69th SWCS International Annual Conference “Making Waves in Conservation: Our Life on Land and Its Impact on Water” July 27-30, 2014 Lombard, IL

1. Modeling Conservation Practices in
APEX: From the Field to the
Watershed
Wendy Francesconia*, Douglas R. Smitha, Dennis C. Flanagana, Chi‐
Hua Huanga, Xiuying Wangb
aNational Soil Erosion Research Laboratory, 275 S Russell Street, West Lafayette, IN 47907,
USA
bTexas A&M University, Blackland Research and Extension Center, Temple, TX 76502, USA

2. Conservation Effects Assessment
Project (CEAP)
• Conservation agricultural programs are designed by the
United States Department of Agriculture – Natural
Resources Conservation Service (USDA‐NRCS), and
implemented through local Soil and Water Conservation
Districts (SWCDs).
• To evaluate the environmental impact of such programs
at the watershed scale, the Conservation Effects
Assessment Project (CEAP) was established (Richardson
et al., 2008).
o Monitoring and Modeling

3. The St. Joseph River and Maumme
Watershed on Receiving Waters

4. The Need for Effective Conservation
Practices
• After a short‐lived
reduction in nutrient
loading in the Maumme,
DRP loads and
concentrations have been
increasing despite
constant or slightly lower
fertilizer applications.
(Baker and Richards, Heidelberg University)

5. St. Joseph Watershed Monitoring
• Four Monitoring Field Sites
• Conservation Practices Evaluated:
1. No‐till
2. Conservation crop rotation
3. Grass waterways
4. Blind inlets.

6. Methods: Monitoring
Surface Flow Tile Flow
Dropbox weir and pipes
that connect to auto
sampler.
Pipes that connect tile flow
to auto sampler.

7. Monitoring Data
Variables
• Surface Runoff
• Sediments in runoff
• Total Phosphorus (TP)
• Dissolve Reactive Phosphorus (DRP)
• Soluble Nitrogen (SN)
• Tile Flow
• Soluble Nitrogen in Tile Flow (SN‐Tile)

8. Watershed Modeling
• Whole farm or small watershed model that can simulate hydrological,
sediment, nutrients and pesticide routing.
• Developed to evaluate land management strategies for environmental
conservation and crop productivity purposes.
Model Inputs

9. Calibration and Validation of the
Model
Calibration
(2005‐2010)
Validation
(2011‐2012)
R2 NSE R2 NSE
Runoff 0.81 0.55 0.83 0.77
Sediment 0.75 0.74 0.90 0.78
TP 0.47 0.46 0.61 0.55
DRP 0.63 0.52 0.56 0.38
SN* 0.96 0.42 0.64 0.61
Tile Flow** 0.43 0.42 0.44 0.42
SN—Tile** 0.58 0.28 N/A N/A
*Values for SN were calibrated for 2007 ‐ 2009 instead of 2010 and 2011.
**Tile flow and SN‐Tile data collection began in 2008. Calibration and validation scores are for the periods 2010 and 2011
(respectively).

10. Practices and Extents
*Number of units installed

11. Stacking Conservation Practices
NRCS Code Conservation Practice Description
Extent of Conservation Practices incorporated in the St.
Joseph Watershed from
2005‐2012 (ha)
Combined Practice First Level
412 + 329 Grassed waterway + No‐till 336
340 + 329 Cover Crop + No‐till 1366
327 + 329 Conservation Cover + No‐till 42
328 + 329 Conservation Crop Rotation + No‐till 7512
590 + 329 Nutrient Management + No‐till 1960
633 + 329 Waste Utilization + No‐till 78
393 + 329 Filter Strip + No‐till 1205
410 + 329 Grade stab. + No‐till 241
511‐12 + 329 Forage + No‐till 162
328 + 345 Conservation Crop Rotation + Mulch Till 148
Total 14050
Combined Practice Second Level
328 + 340 + 329 Conservation Crop Rotation + Cover Crop + No‐till 1331
511‐12 + 633 + 329 Forage + Waste + No‐till 2
393 + 345 + 340 Filter + Mulch‐till + Cover Crops 111
393 + 328 + 329 Filter + Conservation Crop Rotation + No‐till 1135
327 + 393 + 329 Conservation Cover + Filter Strip + No‐till 0.4
590 + 633 + 329 Nutrient Management + Waste + No‐till 61
Total 2640

12. Results at the Field Scale
Some generalizations of single practices
• No‐till compared to tillage resulted in 56% , 9% and 5% reductions of
sediment, TP and SN‐Tile (respectively), but in 11% and 20% increases in DRP
and SN losses.
• Tree and shrub planting was the most successful practice reducing DRP and
SN in surface runoff, however they resulted in the highest SN‐Tile.
• Cover crops (oats and cereal rye) and forage planting (alfalfa) resulted in the
highest sediment and nutrient reductions (80% for SN and 76% SN‐Tile, and
91% for sediment, 82% TP, and 55% DRP, respectively).
• The implementation of a structural practice such as a grade stabilization
showed little impact on improving water quality.
• As far as other structural conservation practices, greater reductions were
predicted by the filter strip scenario (40% for TP, 45% for DRP, and 59% for
SN) than in the grassed waterway (16% for TP, 6% for DRP, 11% for SN and
5% for SN‐Tile) when compared to the tillage scenario.

13. Results at the Field Scale
Generalizations of combined practices
• Overall, when two or three conservation practices commonly used at the St.
Joseph River watershed were modeled together at the edge‐of‐field scale,
the results showed greater sediment and nutrient reductions than the
practices separately.
• Forage + no‐till, was followed by conservation cover + no‐till, and by cover
crops + no‐till, as the most efficient paired practice combinations reducing
sediment and nutrient losses.
• Conservation crop rotation + cover crops + no‐till was the most successful
trio of practices reducing nutrient losses compared to the baseline (89% for
TP, 78% for DRP, 81% for SN, and 90% for SN‐Tile).
• The Food and Agriculture Organization (FAO) has proposed a new concept
for sustainable food production systems called Conservation Agriculture,
which consist of the combination described above
(www.fao.org/ag/ca/1a.html).

14. Results at the Watershed Scale
DRP (Kg)
DRP (Kg)
DRP
(Kg)
(SN‐Tile data not
showing)

15. Conclusions
• While single conservation practices may be effective at targeting
specific sediment and nutrient transport problems in agriculture,
multiple practices resulted in the most successful water quality
strategies.
• Among the single conservation practices, cover crops and forage
were the most successful at reducing sediment and nutrient losses
(by 56 ‐ 88% and 28 ‐ 91%, respectively).
• Compared to the single practices, the first and second level
combined conservation practices extrapolated at the watershed scale
had reductions that were 29% and 52% greater for sediments, 28%
and 67% greater for TP, 4% and 43% greater for DRP, 14% and 85%
greater for SN, and 35% and 61% greater for SN‐Tile.
• This information helps validate the positive aggregate effect of some
of the conservation practices available through cost share programs
on the environment.

16. Thank you!