2. Development of BMP Cost-Effectiveness Values
Diversions
Diversrons are in-field practices designed to prevent
and gully formation by
diverting surface flow off of the field. Because diversions are essentially a method of
water off of a field, it is unlikely that they have much of an effect in
reducing dissolved nutrient loads to the stream. However, by reducing length of slope
and subsequent soil loss, diversions can help retain soil-associated phosphorus on
the field.
Table 2-15 presents cost data for grassed waterways and diversions in the
Pamlico basin.
Table 2-15. Cost Data for Grassed Waterways and Diversions
5% of base
3,256
10 years
4766 ha'
9,770
Grassed
cost
waterway
Assuming 0.06 acres of waterway per acre of
(USDA SCS, 1991).
Assuming 200' of diversion per acre of
(USDA SCS, 1991).
Conversion to Trees Grass
2.3.4
Crop conversion to trees or grass has historically been used to remove highly
erodible land (HEL) from production. This practice is typically implemented via the
Conservation Reserve Program (CRP) whereby farmers receive cost-share funds
to take land out of production and plant grass or trees. By taking land out of
cultivation and establishing year-round cover, soil loss from the site can be
decreased dramatically. Additionally, runoff nutrient loads would also be expected
to decrease due to discontinued fertilizer application and uptake of nutrients by
plants. Depending on the location of the site relative to other nutrient source
areas, converted land may also-effectively reduce nutrient loadings from upland
conversion practices in the
areas. Table 2-16 presents cost data for
Tar-Pamlico basin.
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