tile drains remediation and best management practices group members: kelly davis, krista hoffsis,...
TRANSCRIPT
Tile Drains
Remediation and Best Management Practices
Group Members: Kelly Davis, Krista Hoffsis, Nic Lucore, Sam Wallace
Function
• Surface and subsurface flowo erosion mitigation
• Sedimentation o phosphorus
• Denitrification
Function of bio-reactors
• Contained biological processeso removal targets
• Aerobic and Anaerobic
• Simple exampleo Denitrification o Sedimentation
Construction
• Two stage containment system o First stage prevents
overflow o Second stage filters
drainage
• Inputs o Sando Carbon source
woodchips compost
o Bacteria obtained from
river sediment
Maintenance
• Very cost effectiveo Minimal upkeep after construction
• Inputs are cheap and readily available
• Scale can be augmented for the agricultural area
Construction
• Location
• Designo Sizeo Shapeo Embankments & sealingo Inlet & outlet structureso Sediment traps
Maintenance
• Assess plant health, identify pest damage
• Manage water levelo Adequate inflow and even dispersal
• Check for blockages in inlet & outlet systems
• Inspect embankments for weeds and erosion
Best Management Practices
• Controlled drainage
• Subirrigation
• Winter crop cover
• Optimal spacing
• Optimal depth
• Fertilizer application rates
Controlled Drainage
• Keeps water table
high during the
off-season
• Increased rate of
denitrification
Subirrigation
• Irrigations back through subsurface drain tiles
• used during dry periods
Management of Controlled Drainage/Subirrigation
Farmer needs to know:1. when to raise/lower the control structure2. at what height to maintain the weir in the
control structure3. when to add water to the systemDepends on: specific site, crops, soil type, drain depth, etc.
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)
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
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
Optimal Drain DepthPrior to Installation• A decrease in drain depth from 1.5 to 0.9m decreased Nitrogen
losses by 14%o Little change when deeper than 1.2 meterso Water has drained
• Shallower drains not examinedo Could impede root
growth and water absorption
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 performedo also aligns with other regional
recommendations
(http://www.novum-nl.com/webtheek/dscf1714.gif)
At Risk Soil Types
1. Clay soils that easily slake
2. Silty soil with low Organic contento Prone to erosion
3. Sandy soil profiles with low P sorption capacity
o Iron and Aluminum in subsoil raise P sorption cap.
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