69th SWCS International Annual Conference July 27-30, 2014 Lombard, IL

1. Conservation Practice Impacts on
Nutrient Loads from the Maryland CEAP
Choptank Watershed using AnnAGNPS
• Ronald L. Bingner, USDA-ARS, Oxford, MS
• Ali Sadeghi, USDA-ARS, Beltsville, MD
• Henrique Momm, Middle TN State Univ.,
Murfreesboro, TN
• Greg McCarty, USDA-ARS, Beltsville, MD
• Dean Hively, USGS-EGSC, Reston, VA
• Yongping Yuan, USEPA, Las Vegas, NV
• Eugenie Kamgue, Middle TN State Univ.,
Murfreesboro, TN

2. Objective
To evaluate conservation practice
effects on sediment and nutrient
loads within the ARS
Conservation Effects and
Assessment Project (CEAP)
Choptank, Maryland Benchmark
Watershed.

3. Choptank Watershed, MD

4. German Branch
4960 ha

5. Landuse
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Crop
Forest
Urban
Farms

6. Crop Distribution
corn
wheat
barley
soybean

7. Management
Rotation 1 (reduced tillage): Corn, commodity wheat,
double crop soybeans.
April 12th poultry manure
application; 2 T/A
April 30th plant corn; no-till
June 15th sidedress 30% UAN; 100 lbs/acre
October 15th harvest corn
October 25th disk
October 30th poultry manure application; 1 T/A
November 5th plant winter wheat; drill
March 5th 30% UAN applic; 60 lbs N/A
June 10th harvest wheat
June 15th plant double crop soybean; no till
November 10th harvest soybean
Winter fallow
Rotation 2 (conventional tillage): Corn, commodity wheat,
double crop soybeans
April 18th poultry manure application; 2 T/A
April 19th subsurface chisel
April 27th plant corn; conventional tillage
June 19th sidedress; 30% UAN; 100 lbs/A
September 30th harvest corn
October 6th disk
October 9th poultry manure application; 1T/A
October 12th plant wheat
March 10th 30% UAN applic.; 60 lbs/A
June 12th harvest wheat
June 15th plant soybean; conv.till
November 10th harvest soybean
Winter fallow
Reduced Tillage
70% of cropland
Conventional Tillage
30% of cropland

8. Ephemeral Gully Locations
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1607
Actual
Gullies
Identified

9. NRCS Photo Gallery: Ephemeral Gully (?)
Where does sheet & rill end
& ephemeral gullies begin?

10. NRCS Photo Gallery: Gully
Gully forming in a corn field in Pennsylvania
Narrow & Deep Gullies

11. German Branch

12. AGBUF
AGNPS‐GIS Buffer Utility Feature
Provides buffer characterization for
AnnAGNPS input parameters

13. AGBUF
Riparian Buffer GIS representation
AnnAGNPS cells &
reaches
Buffer

14. AGBUF (continued)
TE Estimation in AnnAGNPS Cells includes the effect of
concentrated flow paths through buffers (short‐circuits)
A
0
0
0
1 2
3 4
5 6 TE = 97%
Potential short‐
circuits
TE = 90%
TE = 47%
Varying widths & lengths

15. Runoff
0
20
40
60
80
100
120
140
Jan_91
May
Sep
Jan_92
May
Sep
Jan_93
May
Sep
Jan_94
May
Sep
Jan_95
May
Sep
Flow(mm)
Observed Simulated
NSE = 0.71

16. Total Nitrogen
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Jan_91
May
Sep
Jan_92
May
Sep
Jan_93
May
Sep
Jan_94
May
Sep
Jan_95
May
Sep
NLosses(kg/ha)
Observed Simulated
NSE = 0.51

17. Buffer/Gully Comparisons
Sediment Load
Sheet & Rill
(% Change from
Base)
Sediment Load
Ephemeral Gully
(% Change from
Base)
Nitrogen Load (%
Change from
Base)
No gullies/No
buffers
216 - -2
Gullies/No buffers 214 191 1
Buffer/No gullies 2 - -3
Buffers and
Gullies (BASE)
- - -
Since most N load is dissolved from poultry litter,
buffers do not have much impact on controlling N

18. Average Annual Runoff
Runoff
0.098 - 3.658
3.658 - 8.874
8.874 - 13.206
13.206 - 16.441
16.441 - 45.583
tn/ac/yr

19. Average Annual Sediment Load
Sediment
0 - 0.017
0.017 - 0.069
0.069 - 0.19
0.19 - 0.579
0.579 - 1.25
tn/ac/yr

20. Average Annual Nitrogen Load
Nitrogen
0
0 - 36.592
36.592 - 44.342
44.342 - 84.071
84.071 - 165.311
lb/ac/yr

21. 0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100
ContributedLoad(%)
Contributing Drainage Area (%)
TOTAL CELL NITROGEN FROM ALL SOURCES
OUTLET

22. Areas of 50% Nitrogen Load
Nitrogen
0
0 - 36.592
36.592 - 44.342
44.342 - 84.071
84.071 - 165.311
lb/ac/yr

23. Summary
 AnnAGNPS adequately simulated runoff and
nitrogen loads in the watershed.
 Ephemeral gullies impacted sediment and nitrogen
loads, while buffers mainly only had an impact on
sediment. Since most N is transported as dissolved
N from poultry litter applications.