Manure Management and Water Quality

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Manure Management and Water Quality
By Jeff Lorimor, Iowa State University, Ames
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Main Message

• Properly managed manure is not an environmental
  threat. The main issues for water quality are
• 1) accidents and mismanagement
• 2) whole farm nutrient balance

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What are the Pathways by which Manure
Contaminates Water?
Precipitation
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Unsaturated Zone Water Table Sand Gravel
Aquifer Bedrock
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Private Well

• Surface runoff

• Well casings

• Leaching to groundwater

• Ammonia deposition

• Macropore flow

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Potential Pathways

• Pollutant Pathway
• Nitrate N Leaching
• Ammonium N Surface water runoff Aerial
  deposition
• Phosphorus Surface water runoff
• Pathogens Surface water runoff
• Organic Matter Surface water runoff

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Review of historical soil conservation
experimental data (Risse and Gilley 2000)

• Manure reduced total runoff by 1 to 68.
• Manure reduced soil erosion by 13 to 77.

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Groundwater

• Iowa does have some vulnerable areas if
  contaminants get into aquifers
• Simpkins, et al report
• http//www.nstl.gov/pubs/burkart/hogpap/hogpap7.ht
  ml

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Groundwater

• In general, groundwater contamination resulting
  from manure storages has not been documented in
  Iowa
• Cl H2O movement, but little else moving away
  from earthen storages
• Libra earthen basin study
• ISU earthen basin study
• http//www.ag.iastate.edu/iaexp/reports/
• KSU earthen basin study
• http//www.oznet.ksu.edu/kcare/AW20Reports/KCAREa
  nimalwastereport/AWreport-Ham.htm

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http//www.uhl.uiowa.edu/HealthIssues/WellWater/i
ndex.html
Developed from Hygienic Labs website data on
private wells tested from 1993 to 2001. First
three years results are compared to last three.
240 wells/bar average
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Developed from Hygienic Labs website data on
private wells tested from 1993 to 2001. First
three years results are compared to last three.
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Manure IssuesReleases

• Primarily surface water issue
• Very few pits or lagoons have burst or had
  releases due to structural failures
• The vast majority of releases are due to
  .Management
• Out of 127 reported releases from 1992 thru 2000
• 17 (13) have been due to construction failures
• 110 (87) have been management related

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Reported Releases in Iowa
First MAC Meetings
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Release Breakdown

• Out of 127 releases since 1992
• Construction failures 17 (13)
• Management releases 45 (35)
• Land application 35 (28)
• Open lot runoff 30 (24)
• Mgmt and Land Application accounted for 63 of
  all releases

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Management Failures

• Not pumping in timeovertopping
  (this included deep pits!!)
• Stuck or broken valves in manure lines
• Leaky waterers causing overtopping
• Mistakes while transferring manure
• Mistakes or overapplying during land application
• Nearby tilelines when mistakes occur

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Too High RatePoor Coverage
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Broadcast
May be risky for surface runoffvery weather
dependent immediately after application.
Minimizes residue disturbance.
New legislation may require 200 setback
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Irrigation
Potential for runoff losses due to high
application rates and amounts typically applied
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Injection
Properly done direct injection of manure at the
right rates is the most effective way to minimize
both short term and long term water quality risks.
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Land Application is Primary Issue

• Not making mistakes during application is
  critical from acute water quality problems
• Ammonia
• BOD/COD
• Applying the right rates is critical issue to
  avoid chronic water quality problems
• Long term issue
• Soil P test issue

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Properly Managed Manure Will Reduce Nitrates in
Tilelines
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Nitrates in TileflowPoultry Manure Plots
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Phosphorus in Tileflow RunoffPoultry Manure
Plots
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Whole Farm Nutrient Planning
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Are Inputs Outputs In Balance?
Managed Outputs
Inputs


Farm boundary
Losses or Soil Storage
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Summary

• Manure is more of a surface water concern than a
  groundwater issue
• Two primary issues to minimize impacts of manure
  on water quality are...
• Accidental spills and discharges
• Whole farm nutrient management
• If manure is managed correctly it does not cause
  water quality deterioration