USDA, NRCS, Watershed Science Institute WATERSHED ECOSYSTEM NUTRIENT DYNAMICS (WEND) Modeling Phosphorus (P) at a Watershed Scale: A Mass Balance Approach
USDA, NRCS, Watershed Science Institute WEND §A New Tool for Phosphorus (P) Management Using Off-the-Shelf Software §Used to Balance the Input and Output of P into, out of, and within a Watershed
USDA, NRCS, Watershed Science Institute Basic Watershed Concepts §Watersheds Store and Cycle P based on: u biological, physical, chemical mechanisms u management u land use development. §Phosphorus is stored in soils, sediments, biomass and wastes.
USDA, NRCS, Watershed Science Institute Basic Watershed Concepts §Phosphorus cycles and changes form due to biological, physical and chemical mechanisms. §Phosphorus cycles and changes location within and among land uses (sectors) within a watershed.
USDA, NRCS, Watershed Science Institute Sectors that Process Phosphorus §Agricultural u Cropland u Pasture u Animal Operations §Urban and Industrial §Woodland
USDA, NRCS, Watershed Science Institute P movement into, out of and within these sectors can be modeled using mass balance and dynamic simulation techniques.
USDA, NRCS, Watershed Science Institute ConceptualModel
Four Watersheds Modeled to Date
USDA, NRCS, Watershed Science Institute Models Developed for Different Land Uses and Animal Operations 1. The WEND-1 models the 275,000 ha (679,000 ac) Winooski River Watershed in Vermont, USA DairyDairy Silage Corn,Silage Corn, Hay, Pasture Hay, Pasture
USDA, NRCS, Watershed Science Institute Models Developed for Different Land Uses and Animal Operations 2. The WEND-IBW models the 77,000 ha (190,000 ac) Inland Bays Watershed in Delaware, USA PoultryPoultry Corn-Wheat- Soybean RotationCorn-Wheat- Soybean Rotation
USDA, NRCS, Watershed Science Institute Models Developed for Different Land Uses and Animal Operations 3. The WEND-LCW models the 23,800 ha (58,700 ac) Little Cobb River Watershed in Minnesota, USA SwineSwine Oats, Soybeans, & CornOats, Soybeans, & Corn
USDA, NRCS, Watershed Science Institute Models Developed for Different Land Uses and Animal Operations 4.The WEND-Eucha models the ha (231,700 ac) Lake Eucha Watershed in Arkansas and Oklahoma, USA PoultryPoultry PasturePasture
USDA, NRCS, Watershed Science Institute Characteristics of Watersheds Modeled
USDA, NRCS, Watershed Science Institute Characteristics of Watersheds Modeled
USDA, NRCS, Watershed Science Institute
Monitored Data vs. Modeled Estimates
USDA, NRCS, Watershed Science Institute Management Alternatives Simulated with WEND §Erosion Control §Manure Export
USDA, NRCS, Watershed Science Institute Management Alternatives Simulated with WEND §Increased Treatment of Point Sources §Animal Reduction
USDA, NRCS, Watershed Science Institute
Conclusions §WEND Models Are Valid For Evaluating P Management Scenarios For Watersheds §P Management Strategies Must Be Tailored To Fit Conditions in a Individual Watershed
USDA, NRCS, Watershed Science Institute Conclusions §P Sources Change Over Time §A Reduction in Non-Point Source P Export to a Drainage Net May Take Years
USDA, NRCS, Watershed Science Institute For Additional Information David Anderson NRCS Watershed Science Institute x46