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Research linking P Index Values to Stream Phosphorus Yields

Research linking P Index Values to Stream Phosphorus Yields.

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Research linking P Index Values to Stream Phosphorus Yields

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  1. Research linking P Index Values to Stream Phosphorus Yields Project collaborators: Laura Ward Good, Katie Songer, Matt Diebel, John Panuska, Jeff Maxted, Pete Nowak, John Norman, K.G. Karthikeyan, Tom Cox, Water Resources Management Class, UW-Madison; Pat Sutter, Duane Wagner, Curt Deihl, Dane County Land and Water Resources Department; Jim Leverich and Karen Talarczyk, UW-Extension, and Faith Fitzpatrick, Rebecca Carvin and Dave Graczyk, USGS, Funding Partners: The Nature Conservancy, Wisconsin NRCS, WI DATCP, WI DNR, USGS

  2. Wisconsin P Index Estimate of annual P delivery from a given field using readily available information and assuming average weather Annual edge-of-field runoff losses (Annual sediment-bound P + Annual dissolved P) Field x Total P delivery ratio = P delivery to stream (P Index) Stream Units are lb per acre per year

  3. WBIHypothesis Targeting watershed implementation efforts to the fields that contribute the most nutrients to water is an effective way to improve water quality. And specifically…. Reducing all cropland rotational average P Index values in a watershed below the target maxima (6), will result in measurable water quality changes.

  4. WBI Pilot Project:Testing surface water quality effects of targeted P management strategies Reference Treatment

  5. P Index Map

  6. How do we know if the project succeeds?

  7. Hypothesis Reducing all cropland rotational average P Index values in treatment watershed below the target maxima (6), will significantly reduce the ratio of treatment watershed TP yields to reference watershed TP yields.

  8. Paired Watershed ComparisonSediment Yields - WY2007 and WY2008

  9. Paired Watershed ComparisonPhosphorus Yields - WY2007 and WY2008With April and June 2008

  10. Paired Watershed ComparisonSediment Yields - WY2007 and WY2008 with April and June 2008

  11. Paired Watershed Comparison Dissolved P Concentrations - WY2007 – WY2008

  12. Monthly Precipitation

  13. Monitoring Results Summary

  14. Treatment Watershed Land Use Agriculture Open Land Woodland CRP

  15. Land Use Inventoried - 2007

  16. Soil Test P Average: 39 ppm Min: 3 ppm Max: 383 ppm

  17. Pleasant Valley Watershed P Index Values Rotation Average P Index (lb P/acre/year) Average: 4 Min: 0.1 Max: 45

  18. Soil Test P P Index

  19. P Index Distribution 59 % of load Amount above 6 is 30% of total load 84% 7% 9%

  20. Annual P Index Distribution from Mead Lake 67% acres, 35% P load 26% acres, 42% P load 7% acres, 23% P load

  21. Pheasant Branch P Load Distribution C. Anderson

  22. Pheasant Branch P Load Distribution C. Anderson

  23. Missing P Loss Sources Barnyards Some dry lots, pastures Lanes, other places where uncollected manure goes Animals with direct access to streams P in sediment eroded from flow channels Construction sites Stream bank erosion

  24. Example Farm • Dairy farm, animal housing not in watershed • Almost all fields have: • Soil test P > 50 • Soil loss > T • P Index > 6 Rotation: 3 yr corn silage or 2 yr corn silage & 1 yr grain, + 3 yr alfalfa Tillage: Fall chisel plow To get all fields below T and P I < 6: 1) No-till 2) Add grass to alfalfa mix 3) Never grow more than 2 yrs of silage

  25. Comparison of P Index Values for Continuous Corn Silage Managements, Pheasant Branch, C. Anderson

  26. Reducing Soil Loss vs. Reducing Soil P

  27. Current Project Efforts Dane County initiating work with farmers, targeting high P loss farms first Dane County assessing barnyards (model?) Economic evaluation of management alternatives for selected farms Research on P transport Statistical analysis of rotational and average annual P Index distribution, development of screening tool, sampling protocol (Katie Songer’s talk)

  28. On-Farm EconomicsDr. T. Cox, UW-Madison and J. Leverich, UW-Extension • Economic/Environmental Tradeoffs!!! • Farm Management/Economics provides an integrated framework for assessing these tradeoffs in the context of particular farms/farmers. • Many Nutrient BMPs Involve “Optimal” BMPs provide Win/Win (economic/environmental) opportunities to the farm/farmers: improved profits with improved NMP. • In Non-Win/Win situations, farm management/economics can help to identify and rank least-cost practices to attain NMP objectives.

  29. Research strategies to link P Index to water body P yields

  30. Acceptable P delivery Average stream P yield (lb/a) P Index Threshold Area-weighted average P Index (lb/acre) What P Index threshold is compatible with acceptable P delivery?

  31. Considerations May take years for land use changes to result in measurable drop in P yields because of P stored in flow channels Agricultural land use management is not static Need to take adaptive management approach, commit to continued monitoring and reassessment

  32. Summary Phosphorus loss potential is much greater on some fields than others in watershed Use of the P Index to evaluate potential P loss reductions allows management flexibility We are testing the hypothesis that implementing changes to reduce P lndex values for the highest P loss areas in a watershed will improve water quality

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