Definition of Terms
In the interest of clarity, we provide the following definitions for terms used in this
The unit cost is the yearly, per hectare (or per
implementing an agricultural BMP. The unit cost accounts
for both state and federal cost-share, farmer contribution,
yearly operation and maintenance costs, area benefitted,
and practice life expectancy. Unit costs do not account for
any cost savings realized by the farmer due to increased
higher yields, or benefits realized
unit of measure for unit cost is $/hectare-year.
Effectiveness is the ability of a practice to reduce nutrient
loads (surface and subsurface) entering the stream.
Because edge-of-stream data are usually not available,
edge-of-field data are often used to estimate effectiveness.
Effectiveness can be expressed as either a percent
reduction or as a load reduction. For
define effectiveness relative to conventional
animal waste practices, we define effectiveness relative to
excess land application or direct
expressed as a mass reduction, the units for effectiveness
are kilograms reduced/hectare-year (or kilograms
Cost-effectiveness is a measure of the cost of reducing a
unit of nutrient load to the stream. It is calculated by
dividing unit cost by effectiveness. The units for
effectiveness are $/kilogram of nutrient load reduced.
Loading factors are a measure of
from a tract of land. In this report, loading factors are used
to convert percent effectiveness values to load reduction
effectiveness. The units for loading factors are kilograms
An agronomic rate of fertilizer application is a rate
calculated to meet the crop's needs without
overfertilization. Agronomic rates are determined based on
manure (fertilizer) analysis, soil nutrient availability, and
crop needs. For animal wastes, agronomic rates are
typically based only on the nitrogen content of the manure.