Change in Irrigated Acreage, 1982-1997
Description
This bar map shows changes in the acreage under
irrigation for each state. The map includes
irrigated cropland and irrigated pastureland.
Each state contains 4 bars showing the increase
or decrease in acres for the following periods:
1982-1987; 1987-1992; 1992-1997; 1982-1997. The
length of each bar is proportional to the number
of acres it represents. There were 67.5 million
acres of irrigated land in 1997.
Cautions for this Product:
This map does not show the amount of acres
currently under irrigation. This map does not
show change in irrigation for land uses other
than cropland and pastureland. Data are not
collected on Federal land. Data are not
available for Alaska, and the Pacific Basin.
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:
State
Other Layers Displayed:
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]
Irrigated land:
Land that shows evidence of being irrigated
during the year of the inventory or during two
or more years out of the last four years. Water
is supplied to crops by ditches, pipes, or other
conduits. Water spreading is not considered
irrigation; it is recorded as a conservation
practice. [NRI-97]
Pastureland and Native Pasture:
A Land Cover/Use category of land managed
primarily for the production of introduced or
native forage plants for livestock grazing.
Pastureland may consist of a single species in a
pure stand, a grass mixture or a grass-legume
mixture. Management usually consists of
cultural treatments-fertilization, weed control,
reseeding, or renovation and control of
grazing. (For the NRI, includes land that has a
vegetative cover of grasses, legumes, and/or
forbs, regardless of whether or not it is being
grazed by livestock.) [NRI-97]
Product Information
Product ID:
5111
Production Date:
5/4/01
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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