Claire Baffaut
Nutrient Management and Edge of Field monitoring:
from the Great Lakes to the Gulf
Memphis, TN 2015
Multi-scale Monitoring
for Improved Nutrient Management

Challenges
of tracking
progress
in streams
Additional
processes
Lack of
targeting
Lack of
control:
Conflicting
factors
Lack of
spatial and
temporal
information
No
replication
Data
interpretation
is difficult.
Changes are
small and
difficult to
detect.

Goodwater Creek Experimental Watershed

• Stream bank erosion
• Subsurface and ground water contributions.
• Nutrient storage in and resuspension from the
streambed sediment.
• Filtering and nutrient uptake by riparian
buffers.
Multiple processes
Bank
sediment
87%
Overland
sediment
13%
Instream sediment in Otter and
Crooked Creek
Bank
nitrogen
23%
Overland
nitrogen
77%
Instream nitrogen in Otter and
Crooked Creek
Willett et al., JSWC 2012.

Replication
Relatively easy at the plot scale:
- Same soils
- Same slope
- Same initial conditions
- Same weather
- Same size and shape
- Same orientation
Repeated treatments on several
plots allow statistical analysis to
detect significant differences

Other monitoring and analysis strategies
• Before and after analysis: difficult because
change in land agricultural practices is
gradual.
• Trend analysis.
• Multiple regression analysis.
• Multiple scale monitoring.

BMPs in Goodwater Creek
Experimental Watershed
15% of the
watershed in
17 years !

• Before and after analysis.
• Trend analysis:
– Issues with conflicting factors.
– Effect of a strong random component
• Multiple regression analysis.
• Multiple scale monitoring.
Other monitoring and analysis strategies

Trend Analysis of Flow in GCEW
Year peak flow : 8 mm more per decade
Number of flooded days: 2 more days per decade

Agricultural Land use
1967 Row crop (corn and soybean)
Small grain (wheat)
Hay and pasture
2006

Soil erosion and water storage capacity
• 13 cm (5.1 in) in 150 years
• 3.5 cm (1.4 in) in 40 years
• 14% of water storage
capacity.
Top soil loss (cm)
-45 -20 0 20 45
(Lerch et al. 2005, JSWC)

1967 2009
Tributary crossing in Centralia
Urbanization
• 11% more people
• 71% more houses

Conservation Practices
0
2
4
6
8
10
12
14
16
18
0
50
100
150
200
250
%watershedprotected
Areaprotected(hectares)
Grassed waterway
Terraces
Seeding
Sod busting
Grazing system
Lagoon
Filter Strip
Diversion
CP33,CRP
Buffer
Cumulative % land
protected

• Before and after analysis.
• Trend analysis.
• Multiple regression analysis: requires good
spatial and temporal knowledge of what is
happening in the watershed.
• Multiple scale monitoring.
Other monitoring and analysis strategies

Multiple regression analysis
• Requires good spatial and temporal
information of:
– Weather
– Land use
– Crop distribution
– Land management, including
• Cropland management and best management practices
• Sanitary sewage treatment
• Management of urban areas
• Management of pastures

Multiple regression
• No trend of nitrate loads
over 92-06 in GCEW
(O’Donnell, 2010).
• Decreasing trend over
1992-2010 (Lerch et al.,
2015), possibly linked to
decrease in wheat
production.
• No BMP linked variable
found significant.
• Not the right BMPs?
• Not the right location?
Crop land
Pasture & grass
Impervious areas
Critical areas
Conservation practices

Time needed to detect change
• Mean Square Error of
model was used to
estimate the monitoring
period needed to detect
a future change
Predicted number of years needed to
detect load reduction
Nitrate load reduction
Season 5% 10% 20% 25%
Year 92 24 7 4
Spring 185 49 13 9
O’Donnell, 2010

• Before and after analysis.
• Trend analysis.
• Multiple regression analysis: requires good
spatial and temporal knowledge of what is
happening in the watershed.
• Multiple scale monitoring.
Other monitoring and analysis strategies

Multiple scale monitoring
Stream Weir W1
Field
1993-2002
Mulch tilled
corn-soybean
2004-2014
Precision
Agricultural
System (PAS)

Field 1
Pre-PAS 1993-2002 PAS 2004-2013
South 40 acres North 52 acres
Odd year Corn (sorghum in 95)
N: pre-plant UAN,
incorporated
P: 1993, 1995, 2001
incorporated
Cultivation
Corn / Cover Crop
N: at planting + top
dress early summer
No-till
Wheat / Cover Crop
N: top dress in April
No-till
Even
year
Soybean
Cultivation
Soybean / Cover Crop
P: 2004, 2006, 2008
broadcast
No-till
Soybean / wheat
N: at wheat planting
P: 2004, 2006, 2008
broadcast
No-till

Effect of no-till and cover crops
Flow

Effect of no-till and cover crop
Dissolved P loss

Effect of no-till and cover crop
Nitrate-N loss

Effect of no-till and cover crop
Sediment

Annual Sediment losses

Summary
• No-till and cover crops did:
 Reduce sediment
 Did not change Nitrate-N transport
 Did increase Dissolved P transport
• Agronomic practices, land use change, urbanization,
stream processes and climate all contribute to
modifying the runoff/sediment/nutrient yield
regime of a watershed and make it difficult to:
 detect a trend,
 discern whether detected trends are due to any
one factor.

Implications
To improve detection of water quality trends resulting
from management changes, these changes should be:
• Implemented within a short time.
• Spatially targeted.
• Of large magnitude.
• Addressing the processes that cause the problem
documented by the monitoring. Scale matters!

Data Management
• Equipment fails  data gaps  fill in the gaps
• Sediment loss measurements
• Inaccurate data
– Flow > Precipitation
– Issues with small events
• Meta data

Acknowledgements
Cropping Systems and Water Quality Research Unit
Newell Kitchen, Ken Sudduth, Bob Lerch
Matt Volkmann, Kurt Holiman, Mark Olson, Aaron Beshears,
Teri Oster, Scott Drummond, Bettina Coggeshall.
ARS CEAP LTAR