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