1a. Objectives (from AD-416):
To minimize downstream nutrient loss in a Chesapeake Bay subwatershed by identifying and encouraging strategic, cost-effective combinations of farm management practices and technologies.
1b. Approach (from AD-416):
Whole-farm and watershed-level models, such as the Integrated Farm System Model (IFSM) and the Soil and Water Assessment Tool (SWAT) will be used to simulate current farm and watershed conditions in the Conewago Watershed in PA. This watershed drains to the Chesapeake Bay and is becoming a focus watershed for a range of research groups on how to more effectively and efficiently control nonpoint source pollution within the Bay catchment. The economic and environmental impact of various agriculturally-based, nonpoint source control combinations will be simulated using the above models in conjunction with literature findings and simple mathematical models. Evaluation of results will include consideration of the predictive and estimated uncertainty of major variables within the natural system. These evaluations will provide comparative efficiencies of various management combinations on protecting and improving water quality within the Chesapeake Bay. Results will be transferred to stakeholders through connections with Penn State Extension.
3. Progress Report:
This work contributes to Objective 3 of the parent project, which is to validate models and quantify uncertainties of model predictions at multiple scales by comparing predictions to measured water, soil, and management effects of conservation practices. This work also contributes to the effort under the Conservation Effects Assessment Project (CEAP) to evaluate the impact of current and proposed agricultural management practices on downstream water quality. Through consultation with NRCS Conservationists and Pennsylvania Cooperative Extension, three farm types were selected for investigation: a crop farm, a machinery-powered (English) dairy farm, and an Amish dairy farm powered by horses and some stationary machinery. These three farm types represented a large portion of the Lancaster, Lebanon, and Dauphin County region of Pennsylvania. Typical characteristics were gathered for these farms to represent them with the Integrated Farm System Model (IFSM). Adjustments in the inputs and in application of IFSM were made so that the outputs properly reflected each farm type. This included researching power, time, and effectiveness constraints of using horse-drawn equipment and representing that in IFSM. Various alternative management practices were then tested for each farm through IFSM simulations in order to determine farm profitability and environmental effectiveness at reducing off-the-farm losses of nutrients and sediment. Critical source areas for nitrogen and phosphorus loss in the Mahantango watershed were identified using the Soil and Water Assessment Tool (SWAT) model and several best management practices (BMP) were optimized for cost-effective placement. Optimization of surface runoff suggested a focus on controlling sediment-bound nutrients because the majority of soluble nitrogen in this watershed is leached into the deep aquifer. In general, controlling phosphorus required a slightly more complex BMP combination than controlling nitrogen. Target results were shared with the USDA Partnership Management Team. This project has resulted in a Master’s of Science thesis, three potential journal papers, and several presentations to researchers and conservationists. Progress was monitored through regular communication with the Penn State collaborator by email, phone calls, and weekly meetings. All expenditures by PSU for the project were within budget and reimbursed by ARS.