Iowa, Kansas, Nebraska, and Missouri
53,810 km2 (20,770 mi2)
Land use: Most of this area is in farms, and about 60
percent is cropland. Corn, soybeans, and hay are the
principal crops. About 20 percent of the area is
permanent pasture. About 10 percent, mainly in
narrow belts of steep slopes bordering stream valleys
and wet bottom land, is forested. Raising beef cattle
and feeding beef cattle and hogs are important enterprises on many farms. The hazard of erosion is severe
on the upland soils. Controlling flooding and sedimentation on bottom lands are concerns of management.
Elevation and topography: Elevation ranges from
200m along the Missouri River flood plain in the
south to 500m on the highest ridgetops in the north.
This rolling to hilly, loess-mantled plain is intricately
dissected. Small valleys have narrow flood plains, but
the larger valleys have broad floors. Local relief is
mainly several meters to more than 50m.
Climate: Average annual precipitation-625 to 925
mm. Two-thirds or more of the precipitation falls
during the freeze-free period. The low precipitation
in winter is mainly snow. Average annual temperature-7 to 13°C, increasing from north to south.
Average freeze-free period-150 to 190 days, increasing from north to south.
Water: The moderate precipitation and abundant
streamflow are important sources of water. Ground
water is abundant in deep outwash in valleys but is
less plentiful on the uplands. The Missouri River is a
major transportation artery and is also used for
recreation.
Soils: Soils of the uplands are mainly Udolls. Orthents
are also extensive. They are deep and medium textured
and moderately fine textured and have a mesic
temperature regime, an udic moisture regime, and
mixed mineralogy. Well drained, gently sloping to
rolling Hapludolls (Galva, Marshall, and Monona series) and gently sloping to rolling, somewhat poorly
drained, Argiudolls (Higginsville series) are on loess-mantled uplands. Somewhat poorly drained, nearly
level to gently sloping Hapludolls (Primghar series)
and poorly drained, nearly level to gently sloping
Haplaquolls (Marcus series) are on loess-mantled
uplands. Somewhat excessively drained and well
drained, strongly sloping to very steep Udorthents
(Hamburg and Ida series) are in thick loess and on
uplands. Well drained Hapludalfs (Knox series) are in
narrow bands on slopes where moisture is favorable
for growth of forest vegetation. Moderately well
drained, moderately sloping to steep Argiudolls are
on side slopes in clay loam glacial till. Well drained
and moderately well drained Udifluvents (Haynie and McPaul series) and Hapludolls (Keg, Kennebec,
and Salix series), somewhat poorly drained or poorly
drained Fluvaquents (Onawa and Albaton series),
and poorly drained or very poorly drained Haplaquolls
(Colo, Luton, and Wabash series) formed in alluvium
and are extensive on bottom lands.
Potential natural vegetation: This area supports
tall prairie grasses. Big bluestem, indiangrass, and
switchgrass are major species. Little bluestem and
sideoats grama grow well on the steep soils adjacent
to the Missouri River. Trees grow throughout the
area. Eastern cottonwood, American elm, honeylocust,
sycamore, and black walnut are common tree species
on the bottom lands. Basswood, red oak, white oak,
and shagbark hickory grow on protected upland
slopes. Bur oak and bitternut hickory are well adapted
to the steep slopes.
Data Source:
U. S. Department of Agriculture, Soil Conservation Service. 1981.
Land Resource Regions and Major Land Resource Areas of the United States.
Agriculture Handbook 296.U. S. Government Printing Office, Washington, D. C.
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