The fate in agricultural soils of natural and synthetic hormones carried in animal and human wastes

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Case Study Best Practices to Minimize
Preferential Flow on Tile-drained Fields
Ed Topp, D. Lapen, B. Ball Coelho, L. Sabourin,
M. Edwards. AAFC, London and Ottawa, ON. M.
Payne. OMAF Stratford ON P. Duenk. UWO, London
ON T. Ho. OME, Toronto
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Collaborators and Partners

• T. Edge, EC
• V. Gannon, PHAC
• C. Metcalfe, Trent U.
• A. Boxall, U. of York, UK
• K. Abbaspour, EAWAG
• A. Hartmann, INRA
• A. Letellier, U. of Montréal
• N. Neumann, U. of Calgary
• C. Duchaine, Hôpital Laval

• Health Canada
• Environment Canada
• Provincial partners, eg. Ontario, British
  Columbia, Alberta
• OFA
• Municipalities
• Farmers

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Risk from

• Microorganisms.
• Endocrine-disrupting chemicals.
• Pharmaceuticals.
• Nutrients
• Livestock and poultry wastes
• Human wastes (municipal biosolids.)

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ExposureOpportunities for managing risk
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Agriculture relies on soils to stabilize wastes

• Hostile environment to enteric microorganisms,
  starvation, predation.
• Organic chemicals dissipate.
• Inorganic constituents are bound.
• Little movement through soil matrix, risk from
  preferential or surface flow.

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Transport CharacteristicsManaging the
application
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Cracks / Worm Channels are Common Macropores
Cracks
Worm Channels
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Conceptual Model Slurry Application Risk
Saturation
Flow via Smaller Pore Network Engaged
Crack-flow for cracking soils (soil bypass)
Tile GW contam. risk
Soil Water Content
Flow via Large Pore Network Engaged
Soil Water Tension
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Incorporation of biosolids

• Reduced risk of runoff
• Less volatile loss of nitrogen
• Less odor
• Physical disruption of macropore flow pathways
• Issues?
• Subsurface contamination potential?
• Persistence of microbial or chemical contaminants?

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Experimental objectives

• Identify soil physical and hydrological
  conditions/processes that support macropore flow
  of biosolids to tile drain systems.
• Identify impact of application methods and site
  specific considerations on potential for
  macropore flow.
• Equipment
• Rate
• Soil texture and soil moisture
• Use modeling approach to generalize findings.
• Use information to inform BMPs.

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Research Plan

• Field experiments in E and SW ON tile drainage
  quality and soil water/biosolid transport in
  soil.
• Application approaches
• Broadcast plus incorporation
• Pre-tillage (AerWay)
• Direct injection
• Numerical modeling on liquid biosolids and water
  flow transport to tile drains

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AerWay SSD Slurry Injector
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AerWay Soil Pocket
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Kongskilde Vibra-Shank Injector
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(No Transcript)
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Field Research Experiments
Valuable investment in data generation
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Application over Instrumentation
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Water Quality and Quantity Data

• Tile drain flow recording
• Water quality sampling
• Soil quality

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Macropores Manure/Biosolid Derived Bacteria to
Tiles and Groundwater

• Over 90 of flow to tile drains
• can result from macropores

• Not all post-application
• flow events are
• contaminating ones

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Risk of Contamination Using soil water flow
models as a tool

• Prediction tool or risk indicator is being used
  to determine tile flow and runoff and evaluation
  of
• When to apply (at what moisture level dry or wet
  conditions)
• How much to apply (rate?)
• Where to apply? (suseptable soils)
• How to apply (methods)

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Bacteria Transport to Tiles
AerWay
Kongskilde injection
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Immediate Preferential Flow of Biosolids to Depth
(10,000 g/a fall application)

• Kongskilde Observed preferential flow of
  biosolids to minimum 30 cm depth seconds after
  application
• Likely reasons
• coarser injection spacing (15 in)
• Injection bypass top 15cm of surface soil
• Less efficient truncation of macropores
• AerWay No observed macropore flow of biosolids
  to 25 cm depth
• Likely reasons
• Tighter injection spacing (7 inch)
• Macropore truncation and augmented infiltration
  in fractured topsoil

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Predicting What Application Rate Will Minimize
Flow?
Dry conditions

• In spring 2003, we applied 10,000 g/a, observed
  no tile flow. Drier sub-soil conditions (0.19 to
  0.26 m3 m-3).
• AerWay tile discharge could have been initiated
  15,000 g/a
• Kongskilde tile discharge could have been
  initiated at 12,000 g/a

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Predicting What Application Rate is Good?
Wet conditions

• In fall 2003, we applied 10,000 g/a, observed
  tile flow. Wetter sub-soil conditions (0.27 to
  0.34 m3 m-3).
• AerWay tile discharge could have been initiated
  at 3,000 g/a
• Kongskilde tile discharge could have been
  initiated at 2,000 g/a

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Threshold Water Contents Inducing
Application-based Tile Flow
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Model Reproduced Excellent Measured Tile
Discharges
Wet conditions 0.27 to 0. 30 m3 m-3 WC
Dry conditions 0.17 to 0. 22 m3 m-3 WC
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Conclusions

• Application methods that fracture, till and
  deposit material to have maximum interaction with
  soil are advantageous.
• Injection applications can promote movement to
  depth. This can be mitigated by reducing spacing
  between injectors.
• Site specific conditions eg. soil moisture and
  indicators can be helpful in identifying
  circumstances that have reduced risk for
  preferential flow.
• Models are proving effective at generalizing
  results with a view to developing BMPs.