Environmental Engineering Reference
In-Depth Information
Critical habitats:
According to U.S. federal law, the ecosystems upon which endan-
gered and threatened species depend; specific geographic areas, whether
occupied by a listed species or not, that are essential for its conservation
and that have been formally designated by a rule published in the
Federal
Register
.
Crop failure:
Consists mainly of the acreage on which crops failed because of
weather, insects, and diseases but also includes some land not harvested due
to lack of labor, low market prices, or other factors. The acreage planted to
cover and soil improvement crops not intended for harvest is excluded from
crop failure and is considered idle.
Crop residue:
Organic residue remaining after the harvesting and processing of a
crop.
Cropland:
Total cropland includes five components: cropland harvested, crop fail-
ure, cultivated summer fallow, cropland used only for pasture, and idle
cropland.
Cropland harvested:
Includes row crops and closely sown crops; hay and silage
crops; tree fruits, small fruits, berries, and tree nuts; vegetables and melons;
and miscellaneous other minor crops. In recent years, farmers have double-
cropped about 4% of the acreage.
Cropland pasture:
Land used for long-term crop rotation; however, some cropland
pasture is marginal for crop uses and may remain in pasture indefinitely.
This category also includes land that was used for pasture before crops
reached maturity and some land used for pasture that could have been
cropped without additional improvement.
Cropland used for crops:
Includes cropland harvested, crop failure, and cultivated
summer fallow.
Crust:
Earth's outer layer of rock; also called the
lithosphere
.
Cryogenic liquefaction:
The process through which gases such as nitrogen, hydro-
gen, helium, and natural gas are liquefied under pressure at very low
temperatures.
Cull tree:
A live tree, 5.0 inches in diameter at breast height (d.b.h.) or larger, that is
not merchantable for saw logs now or prospectively because of rot, rough-
ness, or species.
Cull wood:
Wood logs, chips, or wood products that are burned.
Cultivar:
A horticulturally or agriculturally derived variety of a plant.
Cultural Resource Inventory:
A professional study to locate and evaluate evidence
of cultural resources within a defined geographic area.
Cultural Resources Overview:
A comprehensive document prepared for a field
office that discusses, among other things, project prehistory and cul-
tural history, the nature and extent of known cultural resources, previous
research, management objectives, resource management conflicts or issues,
and a general statement of how program objectives should be met and con-
flicts resolved.
Cut-in speed:
The speed at which a shaft must turn in order to generate electricity
and send it over a wire.
