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Percent of Prime Farmland in Non-Federal Rangeland, 1987
Description
This shaded polygon map shows the percentage of
prime farmland that is used as rangeland within
each 8-digit hydrologic unit. Areas with 95% or
more Federal area are shown as gray. There are
19.4 million acres of prime farmland used as
rangeland. 5% of all prime farmland is used as
rangeland.
Cautions for this Product:
This maps does not show the amount of prime
farmland. This map may not be used to determine
site-specific information. 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 is
shown 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:
8 Digit Hydrologic Unit Areas with Federal Land
Other Layers Displayed:
States, Rivers
Definitions
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]
Hydrologic units:
A hierarchical system developed by the U.S.
Geological Survey that divides the United States
and the Caribbean into 21 major regions, 222
subregions, 352 accounting units, and further
subdivided into 2,150 cataloging units that
delineate river basins having drainage areas
usually greater than 700 square miles. [USGS]
Prime farmland:
Land that has the best combination of physical
and chemical characteristics for producing food,
feed, forage, fiber, and oilseed crops and is
also available for these uses. It has the soil
quality, growing season, and moisture supply
needed to produce economically sustained high
yields of crops when treated and managed
according to acceptable farming methods,
including water management. In general, prime
farmlands have an adequate and dependable water
supply from precipitation or irrigation, a
favorable temperature and growing season,
acceptable acidity or alkalinity, acceptable
salt and sodium content, and few or no rocks.
They are permeable to water and air. Prime
farmlands are not excessively erodible or
saturated with water for a long period of time,
and they either do not flood frequently or are
protected from flooding.[SSM, USDA Handbook No.
18, October 1993]
Rangeland:
A Land cover/use category on which the climax or
potential plant cover is composed principally of
native grasses, grasslike plants, forbs or
shrubs suitable for grazing and browsing, and
introduced forage species that are managed like
rangeland. This would include areas where
introduced hardy and persistent grasses, such as
crested wheatgrass, are planted and such
practices as deferred grazing, burning,
chaining, and rotational grazing are used, with
little or no chemicals or fertilizer being
applied. Grasslands, savannas,
many wetlands, some deserts, and tundra are
considered to be rangeland. Certain communities
of low forbs and shrubs, such as mesquite,
chaparral, mountain shrub, and pinyon-juniper,
are also included as rangeland.
[NRI-97]
Product Information
Product ID:
6032
Production Date:
1/30/01
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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