Illinois Drainage Water Management Demonstration Project Don Pitts Agricultural Engineer State Water Quality Specialist Champaign, IL NRCS USDA

Illinois Drainage Water Management Demonstration Project (Nitrogen Management - It’s the Water) Background Basic principles of managed drainage What we have learned from the demonstration project

Embarras River Flow-Weighted NO 3 -N Concentration Sampling station near Camargo ( ) Increasing nitrate concentrations are typical in Central Illinois streams Is water quality getting better?

Primary Hydrologic Pathway in Most Central Illinois Watersheds This is the most common way for water to enter the surface water systems.

There is a high correlation between the locations of areas with elevated nitrate levels in surface water and the distribution of tile-drained soils.

Gulf of Mexico hypoxic zone in the summer of 2001 (after Rabalais)

Water Quality Concerns Nitrate in Surface Water Local concern –drinking water supplies cannot exceed (10 mg/l) Regional concern –stream and reservoirs with elevated nitrate levels are contributing to eutrophication problems National concern –Gulf of Mexico Hypoxia

Hydrologic Cycle (with tiles) High N Low N

Benefits of Subsurface Drainage Some of the most agriculturally productive soils in Illinois (Midwest) require subsurface drainage for economic crop production Subsurface drainage allows –for improved soil aeration and increased crop production – for field access with equipment cultivation, planting, harvesting, etc.

Current Situation Many tile systems are old and are subject to being replaced. Yield monitors on combines are showing growers the benefits for more intensive drainage Economics forces dictate for improving or replacing existing drainage systems to increase production

Problem Statement Drainage is needed for economical crop production Tile drainage water is a primary source of nitrate to surface water

Iroquois River - Average Monthly Nitrate Load Half the Load Occurs During the Fallow Season! Gauge Station near Chebanse, IL ( ) Mean Annual Load = 11.5 E6 kg Average annual N loss = 21 kg/ha ~ value of nitrogen = $5 million/year

Hydrologic Cycle (with drainage management)

Water Level Control Device is Installed in the Tile Drain Near the Outlet and at Various Locations within the Field Depending on Topography Ditch Raised Water Table Riser Boards (Adjustable) Drain Water Solid pipe

Illinois NRCS Drainage Management Demonstration Project

Illinois Drainage Management Pilot Status Report (August 2005) More than 60 control structures installed - Structures Installed Structures Planned Structures Proposed Monitored site

Subsurface tile line Flow monitor Control Structure Weather Station Monitoring well Field layout of monitoring equipment at the Ford county demonstration site - (USGS partnership). ~ 40 ac conventional field ~ 40 ac conventional field ~ 40 ac managed field managed field ~ 40 ac managed field managed field

Nitrate plus Nitrite Loading (52% Load Reduction) YearManaged (lb/ac) Conventional (lbs/ac) 2001 (May- Dec) Annual Average (lbs/ac) Source: USGS (Preliminary)

Drainage Management Opportunities to Enhance Production Minimize Unnecessary Drainage –in some cases, drainage systems remove water that may be needed for crop production later in the season Drainage Management Opportunity –conserving water in field to be used by the crop later in the season may benefit production

Drainage Management Target Water Levels = board setting for water table depth

4 ft Conventional Drainage When Plants are Young

Drainage Management when Plants are Young Soil Surface Tile Water Table with Drainage Management Tile Drainage Management 4 ft 2 ft

Potential Water Available from Drainage Management Source: Based on DRAINMOD Simulations ~ 1.6 inches

Monthly Rainfall Average vs Water Year Champaign, IL (Average: ) Average annual = 38.5 inches Source: IL. State Water Survey

NRCS Drainage Water Management Practice Standard 554 Purposes –Improve Water Quality –Improve the soil environment for vegetative growth –Reduce the rate of soil organic matter oxidation –Reduce wind erosion –Enable seasonal shallow flooding for wildlife USDA can cost-share or make enhancement payments for this practice

Where Does the Practice* of Drainage Management Apply? In flat topography Where patterned (or intensive) subsurface tile systems exist Where nitrate is a surface water quality problem No or minimal impact to neighbors Producer to raise water table in fallow season Conditions necessary for USDA financial assistant in Illinois

Drainage Management (Parallel System and Flat Topography) Field Boundary main laterals Water level control structure

The Influence of Slope The water level control device is placed in a tile line. The area impacted is a function of the slope of the field. The flatter the field the greater the area impacted. Ditch Raised Water Table Riser Boards (Adjustable) Tile 2 ft 4ft

Drainage Management – Retrofit to Existing Tile System (gentle sloping topography) Field Boundary Water Level Control Device Zone of influence > 20 ac Solid Pipe

New Tile Systems – Should be Designed with Drainage Management in Mind This could mean: –designs with laterals following field contours –designs with main lines along field edges to facilitate access to control structures

When Practical, Align Laterals with Contours

Drainage Management System (possible future tile system design on gentle sloping topography) Water Level Control Device =

Some of the Objections to Drainage Management (Some of the reasons that were given why the practice would not work) “Tile will fail” “Tile will silt in” “Winter-time freezing limits tile flow” “Soil will compact ” “Field will not dry out in time to plant” “Earthworms will be killed” “Root development will be limited and plants will lodge” So far none of these have turned out to be valid concerns!

Golden Rule of Drainage Only release the amount water necessary to insure trafficable conditions for field operations and to provide an aerated crop root zone –any drainage in excess of this rule likely carries away nitrate and water that is no longer available for crop uptake Source: R.W. Skaggs