Conservation Drainage: Drainage for the 21st Century

5’ Soil Backfill

Trench bottom 1’ Below tile invert

20’ section of tile

Length dependent on treatment area

DiversionStructure

CapacityControlStructure

Woodchips

Conservation Drainage: Conservation Drainage: Drainage for the 21st Drainage for the 21st

CenturyCentury

1890s Scientists sound alarm about

need for new source of nitrates

The Nitrate Saga

Carl Bosch Fritz Haber

Nutrient contributions to the Gulf, by State

Distribution of Subsurface Tile Drainage in Illinois

3-4 million ha (6-10 millionacres) drained with subsurface tile inIllinois

This comprises some of the most productive agricultural land in theUS.

HYDROLOGIC CYCLE (with tiles)

7.2 km/km2

The solutions that you seekwill not be found in the streakof a pen, or even one thousand words of mine.

Mutabaruka

Nitrate Reduction Techniques

Altering Nitrogen Application Amounts

Altering Nitrogen Application Timing

Edge-of-Field Treatment Optimizing Drainage System

Conservation Drainage

The incorporation of environmentally friendly

practices and structures into existing drainage infrastructure

Minnesota Department of Agriculture

Conservation Drainage

The optimization of drainage systems for crop production,

water quality and water harvesting benefits

Convenient and Cost-Effective

No D

ecre

ase

in D

rain

age

Effic

ienc

y No Adverse Effects on Neighbors

DrainageWater

Management

Depth/Spacing Modifications

Subsurface Bioreactors

ConservationDrainage

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

Drainage Water Management

Float Structure

AutomatedGate Structure

ManualGate Structure

Control Setting*(inches)

Nov.1-Mar.15 Fallow 6-18Minimize drainage outflow and

encourage denitrification

Mar. 15 – Apr.15 Tillage, corn seedbed preparation, planting

36-48Just deep enough to provide

trafficability and good conditions for seedbed preparation. 

Corn establishment, early growth

24 – 30Deep enough to promote good root

development.

Nitrogen sidedressing Just low enough to allow trafficability

24-36

May 15 - Aug. 15Corn development and

maturity18-24

Temporary adjusting during wet periods

Aug.15 - Oct. 31 Harvesting, tillage 36-48 Lower enough to provide trafficabilty

Period Production Activity Comments**

Apr. 15 – May 15

Drainage Water Management GuidelinesDrainage Water Management Guidelines

– in an unusually dry season, control can be 3 to 6 inches higher; – in an unusually wet season, control should be 3 to 6 inches lower; – in coarse-textured soils, trafficability can be provided with the water table approximately 6 inches higher.

Managed Drainage - WinterConservation Mode for Fallow Season

Managed Drainage - SpringFull Drainage Mode for Planting Season

Managed Drainage -SummerShallow Drainage Mode for Growing Season

Managed Drainage - FallFull Drainage Mode for Harvest Season

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

Vol

um

e (i

nch

es)

.

Sable

Source: Based on DRAINMOD Simulations

~ 1.5 inches

Water Deficit StressWater Deficit Stress

DWM Benefits

• Reduces Nitrate Concentrations in Effluent– 30-95% reductions annually

• Increased Yield– 76% higher yield in a dry year

• Lower Concentrations of Other Pollutants

Required Information for Economic Analysis of DWM System

•Drainage Costs•Added Revenue•Capital Costs•Timeliness Benefits

Drainage Water Management

Hume 2004

0

2

4

6

8

10

12

14

16

0

2

4

6

8

10

12

14

16

18

3/4/04 4/23/04 6/12/04 8/1/04 9/20/04 11/9/04 12/29/04 2/17/05

Cum

Flo

w (c

m)

.

Flow

rate

L/s

.

Managed Drainage Free Drainage

3.4 3.6

10

0.3

13.4

3.9

0

2

4

6

8

10

12

14

Mar.-Oct. Nov.-Feb. Annual

Free DrainageManaged Drainage

Flow Depths (cm) From a Paired Drainage Site

Free DrainageManaged Drainage

Hume 2006

0

2

4

6

8

10

12

14

16

18

20

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

11/19/05 1/8/06 2/27/06 4/18/06 6/7/06

Cu

mu

lati

ve F

low

(cm

)

Flo

w (c

m/d

ay)

Free Drainage Managed Drainage

Long Term Nitrate Trends: 2005

2005 T ile Nitrate C onc entrations at Hume

0

5

10

15

20

25

11/9 12/29 2/17 4/8 5/28 7/17

Nitr

ate-

N C

once

ntra

tion

(ppm

)

F ree Drainage Managed Drainage

2008 T ile Nitrate C onc entrations at Hume

6

7

8

9

10

11

12

13

14

15

16

2/2 2/22 3/13 4/2 4/22 5/12 6/1 6/21 7/11

Nitr

ate-

N C

once

ntra

tion

(ppm

)

F ree Drainage Managed Drainage

Long Term Nitrate Trends: 2008

Managed Drainage13.1 acres

50-70 ft Spacing

Free Drainage11.3 acres

50-70 ft Spacing

Kinderhook Site

0

20

40

60

80

100

120

140

9/20/04 12/29/04 4/8/05 7/17/05

NIt

rate

-N (

pp

m)

Free Drainage Controlled Drainage

Nit

rate

-N (

mg

/L)

System Layout for Drainage Water

Management

90.0 ft

91.5 ft

93.0 ft

94.5 ft

96.0 ft.

90.0 ft

91.5 ft

93.0 ft

94.5 ft

96.0 ft.

Optimized for Drainage Water ManagementOptimized for Cost of Installation

90.0 ft

91.5 ft

93.0 ft

94.5 ft

96.0 ft.

90.0 ft

91.5 ft

93.0 ft

94.5 ft

96.0 ft.

Optimized for Drainage Water ManagementOptimized for Cost of Installation

Cost Differential: $50/acre

Layout Costs