Acres of Non-Highly Erodible Cropland, 1987
Description
This dot density map shows the total number of
1987 non-highly erodible cropland acres. Dots
are aggregated by and placed randomly within 8-
digit hydrologic units. Each red dot represents
25,000 acres of non-highly erodible cropland.
Areas with 95% or more Federal area are shaded
gray. There were 116.8 million acres of non-
highly erodible cropland in the U.S. in 1987.
For comparison with highly erodible cropland,
see map m5995.
Cautions for this Product:
See definition of Highly Erodible Land. This
map may not be used to determine site-specific
information. Within an 8-digit hydrologic unit,
dot counts represent acreage totals correctly
plus or minus one dot to account for
remainders. Data are not collected on Federal
land. Data are not available for Alaska or the
Pacific Basin. Data for Puerto Rico and the U.S.
Virgin Islands are aggregated by 6-digit
hydrologic unit.
Sources
Source:
National Resources Inventory, 1997
Distributor:
USDA-NRCS-RIAD
Reliability:
NRI sample data are generally reliable at the
95% confidence interval for state and certain
broad substate area analyses. Generally,
analyses that aggregate data points by smaller
geographic areas and/or more specific criteria
result in fewer data points for each aggregation
and therefore less reliable estimates. NRI maps
reflect national patterns rather than site-
specific information.
Layers
Aggregate Layer:
Cross of State with 8 Digit Hydrologic Units and
Federal Land
Other Layers Displayed:
States, Rivers
Definitions
Cropland:
A Land cover/use category that includes areas
used for the production of adapted crops for
harvest. Two subcategories of cropland are
recognized: cultivated and noncultivated.
Cultivated cropland comprises land in row crops
or close-grown crops and also other cultivated
cropland, for example, hayland or pastureland
that is in a rotation with row or close-grown
crops. Noncultivated cropland includes permanent
hayland and horticultural cropland. [NRI-97]
Erodibility Index (EI):
The soil erodibility index (EI) provides a
numerical expression of the potential for a soil
to erode considering the physical and chemical
properties of the soil and the climatic
conditions where it is located. The higher the
index, the greater the investment needed to
maintain the sustainability of the soil resource
base if intensively cropped. It is defined to
be the maximum of (RxKxLS)/T (from the Universal
Soil Loss Equation) and (CxI)/T (from the Wind
Erosion Equation), where R is a measure of
rainfall and runoff, K is a factor of the
susceptability of the soil to water erosion, LS
is a measure of the combined effects of slope
length and steepness, C is a climatic
characterization of windspeed and surface soil
moisture and I is a measure of the
susceptability of the soil to wind erosion.
Erodibility Index scores equal to or greater
than 8 are considered highly erodible land.
(NRI, 1992)
Erosion:
The wearing away of the land surface by running
water, waves, or moving ice and wind, or by such
processes as mass wasting and corrosion
(solution and other chemical processes). The
term "geologic
erosion" refers to natural erosion processes
occurring over long (geologic) time spans.
"Accelerated
erosion" generically refers to erosion that
exceeds what is presumed or estimated to be
naturally occurring
levels, and which is a direct result of human
activities (e.g., cultivation and logging).
[NSSH-96]
Federal land:
A land ownership class designating land that is
owned by the Federal Government. It does not
include, for example, trust lands administered
by the Bureau of Indian Affairs nor Tennessee
Valley Authority (TVA) land. No data are
collected for any year that land is in this
ownership. [NRI-97]
Highly Erodible Land (HEL):
Land that has an erodibility index of eight or
more (NFSAM).
Non-Highly Erodible Land:
Land that has an erodibility index of less than
eight. NRI, 1997
Product Information
Product ID:
5995
Production Date:
5/7/01
Product Type:
Map
For additional information
contact the Resources Inventory and Assessment Division.
Please include the Product ID you are inquiring about.
nri@wdc.usda.gov
or 1400 Independence Avenue SW - P.O. Box 2890 -
Washington D.C. 20013. If you use our analysis products,
please be aware of our disclaimer.
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