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Phosphorus Risk Index How Should It Be Used in a TMDL?

Phosphorus Risk Index How Should It Be Used in a TMDL?. Daniel E. Storm Michael D. Smolen Associate Professor Professor. Biosystems and Agricultural Engineering Oklahoma State University. TMDLs Involving Land Application of Animal Manures.

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Phosphorus Risk Index How Should It Be Used in a TMDL?

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  1. Phosphorus Risk IndexHow Should It Be Used in a TMDL? Daniel E. Storm Michael D. Smolen Associate Professor Professor Biosystems and Agricultural Engineering Oklahoma State University

  2. TMDLs InvolvingLand Application of Animal Manures

  3. USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates • Soil amendments are recommended to maintain optimum availability and utilization of nutrients

  4. USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates • Soil amendments are recommended to maintain optimum availability and utilization of nutrients • Recommended nutrient application rates based upon Land Grant University guidance

  5. USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates • Soil amendments are recommended to maintain optimum availability and utilization of nutrients • Recommended nutrient application rates based upon Land Grant University guidance • When using commercial fertilizer, recommended application rates not normally exceeded

  6. USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates • Soil amendments are recommended to maintain optimum availability and utilization of nutrients • Recommended nutrient application rates based upon Land Grant University guidance • When using commercial fertilizer, recommended application rates not normally exceeded • When using animal manure or organic by-products, recommended application rates may be exceeded

  7. USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates • Phosphorus application will be in accordance with one of the following options: • Phosphorus Index Rating • Soil Phosphorus Threshold Level • Soil Test Phosphorus Level

  8. Phosphorus Index Rating Phosphorus Application Low Risk Nitrogen Based Medium Risk Nitrogen Based High Risk Phosphorus Based (e.g. crop removal) Very High Risk Phosphorus Based (e.g. no application) OPTION 1: USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates

  9. Soil Phosphorus Threshold Level Phosphorus Application < 3/4 TH Nitrogen Based => 3/4 TH, < 1 1/2 TH Phosphorus Based (e.g. crop removal) => 1 1/2 TH, < 2 TH Phosphorus Based (e.g. 1/2 crop removal) => 2 TH Phosphorus Based (e.g. no application) OPTION 2: USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates

  10. Soil Test Phosphorus Level Phosphorus Application Low Nitrogen Based Medium Nitrogen Based High Phosphorus Based (e.g. 1.5 times crop removal) Very High Phosphorus Based (e.g. crop removal) Excessive Phosphorus Based (e.g. no application) OPTION 3: USDA NRCS Nutrient Management Policy & Technical GuidanceGeneral Manual Title 190 Part 402 Nutrient ManagementSection 402.06 Nutrient Application Rates

  11. What is Risk? • Risk (American Heritage Dictionary) • The possibility of suffering harm or loss • A factor, element, or course involving uncertain danger

  12. What is Risk? • Risk (American Heritage Dictionary) • The possibility of suffering harm or loss • A factor, element, or course involving uncertain danger • Risk Assessment • Process of gathering information to estimate the level of risk to people or the environment.

  13. What is Risk? • Risk (American Heritage Dictionary) • The possibility of suffering harm or loss • A factor, element, or course involving uncertain danger • Risk Assessment • Process of gathering information to estimate the level of risk to people or the environment • Risk – Phosphorus Risk Index • Probability that a specific phosphorus concentration and/or loading to a receiving water body will cause an adverse response

  14. What Should the Index Be Called? Phosphorus Risk Index Phosphorus Index Phosphorus Policy Index

  15. USDA NRCSPhosphorus Index Purpose “…. a tool for understanding the contribution that individual landform and management parameters have toward risk of phosphorus movement and … a method for developing management guidelines for phosphorus at the site to lessen their impact on water quality.” http://www.nhq.nrcs.usda.gov/BCS/nutri/manageT.html

  16. USDA NRCSPhosphorus Index Purpose “The Phosphorus Index is not intended to be an evaluation scale [tool] for determining whether land users are abiding within water quality or nutrient management standards that have been established by local state or federal agencies.” http://www.nhq.nrcs.usda.gov/BCS/nutri/manageT.html

  17. SUMMARYPhosphorus Index Purpose • USDA NRCS – Intended Application • Qualitative tool • Used by planners and farmers to assess the relative potential for phosphorus to leave field • Used by planners to set guidelines for nutrient application rates and limits • To allow for regional differences, each State will develop their own index

  18. Methods to Develop Phosphorus Index Knights of theRound Table Method

  19. Surface Runoff P Diffusion From Soil P Diffusion From Surface Layer Manure/Residue Soil Methods to Develop Phosphorus Index Physically (Science) Based

  20. Comparing MethodsRound Table vs. Physically Based • Round Table • Strictly qualitative • Useful to the field planner • Guide for selecting management approach • Identify field-level problem areas • Physically Based • Quantitative • Gives loading estimate • Predicts off-site impact • Prioritize management practices based on water quality impact

  21. Using the Phosphorus Index to quantify phosphorus loading requires a physically based hydrologic/water quality modeling framework Water Body Loading Edge of Field Loss

  22. Requirements for thePhysically-based Approach • How much runoff does the field produce? • How does the soil and manure release its Phosphorus and in what form(s)? • How much Phosphorus reaches the receiving water body and in what form(s)? • How much, when, and where should manure be applied? • What reductions in loadings result from different BMPs? • What overland/in-stream processes affect the loading?

  23. Phosphorus Index Applications • Qualitative Mode • Develop policy guidelines • Demonstrate relative impacts from varying management practices at the field level • Quantitative Mode • Determine magnitude of differences between management practices • Determine phosphorus loading to receiving water bodies • Development and implementation of a TMDL

  24. Qualitative vs. Quantitative IndexQualitative Index • Advantages • Can be used to improve farm planning • Rational framework and easy to explain • Disadvantages • Does not consider or account for other factors in the watershed • Will not provide a means of developing a TMDL

  25. Qualitative vs. Quantitative IndexQuantitative Index • Advantages • Provides means for developing a TMDL • Allows pollution source trading • Disadvantages • Complex model that may not be suited for use in the field • May require extensive training • Requires a comprehensive research base

  26. Issues • Each State will have their own index • Some qualitative indexes in development are claiming to be quantitative with little or inappropriate validation and verification • NRCS will be using the Phosphorus Index to develop nutrient and waste management plans

  27. Need to develop a water body specific Phosphorus Risk Index

  28. USDA and USEPA Need to CoordinateDevelopment and Implementationof the Phosphorus Index

  29. Surface Runoff P Diffusion From Soil P Diffusion From Surface Layer Manure/Residue Soil Model Development OSU • Physically based Phosphorus Risk Index under development • Initially developed for poultry litter applied to permanent pasture • Monthly loading to surface water • Relatively simple model that may be used by field personnel • Surface layer model • Soil layer model • Require basin specific parameters

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