2005 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and The Pennsylvania State University. Additional details of research can be found in the report for the parent CRIS 1902-13000-009-00D, "Optimizing Nutrient Management to Sustain Agricultural Ecosystems and Protect Water Quality." A support scientist was hired to conduct research under this project, as no suitable Post-Doctorate was found. Fluvial sediments modify edge-of-field losses of P: The physical and chemical properties of stream and river sediments have a major influence on the forms and amounts of nutrients, particularly P, after it leaves a field in runoff and before it enters a lake or reservoir. Stream environments can be subject to large variations in water level, which can expose some of the sediment, allowing it to dry and alter sediment mineralogy. This, in turn, can influence the reaction of these sediments with P and thereby P inputs to lakes. ARS scientists at University Park, PA, studied the P chemistry of exposed stream banks and submerged bed sediments from an agricultural catchment in central Pennsylvania, U.S. It was found that although bank sediments contribute less P to stream flow than does the resuspension of bed sediments, the latter have the potential to be a large source in downstream lakes. Fluvial sediments can be used to trace major sources of nutrient export from a watershed: The release of P from sediments that have been deposited in stream and river bottoms (fluvial sediments) to aquatic flora and fauna is central to the onset of eutrophication, a process of accelerated growth of weeds in water that make fishing, navigation, and drinking impossible. The amounts of P on these sediments and its release to stream water is related to a series of complex chemical and physical processes that can reflect the sediments' origin and history of land use. In fact, the chemistry of P in fluvial sediments is the end result of many land use factors in a watershed, such as manure management, erosion control measures, and dominant topography, as well as how fast the stream or river flows. ARS scientists at University Park, PA, conducted research to link land use and/or chemical and physical processes with the behavior of P in fluvial sediments and stream waters, and to identify where within the watershed it would be most effective to place remedial measures to decrease the loss of P. The results of this study identified the major areas of the watershed where P was being moved from the land to the stream. From this, it is possible to target remedial measures to diminish these main sources without the expense, labor, and short-term variation inherent in taking a broad-based, "blanket" watershed approach to mitigating P loss. Field and drainage ditch management in the Delmarva Peninsula research to decrease nutrient export: Ditches provide vital drainage to agricultural soils with high water tables, but can also exacerbate nutrient transfers from agricultural soils to downstream water bodies. Despite the vital role of ditches in water quantity and quality of coastal plain surface waters, no systematic management recommendations currently exist for ditches to reduce their role in non-point source nutrient pollution. ARS scientists at University Park, PA, are conducting research at University of Maryland-Eastern Shore to develop ditch management recommendations by evaluating several alternative management practices. A total of eight ditches are monitored to take advantage of adjacent field and/or sub-surface monitoring as well as to represent a variety of conditions (depth of ditch, relationship to local vs. regional water table, area of catchment). Objectives are to assess flow entering and exiting a ditch segment, flow entering and exiting wetlands is monitored to evaluate wetland function before and after dredging of one of the wetlands, and the use of flow control structures in combination with nutrient-sorbing materials in minimizing P exported by ditches.