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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING CROP AND ANIMAL PRODUCTION SYSTEMS FOR SOUTHERN PRODUCERS Title: Water quality in the Fort Cobb Watershed, USA: Spatial and temporal patterns of dissolved P stream concentrations

Authors
item Franklin, Dorcas
item Steiner, Jean
item Starks, Patrick
item Moriasi, Daniel
item Duke, Sara

Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2011
Publication Date: N/A

Technical Abstract: Dissolved phosphorus (P) has often been identified as the nutrient of concern in lakes, reservoirs and streams especially where there is evidence of eutrophication. The objective of this work is to identify spatial and temporal patterns in dissolved P [soluble reactive P (SRP) and bioavailable P (BAP)] and relate those to landscape metrics. From 2005-2009, bi-weekly 1-L samples were collected at 15 sites distributed throughout the stream network and analyzed for SRP and BAP. We analyzed contiguous-spatial and temporal variability of dissolved P (PO4) stream concentrations during times with drought and during times with a series of severe storms in the Fort Cobb Reservoir watershed located in southwestern, OK. Horizontal, longitudinal, and vertical biogeophysical metrics were compiled, respectively for each contributing area, within each stream reach, and from climate and precipitation data and were related to dissolved P concentrations for spatially autocorrelated data and not spatially autocorrelated data. After a series of extreme rainfall events [drought (Dry Phase) to heavy rainfall (Wet Phase)] the proportion of spatial autocorrelation of stream PO4 increased significantly (p < 0.05) as did the corresponding mean stream concentration of PO4. Analysis with recursive partitioning, by Dry and Wet Phase and presence or absence of SAC, resulted in higher R2 with SAC than without SAC and indicated that Horizontal Variables (topography, soil, geology, management) were better predictors for SRP when SAC was present.

Last Modified: 9/10/2014
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