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Baffaut - Multi-Scale Monitoring
1. 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
4. โข Stream bank erosion
โข Subsurface and ground water contributions.
โข Nutrient storage in and resuspension from the
streambed sediment.
โข 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.
5. 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
6. Other monitoring and analysis strategies
โข Before and after analysis: difficult because
change in land agricultural practices is
gradual.
โข Trend analysis.
โข Multiple regression analysis.
โข Multiple scale monitoring.
7. BMPs in Goodwater Creek
Experimental Watershed
15% of the
watershed in
17 years !
8. โข Before and after analysis.
โข Trend analysis:
โ Issues with conflicting factors.
โ Effect of a strong random component
โข Multiple regression analysis.
โข Multiple scale monitoring.
Other monitoring and analysis strategies
9. Trend Analysis of Flow in GCEW
Year peak flow : 8 mm more per decade
Number of flooded days: 2 more days per decade
11. Soil erosion and water storage capacity
โข 13 cm (5.1 in) in 150 years
โข 3.5 cm (1.4 in) in 40 years
โข 14% of water storage
capacity.
Top soil loss (cm)
-45 -20 0 20 45
(Lerch et al. 2005, JSWC)
14. โข Before and after analysis.
โข Trend analysis.
โข Multiple regression analysis: requires good
spatial and temporal knowledge of what is
happening in the watershed.
โข Multiple scale monitoring.
Other monitoring and analysis strategies
15. Multiple regression analysis
โข Requires good spatial and temporal
information of:
โ Weather
โ Land use
โ Crop distribution
โ Land management, including
โข Cropland management and best management practices
โข Sanitary sewage treatment
โข Management of urban areas
โข Management of pastures
16. Multiple regression
โข No trend of nitrate loads
over 92-06 in GCEW
(OโDonnell, 2010).
โข Decreasing trend over
1992-2010 (Lerch et al.,
2015), possibly linked to
decrease in wheat
production.
โข No BMP linked variable
found significant.
โข Not the right BMPs?
โข Not the right location?
Crop land
Pasture & grass
Impervious areas
Critical areas
Conservation practices
17. Time needed to detect change
โข 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
OโDonnell, 2010
18. โข Before and after analysis.
โข Trend analysis.
โข Multiple regression analysis: requires good
spatial and temporal knowledge of what is
happening in the watershed.
โข Multiple scale monitoring.
Other monitoring and analysis strategies
19. Multiple scale monitoring
Stream Weir W1
Field
1993-2002
Mulch tilled
corn-soybean
2004-2014
Precision
Agricultural
System (PAS)
20. 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
26. Summary
โข No-till and cover crops did:
๏ Reduce sediment
๏ Did not change Nitrate-N transport
๏ Did increase Dissolved P transport
โข 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.
27. Implications
To improve detection of water quality trends resulting
from management changes, these changes should be:
โข Implemented within a short time.
โข Spatially targeted.
โข Of large magnitude.
โข Addressing the processes that cause the problem
documented by the monitoring. Scale matters!
28. Data Management
โข Equipment fails ๏ data gaps ๏ fill in the gaps
โข Sediment loss measurements
โข Inaccurate data
โ Flow > Precipitation
โ Issues with small events
โข Meta data
29. 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