illinois drainage water management demonstration project don pitts agricultural engineer state water...

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 NO3-N Concentration

Sampling station near Camargo (1978-2001)

0

10

20

30

40

50

60

10-Jan-78 3-Jul-83 23-Dec-88 15-Jun-94 6-Dec-99

Date

(m

g/l)

Increasing nitrate concentrations are typical in Central Illinois streamsIs 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 ConcernsNitrate 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

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 (1984-1998)

0

500000

1000000

1500000

2000000

2500000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Nit

rate

as

N (

kg)

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

Ditc

h

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 ~ 40 ac

conventional conventional fieldfield

~ 40 ac ~ 40 ac

conventional conventional fieldfield

~ 40 ac~ 40 ac

managed fieldmanaged field

~ 40 ac~ 40 ac

managed fieldmanaged field

Nitrate plus Nitrite Loading(52% Load Reduction)

Year Managed

(lb/ac)

Conventional

(lbs/ac)

2001 (May-Dec)

16.4 24.1

2002 47.0 89.3

2003 23.7 68.7

Annual Average (lbs/ac)

29.0 60.6

0

20

40

60

80

100

120

140

160

180

200

Managed Conventional

Nit

rate

+ N

itri

te a

s N

(lb

s/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

Water Level Settings

0

6

12

18

24

30

36

42

48

54

10/31 12/20 2/8 3/29 5/18 7/7 8/26 10/15

Date

Min

imu

m W

ater

Tab

le D

epth

(in

)

Har

vest

Flowrate set tocapacity ofbioreactor

Plan

ting

Potential water storage during growing season

Water table set to mirror root growth

Water Level Settings

0

6

12

18

24

30

36

42

48

54

10/31 12/20 2/8 3/29 5/18 7/7 8/26 10/15

Date

Min

imu

m W

ater

Tab

le D

epth

(in

)

Har

vest

Fallow PeriodPl

anti

ng

Potential water storage during growing season

Water table set to mirror root growth

Water Level Settings

0

6

12

18

24

30

36

42

48

54

10/31 12/20 2/8 3/29 5/18 7/7 8/26 10/15

Date

Min

imu

m W

ater

Tab

le D

epth

(in

)

Har

vest

Flowrate set tocapacity ofbioreactor

Plan

ting

Potential water storage during growing season

Water table set to mirror root growth

Water Level Settings

0

6

12

18

24

30

36

42

48

54

10/31 12/20 2/8 3/29 5/18 7/7 8/26 10/15

Date

Min

imu

m W

ater

Tab

le D

epth

(in

)

Har

vest

Fallow PeriodPl

anti

ng

Potential water storage during growing season

Water table set to mirror root growth

Har

vest

Fallow PeriodPl

anti

ng

Potential water storage during growing season

Water table set to mirror root growth

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

4 ft

Conventional Drainage When Plants

are Young

Soil Surface

Tile

Water Table with Conventional Drainage

Tile

Conventional Drainage

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

0

0.5

1

1.5

2

2.5

3

0 12 24 36 48 60

Depth to Water Table (inches)

Dra

ined

Dep

th o

f W

ate

r

(in

ches

)

Sable

Source: Based on DRAINMOD Simulations

~ 1.6 inches

Monthly Rainfall Average vs 2004-2005 Water Year

Champaign, IL (Average: 1961-1990)

0

1

2

3

4

5

6

7

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Ra

infa

ll (

inch

es)

30-year mean2004-2005

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 main

late

rals

late

rals

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.

Ditc

h

Raised Water Table

Riser Boards (Adjustable)

Tile

2 ft4ft

Drainage Management – Retrofit to Existing Tile System

(gentle sloping topography)Field Boundary

602602

600

600

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)

602602 601

601

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