Upload
kelley-watts
View
220
Download
2
Tags:
Embed Size (px)
Citation preview
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