Abstract
The Choptank River is an estuary, tributary of the Chesapeake Bay, and an ecosystem in decline due partly to excessive nutrient and sediment loads from agriculture. The Conservation Effects Assessment Project for the Choptank River watershed was established to evaluate the effectiveness of conservation practices on water quality within this watershed. Several measurement frameworks are being used to assess conservation practices. Nutrients (nitrogen and phosphorus) and herbicides (atrazine and metolachlor) are monitored within 15 small, agricultural subwatersheds and periodically in the lower portions of the river estuary. Initial results indicate that land use within these subwatersheds is a major determinant of nutrient concentration in streams. In addition, the 18O isotope signature of nitrate was used to provide a landscape assessment of denitrification processes in the presence of the variable land use. Herbicide concentrations were not correlated to land use, suggesting that herbicide delivery to the streams is influenced by other factors and/or processes. Remote sensing technologies have been used to scale point measurements of best management practice effectiveness from field to subwatershed and watershed scales. Optical satellite (SPOT-5) data and ground-level measurements have been shown to be effective for monitoring nutrient uptake by winter cover crops in fields with a wide range of management practices. Synthetic Aperture Radar (RADARSAT-1) data have been shown to detect and to characterize accurately the hydrology (hydroperiod) of forested wetlands at landscape and watershed scales. These multiple approaches are providing actual data for assessment of conservation practices and to help producers, natural resource managers, and policy makers maintain agricultural production while protecting this unique estuary.
Footnotes
Gregory W. McCarty and Ali Sadeghi are research soil scientists, Laura L. McConnell, Cathleen J. Hapeman, and Clifford P. Rice are research chemists, W. Dean Hively and Megan W. Lang are associate research scientists, and Eton E. Codling is a research agronomist at the Henry A. Wallace Beltsville Agricultural Research Center, USDA Agricultural Research Service, Beltsville, Maryland. Carrie Graff is a project scientist at LimnoTech Inc., Washington, DC. Thomas R. Fisher is a professor at the Center for Environmental Science, University of Maryland, Cambridge, Maryland. Thomas Jordan is a senior scientist at the Smithsonian Environmental Research Center, Edgewater, Maryland. David Whitall is an ecologist at the Center for Coastal Monitoring and Assessment, National Oceanographic and Atmospheric Administration, Silver Spring, Maryland. Anne Lynn is the state resource conservationist with the USDA Natural Resource Conservation Service, Annapolis, Maryland. Jason Keppler is an implementation coordinator for the Maryland Department of Agriculture, Annapolis, Maryland. Marilyn L. Fogel is a staff member at the Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC.
- © 2008 by the Soil and Water Conservation Society
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