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Tools for phosphorus management
This document summarizes a presentation about tools for phosphorus management. It discusses the history of phosphorus risk assessment and revisions to nutrient management standards. It also outlines outcomes from national phosphorus research projects, including standardized rainfall runoff study methods. Additionally, it provides an overview of phosphorus indices used for risk assessment and nutrient planning, and discusses best management practices to reduce phosphorus loss from agricultural lands.
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Tools for phosphorus management
- 1. Tools for Phosphorus Management AndrewSharpley Water to Worth: Spreading Science and Solutions Denver, CO; April 1 – 5, 2013
- 2. History risk assessment Revisionof the NRCS 590 Nutrient Management Standard & P Indices Its use & misuse for P management BMPs and their assessment The way forward Today’s presentation
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- 4. • National PResearch Project outcomes Standardized methods for rainfall – runoff studies Established relationships between STP and runoff Integrated into P Indices Incorporated into NMP process • Success partly due to Group effort – Land Grant & ARS Flexibility to adapt to State needs
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- 13. Dissolved P mg L-1 Mehlich-3P, mg kg-1 FD-36 watershed - PA 1 0 2 3 0 200 400 600 800 R2 = 0.86 Crop response 200 mg L-1 Change point
- 14. P loss affectedby many factors177 144 44 4620 1 <1 97 55 DP 8 DP78 92 0 Tony Buda, ARS, PA Soil P – ppm P added – kg P/ha/yr Runoff – liters P loss – kg P/ha/yr
- 15. High source High transport Critical Source Area Ledto the 80/20 rule: 80% of P comes from 20% of land area Risk assessment used by most states for nutrient management planning (CPS 590)
- 16. • Runoff potential •Erosion potential • Leaching potential • Proximity to stream TransportSource • Soil P content • Added P • Rate, method, timing of fertilizer & manure • Manure P solubility
- 17. 1 0 2 3 P index valuefor the site 0 50 100 150 200 R2=0.80 75 kg P/ha TSP 112 kg P/ha poultry litter 150 kg P/ha poultry manure Runoff P, g/ha Very highHighMedLow Soil P, mg/kg
- 18. P loss iscontrolled by many factors
- 19. • Disparity amongIndices across the country 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 • The P Index was never meant to be the solution to P management issues
- 20. P loss kg ha-1 ALAR 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
- 21. • Appropriately accountfor major sources & processes determining P loss & rank risk of loss for any given site • Directionally and magnitudinally correct • Interpretations based on assigned risk are equivalent across state borders, given similar site & water resource conditions • Where inadequacies exist, the causes can be identified & addressed
- 22. •At a minimumthis should include Site runoff, management, climate, water quality Event, planning / rotation period & annual loss Natural rainfall • Network of sites and data exchange being developed – Kleinman et al. • MANAGE – Daren Harmel
- 23. •Select appropriate model APEX, APLE, DrainMod Locally calibrated (within state) Event, planning / rotation period & annual loss • Model & Index must estimate P loss & simulate P mobilization & transport over same time scales
- 24. Dietary P mgt.& use of enzymes enhances nutrient absorption & reduces excretion Manure additives can reduce P solubility & NH3 loss Manure treatment Solid-liquid separation, struvite, zeolite Struvite
- 25. Subsurface injection reduces Prunoff & N volatilization Soil & manure testing to tailor rates of P to apply 4 R’s Appropriate rate, method timing, & placement of P can increase crop uptake & decrease runoff loss
- 26. Rotational grazing reduces Prunoff & N leached Stream bank fencing Decreases P deposition in streams Conservation tillage reduces P runoff Riparian buffers trap particulate nutrients Cover crops reduces P runoff
- 27. BMP Credit Diversion 5% Terrace10% Pond 20% Fenced Pond 30% Filter Strip 20% Fenced Filter Strip 30% Grassed waterway 10%
- 28. BMP Credit Fencing 30% RiparianForest Buffer 20% Fenced Riparian Forest Buffer 35% Riparian Herbaceous Cover 20% Fenced Riparian Herbaceous Cover 30% Field Borders 10%
- 29. -100 1000 Effect ontotal P loss, % Decreased loss Increased loss Manure mgt. system (14) Nutrient mgt. plan (14) Stream fencing (3) Vegetated buffers (34) Dinnes et al., 2004 & Gitau, 2005 -40% -15% Farm pond (12) -50% -28% -65%
- 30. AR Water ResourcesCenter, 2012 Dissolved P Total P 2000 0.224 0.377 2003 0.148 0.244 2011 0.070 0.130 Mean annual concentration, ppm
- 31. Maumee River watershed Sandusky River watershed MICHIGAN LakeErie OHIO Lessons from Lake Erie Basin
- 32. Annual flow-weighted totalP, ppm 1975 1985 1995 2005 0.8 0.6 0.4 0 0.2 50% decrease Dave Baker & Peter Richards, OH
- 33. Adoption of mulchand no-till soybeans, % 1975 1985 1995 2005 0.12 0.09 0.06 0 0.03 Annual flow-weighted dissolved P, ppm 75% decrease 80 60 40 20
- 34. 1975 1985 19952005 0.12 0.09 0.06 0 0.03 Adaptive management may have reduced nutrient loss Incorporation of fertilizer and manure Winter cover crops Spring fertilization
- 35. • Spring workloadis huge with more time-sensitive tasks • Fertilizer usually costs more in spring • Less soil compaction on frozen ground But the reality is …….
- 36. • Researchers needto step back and look at the big picture