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Schmidt, John P.

Summary Non-point nitrogen (N) loss from agriculture is an environmental concern among scientists, decision-makers, and the public. This study investigated NO3–N and total N losses from a mixed land use watershed (39.5 ha) in the Appalachian Valley and Ridge Physiographic Province as influenced by hydrology (flow type, runoff volume, storm sizes, and precipitation amount) and seasons (pre-growing, growing, and post-growing seasons) from 2002 to 2006. Stream discharge was monitored every 5-min and water samples for NO3–N and total N analyses were collected weekly for base flow and for every storm. The majority of NO3–N (about 75%) and total N (about 65%) were exported in base flow, which contributed about 64% of...
Summary Non-point nitrogen (N) and phosphorus (P) pollution from agriculture has increasingly received more public attention. In this study, NO3–N, dissolved P (DP) and particulate P (PP) concentrations and loads were investigated for four sub-basins (labeled 1–4 going up the watershed) within a mixed land use watershed (39.5 ha) in the Appalachian Valley and Ridge Physiographic Province. The hot moments of NO3–N concentration and load occurred in base flow and during the non-growing season. Great and temporally variable DP and PP concentrations were observed in storm flow. The hot moments of DP concentration and load were in storm flow from May to December and from September to Nov, respectively, while the hot...
A long-term water quality database has been developed by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) Pasture Systems and Watershed Management Research Unit to support water quality research within WE-38, a 7.3 km (super 2) experimental subwatershed of Mahantango Creek Watershed located in east central Pennsylvania and draining to the Susquehanna River. Water quality data were collected at the outflow of WE-38, with record lengths of 24 years (1983-2007) for nitrate-N and ammonium-N and 23 years (1984-2007) for orthophosphate-P. Data are available on USDA ARS Sustaining the Earth's Watersheds--Agricultural Research Data System (STEWARDS) Web site.
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