Tile DrainsA Comparison of Surface &

Subsurface Drainage

Haleahy Craven, Jonathan Farmer, Reese Freeman, & Dan

Maddock

Tile Drains?• little information in VT

• issues with runoff during heavy rain/snowmelt

• rows of perforated piping below ground

• allows water percolation to avoid saturation of soilo absorption of nutrients by plant roots

• 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 characteristicso management recommendations

Our Goals

• extremely little data/info about tile drain in VT

• originally implemented due to increased crop yield

• little consideration to nutrient & sediment loading

Justification

Controlled Drainage Experiments Overview

● 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

● 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

Total P Loads in Free and Controlled Drainage

Caroline Sanchez Valero, Chandra A. Madramootoo, Nicolas Stämpfli

Controlled Drainage Highlights Cont. ● Ontario Nitrate Loss

- cumalituive draiange water volume was slightly greater in controlled system- flow weighted mean nitrate concentration was reduced in controlled (41%)

● 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.

● Sweden N Loses- Reduced outflow rate in controlled system - High risk periods for N losses - Increased N uptake

● P loses - Conventional system- Controlled system

Ingrid Wesström, Ingmar Messing

Grain Yields and N uptake

Controlled Drainage Conclusions

● 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

● 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

● 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● 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!● 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!

What we did not find...

Alternative Impacts

● Hydrologic Cycle- Groundwater Recharge- Nearby Communities and

Ecosystems● Future Site Goals

- Developement- Remediation- Reclamation

● Impacts of Climate Change?

● Clay Soil Map of Vermont

* Recommendations- No drain zones?

THE ENNNNNNDDD...