University of Maryland Phosphorus Management Tool

Transcription

1 University of Maryland Phosphorus Management Tool aka UM-PMT

2 What s Changed in UM-PMT? Gone watershed leaching potential New paradigm shift stabilize soil P by linking maximum P applications to P removal Degree of Phosphorus Saturation (DPS M3 ) types of management options (timing and method of application)

3 Same Terms but Different Inputs subsurface drainage particulate (erosion) runoff buffers distance to water

4 Information Tied to Soil determine dominant map unit Web Soil Survey map of each field with map unit summary essential properties soil erodibility drainage class permeability class hydrologic soil group (HSG)

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6 Dominant Map Unit soil map unit with the greatest percentage area in a field exception multiple phases of the same series? combine areas of same series GgA 30%; GgB 30%, MaB 40% use GgB for dominant map unit copy of map and map unit summary should be in client s file

7 Critical Source Area Second Generation Critical Source Area in PMT Transport Source

8 PMT Paradigm Management Subsurface Drainage + + Management Management Transport Source Transport Source Transport Source Runoff Particulate (Erosion) UM-PMT = Subsurface + Runoff + Particulate Drainage (Erosion)

9 Particulate (Erosion) SED x FIV-P x DBF SED (Table 8) FIV-P - soil test P converted to FIV DBF Distance-Buffer Factor (Table 1)

10 RUSLE Scores and SED Values RUSLE OR RUSLE2 A Value SED Value < >4 10 Either RUSLE or RUSLE2 annual soil loss in tons per acre per year should be used.

11 Distance-Buffer Factor (DBF) 5 distance to water choices <100, , , , 500 ft. 3 buffer types >50 ft. buffer (NRCS specs) >35 ft. buffer <35 ft. buffer or no buffer

12 DBFs (Table 1) <35 >35 >50 < >

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14 NuMan Pro 4 (erosion)

15 Runoff DBF x SR x DPR DBF distance-buffer factor SR Surface Runoff Transport Risk Factor DPR - Dissolved P Risk Source Risk Factor

16 Surface Runoff Transport Risk Factor (SR, Table 7) Slope (%) Very Rapid Soil Permeability Class (inches/hour) Moderately Moderately Slow Very Rapid Slow Slow and Rapid and Slow Concave < >

17 Runoff Dissolved P Source Risk Factor (DPRr) DPRr = WSPall apps + 2 DPSM3 WSP = TP * PSC * AMr TP - total P as P2O5 rate for each source PSC - Phosphorus Source Coefficient AMr mode and time of application DPS = Degree of P Saturation an indicator P solubility and mobility

18 Phosphorus Source Coefficients (PSCs) for Nutrient Sources (Table 5) Organic P Source PSC default 0.6 inorganic P fertilizer 0.6 swine manure 0.6 other manures 0.5 BPR &BNR biosolids 0.5 alum-treated manures 0.3 biosolids (except BPR & BNR) 0.2

19 Application Method for Runoff Transport (AMr) Application Method and Timing Value no P applied 0 subsurface placement or immediate injection 0.2 full incorporation (>90% residue) incorporated w/in 5 days ( 50% residue) conservation tillage 0.4 surface applied, inc >5 days, incorp. 5 days, <50% residue, Mar- Nov surface applied or incorp. > 5 days Dec-Feb conventional tillage

20 Degree of Phosphorus Saturation relationship been oxalate-extractable P and extractable Al & Fe amorphous reactive oxides believed to contain the surfaces responsible for adsorption measured via Mehlich-3 P, Al and Fe transformed back to oxalate basis DPS M3 = [P /(Al + Fe)]

21 MDA will allow the estimation of PSR for 2014 and 2015 plans

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23 NuManPro 4 Runoff

24 New soil samples this year? if any fields could have high P, consider soil lab issues UDel Soil Testing Lab and AgroLab already provide DPS Brookside provides Al and Fe Spectrum will start reporting DPS other labs must be requested extra fee

25 Subsurface Drainage DBF x SD x DPRSD DBF Distance-Buffer Factor SD- Subsurface Drainage Transport Factor DPRSD- Subsurface Source Risk Factor

26 Subsurface Drainage Transport Factor (SD, Table 6) Soil Drainage Class Hydrologic Soil Group A B C D Risk Factor very poorly drained poorly drained somewhat poorly drained moderately well drained well drained somewhat excessively drained excessively drained

27 Subsurface Dissolved P Source Risk Factor (DPRsub) DPRsub = WSPall apps + 2 DPSM3 WSPsub = TP * PSC * AMsub TP = total P as P2O5 rate for each source PSC = Phosphorus Source Coefficient AMsub mode and time of application DPS = Degree of P Saturation an indicator P solubility and mobility

28 Application Method for Subsurface Transport (AMsub) Application Method and Timing no P 0 incorp. within 5 days, w/soil mixing, Mar Nov incorp. within 5 days, w/soil mixing, Dec - Feb surface-applied or subsurf. no mixing, Mar Nov surface-applied or subsurf. no mixing, Dec Feb Value

29 NuManPro 4 Subsurface

30 UM-PMT Interpretation (Table 9) Score low (0-50) medium (51-100) high (>100) Interpretation P applications shall not exceed P removal over the three-year period; can t exceed N rec of crop to which it is applied P removal the year of application No P can be applied

31 Beware Circularity! a P loss rating does not necessarily allow you to make the application used in the calculation check to assure that rate is consistent with restriction if medium, P-removal is max rate if low and N-based rate exceeds 3-yr P- removal rate, recalculate

32 Evolution of P Risk Assessment Tools USDA/NRCS CIG Grant Improving PIs in the Chesapeake Basin VA, PA, NY, MD and DE participating regional PIs will be developed ongoing final report is probably 3 years in future

33 Last year s PSI is not this year s UM-PMT