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Measuring cropland area is essential
for assessing the economic and environmental performance
of U.S. agriculture. ERS tracks cropland in its
annual “cropland used for crops” data
series, which began in 1910. Cropland used for crops
is the sum of cropland harvested, crop failure,
and summer fallow. (Total cropland is part of the
ERS Major Land Use series, started in 1945, that
accounts for all land use in the 50 States.)
The data behind the ERS cropland series come from
the Crop Production Annual Summary published by
USDA’s National
Agricultural Statistics Service (NASS). This
survey includes harvested acres of principal crops,
the predominant field crops in U.S. agriculture.
In 2003, 21 principal crops accounted for about
95 percent of all harvested crop acreage in the
United States, but just four crops—corn,
soybeans, wheat, and hay—accounted for about
80
percent of all cropland harvested acreage.
The acreages of other crops (fruits and nuts,
vegetables, and minor crops), which are published
every 5 years by the U.S. Census of Agriculture
and change little from one census year to the
next, are added to the acres of principal crops
to derive total crops harvested. In 2002, “other
crops” comprised over 40 other crops plus
nursery and greenhouse products. While these crops
take up relatively little acreage, they can account
for large market value shares of sales.
The Crop Production Annual Summary report counts
all acres harvested, including double cropping.
However, each cropland acre can only be counted
once; thus, double cropping is subtracted from
total crops harvested because cropland used for
crops becomes part of the ERS
Major Land Use series, which must sum to total
U.S. land area. The result is total cropland harvested.
Most double cropping occurs when soybeans are
planted after the harvest of small grains (mainly
wheat) in the same year, and these estimates are
from the annual NASS
acreage report published in June. Smaller
acreages of other crops are also double cropped,
and these estimates are from the Census of Agriculture.
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Crop failure is the difference between
cropland planted and cropland harvested. However,
some cropland planted is not intended to be harvested.
Thus, adjustments are made to account for cover
crops, crops grazed, and crops cut for hay. Data
for these adjustments are from the Crop Production
Annual Summary and the Census.
Cultivated summer fallow occurs predominantly
in the Great Plains where it is a practice used
to conserve moisture and control weeds. Fields
are typically planted and harvested one year and
summer fallowed the next. Acreage estimates are
obtained from NASS, the Census of Agriculture,
or the Conservation Technology Information Center.
When no data are available, ERS estimates summer
fallow based on the acreage of wheat in the major
summer-fallow States. The use of summer fallow
has slowly declined over the last 30 years, due
mostly to the increased adoption of conservation
tillage and herbicides, which reduce the need
for summer fallow to conserve moisture and control
weeds.
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