Environmental Management Practices for Agricultural Phosphorus: Challenges and Recent Advances

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Environmental Management Practices for
Agricultural PhosphorusChallenges and Recent
Advances

• Dr. Tom Sims
• University of Delaware

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Phosphorus is known as the master key to
agriculture because the lack of available P in
soils limits the growth of cultivated and
uncultivated plants (Soil Fertility, Ellis, 1998)
Wheat
Corn
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The Soil Phosphorus Cycle
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Agricultural Phosphorus and Environmental
Quality

• To correct P deficiency farmers have added P to
  soils in manures and fertilizers. Now many soils
  are sufficient or high in P and the waters that
  drain from agricultural fields cause increased
  growth of algae and other plants in surface
  waters. Thus, during the past decade, P has
  become known as the key to eutrophication
• (Soil Fertility, Ellis, 1998)

Algal growth in a tributary of Lough
Conn (Ireland)
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Fertilizer P Use and Trends in Soil Test P in
Ireland (1950-1995)
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STP
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Fertilizer P
Soil Test P (mg/L)
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2
0
(Tunney, 1997)
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Processes Involved in Phosphorus Transport from
Agricultural Lands
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Overview

• Why is the environmental impact of phosphorus
  (P) a major challenge for agriculture in the U.S.
  today?
• How can we develop, and implement, holistic,
  regional-scale management practices for P use by
  agriculture?

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Agricultural P Environmental Quality
Water Quality

• Eutrophication
• Algal blooms
• Low dissolved O2
• Loss of biodiversity
• Turbidity
• Sedimentation
• Odors, foul tastes

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Phosphorus Effects on Human and Ecosystem Health
Pfiesteria Piscicida

Pfiesteria piscicida is a toxic dinoflaggelate
that has been implicated in massive fish kills
and human health disorders in coastal waters of
the eastern U.S.
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Nature of the Agricultural P Problem
Historical Paradigm Controlling soil erosion is
the key to preventing nonpoint source P
pollution of surface waters
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Effect of Biosolids and Poultry Litter on Total P
Concentrations in Runoff
(Sims and Coale, 2003)
Particulate P
Dissolved P
May 2000
June 2000
April 2001
June 2001
April 2002
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Agricultural Best Management Practices (BMPs) for
Phosphorus

• Establish a realistic crop yield goal
• Define crop P requirements at that yield
• Use soil testing to identify available soil P
• Apply any additional P needed using the most
  efficient and economic methods
• Use integrated soil and water conservation
  practices to prevent P loss to surface waters by
  soil erosion and runoff

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Agricultural BMPs for Phosphorus
Soil and water Conservation BMPs
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Emerging Issue

• Long-term over-fertilization with P in animal
  manures, biosolids, and fertilizers has
  saturated some soils to the point that
  bio-available and soluble P losses in surface
  and subsurface runoff are now of environmental
  concern

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USDA-NRCS Analysis of the US Animal Manure
Phosphorus Surplus (2001)
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Mid-Atlantic Manure P and N Surplus

• State P N
• --Million Lbs in Excess--
• DE 7.3 14.6
• MD 10.4 19.6
• NJ 0.9 1.8
• NY 3.3 4.2
• PA 23.7 33.8
• VA 24.8 42.3

(Source USDA, 2001)
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Nitrogen (Mg/state/yr)
Nutrient Surplus (kg/ha/yr) N P NCC
16 -2 Kent 38 15 Sussex 120
42 DE 83 30
Phosphorus (Mg/state/yr)
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Soil Test P Summary for the U. S.
Delaware
of Soil Samples Rated H, VH in P gt 60 30 -
60 lt 30 No data
(PPI, 1994)
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Mid-Atlantic Soil Test P Status

• Soils Testing
• State High or Very High
• DE 82
• MD 78
• NJ 85
• NY 62
• PA 64
• VA 66

(Source PPI, 2001)
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Soil Test P Distribution in the Poultry
Production Region of the Delmarva Peninsula
Total P Available from Poultry Litter 45
kg/ha/yr
of Samples
Somerset
Wicomico
Worcester
Sussex
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Phosphorus Leaching in Delaware Soils
(Mozaffari and Sims, 1994)
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Relationship of Soil Test P and Soil P
Saturation for DE MD Topsoils Subsoils
(Pautler Sims, 2000)
Optimum STP range
European DPS Upper Limits
(n368)
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Water soluble P vs.soil test P - Delaware soils
n465
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Relationship Between DPS-M3 and P Concentrations
in Leachate and Runoff
15.0
0.5
DRP in leachate
DRP in runoff
2
2
r
0.73
r
0.87
y 4.33x - 0.579
0.4
12.0
y 28.44x - 5.71
0.3
9.0
0.2
6.0
y 0.0098x 0.108
y 0.024x 0.005
0.1
3.0
Outliers
(a)
(b)
0.0
0.0
0.0
0.1
0.2
0.3
0.4
0.5
0.0
0.2
0.4
0.6
0.8
Mehlich 3 (P/(AlFe)) Saturation Ratio
Mehlich 3 (P/(AlFe)) Saturation Ratio
(Sims et al., 2002)
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Environmental Policy Rarely Develops in a Social,
Political, or Legal Vacuum

• Poultry Industry Endangers Health of State
  Waterways
• Runoff from Chicken Manure Strangles Life in
  Rivers and Bays but Growers Deny Responsibility
  for Pollution
• Science Doesnt Support Poultry Farmers
  Denials
• Delaware Poultry Industry Writes Own Pollution
  Rules

Wilmington News Journal July, 1998
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Regional Responses to Environmental Issues in the
Mid-Atlantic Region
30 years of research, education, technical
assistance programs addressing nutrient
management water quality

• Pennsylvania Nutrient Management Act (1993-97)
• Maryland Water Quality Improvement Act (1998)
• North Carolina Moratorium on New Swine Farms
  (1998-?)
• Virginia Poultry Waste Management Act (1999)
• Delawares TMDLs (1997) and NMP Act (1999)
• USDA-USEPA Unified AFO Strategy (1999)
• USDA-NRCS National Nutrient Policy (1999)
• USEPA CAFO Rule (2002)

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Improving Agricultural P Management

• Implement BMPs that are already known to reduce P
  losses to water, targeting the critical source
  areas (CSAs) first, using education,
  cost-sharing, and/or regulation

Where are the CSAsfor P?
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USDA-NRCS National Nutrient PolicyPhosphorus
Guidance Options

• Option 1 Agronomic soil test P
• Option 2 Soil P threshold value
• Option 3 Phosphorus site index

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Constraints to the Use of Soil P Testingfor
Environmental Purposes

• Soil tests provide little, if any, information on
  the factors controlling P transport from soil to
  water
• Soil tests tell us little about agricultural
  management practices, good or bad.
• P losses from surface applications of wastes are
  significant and have little to do with soil test
  P
• Basing NMP on soil testing alone ignores mass
  balance issues (P surpluses)

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Soil Test Phosphorus (lb/acre)
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The DE-MD P Site Index
Part B
Part A

• Source Management
• Soil test P
• P fertilizer rate
• P fertilizer application method and timing
• Organic P rate and PAC
• Organic P application method and timing

• Site Transport
• Erosion
• Runoff
• Subsurface drainage
• Leaching
• Distance to water
• Priority of water body

P Site Index Part A x Part B
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Sum of Part A 20 x 0.02 0.40
Part A Site and Transport Value
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Phosphorus Availability Coefficients
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Phosphorus Site Index

• MD (2001) and DE (2002) have adopted the
  Phosphorus Site Index (PSI) and/or soil P testing
  as the approach to identify soils where P-based
  management is required
• MD Conduct PSI if soil test P (Mehlich 3-P)
  gt 150 mg kg-1, follow PSI guidelines for P
  applications
• DE If M3-P gt 150 mg kg-1 P applications cannot
  exceed 3 year crop P removal, unless PSI
  guidance indicates otherwise

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• Re-distribute surplus manure nutrients to areas
  where they are needed (pelletization, composts)

• Transport
• Questions
• Cost
• Safety
• Nuisance
• Liability
• ????

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Delmarva Examples

• Manure re-location programs now provide state
  cost-share support to re-distribute surplus
  manure
• Perdue-Agri-recycle -joint venture receives
  state support to build a pelletization plant that
  now uses 80-120,000 tons of poultry manure/year

Pelletized manure 3-3-3 fertilizer
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• Develop improved source reduction strategies, and
  waste treatment processes for animal agriculture

Sims et al. (1999)
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Alum amendment reduces water soluble P in poultry
litters
Control Mean WSP 1986 mg/kg
Water soluble P (mg/kg)
Alum-treated Mean WSP 678 mg/kg
Sims and McCafferty (2002)
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• Remediate high P soils to reduce risk of P loss

• Phytoremediation
• Lack of P hyper-accumulators
• Opportunities for bio-engineering plants?
• Chemical remediation
• Use of municipal or industrial by-products as
  soil amendments in enhanced buffer strips
• Deep plowing
• To bury high P topsoils within the root zone
• Constructed Wetlands
• Property rights, construction costs ?
• Release of P from flooded, agricultural soils?

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A Holistic, Regional Approach to Agricultural P
Management

• Ongoing pressure from environmental groups, the
  media, regulatory agencies for improved water
  quality
• Institutionalization of nutrient management
  fosters steady progress using best achievable,
  economically realistic technologies and practices
• Improved inter-state cooperation
• Expanded inter-disciplinary research
• Major changes in animal waste management
  practices
• Very slow improvements in water and soil
  quality and thus ecosystem health