Missouri Major Land Resource Areas
MLRA 107: Iowa and Missouri Deep Loess Hills
(back)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.
MLRA 108: Illinois and Iowa Deep Loess and Drift
(back)Illinois, Iowa, and Missouri 79,790 km2 (30,800 mi2)
Land use: Nearly all this area is in farms, and about 80 percent is cropland. Corn, soybeans, and other feed grains grown extensively on the less sloping soils are sold as cash crops. In areas where slopes are strong, more of the land is used for hay and pasture and more of the grain is fed to livestock on farms where it is grown. About 10 percent of the area is in introduced and native grasses. Making up about 5 percent are narrow bands of forest on steep valley sides and wet bottom land. About 5 percent is used for urban development and other purposes. Conservation practices are used to reduce erosion, flooding, and sedimentation.
Elevation and topography: Elevation ranges from 200m on the lowest valley floors to 300m on the highest uplands, increasing gradually from east to west. Much of this dissected loess-mantled glacial plain is rolling to hilly, but some of the broad uplands far from the large streams are level to undulating. The smaller streams have narrow valley floors, but the large streams have broad flood plains. Local relief is mainly several meters to 25 or 50m, but the upland flats have relief of only 1 or 2m.
Climate: Average annual precipitation-750 to 900 mm. Two-thirds or more of the precipitation falls during the freeze-free period. The low precipitation in winter is mostly snow. Average annual temperature-8 to 12°C. Average freeze-free period-160 to 180 days.
Water: The favorably distributed moderate precipitation and the many perennial streams are important water sources. Ground water is abundant in the glacial drift that underlies much of the area. The Mississippi River and a few large tributaries are transportation arteries and are used for recreation.
Soils: Most of the soils are Udolls. They are deep, medium textured soils that formed mainly in loess. These soils have a mesic temperature regime, an udic moisture regime, and montmorillonitic or mixed mineralogy. Somewhat poorly drained, nearly level Argiudolls (Flanagan, Ipava, and Mahaska series) and Hapludolls (Muscatine series) and poorly drained nearly level Haplaquolls (Drummer and Sable series), and Argiaquolls (Taintor and Virden series) are on uplands. Well drained and moderately well drained Argiudolls (Sharpsburg, Shelby, and Tama series) are gently sloping to strongly sloping. Well drained Hapludalfs (Fayette, Seaton, Clinton, and Hickory series) on the steep slopes of valley sides make up only 10 to 15 percent, of the total area. Somewhat poorly drained Hapludolls (Lawson series), well drained Hapludolls (Huntsville series), and moderately well drained Udifluvents (Nodaway series) are in silty alluvium on the flood plains. Poorly drained and very poorly drained Haplaquolls (Colo and Zook series) are in clayey alluvium on the flood plains.
Potential natural vegetation: When this area was settled, it supported tall grass prairie vegetation. The present potential for natural vegetation is unclear. Forest vegetation consisting of black oak, white oak, bur oak, shagbark hickory, and some walnut grows on the steep slopes of valley sides. Silver maple, elm, and ash grow on flood plains.
MLRA 109: Iowa and Missouri Heavy Till Plain
(back)Iowa and Missouri 37,110 km2 (14,330 mi2)
Land use: Nearly all this area is in farms, and about 55 percent is cropland. Corn, soybeans, other feed grains, and hay are the principal crops. About 25 percent of the area is in introduced and native grasses, and about 10 percent is woodland. Beef cattle and swine are important sources of income on many farms. Conservation practices are used to reduce erosion, flooding, and sedimentation.
Elevation and topography: Elevation ranges from 200m in the lowest valleys to 300m on the highest ridges. This dissected till plain has a thin mantle of loess. Slopes are mostly rolling to hilly but some broad ridgetops are nearly level to undulating. The slopes bordering major stream valleys are steep. A few large rivers have nearly level broad valley floors. Local relief is mainly several meters to 25 or 50m, but the upland flats and valley floors have local relief of only 1 or 2m.
Climate: Average annual precipitation-825 to 1,025 mm. About two-thirds of the precipitation falls during the freeze-free period. The low precipitation in winter is snow. Average annual temperature-10 to 13°C. Average freeze-free period-160 to 180 days.
Water: In most years the favorably distributed moderate precipitation provides enough water for crops. The many small perennial streams and a few large streams are additional sources of water but are little used for these purposes. Ground-water supplies are small and undependable. The stream flow fluctuates severely and frequently.
Soils: Most of the soils are Udolls. They are deep and have a medium textured surface layer and a fine textured subsoil. They have a mesic temperature regime, an udic moisture regime, and montmorillonitic mineralogy. Somewhat poorly drained, nearly level to moderately sloping Argiudolls (Haig series) and Ochraqualfs (Kilwinning, Kniffin, and Pershing series) and nearly level to moderately sloping, poorly drained, Argialbolls (Edina series), are on upland divides on loess-covered till plains. Somewhat poorly drained, gently sloping to strongly sloping Argiudolls (Adair, Lagonda, and Lamoni series) and poorly drained, gently sloping to strongly sloping Argiaquolls (Clarinda series) are on convex side slopes with a thin mantle of loess or pedisediment over glacial till. Well drained and moderately well drained, moderately sloping to steep Argiudolls (Shelby series) and Hapludalfs (Armster, Armstrong, Gara, Keswick, and Lindley series) are on side slopes on clay loam glacial till. Moderately well drained Hapludolls (Kennebec and Lawson series) and Udifluvents (Nodaway series) are on silty alluvium flood plains. Poorly drained and very poorly drained Haplaquolls (Chequest, Colo, Zook, and Wabash series) and somewhat poorly drained Argialbolls (Vesser series) are on clayey alluvium flood plains.
Potential natural vegetation: This area supports grassland vegetation. Big bluestem, indiangrass, little bluestem, and switchgrass are the major species. The natural drainageways and the lowland soils interspersed throughout the area support forest vegetation. Oak and hickory species are dominant. Most of the native grasses have disappeared because of cultivation and overgrazing. Naturalized bluegrass is prevalent on noncultivated areas.
MLRA 112: Cherokee Prairies
(back)Kansas, Missouri, and Oklahoma 59,410 km2 (22,940 mi2)
Land use: Nearly all this area is in farms, and about one-half is cropland. Winter wheat, soybeans, corn, grain sorghum, other feed grains, and hay are the major crops. Some cotton is grown in a few counties in Oklahoma. About one-third of the area is in pasture grasses and legumes; native grasses grow on the more sloping parts. About one-tenth of the area, the steeper valley slopes and some of the wet bottom land, is woodland. The acreage of woodland in Kansas is considerably less than that in Missouri and in Oklahoma.
Elevation and topography: Elevation ranges from 100 to 400m. These gently sloping to rolling dissected plains are underlain by sandstone, shale, and limestone. The northern part has a thin mantle of loess. Even though the area is thoroughly dissected, local relief is in meters, and large valleys are about 25m below the adjacent uplands.
Climate: Average annual precipitation-900 to 1,050 mm. Maximum precipitation is from late in spring through autumn. Annual snowfall ranges from about 12 cm in the south to 45 cm in the north. Average annual temperature-13 to 17°C. Average freeze-free period-190 to 235 days.
Water: In many years the moderate precipitation is adequate for crops and pasture, but in some years summer droughts reduce crop yields. In much of the area, shallow wells are the principal source of water for domestic use and for livestock, but small ponds and reservoirs on individual farms are increasingly important sources of water for livestock. Deep wells, especially in limestone areas, also provide water.
Soils: Most of the soils are Aqualfs and Udolls. They are shallow to deep and medium textured and moderately fine textured. These soils have a thermic temperature regime, an aquic or udic moisture regime, and mixed mineralogy. Somewhat poorly drained nearly level and gently sloping Albaqualfs (Parsons and Taloka series), Argiaquolls (Woodson series), and Argialbolls (Hartwell series) are on clay-mantled uplands. Moderately well drained and well drained, gently sloping and sloping Paleudolls (Dennis and Okemah series), Hapludalfs (Barden and Liberal series), and Argiudolls (Bates and Eram series) are on uplands underlain by silty and sandy shale and sandstone. Well drained, gently sloping Argiudolls (Lula and Catoosa series) are underlain by limestone and are on uplands; shallower and more stony Argiudolls (Clareson series), Haplustolls (Shidler series), and Hapludolls (Coweta and Collinsville series) are on steeper slopes of limestone, sandstone, and loamy shale. Gently sloping to moderately sloping clayey Argiudolls (Summit series) are underlain by clayey shale and clay beds and are on foot slopes. Haplaquolls (Osage series), Hapludolls (Verdigris and Wynona series), and Ochraqualfs (Hepler series) are on the flood plains of most streams.
Potential natural vegetation: The western part of this area supports tall grass prairie vegetation. Big bluestem, little bluestem, indiangrass, and switchgrass are the dominant species. The eastern part and the valleys in the western part support natural vegetation characterized by trees. Red oak, white oak, and shagbark hickory are major species. Islands of tall grass prairie vegetation are common.
MLRA 113: Central Claypan Areas
(back)Illinois and Missouri 28,570 km2 (11,030 mi2)
Land use: Nearly all this MLRA is in farms, and about 60 percent is cropland. Corn, soybeans, other feed grains, and hay for cattle and other livestock are the main crops. About 10 percent is in permanent introduced and native grasses. An additional 20 percent, mainly on the steeper slopes and on wet bottom land, is forested. About 5 percent is used for urban development; the remainder is used for miscellaneous purposes. Wetness is the major land use problem.
Elevation and topography: Elevation ranges from 200 to 300m in Missouri and is about 200m in Illinois, increasing gradually from south to north in both states. This MLRA consists of nearly level to gently sloping silt-mantled old till plains. Stream valleys are shallow, and most of them are narrow. Local relief is mainly a few meters.
Climate: Average annual precipitation-About 1,025 mm. About 60 percent of the precipitation falls during the freeze-free period. Average annual temperature-13°C. Average freeze-free period-180 to 190 days.
Water: In most years the moderate precipitation is adequate for crops. Small to moderate quantities of water are available from ground water. A few large perennial streams are potential sources of water, but they are little used for this purpose. Most of the soils are somewhat poorly drained to poorly drained, and claypans prevent effective artificial drainage on most of them.
Soils: Most of the soils are Aqualfs. They have a deep, medium textured surface layer and a fine textured and moderately fine textured subsoil. These soils have a mesic temperature regime, an aquic moisture regime, and montmorillonitic mineralogy. In areas in Missouri are nearly level, poorly drained Albaqualfs (Putnam series) and gently sloping, somewhat poorly drained Ochraqualfs (Mexico and Leonard series). On some sites in Illinois are nearly level Albaqualfs (Cisne, Cowden, and Wynoose series). Somewhat poorly drained, nearly level and gently sloping Hapludalfs (Bluford and Hoyleton series) and moderately well drained, nearly level and gently sloping Fragiudalfs (Ava series) are on loess-covered old till plains. Well drained and moderately well drained, moderately sloping to steep Hapludalfs (Armstrong, Gara, Keswick, Lindley, and Weller series in Missouri and Hickory series in Illinois) are on side slopes. Fluvaquents (Belknap, Piopolis, and Westerville series) and Udifluvents (Sharon series) are in silty alluvium. Haplaquolls (Wabash series) are in clayey alluvium on narrow flood plains of small extent.
Potential natural vegetation: When this MLRA was settled, most of the level upland soils supported tall grass prairie vegetation characterized by big bluestem, indiangrass, prairie dropseed, and switchgrass. The present potential for natural vegetation on the level upland soils is unknown. Forests of post oak, swamp white oak, blackjack oak, and pin oak grow on poorly drained soils. White oak, shingle oak black oak, hickory, white ash, basswood, sugar maple elm, and walnut grow on the better drained soils. Silver maple, willows, cottonwood, sycamore, elm pin oak, white oak, hickory, and ash grow on floodplains.
MLRA 115: Central Mississippi Valley Wooded Slopes
(back)Indiana, Illinois, and Missouri 60,860 km2 (23,500 mi2)
Land use: Nearly all this area is in farms, and about 40 percent is cropland. Feed grains and hay for livestock are the principal crops, but grape vineyards and peach and apple orchards are important in some places. About 35 percent of the area is forested, which includes some national forests. Most of the remainder of the farmland is in permanent pasture and native grasses. The hazards of erosion and sedimentation are severe in urban areas near St. Louis and other cities and on the farmland.
Elevation and topography: Elevation ranges from 100m on the main valley floors to 300m on the ridgetops. This dissected glacial till plain has rolling narrow ridgetops and hilly to steep ridge slopes and valley sides. The small streams have narrow valleys and steep gradients. The major rivers have nearly level broad flood plains. Valley floors are tens of meters below the adjoining hilltops.
Climate: Average annual precipitation-900 to 1,150 mm. About two-thirds of the precipitation falls during the freeze-free period. The maximum is in spring and early in summer and the minimum from mid-summer through autumn. Average annual temperature-12 to 14°C. Average freeze-free period-180 to 200 days, increasing from north to south.
Water: In most years precipitation is adequate for the crops commonly grown, but in some years yields are reduced by drought. Ground water is the source of water for domestic and livestock needs on farms. The Mississippi, Missouri, and Ohio Rivers are major transportation arteries and are also used for recreation.
Soils: Most of the soils are Udalfs. They are deep and medium textured to moderately fine textured and have a mesic temperature regime, an udic moisture regime, and mixed mineralogy. Well drained and moderately well drained Hapludalfs (Alford, Fayette, Menfro, Muren, Weller, and Winfleld series) are in silty loess; other Hapludalfs (Gara, Hickory, Keswick, and Lindley series) are in glacial till; and still others (Bloomfield and Princeton series) are in sandy aeolian material. Well drained and moderately well drained Fragiudalfs (Grenada, Hatton, and Hosmer series) are on ridgetops in silty material. Well drained, cherty Paleudalfs (Goss series) weathered from cherty limestone. Somewhat excessively drained shallow Hapludolls (Gasconade series) are on steep slopes. Udifluvents (Eel, Genesee, Haymond, Nodaway, and Sharon series), Fluvaquents (Piopolis, Shoals, and Wakeland series), Haplaquolls (Beaucoup, Darwin, and Wabash series), and Hapludolls (Leta series) are on flood plains.
Potential natural vegetation: This area supports a forest flora consisting mainly of oak and hickory species.
MLRA 116A: Ozark Highland
(back)Arkansas, Missouri, and Oklahoma 69,810 km2 (26,950 mi2)
Land use: About 70 percent of this area is forests or woodland, most of which is in large holdings, national forests, or farm woodlots. About 20 percent is pas- ture, mainly of introduced grasses and legumes. About 10 percent is cropland. Corn, feed grains, and hay for dairy cattle and other livestock are the principal crops. Orchards, vineyards, and truck crops are important on some of the more friable deep soils. Summer droughts and steep slopes are major land use problems.
Elevation and topography: Elevation ranges from 200 to 500m. These sharply dissected limestone plateaus have narrow rolling ridgetops that break sharply to steep side slopes. Valleys are narrow and have steep gradients, especially in the upper reaches. Local relief is in meters to tens of meters.
Climate: Average annual precipitation-1,025 to 1,225 mm. Maximum precipitation is in spring and early in summer, and the minimum is in midsummer. Average annual temperature-13 to 16°C. Average freeze-free period-180 to 200 days.
Water: The moderate precipitation is adequate for crops and pasture. On most farms shallow wells or springs supply water for domestic needs and for livestock, but deep wells are required for large quantities. Water from deep wells is of good quality but is hard. Small ponds on many individual farms provide some water for livestock, and a few large reservoirs are used for flood control and for recreation.
Soils: Most of the soils are Udults and Udalfs. They are deep, medium textured to fine textured, cherty soils that weathered from limestone. They have a mesic temperature regime, an udic moisture regime, and siliceous or mixed mineralogy. Somewhat excessively drained to well drained Paleudults (Clarksville, Coulstone, Macedonia, Noark, and Poynor series) and Paleudalfs (Peridge and Goss series) are on ridges and side slopes. Moderately well drained, nearly level to moderately steep Fragiudults (Captina and Nixa series) are on slopes. Somewhat excessively drained, shallow Hapludolls (Gasconade series) and areas of rock outcrop are on steep, dissected landscapes. Udifluvents (Midco and Elsah series) on flood plains and Hapludalfs (Razort and Secesh series) on terraces are in stream valleys. Fine textured Hapludults (Agnos and Gassville series), Paleudalfs (Gepp series), and Paleudults (Doniphan series) also occur.
Potential natural vegetation: This area supports oak-hickory and oak-hickory-pine forests. Oak-hickory-pine forests are more dominant in the east. Glades, openings having bedrock outcrops or that are shallow to bedrock, support a more herbaceous vegetation consisting primarily of indiangrass, little bluestem, and dropseeds. Glades are more common in the southwest.
MLRA 116B: Springfield Plain
(back)This area is predominantly in southwest Missouri and extends for a short distance into the northeast corner of Oklahoma and southeast Kansas. It makes up about 352.01 square miles. The towns of Springfield and Joplin, Missouri are in this MLRA.
Land use: Farms and ranches make up most of this area. Forage and grain are grown for beef, dairy cattle, and other livestock. Raising of beef cattle is one of the major industries in the area. In addition, the poultry business has grown into a major industry. From the practice of keeping a few chickens on each farm, the poultry business has developed into a very specialized multimillion-dollar industry. Soybeans and winter wheat are the major cash crops. Loss of farmland is a concern in the area. Urbanization pressures are greatest in the Springfield and Joplin areas.
Elevation and topography: Elevation ranges from 200 to 500m. These broad limestone ridges and remnants of plateaus have gently sloping to moderately sloping tops and strongly sloping to steep side slopes. The stream valleys are narrow to moderately wide and have relatively steep gradients. Local differences in elevation range from 1 to 10 meters. Climate: Average annual precipitation-975 to 1,225 mm. Maximum precipitation is in spring and early in summer, and the minimum is in midsummer. Average annual temperature-13 to 16°C. Average freeze-free period-180 to 200 days.
Water: In many years the moderate precipitation is adequate for crops and pastures, but summer droughts of sufficient severity and duration to reduce crop yields are common. On most farms shallow wells or springs supply water for domestic needs and for livestock, but deep wells are required for large quantities. Water from deep wells is of good quality but is hard. Small ponds on many individual farms provide some water for livestock, and a few large reservoirs are used for flood control and for recreation.
Soils: Most of the soils are in the alfisol, ultisol, or mollisol orders. They formed in materials weathered from cherty limestone partly covered with a thin mantle of loess. Physical and chemical weathering has caused the cherty limestone to disintegrate into its least soluble components, which are chert and clay. The chert remains in the form of angular fragments or wavy horizon beds sandwiched between layers of clay. Down slope movement by gravitational creep has altered the upper cherty material on some soils. In general, the soils are moderately deep to very deep, moderately well drained to well drained, and medium to fine textured. The temperature regime is typically mesic and extends slightly into thermic. The moisture regime is udic and the mineralogy is mixed or siliceous. Soils on the nearly level to moderately sloping upland divides are frequently Paleudolls (Newtonia and Wanda series), Paleudalfs (Peridge series), Fragiudalfs (Creldon, Hoberg, Keeno, and Viraton series), Fragiaqualfs (Bado and Gerald series), Fragiudults (Captina, Needleye, Nixa, and Tonti series) and Hapludalfs (Barden and Bolivar series). Soils on the moderately sloping to steep upland side slopes are frequently Paleudalfs (Eldon, Goss, and Rueter series), and Paleudults (Clarksville series). Soils on the terraces and adjacent floodplains are frequently Hapludalfs (Razort, Secesh, and Waben series), Hapludolls (Cedargap and Huntington series), Paleudalfs (Britwater and Pembroke series) and Eutrudepts (Jamesfin series).
Biological Resources: This area supports oak-hickory savanna vegetation. It is a transitional area between oak-hickory forests and bluestem prairies. Big bluestem, little bluestem, indiangrass, and switchgrass are the dominant grassland species. The forests and grasslands are interspersed. The oakhickory forests are more common on north slopes and on deeper soils and the grasslands on south slopes and on soils with low available moisture capacity.
MLRA 116C: St. Francois Knobs and Basins
(back)This MLRA is newly approved. The description of this MLRA has not yet been completed. This MLRA was part of the Ozark Highland MLRA (116A). Please refer to that description until the St. Francois Knobs and Basins MLRA is complete.
Land use:
Elevation and topography:
Climate:
Water:
Soils:
Biological Resources:
MLRA 131: Southern Mississippi Valley Alluvium
(back)Arkansas, Mississippi, Missouri, and Tennessee 93,600 km2 (36,140 mi2)
Land use: Most of this area is in farms. About 55 percent is cropland, 35 percent woodland, and 7 percent pasture. About 3 percent is used for miscellaneous purposes. Cropland makes up about three-fourths of the acreage in the north and less than one-fourth in the south. The proportion of forest land varies inversely with that planted to crops; the proportion of pasture is a little higher in the south. This is an important cash-crop area. Soybeans, cotton, and wheat grown by highly mechanized methods are the major crops throughout the area. Corn is an important crop in Missouri. Rice is an important crop in Arkansas, Louisiana, and Mississippi, and sugarcane is important in southern Louisiana. Controlling surface water and artificially draining the wet soils are major concerns of management.
Elevation and topography: Elevation is at sea level in the south and increases gradually to about 200m in the north. The area consists of level to gently sloping broad flood plains and low terraces. Most of the area is flat. The only noticeable slopes are sharp terrace scarps and natural levees that rise sharply to several meters above adjacent bottom lands or stream channels. Swamps are significant in the extreme southern part in Louisiana.
Climate: Average annual precipitation-1,150 to 1,650 mm, increasing from north to south. In most of the area maximum precipitation is in winter and early in spring, decreasing gradually to a minimum in autumn. Along the Gulf Coast, maximum precipitation is in midsummer and early in autumn. Snowfall is negligible. Average annual temperature-14 to 21°C, increasing from north to south. Average freeze-free period-200 to 340 days, increasing from north to south.
Water: Precipitation, streamflow, and aquifers supply moderate to large quantities of potable ground water. The Mississippi River crosses the area from north to south, and many of its tributaries also cross the area. Oxbow lakes and bayous are extensive throughout. Potable ground water is not available in extreme southern Louisiana.
Soils: The dominant soils are Aquepts, Aqualfs, Aquents, Udolls, and Udalfs. They are deep, medium textured and fine textured soils that have an udic or aquic moisture regime, a thermic temperature regime, and mostly montmorillonitic or mixed mineralogy. Fine textured Haplaquepts (Alligator, Perry, Portland, Sharkey, and Tunica series), Hapludolls (Desha, Bowdre series), and Ochraqualfs (Jackport series), and medium textured Fluvaquents (Commerce, Mhoon, and Convent series), Natraqualfs (Foley series), Ochraqualfs (Dundee, Amagon, and Hebert series), and Hapludalfs (Dubbs, Bosket, and Rilla series) occupy backswamp areas and older natural levees. Minor soils include moderately coarse textured Dystrochrepts (Beulah series) and Udifluvents (Robinsonville series), medium textured Fluvaquents (Gideon series), fine textured Hydraquents (Barbary series), and organic Medisaprists (Maurepas series). The Hydraquents and Medisaprists are in the extreme southern part in Louisiana.
Potential natural vegetation: This area supports deciduous bottom land forest vegetation. Willow oak, water oak, Nuttall oak, swamp white oak, sweetgum, water tupelo, baldcypress, native pecans, and hickories are the principal species. Black willow, eastern cottonwood, sycamore, sugarberry, and green ash are dominant on the more recent soils. Switchgrass, eastern gamagrass, little bluestem, indiangrass, Florida paspalum, plumegrass, sedges, and rushes are the dominant understory species.
MLRA 134: Southern Mississippi Valley Silty Uplands
(back)Arkansas, Kentucky, Louisiana, Mississippi, and Tennessee 51,410 km2 (19,850 mi2)
Land use: Most of this area is in farms; a small acreage is federally owned. About 35 percent of the area is cropland, but the proportion varies greatly from county to county, depending on the soils and the topography. This is largely a cash-crop area. Cotton, corn, soybeans, and wheat are major crops, but rice is important locally in Arkansas and in Louisiana, and strawberries are important in Louisiana. Feed grains and forage are grown on dairy farms. About 16 percent of the area is in pasture or hay. About 46 percent is in forest of mixed pine and hardwoods. Lumber is the major forest product, and some pulpwood is harvested. The present trend is toward the conversion of the pasture and forest to cropland. About 3 percent of the area is used for urban development or other purposes. There is an increase in urban development near the metropolitan areas.
Elevation and topography: Elevation ranges from 25 to 100m. The sharply dissected plains have a thick loess mantle that is underlain by unconsolidated sand, silt, and clay, mainly of marine origin. Valley sides are hilly to steep, especially in the west. The intervening ridges are mostly narrow and rolling, but some of the interfluves between the upper reaches of the valleys are broad and flat. Stream valleys are narrow in the upper reaches but broaden rapidly downstream and have wide, flat flood plains and meandering stream channels. Local relief is mainly several meters to 25 or 50m.
Climate: Average annual precipitation-1,150 to 1,525 mm, increasing from north to south. Maximum precipitation is in winter and in spring, decreasing gradually through summer to autumn except for a moderate increase in midsummer. Average annual temperature-16 to 20°C, increasing from north to south. Average freeze-free period-200 to 280 days, increasing from north to south.
Water: Precipitation and ground water are abundant, On the uplands shallow wells, cisterns, ponds and rural water systems are the main sources of water for domestic use and livestock. Shallow wells provide small quantities of water, but deep wells in underlying sand and gravel yield large quantities. Most steams are small and flow intermittently. They flow most of the time in winter and in spring but only during and immediately after storms in summer and in autumn.
Soils: Most of the soils are Udalfs. They are deep, medium textured soils that have a thermic temperature regime, an udic moisture regime, and mixed mineralogy. Well drained, nearly level to very steep Hapludalfs (Memphis series) are on uplands. Moderately well drained, nearly level to strongly sloping Fragiudalfs (Grenada and Loring series) are on ridgetops, side slopes, and terraces. Somewhat poorly drained Fragiudalfs (Galloway series) and poorly drained Udifluvents (Morganfield and Vicksburg series), moderately well drained Udifluvents (Adler and Collins series), and somewhat poorly drained Fluvaquents (Falaya series) are on flood plains. In the east where the loess mantle thins, well drained Paleudalfs (Lexington series), moderately well drained Fragiudalfs (Dulac and Providence series), well drained Hapludults (Brandon and Silerton series), and well drained Paleudults (Smithdale series), all of which are gently sloping to steep, are on ridgetops and side slopes. Well drained Dystrochrepts (Ariel series), moderately well drained Udifluvents (Collins series), moderately well drained Dystrochrepts (Oaklimeter series), and somewhat poorly drained Fluvaquents (Falaya and Gillsburg series) are on the flood plains.
Potential natural vegetation: This area supports hardwood and pine forest vegetation. Cherrybark oak and Shumard oak are widely distributed. Yellowpoplar, white ash, cottonwood, and black walnut are important species on the flood plains. Loblolly and shortleaf pines are on a wide variety of sites, mainly the eroded soils of the uplands and ridges. Other hardwood species that commonly grow in this area are white oak, basswood, sweetgum, water oak, American elm, blackgum, sycamore, sassafras, southern red oak, chinkapin oak, American beech, and hickory.
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.