Post on 16-Jan-2017
transcript
Linking Agricultural Practices to Water Quality Improvement
William Crumpton & Matt Helmers Iowa State University
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:
[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
Calculated based on close interval monitoring of flows and concentrations
Comparison of predicted and observed load for 1) Validation and error estimation2) Iterative improvement of approach/tool3) 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
Plot Scale Research Facilities
Delivery Scale Monitoring SitesPlot Scale Research Facilities
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:
Field scale reflects processes and practices but may not reflect actual delivery to streams
Field scale reflects processes and practices but may not reflect actual delivery to streams
Field to stream transport
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
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
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
Monitoring sites instrumented for close interval sampling and
flow measurement
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:
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
30FW
A N
itrat
e Co
ncen
trati
on(m
g N
L-1
)
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
30FW
A N
itrat
e Co
ncen
trati
on(m
g N
L-1
)
0
50
100
150
200
250
300
350
400
450
500
FWA
Tota
l Pho
spho
rus C
on-
cent
ratio
n (p
pb)
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
30FW
A N
itrat
e Co
ncen
trati
on(m
g N
L-1
)
0
10
20
30
40
50
60
70
80
90
100
Nitr
ate
Yiel
d(k
g N
ha-
1 yr
-1)
0
50
100
150
200
250
300
350
400
450
500
FWA
Tota
l Pho
spho
rus C
on-
cent
ratio
n (p
pb)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Tota
l Pho
spho
rus Y
ield
(k
g ha
-1 y
r-1)
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
30FW
A N
itrat
e Co
ncen
trati
on(m
g N
L-1
)
0
10
20
30
40
50
60
70
80
90
100
Nitr
ate
Yiel
d(k
g N
ha-
1 yr
-1)
0
50
100
150
200
250
300
350
400
450
500
FWA
Tota
l Pho
spho
rus C
on-
cent
ratio
n (p
pb)
Site
Average TN Yield(kg/ha/yr)
Average Nitrate Yield(kg N/ha)
Nitrate percent of TN
CLA1 27 26 98PAL16 29 28 97PAL11 37 36 96POC2 37 37 98PAL3 37 35 92POC8 45 43 97PAL5 48 46 94PAL7 50 48 97
Average yields: Total nitrogen and nitrate
CLA1 PAL16PAL11 POC2 PAL3 POC8 PAL5 PAL70
10
20
30
40
50
60
Average TN Yield(kg/ha/yr)Average Nitrate Yield(kg N/ha)
Conc
entr
ation
(mg
N/L
)
25 30 35 40 45 50 550
10
20
30
40
50
60
f(x) = 0.959214451565202 xR² = 0.999644806567312
Total nitrogen yield (kg N/ha)
Nitr
ate
yiel
d (k
g N
/ha)
Average TP Yield (kg/ha/yr)
Average TRP Yield (kg/ha/yr)
TRP percent of TP
CLA1 0.46 0.36 78PAL3 0.76 0.55 72PAL5 0.73 0.49 67PAL7 1.04 0.82 79PAL11 0.88 0.75 85PAL16 0.41 0.33 80POC2 0.33 0.24 73POC8 0.52 0.39 75
Average yields: Total phosphorus and total reactive phosphorus
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
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
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
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
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
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:
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.
Organic N
Soil bound NH4+
NH4+
N transformation in wetlands
W.G. Crumpton, Iowa State University
NO3-
Organic N
Soil bound NH4+
NH4+
N transformation in wetlands
W.G. Crumpton, Iowa State University
NO3-
Organic N
Soil bound NH4+
NH4+
N2
N transformation in wetlands
W.G. Crumpton, Iowa State University
NO3-
External NO3- Loading
Organic N
Soil bound NH4+
NH4+
Fate of NPS nitrate loads in wetlands
W.G. Crumpton, Iowa State University
NO3-
External NO3- Loading
DenitrificationOrganic N
Soil bound NH4+
NH4+
N2
Fate of NPS nitrate loads in wetlands
W.G. Crumpton, Iowa State University
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
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
1 0
1 5
2 0FW
A ni
trate
-N c
onc.
(mg/
L)
Rank order: Low to high Nitrate concentration
Hydraulic loading rate
Nitrate loading rate
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
1 0
1 5
2 0FW
A ni
trate
-N c
onc.
(mg/
L)
Rank order: Low to high
0
0.1
0.2
0.3
0.4
Hyd
raul
ic lo
adin
g ra
te(a
vera
ge m
/day
)
Rank order: Low to high
Nitrate concentration
Hydraulic loading rate
Nitrate loading rate
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
1 0
1 5
2 0FW
A ni
trate
-N c
onc.
(mg/
L)
Rank order: Low to high
0
0.1
0.2
0.3
0.4
Hyd
raul
ic lo
adin
g ra
te(a
vera
ge m
/day
)
Rank order: Low to high
0
2000
4000
6000
8000
10000
Nitr
ate-
N lo
ad (k
g/ha
)
Rank order: Low to high
Nitrate concentration
Hydraulic loading rate
Nitrate loading rate
W.G. Crumpton, Iowa State University
Field sites instrumented for automated sampling and flow
measurement
Monitoring of Wetland Performance
0
5
10
15
20
25
Nitr
ate-
N (m
g L-1
)
0
100 0 0
200 0 0
300 0 0
Inflo
w (m
3 d-1
)
Jan Fe b M ar A p r M ay Ju n Ju l A u g S ep O c t N o v D ec
A L W e tlan d2 0 0 7
0
10 00 0 0
20 00 0 0
30 00 0 0
40 00 0 0
50 00 0 0
Inflo
w (m
3 d-1
)
0
5
10
15
20
25
Nitr
ate-
N (m
g L-1
)
Jan F eb M ar A p r M ay Ju n Ju l A u g S ep O c t N o v D ec
B G W etlan d2 0 0 7
0
5
10
15
20
25
Nitr
ate-
N (m
g L-1
)
0
20 0 00
40 0 00
60 0 00
80 0 00
10 0 00 0
Inflo
w (m
3 d-1
)
J an F eb M ar A p r M ay J un Ju l A u g S ep O c t N o v D e c
D J W e tla n d2 0 0 7
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
400 00
800 00
120 00 0
160 00 0
Inflo
w (m
3 d-1
)
Jan F eb M ar A pr M ay Jun Ju l A u g Sep O ct N o v D ec
N D W e tlan d2 0 0 7
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
4 0 00 0
8 0 00 0
1 2 00 0 0
1 6 00 0 0
2 0 00 0 0
Inflo
w (m
3 d-1
)
Ja n F e b M a r A pr M a y Ju n Ju l A u g S e p O c t N o v D e c
JR W e tla nd2 0 0 7
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
4 00 00
8 00 00
1 20 00 0
1 60 00 0
2 00 00 0
Inflo
w (m
3 d-1
)
Jan F eb M a r A p r M ay Ju n Jul A ug S ep O c t N o v D ec
V H W etla n d2 0 0 7
0
5
10
15
20
25
Nitr
ate-
N (m
g L-1
)
0
40 000
80 000
12 000 0
Inflo
w (m
3 d-1
)
Ja n F e b M a r A p r M ay Jun Ju l A ug Se p O c t N o v D ec
H S N o rth W etla n d2 0 07
0
40 0 0 0
80 0 0 0
12 0 0 0 0
16 0 0 0 0
20 0 0 0 0
Inflo
w (m
3 d-1
)
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g/L)
Ja n F eb M ar A p r M ay Ju n Ju l A u g S ep O c t N o v D ec
H M W e tla n d2 0 0 6
0
2 0 00 0
4 0 00 0
6 0 00 0
8 0 00 0
1 0 00 0 0
Inflo
w (m
3 d-1)
0
5
10
15
20
25
Nitr
ate-
N (m
g L-1
)
U M L W e tlan d2 0 0 4
Ja n F eb M ar A p r M ay J u n Ju l A u g S ep O c t N o v D ec
0
2000 0
4000 0
6000 0
8000 0
1000 00
Inflo
w (m
3 d-1
)
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
Jan F eb M ar A p r M ay Jun Ju l A u g S e p O c t N ov D ec
T I W e tlan d2 0 06
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
4 0 0 0 0
8 0 0 0 0
1 2 0 0 0 0
1 6 0 0 0 0
2 0 0 0 0 0
Inflo
w (m
3 d-1
)
J an F eb M a r A p r M ay Ju n Ju l A u g S ep O ct N o v D ec
K S W etlan d2 0 0 8
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
1 0 0 0 0
2 0 0 0 0
3 0 0 0 0
Inflo
w (m
3 d-1
) Jan F e b M ar A p r M a y Jun Ju l A u g S ep O ct N o v D ec
D S W etlan d2 0 08
Examples from 2007 to 2009 monitoring
W.G. Crumpton, Iowa State University
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
5 0 0 0
1 0 0 0 0
1 5 0 0 0
2 0 0 0 0
2 5 0 0 0
Inflo
w (m
3 d-1
)
Ja n F e b M ar A p r M a y Ju n Ju l A ug S ep O c t N o v D ec
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
100 0 0
200 0 0
300 0 0
400 0 0
500 0 0
Inflo
w (m
3 d-1
)
J an F e b M ar A p r M ay Ju n Ju l A ug S e p O c t N ov D e c
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
500 0
100 0 0
150 0 0
200 0 0
250 0 0
Inflo
w (m
3 d-1
)
Ja n F e b M ar A p r M ay Ju n Ju l A u g S e p O c t N ov D ec
W.G. Crumpton, Iowa State University
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
5 0 0 0
1 0 0 0 0
1 5 0 0 0
2 0 0 0 0
2 5 0 0 0
Inflo
w (m
3 d-1
)
Ja n F e b M ar A p r M a y Ju n Ju l A ug S ep O c t N o v D ec
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
100 0 0
200 0 0
300 0 0
400 0 0
500 0 0
Inflo
w (m
3 d-1
)
J an F e b M ar A p r M ay Ju n Ju l A ug S e p O c t N ov D e c
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
500 0
100 0 0
150 0 0
200 0 0
250 0 0
Inflo
w (m
3 d-1
)
Ja n F e b M ar A p r M ay Ju n Ju l A u g S e p O c t N ov D ec
Residence time
Longer
Shorter
W.G. Crumpton, Iowa State University
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
5 0 0 0
1 0 0 0 0
1 5 0 0 0
2 0 0 0 0
2 5 0 0 0
Inflo
w (m
3 d-1
)
Ja n F e b M ar A p r M a y Ju n Ju l A ug S ep O c t N o v D ec
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
100 0 0
200 0 0
300 0 0
400 0 0
500 0 0
Inflo
w (m
3 d-1
)
J an F e b M ar A p r M ay Ju n Ju l A ug S e p O c t N ov D e c
0
5
1 0
1 5
2 0
2 5
Nitr
ate-
N (m
g L-1
)
0
500 0
100 0 0
150 0 0
200 0 0
250 0 0
Inflo
w (m
3 d-1
)
Ja n F e b M ar A p r M ay Ju n Ju l A u g S e p O c t N ov D ec
Residence time
Longer
Shorter
Hydraulic Loading
Rate
Lower
Greater
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
Mass loss kg ha-1 yr-1
W.G. Crumpton, Iowa State University
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:
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
Wetland Siting and Design for Watershed Scale Endpoints
W.G. Crumpton, Iowa State UniversityTile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape PositionLegend
Total Load50 metric tons
\
Annual Nitrate Budget
W.G. Crumpton, Iowa State UniversityTile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape PositionLegend
Loss in Ditch and Stream1.6 metric tons
Exported48.4 metric tons
\
Annual Nitrate Budget
W.G. Crumpton, Iowa State UniversityTile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape PositionLegend
Upslope sites
Loss in Ditch and Stream1.6 metric tons
Exported48.4 metric tons
\
Annual Nitrate Budget
W.G. Crumpton, Iowa State UniversityTile
Upland Depression
Upland Non-hydric
Upland Swale
Lowland Drainageway
Soils by Landscape PositionLegend
Loss in Ditch and Stream1.6 metric tons
Exported46.5 metric tons
Loss in Wetlands1.9 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 PositionLegend
Downslope sites
Loss in Ditch and Stream1.6 metric tons
Exported46.5 metric tons
Loss in Wetlands1.9 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 PositionLegend
Loss in Ditch and Stream1.6 metric tons
Loss in Wetlands17 metric tons
Exported29.8 metric tons
Loss in Ditch and Stream1.6 metric tons
Exported46.5 metric tons
Loss in Wetlands1.9 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 PositionLegend
Downslope sites
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
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
W.G. Crumpton, Iowa State University
Nitrate Concentrations and Loads with Existing N Management
W.G. Crumpton, Iowa State University
Nitrate Concentrations and Loads with Existing N Management
Nitrate Concentrations and Loads with MRTN Based N Management
Water yield grid
Nitrate yield grid
and loss function
Nitrate loss gridgenerate
W.G. Crumpton, Iowa State University
Estimating Potential Nitrate Loss in Wetlands
W.G. Crumpton, Iowa State University
Nitrate Loads & Potential Loss in Wetlands with Existing N Management
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
W.G. Crumpton, Iowa State University
45% mass reduction
Potential N Reduction in Wetlands with Existing N Management
W.G. Crumpton, Iowa State University
45% mass reduction
Reduction due to Fertilizer Management
Potential N Reduction in Wetlands with MRTN based N Management
W.G. Crumpton, Iowa State University
45% mass reduction
Reduction due to Fertilizer Management
Potential N Reduction in Wetlands with MRTN based N Management
[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
Calculated based on close interval monitoring of flows and concentrations
Comparison of predicted and observed load for 1) Validation and error estimation2) Iterative improvement of approach/tool3) 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
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 StewardshipIowa Department of Natural ResourcesUS Department of AgricultureUS Environmental Protection Agency
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
W.G. Crumpton, Iowa State University
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
1 0
1 5
2 0
2 5
Nitr
ate-
N (
mg
L-1
)
0
4 0 0 00
8 0 0 00
1 2 0 00 0
1 6 0 00 0
2 0 0 00 0
Infl
ow (
m3 d
-1)
Jan F eb M ar A p r M ay Ju n Ju l A u g S ep O c t N o v D ec
V H W e tland2 0 0 7
W.G. Crumpton, Iowa State University
F lowO b serv ed in flow n itra te -N con cen tration O b serv ed ou tflow n itra te -N con cen tra tion
M ar A p r M ay Ju n Ju l A u g S ep O ctV an H orn 2 004
0
5
10
15
20
25
Nitr
ate-
N c
once
ntra
tion
mgl
-1
0
5000
1000 0
1500 0
2000 0
2500 0
flow m
3day -1
Observed Nitrate concentrations and flow rates for Van Horn Wetland in 2004
Van Horn Wetland
Monitoring of Wetland Performance
Wetland Monitoring SitesPlot Scale Research Facilities