Transcript Tile Drains A Comparison of Surface & Subsurface Drainage Haleahy Craven, Jonathan Farmer, Reese Freeman, & Dan Maddock.

Tile Drains
A Comparison of Surface & Subsurface
Drainage
Haleahy Craven, Jonathan
Farmer, Reese Freeman, & Dan
Maddock
Tile Drains?
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little information in VT
issues with runoff during heavy rain/snowmelt
rows of perforated piping below ground
allows water percolation to avoid saturation of
soil
o absorption of nutrients by plant roots
Our Goals
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To determine whether regulation on tile drains is
necessary
Provide DEC with:
o data on whether there is a significant difference in
nutrient loading to surface waters
o influential site characteristics
o management recommendations
Justification
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extremely little data/info about tile drain in
VT
originally implemented due to increased crop
yield
little consideration to nutrient & sediment
loading
Controlled Drainage
Experiments Overview
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3 separate experiments on controlled vs conventional (free)
drainage.
- Sites included southwestern Ontario, Quebec, and Sweden
The Canadian experiments used a controlled
drainage/subirrigation system
Swedish experiment was only controlled drainage with no
subsurface irrigation
Controlled Drainage Highlights
Total P Loads in Free and Controlled
Drainage
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Quebec Phosphorus loads
- Increased P loads in drainage from
controlled drainage compared to free
drainage
- Drainage outflow volume was
reduced in controlled drainage
- Majority was dissolved P
Caroline Sanchez Valero, Chandra A. Madramootoo,
Nicolas Stämpfli
Controlled Drainage Highlights
Cont.
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Ontario Nitrate Loss
- cumalituive draiange water volume was slightly greater in controlled
system
- flow weighted mean nitrate concentration was reduced in controlled
(41%)
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Corn Yields
- Soil moisture content was greater in controlled and water table was
not as deep as compared to free drainage system
- Yields increased by about 60%
Nitrate in Drainage
H.Y.F. Ng, C.S. Tan, C.F.
Drury, J.D. Gaynor
Controlled Drainage Highlights
Cont.
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Sweden N Loses
- Reduced outflow rate in controlled system
- High risk periods for N losses
- Increased N uptake
P loses
- Conventional system
- Controlled system
Grain Yields and N uptake
Ingrid Wesström, Ingmar Messing
Controlled Drainage Conclusions
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In most cases outflow volume is reduced in controlled systems
Peak loading in regards to N and P occur during high outflow rates
Increased N uptake as well as other factors, increased crop yields
P seems a bit more unpredictable
Better alternative to conventional
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Issues
- Difficult to figure out how exactly system was controlled
- There seems to be a lot of site specificity
- How will experiments in VT look?
Soil Structure
● Macropore Systems
○ macroinvertebrates
○ root canals
○ cracking marine clay soils
● Preferential flow
○ Reduces nutrient uptake by plants and soils
○ Increases nutrient leaching and sediment loading to surface
waters
Soil Structure Management
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Conventional Ploughing
Shallow Till
No till
Structural Liming
○ Quicklime
■ Clay-2H+ + CaO → Clay -Ca2++ H2O
○ Slaked Lime
Fertilization Techniques
● Broadcast fertilization
● Placement or Injection fertilization
○ Reduces losses in non-growing season and cold weather
climates
DRP vs Pdop
● DRP - Dissolved Reactive Phosphorus
○ Readily available to aquatic organisms
● Pdop - Dissolved Organic Phosphorus + Particulate
● Pt - Total Phosphorus
Considerations...
and Recommendations for Site Specific Studies & Management Practices in Vermont
The Effects of Tile Drains are Site Specific
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Site Characteristics
- soil
- climate
● History
- Joshua Faulkner: study on past tile drain activity
* Recommendations
- complete GIS map of present tile drains
- GIS climate and soil data handouts
Proper Management is Essential!
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Care for Soil Structure
- soil can change
- cracks are bad
Tilling Preferences
- tilling changes soil structure
Fertilization
- green manure can leach
- injection or place based methods
- Timing is Everything!
* Recommendations
- subsurface drainage should be included
into a farm’s management plan
- a reviewed management plan and routine
checkups based on site conditions could be
required for subsurface tile drains (a review
board may need to be created)
- controlled drainage is generally prefered
Poor management is bad!
Alternative Impacts
What we did not find...
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Hydrologic Cycle
- Groundwater Recharge
- Nearby Communities and Ecosystems
Future Site Goals
- Developement
- Remediation
- Reclamation
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Impacts of Climate Change?
Clay Soil Map of Vermont
* Recommendations
- No drain zones?
THE ENNNNNNDDD...