrera
dc.description.committeeMark Risse
dc.description.committeeDavid Radcliffe
dc.description.committeeTodd C. Rasmussen

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