Water to Worth 2015Advancing Sustainability in Animal

AgricultureSeattle, WA

Refining P Indices

Andrew SharpleyCrop, Soil,& Environmental

Sciences

Development of P Indices

Maryland implements restrictive STP thresholds for nutrient mgt. & P

applications

1998

1999

Joint US EPA & USDA Initiative requires P loss assessment prior to applying P Site specific assessment using a P index, Soil-specific P threshold level, or Soil test P recommendations

Development of P Indices

Reviewing P Indices

2009• Disparity among Indices

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”

P loss kg ha-1

AL AR GA MS NC TN TX

0.5 Low Low Low Low Low High Med.

2.7 Med. High High Low LowV.

HighHigh

4.0 Low High Med. Low LowV.

highHigh

5.8 LowV.

highV.

highLow Med.

V. high

High

10.9 LowV.

highV.

highLow Med.

V. high

High

23.7 LowV.

highV.

highLow High

V. high

High

Southern P Indices

Osmond et al., 2012

The P Index was never meant to be the solution to P

loss issues!

Main recommendations of SERA-17’s review All Indices must represent locally relevant P

source & transport factors All Indices must have a zero P application

category All States must show Indices are directionally

& magnitudinally correct

2010

Revising P Indices

2012

Revising P Indices

NRCS funds

six CIGs

across U.S.

to assess P

Indices

Peter Kleinman & Doug Beegle

Chesapeake Bay

Chesapeake Bay

• Establish 11 benchmark watersheds Water quality information Land treatment information

• Identify practices of concerns by physiographic region (4) using expert panels composed of Farmers & farm advisors State & local agencies & environmental

groups

• Panel will Evaluate practices that reduce P loss

from agricultural fields

Assess P indices & recommend changes

• Compare P Indices to water quality data & water quality modeling data

Three models will be used: SWAT, APEX, APLE, & Drainmod

Chesapeake Bay

Deanna Osmond

Southern States

• Collate water quality & land treatment data from 21 plot or watershed projects

• Compare P-Index ratings against water quality data

• Compare water quality models (SWAT, APEX, APLE, Drainmod) against water quality data & P Index ratings

• Refine Southern P Indices

Southern States

John Lory

Heartland States

• Assess rigor required in calibrating APEX Use data from existing runoff studies in

region Compare “out-of-the-box” versus fully

calibrated model for evaluating Indices

• Use calibrated model to assess & modify P Indices

• Develop & assess regional P Index for state’s consideration

• Work with stakeholders throughout project

Heartland States

Libby Dayton

Ohio

Ohio

• Revise OH-PI through use of field-scale, edge-of-field monitoring data

• Improve assessment of the potential for P loss from tile drains

• Integrate additional BMPs into OH-PI

• Develop a web-based, easy to use, web-based GIS tool

Anita Thompson & Laura Good

Wisconsin

Wisconsin

• Previous assessment with field runoff data found WI Index accurate if avg. runoff & erosion estimates accurate

• Modify Index to quantify avg. runoff from frozen/thawing soils

• Identify BMPs to minimize P runoff when animal manure applied to frozen soils

November 14th, 2014

Maryland’s Governor O’Malley pushes forward a P Management Tool

2014

Adopting MD’s revised P Index

January 20th, 2015

Maryland’s newly elected Governor Hogan repeals revised P

Management Tool

2015

Adopting MD’s revised P Index

June 8th, 2015Agriculture Article, §§8-801—8-806,

Annotated Code of Maryland

Newly revised P Management Tool

Adopting MD’s revised P Index

2015

• Define unacceptable / high Index rating that preclude P applications

• Synthesize commonalities among regional projects & integrate different outcomes

• Build a harmonized framework that yields consistent P-based risk assessment across the U.S.

• Lessons learnt

National synthesis

Thank you

Questions ??