2. Performance of in-field practices
NPS N & P loads delivered to streams
Wetlands intercepting NPS loads
Watershed scale outcomes
Linking Agricultural Practices to
Water Quality Improvement:
3. [N]
N Response Curves
N Application Rate
( function of practices)
Practices by field
Water Yield by field
(also yield, for economic analyses)
Established based on
experimental field studies
Established based on GIS
coverages and survey data
Estimated based on
observed flows,
precipitation, etc. and
semi-empirical models
N yield by field
[N] by field
Predicted load at
watershed outlet
Observed load at
watershed outlet
Estimated as
𝑵 𝒚𝒊𝒆𝒍𝒅 𝒂𝒄𝒓𝒐𝒔𝒔 𝒇𝒊𝒆𝒍𝒅𝒔
Calculated based on close
interval monitoring of
flows and concentrations
Comparison of predicted and observed load for
1) Validation and error estimation
2) Iterative improvement of approach/tool
3) Establishing capabilities and limitations of approach/tool
(IDALS and INRC)
(Iowa Corn Promotion Board
and USDA)
(IDALS and USDA NIFA)
(IDALS and INRC)
(IDALS, INRC, and USDA-NRCS)
Conceptual Framework
6. Performance of in-field practices
NPS N & P loads delivered to streams
Wetlands intercepting NPS loads
Watershed scale outcomes
Linking Agricultural Practices to
Water Quality Improvement:
7. Field scale reflects processes and practices but
may not reflect actual delivery to streams
8. Field scale reflects processes and practices but
may not reflect actual delivery to streams
Field to stream
transport
9. Larger scales reflect combination of
delivery and in-stream processes
Field scale reflects processes and practices but
may not reflect actual delivery to streams
Field to stream
transport
10. Larger scales reflect combination of
delivery and in-stream processes
Field scale reflects processes and practices but
may not reflect actual delivery to streams
Field to stream
transport
In-stream
processes
11. Larger scales reflect combination of
delivery and in-stream processes
This scale reflects nutrient load
actually delivered to stream
Field scale reflects processes and practices but
may not reflect actual delivery to streams
Field to stream
transport
In-stream
processes
14. Performance of in-field practices
NPS N & P loads delivered to streams
Wetlands intercepting NPS loads
Watershed scale outcomes
Linking Agricultural Practices to
Water Quality Improvement:
15. Nitrate and Total Phosphorus: Yields and flow-weighted average concentrations
versus rank order
Minimums: FWA NO3=3.32, NO3 yld=2.3, FWA TP=39, TP yld=0.043.
0
5
10
15
20
25
30FWANitrateConcentration
(mgNL-1)
16. Nitrate and Total Phosphorus: Yields and flow-weighted average concentrations
versus rank order
Minimums: FWA NO3=3.32, NO3 yld=2.3, FWA TP=39, TP yld=0.043.
0
5
10
15
20
25
30FWANitrateConcentration
(mgNL-1)
0
50
100
150
200
250
300
350
400
450
500
FWATotalPhosphorus
Concentration(ppb)
17. Nitrate and Total Phosphorus: Yields and flow-weighted average concentrations
versus rank order
Minimums: FWA NO3=3.32, NO3 yld=2.3, FWA TP=39, TP yld=0.043.
0
5
10
15
20
25
30FWANitrateConcentration
(mgNL-1)
0
10
20
30
40
50
60
70
80
90
100
NitrateYield
(kgNha-1yr-1)
0
50
100
150
200
250
300
350
400
450
500
FWATotalPhosphorus
Concentration(ppb)
19. Site
Average TN
Yield
(kg/ha/yr)
Average
Nitrate Yield
(kg N/ha)
Nitrate
percent of
TN
CLA1 27 26 98
PAL16 29 28 97
PAL11 37 36 96
POC2 37 37 98
PAL3 37 35 92
POC8 45 43 97
PAL5 48 46 94
PAL7 50 48 97
Average yields: Total nitrogen and nitrate
0
10
20
30
40
50
60
CLA1 PAL16PAL11 POC2 PAL3 POC8 PAL5 PAL7
Concentration(mgN/L)
Average TN Yield
(kg/ha/yr)
Average Nitrate Yield
(kg N/ha)
y = 0.96x
R² = 0.99
0
10
20
30
40
50
60
0 20 40 60
Nitrateyield(kgN/ha)
Total nitrogen yield (kg N/ha)
20. Average TP
Yield
(kg/ha/yr)
Average TRP
Yield
(kg/ha/yr)
TRP
percent of
TP
CLA1 0.46 0.36 78
PAL3 0.76 0.55 72
PAL5 0.73 0.49 67
PAL7 1.04 0.82 79
PAL11 0.88 0.75 85
PAL16 0.41 0.33 80
POC2 0.33 0.24 73
POC8 0.52 0.39 75
Average yields: Total phosphorus and total reactive phosphorus
21. Wide range in N & P yields across systems having similar
land use, soils and drainage.
– How much of this variation can be attributed to in field management?
Very large annual variation in N & P loads
– What are implications for load reduction targets?
Tile drains deliver much higher P loads to streams than
previously thought based on plot scale research.
Surface runoff contributes only about half of the total P load
in these tile drained landscapes.
– Practices that target surface runoff will have less effect on P loads than
expected.
NPS N & P loads delivered to streams
22. Wide range in N & P yields across systems having similar
land use, soils and drainage.
– How much of this variation can be attributed to in field management?
Very large annual variation in N & P loads
– What are implications for load reduction targets?
Tile drains deliver much higher P loads to streams than
previously thought based on plot scale research.
Surface runoff contributes only about half of the total P load
in these tile drained landscapes.
– Practices that target surface runoff will have less effect on P loads than
expected.
NPS N & P loads delivered to streams
23. Wide range in N & P yields across systems having similar
land use, soils and drainage.
– How much of this variation can be attributed to in field management?
Very large annual variation in N & P loads
– What are implications for load reduction targets?
Tile drains deliver much higher P loads to streams than
previously thought based on plot scale research.
Surface runoff contributes only about half of the total P load
in these tile drained landscapes.
– Practices that target surface runoff will have less effect on P loads than
expected.
NPS N & P loads delivered to streams
24. Wide range in N & P yields across systems having similar
land use, soils and drainage.
– How much of this variation can be attributed to in field management?
Very large annual variation in N & P loads
– What are implications for load reduction targets?
Tile drains deliver much higher P loads to streams than
previously thought based on plot scale research.
Surface runoff contributes only about half of the total P load
in these tile drained landscapes.
– Practices that target surface runoff will have less effect on P loads than
expected.
NPS N & P loads delivered to streams
25. Wide range in N & P yields across systems having similar
land use, soils and drainage.
– How much of this variation can be attributed to in field management?
Very large annual variation in N & P loads
– What are implications for load reduction targets?
Tile drains deliver much higher P loads to streams than
previously thought based on plot scale research.
Surface runoff contributes only about half of the total P load
in these tile drained landscapes.
– Practices that target surface runoff will have less effect on P loads than
expected.
NPS N & P loads delivered to streams
26. Performance of in-field practices
NPS N & P loads delivered to streams
Wetlands intercepting NPS loads
Watershed scale outcomes
Linking Agricultural Practices to
Water Quality Improvement:
27. Corn
Soybean
1 km
Targeted Wetland Restoration
DD Tile
W.G. Crumpton, Iowa State University
There is considerable interest in using wetlands to intercept and
reduce nitrogen loads in tile drained landscapes.
28. Organic N
Soil bound NH4
+
NH4
+
N transformation in wetlands
W.G. Crumpton, Iowa State University
29. NO3
-
Organic N
Soil bound NH4
+
NH4
+
N transformation in wetlands
W.G. Crumpton, Iowa State University
30. NO3
-
Organic N
Soil bound NH4
+
NH4
+
N2
N transformation in wetlands
W.G. Crumpton, Iowa State University
33. W.G. Crumpton, Iowa State University
Wetlands were chosen to ensure a
broad range in factors expected to
affect N loss rates, including:
Nitrate concentration
Hydraulic loading rate
Nitrate loading rate
Sites for Wetland Performance Monitoring
34. W.G. Crumpton, Iowa State University
Wetlands were chosen to ensure a
broad range in factors expected to
affect N loss rates, including:
0
5
10
15
20
FWAnitrate-Nconc.(mg/L)
Rank order: Low to high Nitrate concentration
Hydraulic loading rate
Nitrate loading rate
35. W.G. Crumpton, Iowa State University
Wetlands were chosen to ensure a
broad range in factors expected to
affect N loss rates, including:
0
5
10
15
20
FWAnitrate-Nconc.(mg/L)
Rank order: Low to high
0
0.1
0.2
0.3
0.4
Hydraulicloadingrate
(averagem/day)
Rank order: Low to high
Nitrate concentration
Hydraulic loading rate
Nitrate loading rate
36. W.G. Crumpton, Iowa State University
Wetlands were chosen to ensure a
broad range in factors expected to
affect N loss rates, including:
0
5
10
15
20
FWAnitrate-Nconc.(mg/L)
Rank order: Low to high
0
0.1
0.2
0.3
0.4
Hydraulicloadingrate
(averagem/day)
Rank order: Low to high
0
2000
4000
6000
8000
10000
Nitrate-Nload(kg/ha)
Rank order: Low to high
Nitrate concentration
Hydraulic loading rate
Nitrate loading rate
37. W.G. Crumpton, Iowa State University
Field sites instrumented for
automated sampling and flow
measurement
Monitoring of Wetland Performance
38. 0
5
10
15
20
25
Nitrate-N(mgL-1
)
0
10000
20000
30000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
AL Wetland
2007
0
100000
200000
300000
400000
500000
Inflow(m3d-1)
0
5
10
15
20
25
Nitrate-N(mgL-1
)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
BG Wetland
2007
0
5
10
15
20
25
Nitrate-N(mgL-1
)
0
20000
40000
60000
80000
100000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
DJ Wetland
2007
0
5
10
15
20
25
Nitrate-N(mgL-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(mgL-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(mgL-1
)
0
40000
80000
120000
160000
200000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
VH Wetland
2007
0
5
10
15
20
25
Nitrate-N(mgL-1
)
0
40000
80000
120000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
HS North Wetland
2007
0
40000
80000
120000
160000
200000
Inflow(m3d-1)
0
5
10
15
20
25
Nitrate-N(mg/L)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
HM Wetland
2006
0
20000
40000
60000
80000
100000
Inflow(m3d-1)
0
5
10
15
20
25
Nitrate-N(mgL-1)
UML Wetland
2004
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
20000
40000
60000
80000
100000
Inflow(m3d-1)
0
5
10
15
20
25
Nitrate-N(mgL-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
TI Wetland
2006
0
5
10
15
20
25
Nitrate-N(mgL-1
)
0
40000
80000
120000
160000
200000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
KS Wetland
2008
0
5
10
15
20
25
Nitrate-N(mgL-1
)
0
10000
20000
30000
Inflow(m3d-1)Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
DS Wetland
2008
Examples from 2007 to 2009 monitoring
W.G. Crumpton, Iowa State University
39. 0
5
10
15
20
25
Nitrate-N(mgL-1)
0
5000
10000
15000
20000
25000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
5
10
15
20
25
Nitrate-N(mgL-1)
0
10000
20000
30000
40000
50000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
5
10
15
20
25
Nitrate-N(mgL-1)
0
5000
10000
15000
20000
25000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
W.G. Crumpton, Iowa State University
40. 0
5
10
15
20
25
Nitrate-N(mgL-1)
0
5000
10000
15000
20000
25000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
5
10
15
20
25
Nitrate-N(mgL-1)
0
10000
20000
30000
40000
50000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
5
10
15
20
25
Nitrate-N(mgL-1)
0
5000
10000
15000
20000
25000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Residence
time
Longer
Shorter
W.G. Crumpton, Iowa State University
41. 0
5
10
15
20
25
Nitrate-N(mgL-1)
0
5000
10000
15000
20000
25000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
5
10
15
20
25
Nitrate-N(mgL-1)
0
10000
20000
30000
40000
50000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
5
10
15
20
25
Nitrate-N(mgL-1)
0
5000
10000
15000
20000
25000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Residence
time
Longer
Shorter
Hydraulic
Loading
Rate
Lower
Greater
W.G. Crumpton, Iowa State University
49. Performance of in-field practices
NPS N & P loads delivered to streams
Wetlands intercepting NPS loads
Watershed scale outcomes
Linking Agricultural Practices to
Water Quality Improvement:
50. Wetland Siting and Design for Watershed
Scale Endpoints
Potential Load Reductions from Wetland
Restoration and N Management in Iowa
Targeting Wetland Restorations to
Reduce NPS N loads
W.G. Crumpton, Iowa State University
51. Wetland Siting and Design for
Watershed Scale Endpoints
W.G. Crumpton, Iowa State University
Tile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape Position
Legend
52. Total Load
50 metric tons
Annual Nitrate Budget
W.G. Crumpton, Iowa State University
Tile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape Position
Legend
53. Loss in Ditch and Stream
1.6 metric tons
Exported
48.4 metric tons
Annual Nitrate Budget
W.G. Crumpton, Iowa State University
Tile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape Position
Legend
54. Upslope
sites
Loss in Ditch and Stream
1.6 metric tons
Exported
48.4 metric tons
Annual Nitrate Budget
W.G. Crumpton, Iowa State University
Tile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape Position
Legend
55. Loss in Ditch and Stream
1.6 metric tons
Exported
46.5 metric tons
Loss in Wetlands
1.9 metric tons
Annual Nitrate Budget
W.G. Crumpton, Iowa State University
Upslope
sites
Tile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape Position
Legend
56. Downslope
sites
Loss in Ditch and Stream
1.6 metric tons
Exported
46.5 metric tons
Loss in Wetlands
1.9 metric tons
Annual Nitrate Budget
W.G. Crumpton, Iowa State University
Upslope
sites
Tile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape Position
Legend
57. Loss in Ditch and Stream
1.6 metric tons
Loss in Wetlands
17 metric tons
Exported
29.8 metric tons
Loss in Ditch and Stream
1.6 metric tons
Exported
46.5 metric tons
Loss in Wetlands
1.9 metric tons
Annual Nitrate Budget
W.G. Crumpton, Iowa State University
Upslope
sites
Tile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape Position
Legend
Downslope
sites
58. Wetland Siting and Design for Watershed
Scale Endpoints
Potential Load Reductions from Wetland
Restoration and N Management in Iowa
Targeting Wetland Restorations to
Reduce NPS N loads
W.G. Crumpton, Iowa State University
59. Nitrate concentration and loads
Potential load reductions from
improved N management
Potential load reductions from
targeted wetland restoration
Potential Load Reductions from Wetland
Restoration and N Management in Iowa
W.G. Crumpton, Iowa State University
60. W.G. Crumpton, Iowa State University
Nitrate Concentrations and Loads with Existing N Management
61. W.G. Crumpton, Iowa State University
Nitrate Concentrations and Loads with Existing N Management
Nitrate Concentrations and Loads with MRTN Based N Management
62. Water yield grid
Nitrate yield grid
and loss function
Nitrate loss gridgenerate
W.G. Crumpton, Iowa State University
Estimating Potential Nitrate Loss in Wetlands
63. W.G. Crumpton, Iowa State University
Nitrate Loads & Potential Loss in Wetlands with Existing N Management
64. W.G. Crumpton, Iowa State University
Nitrate Loads & Potential Loss in Wetlands with Existing N Management
Nitrate Load & Potential Loss in Wetlands with MRTN Based N Management
65. W.G. Crumpton, Iowa State University
45% mass reduction
Potential N Reduction in Wetlands with Existing N Management
66. W.G. Crumpton, Iowa State University
45% mass reduction
Reduction due to
Fertilizer Management
Potential N Reduction in Wetlands with MRTN based N Management
67. W.G. Crumpton, Iowa State University
45% mass reduction
Reduction due to
Fertilizer Management
Potential N Reduction in Wetlands with MRTN based N Management
68. [N]
N Response Curves
N Application Rate
( function of practices)
Practices by field
Water Yield by field
(also yield, for economic analyses)
Established based on
experimental field studies
Established based on GIS
coverages and survey data
Estimated based on
observed flows,
precipitation, etc. and
semi-empirical models
N yield by field
[N] by field
Predicted load at
watershed outlet
Observed load at
watershed outlet
Estimated as
𝑵 𝒚𝒊𝒆𝒍𝒅 𝒂𝒄𝒓𝒐𝒔𝒔 𝒇𝒊𝒆𝒍𝒅𝒔
Calculated based on close
interval monitoring of
flows and concentrations
Comparison of predicted and observed load for
1) Validation and error estimation
2) Iterative improvement of approach/tool
3) Establishing capabilities and limitations of approach/tool
(IDALS and INRC)
(Iowa Corn Promotion Board
and USDA)
(IDALS and USDA NIFA)
(IDALS and INRC)
(IDALS, INRC, and USDA-NRCS)
Conceptual Framework
69. Iowa State University Wetlands Research Lab:
W. Crumpton, A. van der Valk, T. Jurik
G. Stenback, J. Stenback, S. Fisher,
D. Green, I. Ellickson, C. Judge, S. McDeid, H. Hoglund,
K. Halpin, A. Albertson, M. Baalman, J. Eeling
Iowa Department of Agriculture and Land Stewardship
Iowa Department of Natural Resources
US Department of Agriculture
US Environmental Protection Agency
W.G. Crumpton, Iowa State University
73. W.G. Crumpton, Iowa State University
Observed Nitrate concentrations and flow rates
for Van Horn Wetland in 2004
Van Horn Wetland
Monitoring of Wetland Performance
0
5
10
15
20
25
Nitrate-N(mgL-1
)
0
40000
80000
120000
160000
200000
Inflow(m3d-1)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
VH Wetland
2007
74. W.G. Crumpton, Iowa State University
Flow
Observed inflow nitrate-N concentration
Observed outflow nitrate-N concentration
Mar Apr May Jun Jul Aug Sep Oct
Van Horn 2004
0
5
10
15
20
25
Nitrate-Nconcentrationmgl-1
0
5000
10000
15000
20000
25000
flowm3day-1
Observed Nitrate concentrations and flow rates
for Van Horn Wetland in 2004
Van Horn Wetland
Monitoring of Wetland Performance