SEVERAL OTHER areas within the region that have similar soil problems are too small to justify separate delineation and treatment as subregions.

These areas occur in parts of six States as follows: The Highland Rim area of Tennessee; all of Kentucky west of the Appalachian-Cumberland Highlands and the Bluegrass subregions; the extreme southwestern part of Ohio; approximately the southern one-third of Indiana and Illinois, except the Southern Illinois Gray Prairie subregion; and the area in east-central Missouri along the Mississippi and Missouri Rivers.

Elevations of uplands are as high as 1,200 feet near the escarpment of the Appalachian-Cumberland Highlands in Tennessee and Kentucky and decline to the west to around 700 feet in Tennessee and 500 feet in Kentucky. Maximum elevations near the Ozarks in Missouri are about 900 feet. In Indiana, Illinois, and the rest of the area in Missouri, elevations range between 500 and 800 feet. The elevation of the Mississippi River at St. Louis is about 400 feet; at the junction with the Ohio, about 270 feet.

Uplands adjacent to these streams and their tributaries, which include the Tennessee and Cumberland Rivers, are extensively dissected and have many steep slopes.

The growing season averages about 180 days across the northern boundary of these areas in Ohio, Indiana, Illinois, and Missouri. It is as long as 210 days along the western boundary in Kentucky and Tennessee. Average annual precipitation is 40 to 45 inches in Missouri, Illinois, and Indiana, up to 50 inches in southern Kentucky, and 52 inches in Tennessee.

The acreage in corn and wheat and the number of hogs are nearly twice as great and the acreage of soybeans is more than twice as great per farm in these areas than in the whole region.

Corn, wheat, and soybeans are concentrated in the northern portion, where fertile bottom lands occur along the Mississippi, Missouri, Ohio, and Wabash Rivers.

Tobacco production is concentrated in the central portion. The largest acreage is in Kentucky. Production extends only a short distance northward from Kentucky along the river in Ohio and Indiana. Practically no tobacco is grown in Missouri and Illinois. The center of dark-fired tobacco production is along the Kentucky-Tennessee border near Clarksville and Springfield, Tenn., and Hopkinsville, Ky. Burley tobacco is grown throughout this area, although in smaller amounts; it is the major type grown throughout the portion of these areas in Tennessee south of the dark-fired tobacco area.

Less difference exists in the pattern of forage crop production, except that very little lespedeza is grown in southwest Ohio and the adjacent area in eastern Indiana. Little alfalfa is grown on the cherty soils of the Highland Rim in Kentucky and Tennessee. Commercial apple and peach orchards are in Illinois east of St. Louis. Another commercial peach area is in the southern part of Illinois.

Bedrock important in these areas includes sandstone, shales, limestone, and very cherty limestone. The land surface in areas underlain by limestone is characterized in many places by numerous sinkholes. There is limestone bedrock in the famous cave region of central Kentucky. Limestone rock continues north across the Ohio River into the unglaciated section of southern Indiana and southwest into the border counties of Tennessee near Clarksville. A narrow belt of relatively chert-free limestone extends across Tennessee adjacent to the Cumberland Plateau on the eastern Highland Rim. Another small area of limestone occurs near the Mississippi River in eastern Missouri.

Cherty limestones underlie most of the Highland Rim area of Tennessee and extend northeastward in Kentucky to the Appalachian-Cumberland Highland subregion. The weathered residues from them are stony, particularly on steeper slopes. Inter-bedded sandstone and shale rocks, underlain by coal deposits in most places, occur in Kentucky north and west of the limestone area and extend into Indiana. Inter-bedded limestone and shale occur on the eastern edge of Indiana and extend into southwestern Ohio. A small area of coastal plain materials is found in Kentucky between the Tennessee and Mississippi Rivers.

Old glacial drift overlies bedrock in parts of Missouri, Illinois, Indiana, and Ohio. Much of this glaciated area has a relatively smooth topography. Loess deposits of varying depth occur on most of the uplands with smooth relief near the Missouri, Mississippi, Ohio, and Wabash Rivers. The deposits are especially deep in western Illinois. Thin deposits of loess can be identified in Tennessee on the western Highland Rim, and loess covers all the coastal plains deposits in Kentucky where the topography is moderately smooth. Loess usually is not found on steep slopes, perhaps because it was removed by erosion as fast as it was deposited or has been eroded since.

Soils developed from relatively chert-free limestone residuum are productive, well adapted to a large number of crops, and moderately resistant to erosion. These soils have brown to light-brown surface layers and red subsoils. They include the Decatur and Cookeville on the Tennessee Eastern Highland Rim and in southern Kentucky; the Pembroke, which has a shallow layer of loess over limestone residuum and occurs chiefly northwest of Clarksville; and the Hagerstown in Missouri, Indiana, and the northern part of Kentucky.

Much of the land in the limestone areas is relatively smooth, although in places sinkholes have caused irregularities of slope that are inconvenient in cultivated fields. Soils of the bottom lands, such as the Huntington and Lindside, are fertile and productive of summer crops. The bottom lands along the smaller streams are fairly extensive and give opportunity for concentration of summer row crops to relieve somewhat the pressure for cultivated crops on the uplands.

Soils developed in the cherty limestone areas resemble those in the Ozark subregion, which also is a region largely of cherty to very cherty limestone bedrock. Some of these soils are not highly productive.

These cherty soils are among the most resistant to erosion, however. Bottom lands along small streams are relatively narrow because of the resistant nature of the bedrock and the alluvial soils therefore are of limited extent. Bodine, a Lithosol, occurs on steep slopes and is suited primarily for trees. Baxter, a Red-Yellow Podzolic soil, occurs on moderate slopes, is less cherty than Bodine, and has a brown-gray surface and yellowish-red subsoil. It is moderately well suited to cultivation; with fertilization, it is moderately productive. Dickson and Lawrence Planosols occur on relatively smooth topography and have little chert in the surface, but they have a fragipan at 20 to 24 inches. Mount-view resembles Dickson but does not have a fragipan.

Dellrose, of minor extent, is an unusual soil that occurs below the Bodine and Baxter on steep slopes, where dissection from the Nashville Basin is cutting into the Highland Rim.

Because many of the cherty soils are adapted only for forests, management of woodland areas is important in obtaining maximum farm income.

Soils developed in the areas of interbedded sandstone and shale in Kentucky and Indiana resemble soils of the Appalachian-Cumberland Highland subregion.

Soil series include Muskingum, a Lithosol occurring most commonly on steep slopes; Wellston, on moderate slopes and with moderate depth over bedrock; and Tilsit, which has a fragipan and is on quite smooth areas.

The Muskingum is less extensive than in the Appalachian-Cumberland Highland subregion because the topography is less rugged and the soil mantle over bedrock is somewhat deeper. Present management practices and the recommended changes in the soil-management systems are similar to those described for the Appalachian-Cumberland Highland subregion, except as affected by the less favorable moisture conditions in summer.

Soils developed on moderately deep to deep loess include Memphis, Loring, and related soils. Where they occur on sloping lands, they are susceptible to erosion because of their silty nature.

Associated with them on smooth areas of western Kentucky is Grenada, which has a thick fragipan about 24 inches below the surface where no erosion has occurred. Where erosion has exposed the coastal plain materials on the slopes, Regosols of various kinds are found. Soils developed from loess are somewhat higher in available phosphate and potash than the average soil of the subregion. The use of fertilizer is important, nevertheless, in order to help maintain a vigorous plant cover.

More emphasis is desirable on the production of pasture and hay crops to keep the land surface covered a longer time. Sloping soils should not be in row crops for more than 1 year between sod crops.

Trees are recommended for critical eroding areas. Controlled grazing of pastures will help maintain vigorous sod cover.

The glaciated areas in Indiana, Illinois, and Ohio with smooth relief have many soils with claypans similar to the soils of the Southern Illinois Gray Prairies that developed under forest vegetation. West of the Illinois Gray Prairie subregion are some claypan soils with moderately dark surface layers, which were developed under tall grass vegetation. Some slick spots occur in association with the Planosols developed under grass but are not so common as in the Southern Illinois Gray Prairie subregion. Because of the silty character of the surface layer of most of the soils in the glaciated areas, erosion is a serious problem in cultivated fields. Soil-management problems are like those of the Southern Illinois Gray Prairie subregion.

Soils developed over shale, and interbedded limestone and shale, in the unglaciated portions of southwest Ohio and adjacent areas of Indiana resemble those across the Ohio River in the outer portion of the Bluegrass subregion of Kentucky. Their suggested management would be similar.

Bottom land (alluvial) soils are extensive along the Wabash River, along the Ohio River from its junction with the Mississippi River to a point somewhat east of its junction with the Wabash River, and along the Mississippi from the north extremity of the region to a point about halfway to the Ohio junction. These bottom lands are fertile, but they often are flooded. Some levees have been constructed to protect the bottom lands from overflow. The control of weeds is a major problem in the bottom lands. Bottom lands along the Tennessee River have been largely flooded by the construction of Kentucky Dam near Paducah. Bottom land along the Cumberland River is fertile but relatively narrow. Except where it is too poorly drained, this land is well adapted for continuous production of summer crops, such as corn and soybeans.