Iowa Programs and Initiatives for 

Reducing Nutrient Transport to Water 

Resources from Ag Lands

Dean Lemke, P.E.

Iowa Department of Agriculture and Land Stewardship

October 1, 2010
Iowa’s Approach to Reducing 

Nutrient Transport From Ag Lands

1. Continue long-standing programs to 

encourage adoption of traditional 

conservation practices.

2. Develop new, innovative technologies 

and programs targeted to reducing 

nutrient transport to water resources.
Iowa Conservation Programs Which Reduce 

Nutrients to Water – State Fiscal Year 2011

Implementation &

Watershed Protection $87.04 million

Research & Technology

Development $13.16

Education & Outreach $0.45

TOTAL* $100.65 million

*includes landowner match $
New Innovative Technologies and Programs 

Targeted to Reduce Nutrient Transport

• On-Farm Nitrogen Network – Iowa Soy Association

• Iowa Learning Farms – Iowa State University

• Iowa CREP Nitrogen Removal Wetlands

• Cedar River Watershed Case Study

• Iowa Wetland Landscape Systems Initiative

• Iowa Strategy for Nutrient Reduction – Gulf of Mexico 

Hypoxia

• Voluntary BMP Adoption/Recognition Program – Iowa 

Ag Organizations
Over 3,000 guided stalk nitrate evaluations

Over 1,000 replicated strip trials

Focused on in-field comparisons of:

N stabilizers

Timing of N (fall vs. spring; Preplant vs SD)

Forms of N (UAN, NH3, Urea, Manure)

Type of application (injection vs dribbling)

Crop sensors

Potential for variable rate

www.isafarmnet.com
35 grower groups

www.isafarmnet.com
Fertilizer N Grain Yield

--------lb N/acre------- ------------bu/acre----------------

2001 C-SB 80 130 177 176 -1

2002 C-SB 70 120 193 195 2

2003 C-C 130 180 167 166 -1

2004 C-SB 60 110 200 206 6

C-C 110 160 172 178 6

2005 C-SB 60 110 192 197 5

C-C 110 160 182 194 12

2006 C-C 120 150 188 193 4

2007 C-C 125 150 177 182 5

2008 C-C 130 155 169 174 4

www.isafarmnet.com

Year Rotation Low Rate High Rate Low Rate High Rate Diff.
www.isafarmnet.com

Need to 

evaluate what 

actually 

happened.
Iowa Learning Farms

• Conducted by Iowa State University

• Farm cooperator demonstrations – crop 

residue and tillage management

• Education and outreach, awareness

• Rainfall simulator educational tools

• “Building A Culture of Conservation”

Drainage District

Boundary Hydric Soils

Subsurface Tile

Drain

CREP Wetland

Iowa Conservation Reserve Enhancement Program
0

5

10

15

20

25

Nitrate-N (mg L-1

)

0

10000

20000

30000

Inflow (m3 d

-1

)

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

AL Wetland

2007

0

100000

200000

300000

400000

500000

Inflow (m3 d

-1

)

0

5

10

15

20

25

Nitrate-N (mg L-1

)

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

BG Wetland

2007

0

5

10

15

20

25

Nitrate-N (mg L-1

)

0

20000

40000

60000

80000

100000

Inflow (m3 d

-1

)

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

DJ Wetland

2007

0

5

10

15

20

25

Nitrate-N (mg L-1

)

0

40000

80000

120000

160000

Inflow (m3 d

-1

)

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

ND Wetland

2007

0

5

10

15

20

25

Nitrate-N (mg L

-1

)

0

40000

80000

120000

160000

200000

Inflow (m3 d

-1

)

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

JR Wetland

2007

0

5

10

15

20

25

Nitrate-N (mg L-1

)

0

40000

80000

120000

160000

200000

Inflow (m3 d

-1

)

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

VH Wetland

2007

0

5

10

15

20

25

Nitrate-N (mg L-1

)

0

40000

80000

120000

Inflow (m3 d

-1

)

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

HS North Wetland

2007

Observed and modeled 

wetland performance

(2007)

W.G. Crumpton, Iowa State University

Iowa CREP Status

72 wetlands restored, under construction or 

design

– 715 acres total wetland pool

– Remove 40-70% of nitrate from 86,100 acres

– Estimated nitrate removal over practice 

lifetime is 53,600 tons

– Nitrogen removal cost $0.23/lb, below current 

cost of fertilizer N
Cedar River Watershed Case Study – scenario to 

reduce nitrate losses 35% (9,200 tons/non-point 

source allocation) while retaining row-crop production

Practice % reduction Acres* treated Tons reduced

140 to 100 N rate - CB 20.1% or 

3.9 lb/ac 

all or 1.70 M ac 3,315

190 to 150 N rate - CC 16.2% or 

3.8 lb/ac

all or 0.10 M ac 190

Avoid fall N application 15% or 

2.5 lb/ac

all or 300,000 ac 375

Rye cover crops 50% or 

8 lb/ac

10% or 170,000 ac 680

Drainage water mgt 50% or 

8 lb/ac

10% or 167,000 ac 670

N removal wetlands 50% or 

8 lb/ac

59% or 1.00 M ac 4,000

TOTALS [*2/3 of 2.55 M or 1.70 M ac] 9,230
Iowa Wetland Landscape 

Systems Initiative

Pilot Demonstrations
Corn 

Soybean

1 km

Targeted Wetland Restoration

DD Tile

W.G. Crumpton, Iowa State University

Iowa Wetland Landscape Systems Initiative 
Projected Environmental/Ecological Service 

Benefits – Wetland Landscape Systems 

• Reduce nitrate transport – 40-70%
Projected Environmental/Ecological Service 

Benefits – Wetland Landscape Systems 

• Reduce nitrate transport – 40-70%

• Reduce surface runoff overland flow – 50%
Projected Environmental/Ecological Service 

Benefits – Wetland Landscape Systems 

• Reduce nitrate transport – 40-70%

• Reduce surface runoff overland flow – 50%

• Reduce sediment delivery – 50%
Projected Environmental/Ecological Service 

Benefits – Wetland Landscape Systems 

• Reduce nitrate transport – 40-70%

• Reduce surface runoff overland flow – 50%

• Reduce sediment delivery – 50%

• Reduce phosphorus transport – 50%
Projected Environmental/Ecological Service 

Benefits – Wetland Landscape Systems 

• Reduce nitrate transport – 40-70%

• Reduce surface runoff overland flow – 50%

• Reduce sediment delivery – 50%

• Reduce phosphorus transport – 50%

• Reduce N2O greenhouse gas emissions
Projected Environmental/Ecological Service 

Benefits – Wetland Landscape Systems 

• Reduce nitrate transport – 40-70%

• Reduce surface runoff overland flow – 50%

• Reduce sediment delivery – 50%

• Reduce phosphorus transport – 50%

• Reduce N2O greenhouse gas emissions

• Increase habitat and ecological service functions of 

the landscape – potential market force driver?
Projected Environmental/Ecological Service 

Benefits – Wetland Landscape Systems 

• Reduce nitrate transport – 40-70%

• Reduce surface runoff overland flow – 50%

• Reduce sediment delivery – 50%

• Reduce phosphorus transport – 50%

• Reduce N2O greenhouse gas emissions

• Increase habitat and ecological service functions of 

the landscape – potential market force driver?

• Market force economic driver for implementation 

and food security benefit - optimize crop production

Calhoun County – Potential Nitrate Removal Wetlands
Pilot Demonstration Study Sites

• Solicitation of interest across 3000 watershed 

districts

• Pilot demonstration study watersheds

– Pocahontas DD 65 (construction completed)

– Clay DD 8

– Pocahontas DD 48 & 81

– Palo Alto DD15 North

– Palo Alto DD15 South

– Pocahontas/Palo Alto Joint DD36

Iowa Department of Agriculture & Land Stewardship (IDALS)

Iowa State University (ISU)

University of Iowa (UI)

Iowa Institute of Hydraulic Research (IIHR)

Center for Agricultural and Rural Development (CARD)

Iowa Flood Center (IFC) 

Iowa Department of Natural Resources (DNR)

USDA – Farm Service Agency (FSA)

USDA – Natural Resources Conservation Service (NRCS)

USDA – Agricultural Research Service (ARS)

United States Fish & Wildlife Service (FWS)

United States Environmental Protection Agency (EPA)

United States Geological Survey (USGS)

Interagency Working Group
Technical Work Groups and Study Areas

• Hydrology and Water Quality

• Soil Resources

• Habitat

• Green House Gases

• Crop Yield

• Decision Drivers

49 research and technical members
Wetland and Watershed Infrastructure 

Funding of Pilots

Landowners $5.3 million

Iowa cost-share funds 4.0

Iowa CREP 2.0

State revolving fund 0.4 + loan

TOTAL $11.7+ million
Iowa Strategy for Nutrient Reduction – Gulf 

of Mexico Hypoxia

Voluntary BMP Adoption/Recognition 

Program – Iowa Ag Organizations