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Title:   Author  item
                                            McCarty, Gregoryitem
                                            Sadeghi, Aliitem
                                            LEE, S. - University Of Marylanditem
                                            YEO, IN-YOUNG - University Of Marylanditem
                                            HIVELY, DEAN - Us Geological Survey (USGS)item
                                            Lang, Megan
  Submitted to: Meeting Abstract
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 4/1/2014
                                    Publication  Date: 7/28/2014
                                    Citation: Mccarty, G.W., Sadeghi, A.M., Lee, S., Yeo, I., Hively, D., Lang, M.W. 2014. Monitoring and modeling nitrate fate in subbasins within the Choptank River Watershed, Maryland, USA [abstract].  2014 Soil and Water Conservation Society Annual Meeting, July 27-30, Lombard, IL.Interpretive Summary:
                                Technical Abstract: Conservation practices, such as post harvest planting of winter cover crops, are important for water quality improvement in agricultural watersheds. Throughout the Chesapeake Bay watershed (CBW), winter cover crop use has been emphasized and federal and state cost-share programs are available for farmers to compensate for the costs of planting winter cover crops. The objective of this study was to assess the long-term effect of planning winter cover crops at the watershed scale and to identify critical source areas of high nitrate export. A physically-based watershed simulation model, Soil and Water Assessment Tool (SWAT), was calibrated and validated using water quality monitoring data and satellite-based estimates of winter cover crop species performance to simulate hydrological processes and nutrient cycling over the period of 1991-2000. Multiple scenarios were developed to obtain baseline information on nitrate loading without winter cover crops planted and to investigate how nitrate loading could change with different winter cover crop planting scenarios, including different species, planting times, and implementation areas. The results indicate that winter cover crops had a negligible impact on water budget, but significantly reduced nitrate leaching to groundwater and delivery to the waterways. Without winter cover crops, annual nitrate loading was approximately 14 kg/ha, but it decreased to 4.6 = 10.1 kg/ha with cover crops resulting in a reduction rate of 27-67 % at the watershed scale.  To further improve model calibration and validation, we have established two in situ nitrate sensors adjacent to stream gauge stations of two rather diverse subbasins, forming paired basins within the Choptank watershed that are now monitored for nitrate flux.  Experience with operation of the sensors and some preliminary data will be reported.  This study is part of the ARS CEAP Watershed Assessment.


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