Phosphorus index & topo swat weld
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The document discusses comparing the Pennsylvania Phosphorus Index to the TopoSWAT model. It summarizes research objectives to establish watershed networks for evaluating nutrient management tools, identify priority concerns within physiographic provinces, and use water quality data to refine the P Index. It then describes challenges with the P Index, experimental versus modeling approaches, and initial results comparing TopoSWAT and P Index outputs for an agricultural watershed in Pennsylvania. Next steps focus on determining appropriate comparison methods to improve the P Index.
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Phosphorus index & topo swat weld
- 1. Phosphorus Index and TopoSWAT Comparisons for Pennsylvania watersheds Jennifer Weld Dept. of Ecosystem and Science Management Penn State University
- 2. Acknowledgements Committee Members • Douglas Beegle, Dept. of Plant Science • Rick Day, Dept. of Ecosystem Science & Management • Peter Kleinman, USDA-ARS PSWMRU • Tamie Veith, USDA-ARS PSWMRU University of Arkansas • Andrew Sharpley Virginia Tech • Zachary Easton University of Maryland, Eastern Shore • Amy Collick Funding: USDA-NRCS CIG Grant
- 3. 2012 NRCS Conservation Innovation Grants: National effort to improve the P Index and P Management Chesapeake Bay Watershed: “Refining and Harmonizing Phosphorus Indices in the Chesapeake Bay Region” • The Penn State University, University Park, PA. Heartland Region: “Validate, Improve and Regionalize Phosphorus Indices” • University of Missouri, Columbia, MO. Southern Region: “Refine and Regionalize Southern Phosphorus Assessment Tools” • North Carolina State University, Raleigh, NC. National Coordinating Activity: “Synthesize and Extend Lessons and Outcomes from Regional Indexing Efforts” • University of Arkansas, Fayetteville, AR.
- 4. Physiographic Regions and Watershed Network Spring Creek Mahantango Creek Conewago Creek Allegheny Plateau Anderson Creek Brushy Fork Nanticoke River (Bucks Branch) Upper Manokin River Factory Brook Valley & Ridge Piedmont Coastal Plain
- 5. Research Objectives • Establish a network of eight watersheds within the four major physiographic provinces of the Bay watershed for foundational evaluation of nutrient management site assessment tools. • For each physiographic province, identify site conditions and practices of priority concern and corresponding remedial practices of greatest efficacy and adaptability. • Use water quality data (monitored or predicted by model) to refine P Indices, improving their prediction of P loss potential, ensuring consistency across state boundaries and within physiographic provinces, and promoting effective and practical recommendations for P management. • Evaluate P site assessment tools by comparing their output with water quality monitoring data and fate-and-transport models.
- 6. Pennsylvania P transport factors – landscape based • Erosion potential • Runoff potential • Sub-surface drainage • Connectivity to stream channel Pennsylvania P source factors - management based • Soil P content • Fertilizer P – rate, method, timing • Organic P – rate, method, timing, availability coefficient
- 7. PA Phosphorus Index Version 2 PART B: SOURCE FACTORS Field ID SOIL TEST Mehlich-3 Soil Test P (ppm P) Soil Test Rating = 0.20* Mehlich-3 Soil Test P (ppm P) FERTILIZER P RATE Fertilizer P (lb P2O5/acre) FERTILIZER APPLICATION METHOD 0.2 Placed or injected 2" or more deep 0.4 Incorporated <1 week following application 0.6 Incorporated > 1 week or not incorporated following application in April - October 0.8 Incorporated >1 week or not incorporated following application in Nov. - March 1.0 Surface applied to frozen or snow covered soil Fertilizer Rating = Fertilizer Rate x Fertilizer Application Method MANURE P RATE Manure P (lb P2O5/acre) MANURE APPLICATION METHOD 0.2 Placed or injected 2" or more deep 0.4 Incorporated <1 week following application 0.6 Incorporated > 1 week or not incorporated following application in April - October 0.8 Incorporated >1 week or not incorporated following application in Nov. - March 1.0 Surface applied to frozen or snow covered soil MANURE P AVAILABILITY Refer to: Test results for P Source Coefficient OR Book values from P Index Fact Sheet Table 1 Manure Rating = Manure Rate x Manure Application Method x Manure P Availability Source Factor Sum PART B: TRANSPORT FACTORS Field ID EROSION Soil Loss (ton/A/yr) RUNOFF POTENTIAL 0 Excessively 2 Somewhat Excessively 4 Well/Moderately Well 6 Somewhat Poorly 8 Poorly/Very Poorly SUBSURFACE DRAINAGE 0 None 1 Random 2* Patterened CONTRIBUTING DISTANCE 0 > 500 ft. 2 350 to 500 ft. 4 200 to 349 ft. 6 100 to 199 ft. OR <100 ft. with 35 ft. buffer 9‡ < 100 ft. Transport Sum = Erosion+ Runoff Potential + Subsurface Drainage + Contributing Distance MODIFIED CONNECTIVITY 0.85 50 ft. Riparian Buffer APPLIES TO DIST < 100 FT 1.0 Grassed Waterway or None 1.1 Direct Connection APPLIES TO DIST > 100 FT Transport Sum x Modified Connectivity/24 P Index Value = 2 x Source x Transport Field ID Is the CMU in a Special Protection Watershed? Is there a significant farm management change as defined by Act 38? If the answer is yes to any of these Is the Soil Test Mehlich-3 P greater than 200 ppm P? questions Part B must be used. Is the contributing distance from this CMU to water less than 150 ft.? * OR rapid permeability soil near a stream ‡ "9" factor does not apply to fields with a 35 ft. buffer receiving manure. PART A: SCREENING TOOL Low P Index N Based Management Medium P Index N Based Management High P Index P Based: Crop removal Very High P Index No P: Manure or Fertilizer
- 8. Phosphorus Index: Challenges Difference between states Questions from agencies Data availability to improve P Indices
- 9. Experimental vs Modeling • Not feasible to have enough experimental sites to completely calibrate a P Index • Process based models can be used to simulate fate and transport of P over a much wider range of conditions • Models will be used to suggest improvements to the P Index and evaluate revised P Indices
- 10. PLoss (ModeledorMeasured) Representative* Scenarios Modeled Monitored Scenario .Modeled Scenario Integrating Modeling and Monitoring P Index . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . ... . .. .. . . .. . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . ... . .. .. . . .. . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . ... . .. .. . . .. . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . ... . .. .. . . .. . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . ... . .. .. . . .. . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . ... . .. .. . . .. Conceptual
- 11. Options for P Loss Evaluation Complex Simple Risk Assessment IFSM TopoSWAT APEX AnnAGNPS CBM P Index User friendly, quantitative APLE WI Snap-Plus OK PPM TX TBET Farm to Watershed FieldField
- 12. TopoSWAT • Soil and Water Assessment Tool ‐ TopoSWAT accounts for transport • Watershed scale model • Incorporates farm management practices ‐ Nutrient applications ‐ Crop Rotations ‐ Tillage • Uses hydrologic boundaries based on landuse, soil, and slope
- 13. Materials and Methods: Mattern Watershed ‐ USDA-ARS research watershed • 10 square miles • Northumberland County, PA • Agricultural land use ‐ Individual field management obtained from annual farmer surveys ‐ Availability of monitored water quality data • USDA-ARS research watershed ‐ 11 ha ‐ Northumberland County, PA ‐ Agricultural land use • Individual field management based on annual farmer surveys • Availability of measured water quality data ‐ Compared to hydrology, sediment, and P • P Index Version 2.0 assessments completed using source and transport factors • P Index and TopoSWAT results compared for 2006-2010
- 14. Study site: Mattern Watershed ‐ USDA-ARS research watershed • 10 square miles • Northumberland County, PA • Agricultural land use ‐ Individual field management obtained from annual farmer surveys ‐ Availability of monitored water quality data 2029 2028 20272026 2025 CREP
- 15. P Index and TopoSWAT Comparison TopoSWAT: Transport Variability 8 to 10 1 to 45 to 7 Topographic Index Class
- 16. P Index and TopoSWAT Comparison • Runoff was highest in 2006 and 2008 • Generally, near stream fields generated more runoff • Runoff ranged from: • 9450 m3 in 2008 • 211 m3 in 2009 • Based on soil properties P Index assigns a single runoff potential
- 17. P Index and TopoSWAT Comparison Soil test P values (ppm Mehlich-3 P) • Field measured soil test P compared to soil P in TopoSWAT • P in soil change is consistent with crop rotations
- 18. TopoSWAT and P Index TopoSWAT P Index Soil Test P Layer 1 and Layer 2 Field measured Soil Test P Runoff Potential Physical processes Soil properties Soil Erosion Sediment Yield RUSLE 2 calculation Categorization Combination of parameters 4 categories for management recommendations
- 19. Summary • Determination of an appropriate comparison method provides the foundation for improving the P Index • P Index and TopoSWAT comparisons need to evaluate… ‐ Variability of transport ‐ Soil test input and output ‐ Identify a categorization for TopoSWAT values
- 21. Next Steps • Determination of a comparison process is needed to meet challenges to the P Index management approach • Comparison approach will move P Index evaluations into other watersheds and areas on a broader scale
- 22. Phosphorus in the Environment • P is an essential element for plants and animals • High P is generally non- toxic to plants or animals • P causes accelerated eutrophication
- 23. • Overlap P Sources and Transport Indicators • Identify areas on the landscape and manage them differently Phosphorus Management Mahantango Creek Watershed, USDA-ARS Source Transport Critical Source Area
- 24. P Site Assessment tools Sharpley et al., 2003 * Phosphorus Index Adoption
- 25. Mehlich-3 soil P, mg/kg 0 200 400 600 800 P loss, kg/ha 75 kg P/ha TSP 112 kg P/ha swine slurry 150 kg P/ha poultry manure Soil Test vs P Loss with applied P 0.4 0 0.8 1.2 Sharpley, USDA-ARS
- 26. 0.4 0 0.8 1.2 P loss, kg/ha P index value for the site 0 50 100 150 200 Index describes P loss potential Very highHighMediumLow Sharpley, USDA-ARS No recent P applied 75 kg P/ha TSP 112 kg P/ha swine slurry 150 kg P/ha poultry manure R2=0.79
- 27. PLoss (ModeledorMeasured) Representative Scenarios? Limited Monitored Scenarios Integrating Modeling and Monitoring P Index Conceptual
- 28. Hypothesis Ho: There is no difference between P Index assessments and P loss values simulated by TopoSWAT.
- 29. P Index and TopoSWAT Comparison 0 2 4 6 8 10 12 14 16 18 0 20 40 60 80 100 120 SedimentP(kg/ha) P Index Assessment Value Sediment P 0 5 10 15 20 25 30 35 0 20 40 60 80 100 120 TotalP(kg/ha) P Index Assessment Value Total P 0 0.5 1 1.5 2 2.5 0 20 40 60 80 100 120 DissolvedP(kg/ha) P Index Assessment Value Dissolved P
- 30. This morning… • Pennsylvania Project Overview ‐ Objectives ‐ Preliminary Results ‐ Implications
- 31. Next Steps Representing a field in TopoSWAT • Soil test ‐ Entry of soil test on a field by field basis ‐ Output of soil test • Identification of management scenarios ‐ Allow for comparisons of across state-wide management conditions
- 32. Research Questions • Can TopoSWAT simulations be used to improve P Index assessments at a field scale? • What differences exist between the TopoSWAT simulation process and the P Index assessment process?
- 33. Veith et al., 2005 SWAT vs P Index: Field categorization SWAT P Loss Rating Medium P Index Rating Low Medium High Very high Low High Very high Previous Results
- 34. SWAT Ratings P Index Ratings without Distance Factor Medium High Very High P loss vulnerability Low Previous Results Veith et al., 2005
- 35. TopoSWAT and P Index TopoSWAT P Index Time step Daily over several years Annual evaluation Soil test P accounting Beginning of simulation Annually Watershed impact Watershed scale processes Field risk assessments P loss assessment Quantitative Relative vulnerability
- 36. Study site: Mattern Watershed ‐ USDA-ARS research watershed • 10 square miles • Northumberland County, PA • Agricultural land use ‐ Individual field management obtained from annual farmer surveys ‐ Availability of monitored water quality data 2028 Year Sediment Yield (T/A) Sediment P Loss (kg/ha) P Index Value P Index Erosion (T/A) 2006 0.15 0.31 40 2 2007 1.15 6.50 83 2 2008 7.27 15.64 39 2 2009 1.13 1.13 33 2 2010 0.44 0.56 33 2