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

Remediation Techniques Riparian buffers Bio-reactant filtration Constructed wetlands

Riparian Buffers Construction Function Lasting effects

Construction Plant composition Size and shape Cost of construction

Function Surface and subsurface flow o erosion mitigation Sedimentation o phosphorus Denitrification

Bio-reactant Filtration Functional properties Construction Long term maintenance

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

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

Blowes et al., 1994

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

Constructed Wetlands

Construction Location Design o Size o Shape o Embankments & sealing o Inlet & outlet structures o Sediment traps

Plant Selection

Maintenance Assess plant health, identify pest damage Manage water level o 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 structure 2. at what height to maintain the weir in the control structure 3. when to add water to the system Depends 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 ( (

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 Depth Prior 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 meters o Water has drained Shallower drains not examined o 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 performed o also aligns with other regional recommendations (

At Risk Soil Types 1.Clay soils that easily slake 1.Silty soil with low Organic content o 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

Best Management Practices: Flow Chart