is defined as any
or planting system that leaves at
least 30% of the soil surface covered with crop residue after planting. This
such as no-till, and "reduced
practices such as ridge-till,
chisel, and mulch-till (Casman et al., 1989). Conservation
has been well-accepted by the
community, largely due to its success
in reducing production costs, increasing'yields, conserving moisture, and
maintaining the long-term productivity of soils (Heatwole, et al.. 1991).
in the Tar-Pamlico
Table 2-17 presents the cost data for conservation
basin. The funds expended on conservation
via the cost-share program
are incentive payments and do not reflect the actual costs of installing the
practice. incentive payments are paid yearly for up to three years. it is hoped that
incentive period, the farmers will see the benefits of
and continue to use the practice on their own.
Table 2-17. Cost Data for Conservation
There are many site-specific factors that influence the effectiveness of
These include soil properties, surface slope, the previous
crop, the amount of residue removed, fertilizer variables (placement, type,
quantity, and timing), harvesting practice, variety of crop, planter style, orientation
of contour, and the local climate. Not surprisingly, the reduction efficiencies
reported for groundwater and surface water N and P loads vary tremendously
(Casman, 1990). Figure 2-2 summarizes the effectiveness values taken from
runs of the Chesapeake Bay Watershed Model in ecoregions 63 and 65. Note
that the number of model
different for each ecoregion (Appendix 4).
Figure 2-3 presents
the Tar-Pamlico cost data and the effectiveness data from the Chesapeake Bay
Watershed model runs for ecoregions 63 and 65.