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69th SWCS International Annual Conference July 27-30, 2014 Lombard, IL
Citation preview
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
Objective
To evaluate conservation practice effects on sediment and nutrient loads within the ARS Conservation Effects and Assessment Project (CEAP) Choptank, Maryland Benchmark Watershed.
Choptank Watershed, MD
German Branch
4960 ha
Landuse
#
CropForestUrbanFarms
Crop Distribution
cornwheatbarleysoybean
ManagementRotation 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 soybeanWinter 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 soybeanWinter fallow
Reduced Tillage70% of cropland
Conventional Tillage30% of cropland
Ephemeral Gully Locations
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1607 Actual Gullies
Identified
NRCS Photo Gallery: Ephemeral Gully (?)
Where does sheet & rill end & ephemeral gullies begin?
NRCS Photo Gallery: GullyGully forming in a corn field in Pennsylvania
Narrow & Deep Gullies
German Branch
AGBUFAGNPS‐GIS Buffer Utility Feature
Provides buffer characterization for AnnAGNPS input parameters
AGBUFRiparian Buffer GIS representation
AnnAGNPS cells & reaches Buffer
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
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
Flo
w (
mm
)
Observed Simulated
NSE = 0.71
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
N L
oss
es
(kg/h
a)
Observed Simulated
NSE = 0.51
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
Average Annual Runoff
Runoff0.098 - 3.658
3.658 - 8.874
8.874 - 13.206
13.206 - 16.441
16.441 - 45.583
tn/ac/yr
Average Annual Sediment Load
Sediment0 - 0.017
0.017 - 0.069
0.069 - 0.19
0.19 - 0.579
0.579 - 1.25
tn/ac/yr
Average Annual Nitrogen Load
Nitrogen0
0 - 36.592
36.592 - 44.342
44.342 - 84.071
84.071 - 165.311
lb/ac/yr
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100
Con
trib
uted
Loa
d (%
)
Contributing Drainage Area (%)
TOTAL CELL NITROGEN FROM ALL SOURCES
OUTLET
Areas of 50% Nitrogen Load
Nitrogen0
0 - 36.592
36.592 - 44.342
44.342 - 84.071
84.071 - 165.311
lb/ac/yr
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.
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