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Identify and synthesize methods to refine phosphorus indices from three regional indexing efforts


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The full proceedings paper is at:

This project was started to work with regional CIG projects to calibrate and harmonize Phosphorus Indices across the U.S., demonstrate their accuracy in identifying the magnitude and extent of phosphorus loss risk, and provide suggestions to refine or improve existing Indices. This research is important to provide consistency among state Phosphorus Indices and their subsequent recommendations.

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Identify and synthesize methods to refine phosphorus indices from three regional indexing efforts

  1. 1. Water to Worth 2015 Advancing Sustainability in Animal Agriculture Seattle, WA Refining P Indices Andrew Sharpley Crop, Soil,& Environmental Sciences
  2. 2. Maryland implements restrictive STP thresholds for nutrient mgt. & P applications 1998
  3. 3. 1999 Joint US EPA & USDA Initiative requires P loss assessment prior to applying P  Site specific assessment using a P index,  Soil-specific P threshold level, or  Soil test P recommendations
  4. 4. 2009 • Disparity among Indices  Varied with soils, topography, & state priorities • Often, not leading to a decline in STP nor improvement in water quality  Legacy effects • Perceived as “farmer friendly”
  5. 5. P loss kg ha-1 AL AR GA MS NC TN TX 0.5 Low Low Low Low Low High Med. 2.7 Med. High High Low Low V. High High 4.0 Low High Med. Low Low V. high High 5.8 Low V. high V. high Low Med. V. high High 10.9 Low V. high V. high Low Med. V. high High 23.7 Low V. high V. high Low High V. high High Osmond et al., 2012 The P Index was never meant to be the solution to P loss issues!
  6. 6. Main recommendations of SERA-17’s review  All Indices must represent locally relevant P source & transport factors  All Indices must have a zero P application category  All States must show Indices are directionally & magnitudinally correct 2010
  7. 7. 2012 NRCS funds six CIGs across U.S. to assess P Indices
  8. 8. Peter Kleinman & Doug Beegle
  9. 9. • Establish 11 benchmark watersheds  Water quality information  Land treatment information • Identify practices of concerns by physiographic region (4) using expert panels composed of  Farmers & farm advisors  State & local agencies & environmental groups
  10. 10. • Panel will  Evaluate practices that reduce P loss from agricultural fields  Assess P indices & recommend changes • Compare P Indices to water quality data & water quality modeling data  Three models will be used: SWAT, APEX, APLE, & Drainmod
  11. 11. Deanna Osmond
  12. 12. • Collate water quality & land treatment data from 21 plot or watershed projects • Compare P-Index ratings against water quality data • Compare water quality models (SWAT, APEX, APLE, Drainmod) against water quality data & P Index ratings • Refine Southern P Indices
  13. 13. John Lory
  14. 14. • Assess rigor required in calibrating APEX  Use data from existing runoff studies in region  Compare “out-of-the-box” versus fully calibrated model for evaluating Indices • Use calibrated model to assess & modify P Indices • Develop & assess regional P Index for state’s consideration • Work with stakeholders throughout project
  15. 15. Libby Dayton
  16. 16. • Revise OH-PI through use of field-scale, edge-of-field monitoring data • Improve assessment of the potential for P loss from tile drains • Integrate additional BMPs into OH-PI • Develop a web-based, easy to use, web- based GIS tool
  17. 17. Anita Thompson & Laura Good
  18. 18. • Previous assessment with field runoff data found WI Index accurate if avg. runoff & erosion estimates accurate • Modify Index to quantify avg. runoff from frozen/thawing soils • Identify BMPs to minimize P runoff when animal manure applied to frozen soils
  19. 19. November 14th, 2014 Maryland’s Governor O’Malley pushes forward a P Management Tool 2014
  20. 20. January 20th, 2015 Maryland’s newly elected Governor Hogan repeals revised P Management Tool 2015
  21. 21. June 8th, 2015 Agriculture Article, §§8-801—8-806, Annotated Code of Maryland Newly revised P Management Tool 2015
  22. 22. • Define unacceptable / high Index rating that preclude P applications • Synthesize commonalities among regional projects & integrate different outcomes • Build a harmonized framework that yields consistent P-based risk assessment across the U.S. • Lessons learnt