Full proceeds can be found at: http://www.extension.org/72805 The Phosphorus Index (PI) estimates the relative risk of P loss from agricultural fields and encourages the implementation of best management practices to reduce this risk. A majority of states designed their own PI version to address local conditions and priorities, resulting in a large variation in PI structures among states. Currently, multiple projects nationwide are evaluating if the different PIs are directionally and magnitudinally correct in ranking fields based in their potential for P loss. In the Chesapeake Bay, New York (NY), Pennsylvania (PA), Delaware (DE), Maryland (MD), Virginia (VA), and West Virginia (WV) are working cooperatively to fulfill this objective. Several approaches have been proposed to determine the effectiveness of the various PIs. The following results summarize one approach: a survey of certified nutrient management (CNMP) planners with questions specifically related to their perspectives on the NY and PA PIs. This approach recognizes that planners have experience with the PI and have a close knowledge of the landscape scenarios and management that have previously resulted in water quality violations.

1. NUTRIENT MANAGEMENT
PLANNERS' FEEDBACK
ON NEW YORK AND
PENNSYLVANIA
PHOSPHORUS
INDICES
Karl Czymmek
Sebastian Cela
Quirine Ketterings
Jen Weld
Doug Beegle
Pete Kleinman

2. Phosphorus Index:
• Ranks fields based on relative risk of generating P runoff.
• Motivates implementation of BMPs to reduce P loss from
farmer’s fields.
• Overlaps Source and Transport indicators.
Source Transport
Critical Source Area

3. Variability
• Different ratings and P recommendations when different
P indices are applied to similar scenarios
Issues with earlier P Indices
Accuracy
• Poor representation of some conditions
• Impossible to develop one P index to
cover all range condition
• Development of
Physiographic Region P Index

4. Addressed to nutrient management planners in NY and PA.
Questions related to:
• What’s working in the current PI?
• Drivers of water quality violations
• Practices that should be encouraged and discouraged
• The need of a screening tool in the revised PI
• State or physiographic boundaries?
Survey

5. Pennsylvania P Index
Screening tool
• Special protection watershed
• Significant management changes
• STP > 200 ppm Mehlich 3
• Distance to stream < 150 feet
Source factors
• Soil test P (Mehlich 3)
• Manure P (Rate, Timing x Method, P Availability Coeff.)
• Fertilizer P (Rate, Timing x Method)
Transport factors
• Erosion (RUSLE2)
• Runoff potential (Drainage class)
• Subsurface drainage
• Distance to the stream
Modified connectivity
• Riparian buffer • Grassed waterway • Direct connection

6. Source
• Soil Test P (STP)
• Manure P (Rate, Timing, Method)
• Fertilizer P (Rate, Timing, Method)
Dissolved Transport
• Soil drainage class
• Flow distance to stream
• Flooding frequency
Particulate transport
• Erosion (RUSLE2)
• Flow distance to stream
• Flooding frequency
• Concentrated flow
Dissolved NY-PI Particulate NY-PI
New York P Index

7. P Index Interpretation
Value
(NY)
Value
(PA)
Rating Management
guidance
<50 <60 Low N-based management
50 to 74 60 to 79 Medium N-based management with BMPs
75 to 99 80 to 99 High P applications to crop removal
>100 >100 Very High No P can be applied

8. Survey response rate
New York
• 37 certified nutrient management planners were approached
• 36 planners responded
• 58% private sector
• 36% public sector
Pennsylvania
• 200 nutrient management planners approached
• 31 planners responded
• 19% private sector
• 81% public sector

9. Importance of current PI factors
All source and transport factors important
Average of planners in
Factors NY PA
Source Soil Test P 8.0 9.0
Fert. Rate 6.1 7.7
Timing 5.8 6.9
Method 6.4 6.6
Manure Rate 8.5 8.3
Timing 8.5 7.6
Method 8.5 6.9
Transport Drainage class 6.9 -
Flooding frequency 7.1 -
Distance to a stream 8.5 8.6
Concentrated flow 7.3 -
Erosion 7.4 9.0

10. Reasons for water quality violations
Percent of planners in
Reasons NY PA
Manure applications
before rain events 72 23
to frozen soils 50 9
close to streams 33 45
without incorporation 22 0
CNMP not followed 39 9
Unknown geology / Karst soils 19 9
No residue or cover crop 6 5

11. Top 7 practices the PI should encourage
Percentage of planners in
Practices NY PA
Manure applications
with incorporation 58 3
to fields without connectivity 28 0
at lower rates 19 14
Credit
cover crops 39 52
setbacks and buffers 36 59
Practices to 22 62
reduce erosion 22 62
improve infiltration 11 21

12. Top 7 practices the PI should discourage
Percentage of planners in
Practices NY PA
Manure applications
to saturated soils
61 4
to fields close to streams 44 21
without incorporation 36 0
to fields with steep slopes 19 4
to fields without crops 14 82
at high rates 22 7
Fall tillage 8 25

13. Top 7 changes for the PI
Percentage of planners in
Changes NY PA
Weight of coefficients 65 0
Timing of app. 32 0
Flow distance 19 5
Erosion 16 14
Method of app. 16 0
Credit
cover crops / residues 23 38
setback, buffers, diversions 16 5
Adjust weighting of coefficients and include cover crops.

14. Do we need a screening tool?
No
64%
Yes
36%
No
32%
Yes
68%
New York Pennsylvania
NY planners are not in favor of including a screening tool.
PA planners would like to continue using their screening tool

15. State Boundary or
Physiographic Region PI?
NY planners = mostly in favor of physiographic region PI
PA planners = mostly in favor of state-boundary PI
NY PA
Phys. Region
State Boundary
Others
0
10
20
30
40
50
NY PA
(%ofplanners)

16. Timing of manure application
• Open April and September as “safe” months.
• Move away from calendar year, use field conditions and
weather forecast.
Discourage manure applications
• Without incorporation
• To saturated soils
• To fields close to streams and with steep slopes
Evaluate BMPs
• Cover crops, setbacks / buffers, crop residues
Areas to improve the New York P Index

17. Pennsylvania P Index
How to encourage better management
Evaluate all fields with the P Index
More credit for best management practices
• No-till
• Cover crops
More clearly defined methods for:
• Evaluating field conditions
• Communicating options to the farmer
• Information documentation
Discourage
• Winter manure application
• Manure application without
suitable ground cover
Images USDA-NRCS Image Gallery, Bob Nichols

18. Sebastian Cela sc2575@cornell.edu
Quirine Ketterings qmk2@cornell.edu
Karl Czymmek kjc12@cornell.edu
Jen Weld jlw23@psu.edu
Doug Beegle dbb@psu.edu
Pete Kleinman peter.kleinman@ars.usda.gov
THANK YOU !!