User Capabilities andNext Generation

Phosphorus Indices

Waste to WorthApril 2, 2015

John A. LoryUniversity of Missouri

Nathan O. NelsonKansas State University

Timeline of P Management Tools

Initial use of chemical extracts to predict crop response to fertilizers (Anderson, 1960).

Development of current soil test phosphorus extracts for agronomic assessment (Bundy et al., 2005).

Initiation of the environmental assessment era.

ResourceAssessment

1850

1900

1940

1985

2014

Timeline of P Management Tools

Initial research connecting soil test P to runoff water quality (e.g. Romkens and Nelson, 1974; Sharpley et al. 1977; 1978).

Initial P Index framework (Lemunyon and Gilbert, 1993).EPA-NRCS Unified national strategy for CAFO’s calling for P loss assessment on agricultural fields.

CAFO rule requiring P loss assessment for regulated applications.

EnvironmentalAssessment

1970

1994

1999

2008

2014

Apple Pie EffectThe term “P Index” has come to mean different things in different places...

…but the differences are not always appreciated because all are called “P Indices”.

We have an opportunity sharpen our approach to P loss assessment.

Opportunities as we Re-considerP Loss Assessment Tools

• Regional approach.• Focus on the user’s capabilities.• Clarify water quality goal.• Clarify temporal context of each P Index.– Multiple tools to solve multiple challenges?

• Tools that promote voluntary adoption.• Tools with applicability beyond manure.

We have an opportunity…

Opportunities as we Re-considerP Loss Assessment Tools

• Regional approach.• Focus on the user’s capabilities.• Clarify water quality goal.• Clarify temporal context of each P Index.– Multiple tools to solve multiple challenges?

• Tools that promote voluntary adoption.• Tools with applicability beyond manure.

We have an opportunity…

Soil samplingprotocol

Fertilizer recommendationsource

Crop N & P need

Manure samplingprotocol

P lossassessment

protocolNutrient availability

coefficients

Manure nutrient valueP loss rating

Manure application rate

Manure rate calculations

Manure testresults

Soil testresults

Manure applicationmethodTillage

Yield goaldetermination

Crop selection

Management Options: GreenProtocols: RedOutcomes: Black

Nutrient Management: A process, not a result.

Thinking About Time

NM Plan

Soil test result

Manure test result

P Loss assessment

1-5 year Plan (state dependent)

Sample every 3-5 years

Annually Annually Annually AnnuallyAnnually

<1 to 5-year assessment (state dependent)

Future application rate cannot be known… Based on time sensitive information.

Therefore – Initial planning is a strategic process: what is feasible?

Nutrient Management: A process, not a result.

Strategic planning (1 to 5 years)• Determine long-term goals (strategic goals) and mapping out a

strategy to attain those goals.• Feasibility.

Tactical planning (1 to 12 months)• Adjustments to strategic plan based on incoming information.

– New manure test results.– Changes in cropping system.

Implementation (1 to 3 days)• Are conditions today appropriate for P application.

Nutrient Management: A process, not a result.

Capabilities of the planner/decision maker

– Certified nutrient management planner• Expectation for training and competency in use of complex decision

support tools.• Experienced in sophisticated strategic nutrient management planning.

– Farmer or farm manager• Familiarity with computers.• Experienced in strategic planning but not necessarily with specifics related

to nutrient management.

– Contract or professional manure applicator• Uncertain computer skills.• Experienced in short-term tactical assessments and implementation

decisions.

– Farm worker• Limited computer skills.• Experienced in implementation decisions.

Strategic Planning

Tactical Planning

Implementation

DedicatedPlanner

FarmManager

ContractApplicator

FarmWorker

?

?

?

Who is needs to make these decisions?(Who needs to use the tool?)

?

?

?

?

?

?

?

?

?

Strategic Planning

Tactical Planning

Implementation

DedicatedPlanner

FarmManager

ContractApplicator

FarmWorker

Yes Yes? No? No

Yes YesYes?

Yes Yes Yes?

No

No

Who is needs to make these decisions?(Who needs to use the tool?)

P Index Implementation

State STP Erosion RateApplication Method? Timing Apparent time step

IA Yes RUSLE2 Total P Yes No By year

KS Yes RUSLE2 Fertilizer/Manure Yes Yes By year, use highest year (5-yr plan)

MO Yes RUSLE2 No No No 5-yr plan

MD Yes RUSLE Fertilizer/Manure Yes Yes By year

MS Yes RUSLE2 Fertilizer/Manure Yes No By year

NC Yes RUSLE/RUSLE2

Fertilizer/Manure Yes No Based on most erosive in 5-yr plan

NY Yes RUSLE2 Fertilizer/Manure Yes Yes By year for 1-yr plan

PA Yes RUSLE/RUSLE2

Fertilizer/Manure Yes Yes By application for 1-yr plan

Examples of P Assessment ToolsExisting Approaches Examples Complexity Data Needs

Regional Strategic Risk: Which farms? Which fields in a watershed?

Watershed models APEX, SWAT, SPARROW High Extensive

Nutrient Balance Cornell Whole Farm Nut. Bal. Moderate Moderate

Field Strategic/Tactical Risk: Which fields? Which strategies? Changes to my plan?

Simplified model Nutrient Tracking Tool High Extensive

APLE Moderate Moderate

Decision support P Indices Low-Moderate Low-Moderate

Implementation Risk: Application today?

Decision support WI Runoff Risk Advisory Forecast

Low Low

BMP List NRCS Nutrient Mgt. Std. Low Low

Strategic Planning

Tactical Planning

Implementation

DedicatedPlanner

FarmManager

ContractApplicator

FarmWorker

RUSLE2 Challenge: Often needed for strategic and tactical decisions.

Ideally who is makes these decisions?

Opportunities as we Re-considerP Loss Assessment Tools

• Regional approach.• Focus on the user’s capabilities.• Clarify water quality goal.• Clarify temporal context of each P Index.– Multiple tools to solve multiple challenges?

• Tools that promote voluntary adoption.• Tools with applicability beyond manure.

We have an opportunity…

P Index Implementation

State STP Erosion RateApplication Method? Timing Apparent time step

IA Yes RUSLE2 Total P Yes No By year

KS Yes RUSLE2 Fertilizer/Manure Yes Yes By year, use highest year (5-yr plan)

MO Yes RUSLE2 No No No 5-yr plan

MD Yes RUSLE Fertilizer/Manure Yes Yes By year

MS Yes RUSLE2 Fertilizer/Manure Yes No By year

NC Yes RUSLE/RUSLE2

Fertilizer/Manure Yes No Based on most erosive in 5-yr plan

NY Yes RUSLE2 Fertilizer/Manure Yes Yes By year for 1-yr plan

PA Yes RUSLE/RUSLE2

Fertilizer/Manure Yes Yes By application for 1-yr plan

Strategic Planning

Tactical Planning

Implementation

Long-termAverage

RotationalLosses

Long-termAnnual orSeasonal

Losses

SeasonalForecasting

Short-termWeatherForecast

Your choices have direct implications on how you develop and validate your tools

Establish Temporal Context

Event-based loss

Long-term average loss by year

Long-term average rotational loss

06/2

7/11

08/1

7/11

11/1

0/11

11/2

7/11

04/0

6/12

04/1

5/12

04/3

0/12

05/0

2/12

05/0

5/12

05/0

7/12

10/2

4/12

11/1

2/12

04/0

9/13

05/2

1/13

05/2

8/13

0

1

2MeasuredSimulated Best JudgmentSimulated Calibrated

Tota

l Pho

spho

rus

(kg

ha-1

)

Establish a Temporal Context: Some Examples

Agronomic Soil Testing

Farm- and field-level Strategic Assessment

What fields will respond to phosphorus?

What fertilizer rate should I apply to this field?

Potential users

Farmers

Consultants/Ag. advisors

Our Challenge

• Clearly define goals as a first step.

• Tools must be accessible to those who need to use them.

• We are not developing “the P Index”.Our goal is a suite of tools targeted at key decision points.

Our tools can be complex – but they must be simple to use.