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Assessment of in-stream phosphorus dynamics in agricultural drainage ditches
- The intensive agricultural systems in the Midwestern United States can enrich surface waters with nutrients. Agricultural drainage ditches serve as the first and second order streams throughout much of this region, as well as other highly productive agricultural areas in humid regions throughout the world. This project was conducted to evaluate in-stream processing of soluble P (SP) in agricultural drainage ditches. Soluble P injection studies were conducted at seven sites along three drainage ditches (298 to 4300 ha drainage area), and one site on a third-order stream that receives the discharge from the agricultural ditches (19,000 ha drainage area) by increasing the SP concentration in the ditch water by approximately 0.25 mg L⁻¹. Sediments collected from smaller watersheds contained greater amounts of Mehlich 3 and exchangeable P (ExP), silt and clay size particles, and organic matter. Phosphorus uptake lengths (S net) ranged from 40 to 1900 m, and SP uptake rates (U) ranged from 0.4 to 52 mg m⁻² h⁻¹. Phosphorus S net was correlated with ditch geomorphological (i.e. width) and sediment properties (i.e. organic matter, ExP, and equilibrium P concentration; r ² =1.00, P <0.001), indirect drainage in the watershed (r ² =0.92, P <0.001), and the amount of small grains, forest, urban area, alfalfa and corn (r ² =1.00, P <0.0001). Agricultural drainage ditches actively process nutrients and could potentially be managed to optimize this processing to minimize SP export from these landscapes.
phosphorus , nutrients , drainage water , drainage systems , agricultural land , surface water , water pollution , streams , solubility , sediment contamination , agricultural watersheds , particle size , silt , clay , organic matter , geomorphology , small grains , forests , urban areas , alfalfa , corn , optimization , pollution control , intensive farming , Midwestern United States , Indiana
- Includes references
- Science of the total environment 2009 June 1, v. 407, no. 12
- [Amsterdam; New York]: Elsevier Science
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.