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Tile Drains

Tile Drains

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Tile Drains

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  1. Tile Drains Remediation and Best Management Practices Group Members: Kelly Davis, Krista Hoffsis, Nic Lucore, Sam Wallace

  2. Remediation Techniques • Riparian buffers • Bio-reactant filtration • Constructed wetlands

  3. Riparian Buffers • Construction • Function • Lasting effects

  4. Construction • Plant composition • Size and shape • Cost of construction

  5. Function • Surface and subsurface flow • erosion mitigation • Sedimentation • phosphorus • Denitrification

  6. Bio-reactant Filtration • Functional properties • Construction • Long term maintenance

  7. Function of bio-reactors • Contained biological processes • removal targets • Aerobic and Anaerobic • Simple example • Denitrification • Sedimentation

  8. Construction • Two stage containment system • First stage prevents overflow • Second stage filters drainage • Inputs • Sand • Carbon source • woodchips • compost • Bacteria • obtained from river sediment

  9. Blowes et al., 1994

  10. Maintenance • Very cost effective • Minimal upkeep after construction • Inputs are cheap and readily available • Scale can be augmented for the agricultural area

  11. Constructed Wetlands

  12. Construction • Location • Design • Size • Shape • Embankments & sealing • Inlet & outlet structures • Sediment traps

  13. Plant Selection

  14. Maintenance • Assess plant health, identify pest damage • Manage water level • Adequate inflow and even dispersal • Check for blockages in inlet & outlet systems • Inspect embankments for weeds and erosion

  15. Best Management Practices • Controlled drainage • Subirrigation • Winter crop cover • Optimal spacing • Optimal depth • Fertilizer application rates

  16. Controlled Drainage • Keeps water table high during the off-season • Increased rate of denitrification

  17. Subirrigation • Irrigations back through subsurface drain tiles • used during dry periods

  18. Management of Controlled Drainage/Subirrigation Farmer needs to know: • when to raise/lower the control structure • at what height to maintain the weir in the control structure • when to add water to the system Depends on: specific site, crops, soil type, drain depth, etc.

  19. Seeding of Crop Fields for Winter Months • Maintains root integrity year round • Plants are able to take up phosphorus when storm events occur • especially useful in clay and silt dominant soils • Can produce additional crop yields • Improves soil condition for next growing season *** Cost effective compared to fallow field maintenance Legumes such as Hairy Vetch and Subterranean Clover improve soil quality by fixing Nitrogen (http://boyneriver.org/wp-content/uploads/Hairy-Vetch_Web-jpg.jpg) (http://www.mccc.msu.edu/images/covercrops/kura_clover.jpg)

  20. Cover Crops for Vermont Winter Rye • Can germinate at 33 degrees F • Scavenges residual N from previous crops • Can be grown with Hairy Vetch Field Pea (Legume) • Winter kill-crop • Planted in August/September • reaches maturity before first frost • Dead plant material shieds soil and roots remain underground

  21. Optimal Spacing Prior to Installation • The less dense the drains, the lower the amount of leached nitrogen • Closest distance → 20 meters • Closer than that and crop yield decreases and nitrogen runoff increases

  22. Optimal Drain Depth Prior to Installation • A decrease in drain depth from 1.5 to 0.9m decreased Nitrogen losses by 14% • Little change when deeper than 1.2 meters • Water has drained • Shallower drains not examined • Could impede root growth and water absorption

  23. Fertilizer Application • Reducing Nitrogen inputs from: 200 kg ha−1 to 125 kg ha−1 reduced Nitrogen losses by 57% ** NO reduction in crop yields • This application rate aligns with recommendations put forth by Waseca, Minnesota, where the study was performed • also aligns with other regional recommendations (http://www.novum-nl.com/webtheek/dscf1714.gif)

  24. At Risk Soil Types • Clay soils that easily slake • Silty soil with low Organic content • Prone to erosion 3. Sandy soil profiles with low P sorption capacity • Iron and Aluminum in subsoil raise P sorption cap.

  25. Best Management Practices ** NOTE: Often times soils are a mix of sand, silt, and clay The most important objective is to promote a healthy soil profile

  26. Best Management Practices: Flow Chart