Checking Ambition with RealityWhere do we go with the P Index and site

assessment?

Pete Kleinman

D. Beegle, A. Sharpley, D. Osmond, J.

Lory, P. Vadas, J. Weld, T. Veith, A. Collick

P Site Assessment tool(on the books)

*

One national approach, 50 state options?Uniformity vs. flexibility

One national approach, 50 state options?

NATIONAL+ National resources+ Consistency

Regulatory, bureaucratic Uniform changes Equity?

STATE+ Flexibility

Regulatory, bureaucratic, political Nimble in responding to needed

change Local sensitivity

Something in between?Regional approaches

Existing regional groupsSERA-17Mule Barn GroupOther?

National P index assessment

Physiographic Regions

Allegheny Plateau

Ridge and Valley

Coastal Plain

Piedmont

Resistance to changeNutrient management planning in Pennsylvania

Before 2006No standardized format to PA plansAfter 2006Standardized formats (Word docs) with manual calculation

2009 - Spreadsheet automation- Supported by nutrient

management planning community

- Exemptions allowed (most big firms with existing automation/interfaces)

Farmer

Private Planner

Public sectorreview

Successes

• Improved consistency Internal (e.g., N and P recommendations) Plan review and oversight

• Ensures current agronomic information is used e.g., manure N availability changes in Agronomy guide automatically

updated in spreadsheet• Efficiency - automated calculations and facilitated information entry

Barriers

• Meeting all end-user needs with standard output (farmer, private, public) Integration with existing private sector approaches and tools

• Learning curve spreadsheet tool Implementing, updating, and understanding Excel

Resistance to changePennsylvania’s NMP Standard Format Spreadsheet

So we want to improve things. What are our objectives?

Getting lost in the possibilities

•Education

•Predicting outcomes

•Satisfying regulators, public perception

•Implementation of recommendations

•Improved water quality

•Sustainable agriculture

Who are the end users and what do they want?Getting lost in the possibilities

In actuality

Action agencies, regulators, consultants, public

Affect change/ minimize adverse impacts

Implementation• Consistent with other

approaches/rules• Data, resources• Readily applied

Improves water quality • quantifiable results?

Intended

Farmers, turf industry, home owners, land managers

Industry specific recs Understand issues and

management options Actionable guidance

P Index

Watershed model

What is the best tool?Simple index or complex model

Complex

Simple vulnerability assessment

IFSMSWATAPEX

AnnAGNPSCBM

P Index

User friendly, water quality

predicting

APLEWI Snap-Plus

OK PPMTX TBET

Current optionsSimple index or complex model

Farm to Watershed

FieldField

SCALE OF APPLICATION

TYPE OF TOOL

How much is lost?

How much is transferred?

What’s the impact?

Vulnerability to P loss or predicting effectsWhat do we want to know?

Simple P IndexModifying current indices and making new ones

Modeled P loss (kg/ha)

SOURCE Factor• Soil Test• Fertilizer

• Rate• Method

• Manure• Rate• Method• PSC

X

Transport Factor• Erosion• Runoff• Leaching• Distance• Modified

Connectivity= P Index

Each Source Factor weighted

Each Transport Factor weighted

Cur

rent

r2=0.52

X =

P IndexSediment P

SOURCE• Soil Test

Sediment Transport• Erosion

Sediment P Factor

Soluble P SOURCE • Manure P• Fertilizer P• Soil Psat

XRunoff Transport

• Runoff = Runoff Soluble P Factor

XLeaching

Transport• Leaching

=Leaching

Soluble P Factor

Each Source Factor weighted

Each Transport Factor weighted Distance

Connectivity

Soluble P SOURCE • Manure P• Fertilizer P• Soil Psat

r2=0.65

Modeled P Loss (kg/ha)

Rev

ised

“C

ompo

nent

” P

I

X =

Adapted from Bolster et al. (2012)

Appropriate Making management decisions Education about important factors of P loss, in

format that makes sense and is conceptually correct

Directionally correct – If I do “X”, will P loss go up or down?

Not appropriate Quantitative uses (unless proven otherwise)

How much PI score changes not same as or consistently proportional to actual P loss

Challenge to meaningfully compare to measured P loss data

Event-based, spatial, beyond edge-of-field evaluations

Best Use of the P Index

r2 0.78 0.15

Correct 83% 53%

Low 10% 11%

High 7% 35%

High erosion, low P

application

Low runoff, erosion high P

application

Simple IndexRequire the verification of complex models

SWAT Ratings

P Index Ratings without Distance Factor

Medium

High

Very High

P loss vulnerability

Low

SWAT vs P Index:Field-by-field ratings

Complex modelsHow do we make them user friendly and adapt them to state

needs?

• SWAT interface for conservation planners• No GIS - Little or no training required• Evaluate practices funded by TSSWCB• Quantitative sediment & nutrient reductions• Extensively validated

Texas BMP Evaluation Tool• Simulates management practices, cropping

systems, and other land uses across range of agricultural landscapes (whole farms and small watersheds)

• Represents suites of practices: filter strip, intensive rotational grazing scenarios, vegetated grassed waterways, and land application of manure

• GIS‐based or Windows‐based interfaces available

• Not yet in an interface such as TBET

Appropriate What areas and land uses contribute the most P? How will field changes affect water quality

downstream? Where do changes need to be made to have the

most impact? How much land needs new practices?

Not appropriate Spatial BMP placement Farm and field-scale management

• Not designed to evaluate specific practices or fields

Complex models

Are we delivering advice that the farmer needs?Forecasting Models

Pete KleinmanUSDA Agricultural Research Service

University Park, PA 16802peter.kleinman@ars.usda.gov

Thank you