Percent Change in Prime Farmland Used as Cropland, 1992 - 1997
Description
This shaded polygon map shows the percent change
in the amount of prime farmland used as cropland
from 1992 to 1997 within each 8 digit hydrologic
unit, using 1992 as a base year. The
percentages are presented in four categories
based on the following divisions: an increase of
more than 5%, little change (less than 5%
change), a decrease of 5% to 25%, and a decrease
of over 25%. Areas with less than 5% prime
farmland in both 1992 and 1997 are hatched.
Areas with 95% or more Federal area are shown as
gray.
Cautions for this Product:
Areas with small amounts of prime farmland may
have very high rates of change. Changes may be
due to either a change in the amount of prime
farmland or the conversion of cropland on prime
farmland to a non-cropland land cover/use. Data
are not shown where prime farmland is less than
5% of the total area. 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
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]
Cultivated Cropland:
Includes land identified as being in row or
close crops, summer fallow, aquaculture in crop
rotation or other cropland not planted --
including cropland in short-term set-aside
programs; or land in horticulture that is double
cropped; or land in hay which had at least one
of the three previous years in row or close
grown crops; or land in pasture which had at
least one of the three previous years in row or
close grown crops.
Non-cultivated cropland:
Includes land in horticulture that is not double-
cropped; or land in hay which had not been in
row or close-grown crops for any of the previous
three years.
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]
Product Information
Product ID:
5041
Production Date:
1/25/01
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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