Full proceedings available at: http://www.extension.org/72818 Phosphorus indices provide relative loss ratings that then have a corresponding management response. Because most state Phosphorus Indices are qualitative it is not clear how the relative loss rating corresponds to actual phosphorus inputs into the receiving water and how the receiving water would react to these additions. Even with qualitative Phosphorus Indices, unless the water resource has a specific Total Maximum Daily Load, it is not clear how losses correspond to water quality outcomes. These issues will be discussed in the context of the 590 Natural Resources Conservation Standard for nutrient management.

1. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Phosphorus Indicies:
What Is The Water Quality Goal?
(or How Do We Match
P Loss Assessments with
Water Quality Outcomes)
Deanna Osmond
Waste to Worth Conference
Seattle, WA
March 30 – April 2, 2015

2. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Comparing Ratings of the Southern P
Indices: Prior Work

3. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
TX
OK
FL
AL GA
AR
LA
NC
MS
TN
KY
SC
²0 250 500125 Miles
Albers Equal-Area Conic
Southern States and
Types of Phosphorus Indices
IR
IR
IR
IR
IR
IR
N
IR
IR
N
N
N

4. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Southern Phosphorus Indices CIG:
Objectives
1. Determine pre-existing watershed or plot-scale (11) sites where
accuracy of P Indices to estimate site P loss potential can be
evaluated.
2. Compare predictions of P-Indices to water quality data from
benchmark sites.
3. Compare fate and transport models against water quality data. Use
water quality data (monitored or predicted by model) to guide
refinement of P Indices.
4. Compare predictions of P Indices against fate and transport water
quality models (APEX, TBET, APLE) for calibrated and uncalibrated
models.
5. Refine P Indices to ensure better consistency in ratings across state
boundaries and within physiographic provinces.

5. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Locations of Data Sets
TX
OK
FL
AL GA
AR
LA
NC
MS
TN
KY
SC
²0 250 500125 Miles
Albers Equal-Area Conic

6. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Southern Field Sites
State # Plots Date range Site-years Crop STP range (ppm)
1 2 3 4
AR 7 2009 – 2011 21 Pasture 81 - 183 Captina (C)
GA 6 1995 – 1998 24 Pasture 14 - 142 Cecil (B) Altavista (C) Sedgefield (C) Helena (C)
NC 5 2011-2013 15
Corn with wheat
cover
44-121 Delanco (C)
MS 2 1996-1999 8
Cotton or soybens
with wheat cover
37-79 Dubbs (B) Tensas (D) Alligator (D) Dundee (C)
OK 1 1972-1976 4 Cotton 20 McLain (C) Reinach (C)
OK 1 2006-2007 1.17 Pasture 50 Clarksville (B)
OK 1 1977-1992 16 Native grass 15 Bethany (C)
OK 1 1980-1985 6 Wheat 35 Norge (B)
TX 1 1998-2001 4 Hay 435 Duffau (B)
TX 1 2005-2008 4 Sorghum/Oats 34 Topsey (C) Brackett (C) Krum (D)
TX 1 2005-2008 4 Native grass 10 Nuff (C)
TX 1 2001-2008 7
Corn with wheat
cover
51 Houston Black (D)
Soil Series (hydro group)

7. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Arkansas Data:
Southern State P-Index Ratings
Fields Total P
kg/ha
NRCS
Rating
State P-Index Rating
AL AR FL GA KY LA MS NC OK SC TN TX
Check 0.26 Low -- Low Low Low Low Low Low Low High Low Med Low
Broadcast+
Litter
1.52 Low Low Med Low Low Low Low Med Low High High Med Med
Inject+litter 0.63 Low Low Low Low Low Low Low Low Low High Med Med Med
Inject Litterx2 0.86 Low Low Med Low Low Low Low Low Low Severe High Med Med
RotGraz+
Litter
1.03 Low Low Med Med Low Med Low Med Med High High Med Med
ContGraz+
Litter
2.09 Low Low Med Med Low Med Low Med Med Severe High Med Med
Hay+Litter 1.43 Low Low Med Med Low Low Low Med Low High High Med Med
NRCS P Loss Ratings
0 to 2.2 kg/ha/yr = Low
2.2 to 5.6 kg/ha/yr = Medium
> 5.6 kg/ha/yr = High

8. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
North Carolina Data:
Southern State P-Index Ratings
Fields
Total P
kg/ha
NRCS
Rating
State P-Index Rating
AL FL GA KY LA MS NC OK SC TN TX
CTConv2011 7.55 High Low Low Low Med Low -- Low Low Low Low Med
CTConv2012 1.43 Low Low Low Low Low Low Low Low Med Low Low Med
NTConv2011 0.60 Low Low Low Low Low Low Low Low Med Low Low Med
NTConv2012 0.22 Low Low Low Low Low Low Low Low Med Low Low Med
CTOrg2011 3.09 Med Low Med
V.
High
Med Low Low Low Med High High Med
CTOrg2012 1.68 Low Low Med High Low Low Low Low Med Med High Med
NTOrg2011 1.20 Low Med Med
V.
High
Low Low Low High Med V. High High
V.
Low
NTOrg2012 0.40 Low Low Med Med Low Low Low Med Med High High V. Low
• Arkansas Soluble P/Total P Range = 77 to 96%
• North Carolina Soluble P/Total P Range = 2 to 29%

9. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
USEPA Ecoregions of the United States

10. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
USEPA Nutrient (P) Criteria by Ecoregion
Ecoregions - Lakes and Reservoirs
II III IV V VI VII VIII IX XI XII XIII XIV
TP mg/L
0.009 0.017 0.02 0.033 0.038 0.015 0.008 0.02 0.008 0.01 0.018 0.008
Ecoregions - Rivers and Streams
II III IV V VI VII VIII IX XI XII XIII XIV
TP mg/L
0.047 0.01 0.022 0.023 0.067 0.076 0.033 0.01 0.037 0.01 0.04 0.031

11. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
USEPA Nutrient Criteria Information

12. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Nutrient (P) Criteria by State and Water
Resource: Wisconsin Lakes &
Reservoirs
Type of Lake and Reservoir
TP
(mg/L)
Both seepage and stratified lakes 0.02
Drainage lakes, not stratified 0.04
Open and nearshore waters of Lake Michigan 0.007
Open and nearshore waters of Lake Superior 0.005
Seepage lakes, not stratified 0.04
Stratified reservoirs 0.03
Stratified two-story fishery lakes 0.015

13. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Nutrient (P) Criteria by State and Water
Resource: Wisconsin Rivers and Streams
River or Stream TP (mg/L)
Rock River from outlet of Sinissippi Lake downstream to the state line, excl0.1
Sheboygan River from outlet of Sheboygan Marsh to the opening at the end0.1
South Fork of Flambeau River from state highway 13 near Fifield to Flambe0.1
St. Croix River from confluence with Namekagon River downstream to Miss0.1
St. Louis River from state line to the opening between Minnesota Point and0.1
Streams not listed above 0.075

14. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Nutrient (P) Criteria by State and Water
Resource: Florida Estuaries
Estuary Total P (mg/L)
Backshelf 0.011
Blackburn Bay 0.21
Card Sound 0.008
Central Florida Bay 0.019
Charlotte Harbor Proper 0.19
Inner Waterway 0.033
Lower Keys 0.008

15. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Yields per unit area (Ib/ac.y):
TN = 2.86
TP = 2.93
NO3 = 1.01
Total Yields (Ib/y):
TN = 130,887
TP = 130,579
NO3 = 47,267
Total Reductions Available (Ib/y):
TN = 45,541
TP = 69,398
NO3 = 4,475
Yields per unit area (Ib/ac.y):
TN = 2.90
TP = 3.02
NO3 = 0.98
Total Yields (Ib/y):
TN = 51,746
TP = 51,579
NO3 = 17,896
Total Reductions Available (Ib/y):
TN = 18,308
TP = 27,551
NO3 = 1718
Yields per unit area (Ib/ac.y):
TN = 2.87
TP = 3.06
NO3 = 0.91
Total Yields (Ib/y):
TN = 23,125
TP = 22,217
NO3 = 7,725
Total Reductions Available (Ib/y):
TN = 8,321
TP = 12,020
NO3 = 717
Where Do You Measure to Meet the
Criteria?
• Where do you
measure?
• What do you
measure? TP
or SP?
• What do you
report?
Concentration
or Load?
Figure compliments of M. Arabi
and A. Tasdighi

16. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY Slide courtesy of Andrew Sharpley
Mean total P, mg/L Mean dissolved P, mg/L

17. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
But after 2002, greater dissolved P
loads generated relative to flow
than before
Relationship between total PRelationship between total P
loads and flow was the sameloads and flow was the same
before and after 2002before and after 2002
Total P, tons/d
Flow, m3
/second
200 600
20
60
120
0 400 800
0
2002-2012
1988-1999
_
_
_
_
_
_
_
_
_
_
_
2
6
12
Flow, m3
/second
0 200 400 600 800
0
Dissolved P, tons/d
2002-2012
1988-1999
_
_
_
_
_
_
_
_
_
_
_
Slide courtesy of Andrew Sharpley

18. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Tile Losses: Phosphorous
K.W. King et al.,2014 JEQ
Phosphorus Losses (~50% tile and ~50 overland flow)
•Dissolved/soluble P (49%)
•Total P (48%)
Hydrology
•Peak tile discharge occurred concurrently or even before peak
discharge in surface runoff
•Water and P moving via macropores
Slide compliments of L.
Duriancick, USDA-NRCS as
interpreted from
With permission, Douglas R. Smith, et al.,
JEQ, October 10, 2014

19. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Oklahoma Data:
Southern State P-Index Ratings
Fields Total
P
kg/ha
NRCS
Rating
State P-Index Rating
AL AR FL GA KY LA MS NC OK SC TN TX
Demo N 0.02 Low Low High Med Low Low Low Med Low Med Low Med High
Chickasha 5.80 High Low -- Med Med Med Low Low Low Low Low High Med
Cyril 0.18 Low Low -- Low Low Low Low Low Low Low High Low Med
El Reno 0.02 Low Low Low Low Low Low Low Low Low Med Low Low V Low
NRCS P Loss Ratings
0 to 2.2 kg/ha/yr = Low
2.2 to 5.6 kg/ha/yr = Medium
> 5.6 kg/ha/yr = High
Soluble P/Total P Range =
3 to 100%

20. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
How to Match Nutrient (P) Criteria
with USDA-NRCS P Loss Tools?
It’s going to be a challenge
– Most states have yet to develop nutrient criteria and it may
take years if not decades
– Many water resources have unique nutrient (P) criteria
– Where do you measure? Edge of field? Small watershed?
Larger watershed? Receiving water resource?
– What do you measure? TP or DP?
– Concentration is not the entire story
– Small losses can have large consequences

21. DEPARTMENT ofDEPARTMENT of SOIL SCIENCESOIL SCIENCENC STATENC STATE UNIVERSITYUNIVERSITY
Questions
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