1. Organic Soil and Water Management at the Arlington
Agricultural Research Station
Project Background
Introduction Design Standards / Constraints
Badger Lane
N
In recent years multiple environmental Standards
concerns have arisen in the organic •Erosion must be limited to the
S
area at the Arlington Agriculture designated tolerable soil loss (T) for
Research Station (AARS) . This area the soil type (NR 151.02)
can be seen in Figure 1 on the right.
The two primary areas of concern are •Gully erosion must be eliminated
Hopkins Road
soil erosion and the need for evaluation
of the capacity and stability of a •Waterway needs to convey flow
waterway draining a large watershed without over topping or eroding
north of the organic area.
Constraints
•Area needs to remain under organic
Problem Description Ramsey Road management
Erosion Control •Flexibility in field boundaries for
•Significant erosion taking place in Area of concern for
Organic area research projects
boundary.
erosion
organic fields due to steep slopes and
the high level of tillage Location of waterway Arlington Research •Limit Costs to $10,000 over three
being evaluated Station Headquarters
years
Figure 1: Aerial Photograph of Organic Area
•Also, gullies are forming in spots due
at Arlington Agriculture Research Station Approach
to natural topography and erosion of
old diversions NRCS Design Process:
Waterway Design
•Waterway designed and constructed 1.Determine client objectives
2.Conduct a resource inventory
without proper watershed delineation 3.Analyze resource data to identify problems
and opportunities
•Waterway conveys runoff from a 4.Formulate and evaluate resource
nearly 200 acre watershed that includes alternatives
both research station and private 5.Document the client’s planning decisions
farmland
Figure 2: Photograph of Existing Waterway
Team Members: Josh Gable,Tyler Hastings,
Lis Nimani, Ryan Stenjem Advisors: John Panuska, Anita Thompson

2. Organic Soil and Water Management at the Arlington
Agricultural Research Station
Waterway Analysis
Purpose The Design Storm: SCS Type II HydroCAD
In 2008, a grassed waterway was constructed 10–year, 24–hour storm The Stormwater Modeling Software, HydroCAD, uses hydrology
principles that were developed by the NRCS as well as various
to transport flows from an upstream hydraulic calculations. It uses the TR-55 method for calculating Time
watershed, through the AARS Organic Corner of Concentration (tc) values and gives unique hydrographs through
waterways, ponds, culverts and various other hydraulic components.
(denoted with blue arrows in Figure 3).
Because of the immediate need for the
channel, a proper engineering design was not
carried out. In order to verify that this
waterway was adequately built, HydroCAD
was used to model the watershed and
waterway.
Figure 4 Design Storm Unit Hydrograph, exported from HydroCAD
Figure 1 Main Waterway, in Organic Corner, AARS
Figure 6 HydroCAD Layout Map
Results
Figure 5 Design Storm Depth vs. Time Graph, exported from HydroCAD
Figure 2 Cross-Section of Main Waterway
Watershed Parameters
The Contributing Watershed Table 1 Contributing Watershed Characteristics
Sub - Time of Concentration, Tc
Area (acres) Curve Number, CN
Watershed (min)
1 8.2 76 15.6
2 13.4 77 23.2
3 34.4 70 37 Figure 7 Final Hydrograph for Main Waterway
4 42.5 76 32.1
5 127.2 76 78.4
Table 4 10-year, 24-hr Storm Results
6 9.2 76 13.1
Reach Channel Capacity (cfs) Peak Flow (cfs) Max Velocity (ft/s)
7 6.9 76 19.7
1 63.23 17.2 2.2
8 12.2 76 20.2
2 44.84 38.52 1.25
Table 2 Outlet Characteristics Main 316.5 141.34 5
Culvert Diameter (in) Length (ft) Slope (%)
1 24 50.3 2.25 Table 5 25-year, 24-hr Storm Results
2 18 38 1.37
Reach Channel Capacity (cfs) Peak Flow (cfs) Max Velocity (ft/s)
3 18 38 0.66
1 63.23 19.3 2.27
4 24 36 1.78
2 44.84 49.85 1.33
5 36 28.6 2.24
6 36 28.6 0.98 Main 316.5 208.5 5.57
7 18 24.3 3.29
Table 6 100-year, 24-hr Storm Results
Table 3 Sub-Watershed Characteristics Reach Channel Capacity (cfs) Peak Flow (cfs) Max Velocity (ft/s)
Trapezoidal Cross-Section Channel Length Channel Slope
Reach Manning’s No. 1 63.23 20.71 2.32
bottom width (ft) depth (ft) side-slope (horizontal/vertical) (ft) (%)
2 44.84 72.86 1.44
1 10 1 10 1400 0.85 0.033
Main 316.5 257.95 5.9
2 8 1.5 10 1400 0.43 0.07
Main 12 2 6.7 1050 0.84 0.026
Conclusion
In modeling the upstream watershed, culverts After completing the HydroCAD model
were modeled as outlets to ponds with storage analyzing the waterway in the Organic Corner
behind. Where water had the potential to flow and its upstream watershed, we have
Figure 3 Contour Map of Watershed with 4 ft Contours
over a roadway upon a culvert reaching capacity, determined that the current waterway is more
Waterway – Organic Corner the roadway way was treated as a broad-crested than adequate for handling flows from the
Watershed Boundary
weir as an outlet to a pond.
4 ft Contour Lines design storm.

3. Organic Soil and Water Management at the Arlington
Agricultural Research Station
Erosion Management
Problem Description Field Soil Slope Slope Design Options
(%)
Loss Length
(ton/ac/yr) (ft)
•Steep Slopes and intensive tillage •Option 1 – Implement strip cropping
operations have lead to erosion. 401 4.3 140 3.7 and make three fields of equal width
402 2.9 160 2.5 out of fields 447 A and B, and also for
•The DNR requires that erosion be 403 A 2.4 160 2.0 fields 404 and 403C-S and N.
less than the designated tolerable soil 403 B 3.4 155 3.0 Field Soil Loss
loss (T) for the soil type. (NR 403 C-N 6.5 180 4.9 (ton/ac/yr)
151.02). 403 C-S 5.5 180 4.5 401 4.3
404 7.4 175 5.6 402 2.9
•The tolerable soil loss for the 446 3.3 150 2.3 403 A 2.4
Organic Fields are 5 ton/acre/year. 447 A 4.9 175 4.1 403 B 3.4
(Web Soil Survey). 447 B 4.5 175 3.5 403 C-N
Figure 1: Current field boundaries with respective 403 C-S 4.8
•Fields 403 C-N, 403 C-S, and 404 soil loss and LS Inputs. 404
are currently above T, and fields 447 Universal Soil Loss Equation 446 2.6
A and B are near T (Figure 1), so they A=RKLSCP 447 A
4.1
require best management practices, R Rainfall Erosivity Factor 447 B
Figure 4: Soil loss after strip cropping
such as strip cropping, terracing, or K Soil Erodibility Factor
contouring, in order to reduce soil LS Topographic Factor (Slope Length and
loss. Slope) •Option 2 – Design a terrace system to
CP Cropping Management Factors
break up the slope length along the
steepest slopes
Figure 2: USLE Equation
RUSLE2 Field Soil Loss
(ton/ac/yr)
401 4.3
•Is a computer program that utilizes
402 2.9
the Universal Soil Loss Equation
403 A 2.4
(USLE) to model rill and interrill
403 B 3.4
erosion. See Figure 2.
404
403 C-N 4.3
•Used a crop rotation of Winter
403 C-S
wheat, 3 years alfalfa, Corn grain,
446 2.6
soybeans.
447 A
3.9
Figure 3: Screen shot of RUSLE2 447 B
•Tillage operations of chisel plow and
Figure 5: Soil loss after terraced
disk before planting and 2-3
cultivations during spring.

4. Organic Soil and Water Management at the Arlington
Agricultural Research Station
Designs and Recommendations
Designs and Recommendations Final Terrace Design
Q = 2.0 ft3/s (determined from HydroCAD)
Waterway Vpermissible = 1.5 - 5 ft/s
In evaluating the waterway it was determined A = 3.5 ft2
that the current channel will be sufficient to S=2%
handle the peak flow from a 10 yr – 24 hour
storm event. This determination was made
primarily using the results from the
HydroCAD model.
Erosion Control
After Conversations with the Arlington
Research Station staff a modified plan was
devised. The impact of this proposed plan on
erosion rates can be seen in Table 1. Figure 2: Proposed Terrace Cross
Section
•Terraces will be implemented in fields 404
and 403C (See Figure1 and Figure 2)
Table 1: Proposal Impact on Erosion
•A diversion will be cut along the top of field Rates
447 A to reduce the occurrence of gulley Field Current Expected
erosion. (See Figure 1) Soil Loss Soil Loss
Figure 1: Location for Proposed Construction (ton/ac/yr) (ton/ac/yr)
•Strip Cropping is also recommended in the 401 4.3 4.3
area of fields 447 A and 447 B.
Terrace Spacing Calculation 402 2.9 2.9
H.I. = (xs + y) (100/s) 403 A 2.4 2.4
•Impact of proposal can be seen in Table 1
403 B 3.4 3.4
H.I. = horizontal interval in feet 403 C-N 6.5 4.3
Channel Capacity Calculation x = constant determined by geographic location 403 C-S 5.5 4.3
Q = V*A s = land slope in percent
404 7.4 4.3
V = (1.49/n) * R(2/3)*S(1/2) y = constant determined by cropping and soil
erodibility 446 3.3 3.3
447 A 4.9 4.1
Q = Peak flow rate in Channel (ft3/s)
V = Flow velocity (ft/s) H.I .= (0.5 * 6 + 4) (100/6) 447 B 4.5 4.1
A = Cross sectional area of channel
n = Manning’s Roughness Coefficient (varies H.I. = 140
depending on vegetation growth from 0.035 *raised to 150 feet due to farming equipment
to 0.075) restrictions Special Thanks to:
R = Hydraulic radius of channel (ft) Jeff Breuer, Darwin Frye, Scott
S = Channel slope (ft/ft) Mueller, Matt Repking, Anita
Thompson, and John Panuska