|
C.
Agriculture
2.
Agricultural Soils
a.
Prime
Farmland
The following sections summarize prime farmland in the 11
digit subwatersheds of the Darby Watershed.
With proper drainage and flood protection nearly 90 percent of soils in
the Darby Creek Watershed are prime (See Figure 42).
However, only about 20 percent of prime soils are rated prime without
drainage. Removal of water in
drainage ditches from agricultural fields is critical in maintaining high
productivity. The large amount of
prime farmland and extensive drainage account for the high intensity and
productivity of agriculture in the Darby Watershed.
|
Figure
42:
Darby
Creek
Watershed Prime Soils
|
|
Farmland
Rating
|
All
Land Percent
|
Agricultural
Land Percent
|
|
Not
Prime
|
10.05%
|
6.68%
|
|
All
Prime
|
21.00%
|
18.51%
|
|
Prime
If Drained
|
65.91%
|
72.64%
|
|
Prime
if protected from flooding
|
0.13%
|
0.16%
|
|
Farmland
of Local Importance (Union
County
)
|
2.01%
|
1.71%
|
|
Prime
if drained and protected from flooding during the growing season
|
0.33%
|
0.23%
|
|
Water
and other soils
|
0.57%
|
0.07%
|
The farmland ratings in Upper Big Darby and Little Darby
Creek are similar with between 13 and 16 percent of soils rated as “all
prime” and between 70 and 77 percent as “prime if drained.”
In the Middle Big Darby subwatershed over 90 percent of agricultural
land is rated “prime if drained.” In
the Lower Big Darby a considerably higher percentage of soils are rated all
prime compared to the other watersheds (See Figure 44).
These statistics emphasize the importance of drainage to the
productivity of agricultural land in the Darby Watershed.
For maps and a detailed look at all the soils (not just agricultural
land) in the watersheds described below please see Appendix
C.
|
Figure
43: Farmland Ratings by Major Subwatershed for Agricultural Land
|
|
Watershed
|
Not
Prime
|
All
Prime
|
Prime
if Drained
|
Farmland
of Local Importance
|
Prime
if drained and protected from flooding
|
Other
Soils
|
|
Headwaters
Big Darby
|
8.13%
|
16.35%
|
69.76%
|
5.32%
|
0.26%
|
0.18%
|
|
Middle
Big Darby
|
1.48%
|
8.07%
|
90.45%
|
0.00%
|
0.00%
|
0.00%
|
|
Lower
Big Darby
|
5.04%
|
38.75%
|
55.34%
|
0.82%
|
0.05%
|
5.04%
|
|
Little
Darby
Creek
|
8.53%
|
13.52%
|
77.40%
|
0.09%
|
0.42%
|
0.04%
|
b.
Highly
Erodible Soils
The highly erodible factor was derived from soil surveys
from each county. Detailed maps
(four) and descriptions of this factor are available in Appendix
A.
The following figure summarizes the erodibility of soils on
agricultural land.
|
Figure
44: Erodibility of Agricultural Land by Major Subwatershed
|
|
Watershed
|
Highly
Erodible
|
Not
Highly Erodible
|
Potentially
Erodible
|
Water
and Other Soils
|
|
Headwaters
Big Darby
|
12.50%
|
60.10%
|
27.07%
|
0.32%
|
|
Middle
Big Darby
|
0.43%
|
81.33%
|
18.10%
|
0.15%
|
|
Lower
Big Darby
|
1.48%
|
61.24%
|
36.74%
|
0.54%
|
|
Little
Darby
Creek
|
6.00%
|
61.37%
|
32.46%
|
0.17%
|
The Headwaters of Big Darby had the most highly erodible
soils with over 12 percent followed by Lower Big Darby with 6 percent.
Middle Big Darby and Little Darby had the least amount of highly
erodible (See Figure 6). For more
detail on the erodibility of all soils in each watershed below see Appendix
A.
  
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