Figure 2-5. Vegetated filter strip cost-effectiveness.
Figure 2-5 presents estimated edge-of-stream nutrient reduction Lost-effectiveness
values for vegetated filter strips in the Tar-Pamlico basin. Cost-effectiveness values
were calculated using loading factors from the Chesapeake Bay Watershed Model
for ecoregions 63 and 65 and a 30 percent reduction effectiveness for both N and
P. The lower end of the P effectiveness range was used as a conservative
estimate. We believe this to be appropriate in light of research suggesting that the
declines over time and that, without intensive maintenance,
are prone to clogging and/or concentrated flow (Heatwole, 1991).
Nutnent management is the practice of modifying fertilizer usage based on
recommendations regarding optimum rates, timing, and methods for nutrient
application. These recommendations are typically based on soil and manure
analysis and expected crop
(Camacho, 1992). The goal is to provide only
what is needed to grow the crop.
Several important observations have been made regarding the effectiveness of
nutrient management practices in regard to water quality (Reckhow, 1980 as
in Casman, 1990):
Time of application is more important than fertilizer type.