2010 Annual Report
1a.Objectives (from AD-416)
The objective of this cooperative research project is to establish a farm-based research site where the effects of land management on nutrient loss to surface water and develop Best Management Practices that minimize or decrease watershed export of nitrogen (N) and phosphorus (P). This project will also establish a research infrastructure between the 1890 University of Maryland-Eastern Shore (UMES), Princess Anne, MD and USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA, where undergraduate, graduate, and postgraduate students can gain first-hand experience in nutrient management and water quality research. The experimental site is a farm recently acquired by UMES, in partnership with the Manokin River Watershed Project with soils and topography representative of a large portion of the Delmarva Peninsula. Prior to acquisition by UMES, the farm was operated as a poultry farm with its cropped areas receiving large quantities of poultry manure. Consequently, nutrient concentrations, especially P, in the surface soil are excessive and pose a threat to water quality. This threat is exacerbated by the fact that fields are routinely drained by ditches to lower naturally high water tables that restrict field productivity. The ditches provide a rapid conduit for field nutrients to reach impaired surface waters.
1b.Approach (from AD-416)
We will conduct field-scale studies to assess the fate of N and P applied to land as fertilizer and manure, describing chemical and physical interactions that control the transfer of N and P from soil to water and its subsequent transport in surface and subsurface flow from fields and subsequently in drainage ditches in Coastal Plain setting of the Delmarva Peninsula. We will identify key chemical and hydrologic factors controlling N and P loss, so that we can define management practices that minimize nutrient export to the Chesapeake Bay. We will also conduct research to evaluate in-ditch processes controlling when the ditches act as sources or sinks for N and P inputs, and which modify edge-of-field losses before entering the Chesapeake Bay, the ultimate point of impact of these losses. Traditional equipment will be used to collect flow and water samples (flumes, autosamplers, data loggers, piezometers) at selected field and ditch locations. From this research, we will develop land and nutrient management strategies, including models and decision support systems, which will provide viable and reliable solutions to decrease the impact of land-applied N and P on soil and water resources of the Peninsula. The research will enable best management practices to be targeted to critical areas for the most efficient and effective control of nutrient loss, thereby minimizing impacts on receiving waters.
The research contributes to sub-objectives 3.1 (“Quantify processes that control nutrient and sediment interactions in stream channels”), 3.2. (“Selecting chemical amendments to reduce P mobility in terrestrial and aquatic systems”), 3.3 (“Control nutrient export from ditch drained agriculture”). A third year of subsurface litter application trials was completed, continuing to show large improvements in crop yield associated with the novel ARS technology (> 30 bushels/acre). Rainfall simulations on monolith lysimeters collected in FY2009 were summarized, revealing up to 75% reduction in phosphorus loss in runoff with subsurface application over the short-term relative to surface application, but diminished benefits over the long-term. Leaching losses of phosphorus from the lysimeters were actually exacerbated with subsurface application, pointing to the need for modifications to prevent preferential transport of phosphorus to the subsoil. A new permeable reactive filter design was developed and implemented at two locations on the UMES research farm. Preliminary results show a substantial reduction in groundwater phosphorus concentrations following treatment by the filter, at least when concentrations are initially elevated. Rainfall simulations were conducted on packed soil boxes to test the role of different manure and fertilizer sources on urea and bacteria losses from agricultural soils. One manuscript has been developed from the rainfall simulation research. Monitoring of UMES activities involves regular travel to the site, near daily contact with the PI or one of the two on-site technicians, and regular visits by UMES staff to University Park.