Water: If moisture is carefully conserved, the moderate precipitation generally is adequate for crops and pasture. The larger streams can supply water for irrigation, but most of them have not been used for this purpose. Ground water is adequate to meet domestic and livestock needs in most of the area and is used locally for irrigation. Ground water is scarce in the east where shale is near the surface.

Soils: (See top of this document for soils descriptions) Most of the soils are Ustolls. They are shallow to deep and medium textured and moderately fine textured. They have a mesic temperature regime, an ustic moisture regime, and mixed and montmorillonitic mineralogy. The nearly level and gently sloping, well drained and moderately well drained Argiustolls are on loess- mantled uplands (Crete, Smolan, and Longford series) and on side slopes and foot slopes in dissected areas (Lancaster and Geary series). The moderately steep and hilly, shallow Haplustolls (Hedville series) are over sandstone on uplands. Ustifluvents (Hobbs series) are on flood plains of the smaller streams. Haplaquolls (Solomon series) and Haplustolls (Sutphen, Roxbury, and New Cambria series) are on bottom lands of major streams.

Potential natural vegetation: This area supports mid and tall grasses. Little bluestem, big bluestem, switchgrass, sideoats grama, and western wheatgrass are major species.

75—Central Loess Plains
Kansas and Nebraska
34,840 km˛ (13,450 mi˛)

Land use: Nearly all this area is in farms, about two-thirds of which is cropland. Hard winter wheat and grain sorghum are the main cash crops, but large acreages are planted to other small grains and hay. Corn is a major cash crop in the north. Most of the corn is irrigated by water from wells or canals. About one-fourth of the land is rangeland or pastureland grazed by beef cattle.

Elevation and topography: Elevation ranges from 500 to 600 m, increasing from east to west. Most of these nearly level to gently rolling plains are mantled by loess, but the part south of central Kansas is underlain by unconsolidated sediments, soft sandstone, and shale. The present drainage pattern cuts into the upper loess mantle and in places exposes the older Loveland loess. Stream valleys are mostly narrow and are not deeply incised. Relief is in meters to tens of meters.

Climate: Average annual precipitation—625 to 750 mm. Maximum precipitation is from midspring to midautumn. The low winter precipitation is snow. Average annual temperature—10 to 14 C, increasing from north to south. Average freeze-free period—160 to 190 days.

Water: The moderate but somewhat erratic precipitation is the source of water for grain crops, native grasses, and pasture. In the northwest, the Platte River supplies some water for irrigation. Ground water that is hard but otherwise of good quality is abundant in the sand and gravel underlying part of the area. Adequate quantities of ground water are available for irrigation in the northern part. Ground water is scarce in areas where shale and clay are near the surface.

Soils: (See top of this document for soils descriptions) Most of the soils are Ustolls. They are deep silty soils that formed in loess. They have a mesic temperature regime, an ustic moisture regime, and mixed mineralogy. Argiustolls (Hastings, Geary, Holder, Holdrege, and Crete series in the north and Irwin, Ladysmith, and Geary series in the south) are the dominant soils on uplands. Argiustolls (Hall series) are on stream terraces of major streams or rivers. Argiaquolls (Butler series), Argialbolls (Fillmore series), and Pellusterts (Goessel series) are associated soils in level areas and in depressions. Strongly sloping to steep Ustorthents (Coly series) formed in loess. Ustifluvents (Hobbs series) are on flood plains, and Haplustolls (Hord series) are on stream terraces. Shallow, strongly sloping to steep Haplustolls (Kipson series) formed in material weathered from shale.

Potential natural vegetation: This area supports mid and tall grass plant communities. Big bluestem, little bluestem, switchgrass, indiangrass, and sideoats grama characterize the vegetation on silty upland soils. These grasses and western wheatgrass are on bottom lands and in upland basins.

76—Bluestem Hills
Kansas and Oklahoma
19,400 km˛ (7,490 mi˛)

Land use: Nearly all this area is in farms and ranches, about three-fifths of which is in native grasses grazed by beef cattle. Nearly one-fifth of the area, consisting mainly of the deeper soils in valleys and on some of the uplands, is cropland. Some winter wheat is grown as a cash crop. Other small grains, grain sorghum, alfalfa, and other hay are the major crops. These crops are also grown on small irrigated areas along the Arkansas River.

Elevation and topography: Elevation ranges from 300 to 500 m. These dissected limestone and shale uplands have narrow divides and narrow steep-sided valleys. Only a few large streams have a significant area of flood plain. Local relief is commonly in meters or tens of meters.

Climate: Average annual precipitation—750 to 900 mm. Maximum precipitation is from midspring through early autumn. Annual snowfall averages 35 to 50 cm. Average annual temperature—12 to 16 C. Average freeze-free period—170 to 190 days but slightly more than 200 days in the south.

Water: The moderate precipitation provides water for pastures and crops. Much of the water for livestock is stored in small reservoirs and ponds. In the limestone areas, shallow wells yield moderate quantities of good-quality water, but very little is available in areas underlain by shale. Water from deep wells is highly mineralized.

Soils: (See top of this document for soils descriptions) Most of the soils are Ustolls. They are shallow to deep, medium textured to fine textured soils that are stony in some places. These soils have an ustic moisture regime, a mesic (Kansas) or thermic (Oklahoma) temperature regime, and mixed mineralogy. Well drained and moderately well drained, nearly level to moderately sloping Argiustolls (Irwin, Labette, and Ladysmith series) and Natrustolls (Dwight series) are on clay-mantled uplands that in some places are covered by thin loess. Shallow and moderately deep Haplustolls (Sogn and Clime series) are on steeper slopes underlain by limestone and shale. Moderately sloping Argiustolls (Florence series) in cherty limestone are on narrow divides and on side slopes of broader ridges. Haplaquolls (Osage series) and Hapludolls (Ivan and Verdigris series) are on flood plains, and Argiudolls (Reading series) and Haplustolls (Muir series) are on terraces.

Potential natural vegetation: This area supports tall grass prarie vegetation. Big bluestem, indiangrass, switchgrass, and little bluestem are dominant species. Little bluestem and big bluestem grow on the shallow soils.

77—Southern High Plains
Kansas, New Mexico, Oklahoma, and Texas
126,780 km˛ (48,950 mi˛)

Land use: Almost all this area is in farms and ranches. More than two-fifths, consisting of breaks along the Canadian and Cimarron Rivers and their larger tributaries and areas of sandy soils in the southwest, is range of native grasses and shrubs grazed by beef cattle. About one-third of the area, the smooth uplands, is dry-farmed to winter wheat, grain sorghum, and cotton. Nearly one-fifth of the area is irrigated. Wheat and grain sorghum are the major crops south of the Canadian River. Other major crops grown in places where irrigation water is available include soybeans, corn, alfalfa, and vegetables.

Elevation and topography: Elevation ranges from 800 to 2,000 m, increasing gradually from southeast to northwest. These smooth high plains are gently sloping, but along the major rivers, breaks are very steep. The deep sand in the southwest has an irregular dune topography. Local relief is in meters, but the major valleys are tens of meters below the general level.

Climate: Average annual precipitation—375 to 550 mm, but it fluctuates widely from year to year. Maximum precipitation is from late in spring through autumn. The low precipitation in winter is mainly snow. Average annual temperature—13 to 17 C. Average freeze-free period—l30 to 220 days, increasing from north to south and from west to east.

Water: The moderately low and erratic precipitation is the source of water for dry- farmed crops and for range. Perennial streams are few; they fluctuate widely in flow from year to year and are little used for irrigation. Sand and gravel throughout the central and northern parts of the area yield an abundance of ground water. Irrigation water is obtained from wells, but in the central and southern parts withdrawals exceed recharge, and the water table is gradually declining. Some areas formerly irrigated are now dry-farmed.

Soils: (See top of this document for soils descriptions) Most of the soils are Ustolls and Ustalfs. They are deep, fine, and medium textured and coarse textured. These soils have a mesic or thermic temperature regime, an ustic moisture regime, and mixed or carbonatic mineralogy. The level to gently sloping Paleustolls (Pullman, Olton, Acuff, Sherm, Gruver, Texline, and Dumas series), Argiustolls (Richfield series), Paleustalfs (Amarillo, Dallam, Rickmore, and Spurlock series), and Haplustalfs (Dalhart series) are the principal soils on the uplands. Calciustolls (Portales and Dioxice series), Haplustolls (Ulysses series) and Paleustolls (Mansker, Conlen, Sunray, and Estacado series) are dominant on ridges and on the more sloping parts. Haplustolls (Bippus, Humbarger, and Spur series) are on young valley floors and flood plains of the streams. Pellusterts (Randall and Ness series) are in clayey playa lake basins. Shallow Calciorthids (Potter series), Paleorthids (Pastura series), and Torriorthents (Travessilla series) are on the steep slopes and in the breaks. Paleustalfs (Patricia, Springer, and Brownfield series), Haplargids (Triomas, Faskin, and Jalmar series), Ustipsamments (Tivoli 1 series), and Torripsamments (Penwell series) are deep sandy soils in the southwest. Loamy, shallow to moderately deep soils in the southwest are Calciustolls (Kimbrough series), Paleustolls (Lea, Slaughter, and Stegall series), Paleustalfs (Arvana series), Paleorthids (Blakeney and Conger series), and Paleargids (Douro and Sharvana series).

Potential natural vegetation: This area supports a short grass community characterized by blue grama and buffalograss. Mid grasses such as sideoats grama grow on the more open soils and breaks. Tall grasses such as sand bluestem, little bluestem, and indiangrass grow mixed with shinnery oak and sand sagebrush on the sandy soils. A wide range of perennial forbs grow on the sandier soils and are characterized by dotted gayfeather, pitchersage, sagewort, bushsunflower, and daleas.

78—Central Rolling Red Plains
Kansas, Oklahoma, and Texas
130,370 km˛ (50,340 mi˛)

Land use: About 60 percent of this area is rangeland, and 35 percent is cropland. The rest of the area is urban land, woodland, or pasture. Nearly all the area is in farms or ranches. Most rangeland is in the west, but some is throughout the area. Ranges and pastures are grazed mainly by beef cattle. Winter wheat and grain sorghum are the major cash crops grown throughout the area. Cotton is an important crop south of the Cimarron River; alfalfa and peanuts are important locally. The crops grown under irrigation are also grown in nonirrigated areas. Soil erosion is a major concern of management if the soils are cultivated or if range and pasture are overgrazed.

Elevation and topography: Elevation ranges from 500 to 900 m, increasing gradually from east to west. On these dissected plains, the broad divides are nearly level to gently sloping, but slopes are short and steep in the valleys. In places the valleys are bordered by a rolling to steep irregular dune topography. Local relief is mainly in meters, but a few of the larger valleys are tens of meters or more below the general level of the plain. In southwestern Oklahoma, the Wichita Mountains are as much as 300 m above the surrounding plains.

Climate: Average annual precipitation—500 to 750 mm, increasing from west to east. Maximum precipitation is in spring, and the minimum is in winter. Snowfall ranges from 25 cm in the north to 10 cm in the south. Average annual temperature—14 to 18 C. Average freeze-free period—185 days to 230 days.

Water: The moderate but somewhat erratic precipitation supplies water for range and crops. Small ponds on individual farms provide water for livestock. Some larger ponds on individual farms are used for flood control, recreation, irrigation water, or water for livestock. A few large ponds and reservoirs are a source of municipal water and irrigation water. Rivers are a potential source of water for irrigation. Water in some of the larger rivers is highly mineralized. The deep sand and gravel in valleys yield some ground water. In sloping areas where the underlying sandstone and shale are near the surface, ground water is scarce.

Soils: (See top of this document for soils descriptions) The major soils are Ustolls, Ustalfs, and Ochrepts. They have a thermic temperature regime, an ustic moisture regime, and mixed mineralogy. The nearly level to gently sloping, well drained and moderately well drained, deep Argiustolls (Abilene, Carey, and St. Paul series), Paleustolls (Hollister, Rotan, Sagerton, and Tillman series), and Natrustolls (Foard series) are on uplands. The Ustalfs mainly are deep and sandy or loamy and have a loamy subsoil. They have a thermic temperature regime and mixed mineralogy. The nearly level to undulating or rolling, well drained, deep Haplustalfs (Devol and Grandfield series) and Paleustalfs (Miles, Springer, Wichita, Winters, and Nobscot series) are on uplands. The gently sloping to moderately steep Ustochrepts (Dill, Enterprise, Hardeman, Obaro, Quinlan, Vernon, and Woodward series) are on uplands. Ustifluvents (Clairemont, Lincoln, Mangum, Yomont, and Yahola series) are minor soils on flood plains.

Potential natural vegetation: This area supports mid and tall grasses. Sand bluestem, little bluestem, and sand sagebrush are dominant on the coarse textured soils. Little bluestem, gramas, and associated grasses and forbs grow on the finer textured soils.

79—Great Bend Sand Plains
Kansas
10,770 km˛ (4,160 mi˛)

Land use: Nearly all this area is in farms and ranches, and more than two-thirds is cropland. Cash-grain farming is the principal enterprise. Hard winter wheat is the major crop, but grain sorghum and alfalfa are also grown. About one-fifth of the land, consisting of sandy soils and steeply sloping areas, is in native grasses grazed by beef cattle.

Elevation and topography: Elevation ranges from 500 to 800 m. These undulating to rolling plains have a deep mantle of windblown sand and sandy outwash materials. Local relief is mainly in meters.

Climate: Average annual precipitation—525 to 700 mm. Maximum precipitation is from late in spring through early autumn. The annual snowfall averages from 35 to 50 cm. Average annual temperature—13 to 14 C. Average freeze-free period—180 to 190 days.

Water: The source of water for crops and pasture is the moderate but somewhat erratic precipitation. Along the northern edge, the Arkansas River is a potential source of irrigation water but currently is little used for this purpose. Deep sand yields an abundance of good-quality ground water for domestic use, livestock, irrigation, and other purposes.

Soils: (See top of this document for soils descriptions) Most of the soils are Ustalfs. They are deep, coarse textured and moderately coarse textured soils that have a thermic temperature regime and an udic moisture regime. Sandy Haplustalfs (Pratt series) and loamy Haplustalfs (Attica series) are on broad undulating to hummocky plains. Ustipsamments (Tivoli series) are on steeper hummocks and dunes. The nearly level and gently undulating, loamy Argiustolls (Farnum and Naron series) are on slopes. The nearly level Argiaquolls (Carwile series) in depressions and in areas with no defined drainage pattern are moderately extensive throughout the area. Haplustolls on flood plains (Waldeck, Zenda, and Lesho series) and terraces (Canadian series) are along major streams.

Potential natural vegetation: This area supports tall grass prairie vegetation. Sand bluestem, little bluestem, switchgrass, and indiangrass are major species. Sand bluestem, little bluestem, and giant sandreed grow on sandy dunes.

80A—Central Rolling Red Prairies
Kansas, Oklahoma, and Texas
52,700 km˛ (20,350 mi˛)

Land use: About 40 percent of this area is rangeland, and 40 percent is cropland. About 20 percent of the area is urban land, woodland, or pasture or is used for other purposes. Nearly all the area is in farms or ranches. Most cropland is in the north, but some is throughout the area. Winter wheat is the major cash crop. Alfalfa, cotton, grain sorghum, peanuts, and soybeans are important crops locally. The range and pasture are grazed mainly by beef cattle, but locally there are some dairy cattle. Soil erosion is a major concern of management if the soils are intensively cultivated or range and pasture are overgrazed.

Elevation and topography: Elevation ranges from 300 to 500 m, increasing gradually from east to west. On this dissected plain, the divides are undulating to gently rolling and the valley sides are hilly and steep. Flood plains of large streams are wide and level and are less dissected by stream channels than those to the west. Local relief is mainly in meters.

Climate: Average annual precipitation—625 to 900 mm. Maximum precipitation is in spring and the minimum in winter. Annual snowfall ranges from 30 cm in the north to 10 cm in the south. Average annual temperature—14 to 18 C. Average freeze- free period—190 to 230 days.

Water: The moderate and somewhat erratic precipitation is the source of water for crops and pasture. Several large rivers that cross the area from west to east are potential sources of irrigation water but currently are little used for this purpose. Small ponds on individual farms provide flood control, recreation, irrigation water, or water for livestock. A few large ponds and reservoirs are a source of municipal water and are also used for recreation. In areas where the valleys have deep sand and gravel, shallow wells provide moderate quantities of water for domestic use and for livestock. Ground water is scarce and generally is highly mineralized in sloping areas where the underlying sandstone and shale are near the surface.

Soils: (See top of this document for soils descriptions) The major soils are Ustolls. They are loamy or clayey and have a thermic temperature regime, an ustic moisture regime, and mixed mineralogy. The nearly level to sloping, well drained or moderately well drained, deep or moderately deep Argiustolls (Anocon, Grant, Pond Creek, Tabler, Shellabarger, and Stoneburg series) and Paleustolls (Bethany, Kirkland, and Renfrow series) are on uplands. The nearly level to steep, well drained, shallow to deep Haplustolls (Minco, Nash, and Lucien series) are on uplands. The nearly level, well drained or moderately well drained, deep Haplustolls (Miller, Port, and Reinach series) are on flood plains and low terraces. Minor soils include deep Haplustalfs (Bluegrove, Grainola, Pratt, and Steedman series) on uplands and Ustifluvents (Gaddy, Clairemont, and Yahola series) and Udifluvents (Gracemont and Gracemore series) on flood plains.

Potential natural vegetation: This area supports mixed prairie vegetation. Woody trees and shrubs are in the major drainageways. Indiangrass, big bluestem, switchgrass, and little bluestem are dominant species on the deeper soils and in the valleys. Little bluestem usually is dominant on the uplands and on shallow soils.

80B—Texas North-Central Prairies
Texas
26,500 km˛ (9,850 mi˛)

Land use: Nearly all this area is in ranches and farms. More than 80 percent is native range, pasture, or scrub oak forest. About 15 percent of the area is cropland. Most grassland is grazed by beef cattle. Some rangeland is also grazed by sheep and goats. Valleys, bottom land, and outwash areas of deep soils are farmed to wheat, oats, cotton, and grain sorghum. Hunting leases for deer, quail, and wild turkey are an important source of income in the area. The major concern of management is controlling woody brush that encroaches on the grassland.

Elevation and topography: Elevation ranges from 200 to 700 m. These dissected limestone, sandstone, and shale uplands have broad undulating divides and narrow steep-sided valleys. Only a few large, through flowing streams have significant flood plains. Relief is mainly in meters, but the large valleys are tens of meters below the adjacent uplands.

Climate: Average annual precipitation—550 to 750 mm. Maximum precipitation is in spring and in fall. Summer moisture deficit ranges from 200 to 275 mm. Average annual temperature—18 to 19 C. Average freeze-free period—214 to 240 days.

Water: The moderate but somewhat erratic rainfall is the source of water for crops and range. Summer droughts are common. The larger rivers, such as the Brazos and Colorado Rivers, flow most of the year, but local streams flow intermittently. There are several large lakes and numerous flood-detention reservoirs in the area. Some rural residents depend on community systems supplied from lakes for water; others depend on private lakes for water. Livestock water comes from streams or ponds. Ground water is scarce.

Soils: (See top of this document for soils descriptions) Most of the soils are Ustolls, Usterts, Ustalfs, and Ochrepts. These soils are well drained and moderately well drained, somewhat stony, and medium textured to fine textured. They have a thermic temperature regime, an ustic moisture regime, and mixed or montmorillonitic mineralogy. Very shallow to moderately deep Calciustolls (Talpa, Lueders, Kavett, Tarrant, and Valera series), Ustorthents (Yates series), and Argiustolls (Tarpley and Speck series) are on limestone plateaus or cuestas. Deep Chromusterts (Leeray series) and Haplustolls (Nukrum series) are in valleys at the base of cuesta scarps. Shallow and moderately deep Ustochrepts (Owens and Throck series) are on scarps and shaly uplands. Shallow to deep Haplustalfs (Callahan series), Rhodustalfs (Exray series), and Paleustalfs (Bonti and Truce series) are on hills and ridges and are underlain by interbedded sandstone and shale. Shallow Calciustolls (Cho and Mereta series) and deep Calciustolls (Nuvalde and Rowena series), Chromusterts (Reap series), and Pellusterts (Roscoe series) are on ancient alluvium and outwash. Paleustolls (Sagerton series), Paleustalfs (Winters and Wichita series), and Haplustalfs (Thurber series) are on outwash and stream terrace deposits. Deep Haplustolls (Elandco, Deleon, Frio, and Gowen series) and Ustifluvents (Bunyan, Yahola, Clairemont, and Lincoln series) are on younger stream deposits on flood plains.

Potential natural vegetation: This area supports savanna vegetation. The potential vegetation is rather uniform throughout the area despite the wide variation in soils. Little bluestem, indiangrass, big bluestem, sideoats grama, hairy grama, and Texas wintergrass are the dominant grass species. Post oak and blackjack oak, sumacs, bumelias, and elm are the dominant woody species. There also are numerous perennial forbs, including Maximilian sunflower, heath aster, bushsunflower, and Engelmann-daisy.

J—SOUTHWESTERN PRAIRIES COTTON AND FORAGE REGION
145,120 km˛ (56,030 mi˛)

This region consists of prairies and savannas in eastern Texas, in south-central Oklahoma, and in southeastern Kansas. The average annual precipitation ranges from 625 to 1,150 mm. The average annual temperature ranges from 15 to 22 C, and the freeze-free period is 190 to 280 days.

Ustalfs, Ustolls, and Usterts are the dominant soils. Ustalfs are on the upland savannas, and Ustolls and Usterts are in the praries.

The prairies are intensively farmed. Cotton, grain sorghum, wheat, other feed grains, and hay are important crops. The more sloping savannas are used mainly for grazing. Locally, peanuts and watermelons are important crops.

84A—Cross Timbers
Kansas, Oklahoma, and Texas
27,400 km˛ (10,580 mi˛)

Land use: Nearly all this area is in farms and ranches. About 40 percent is rangeland, 30 percent woodland, 15 percent pastureland, and almost 15 percent cropland. The rest is used for urban development and for other purposes. All the rangeland, woodland, and pastureland is grazed by beef cattle, but locally there are some dairy cattle. Small grains, grain sorghum, cotton, alfalfa, and other hay crops are important in much of the area. Large acreages of peanuts, tree fruits, and vegetables are grown in the south.

Elevation and topography: Elevation ranges from 300 to 400 m, but along the Red River it is 200 m. Ridgetops on these rolling to hilly uplands are nearly level to strongly rolling and narrow to moderately broad. Stream valleys are narrow and have steep gradients. Local relief is mostly a few tens of meters, but the large valleys are 50 m or more below the adjacent uplands.

Climate: Average annual precipitation—625 mm in the west to 900 mm in the east. Maximum precipitation is in spring, and the minimum is in winter. Snowfall ranges from 30 cm in the north to 10 cm in the south. Average annual temperature—15 to 17 C. Average freeze-free period—190 to 240 days.

Water: The moderate and somewhat erratic rainfall is the source of water for range and crops. Large reservoirs provide water for cities and towns and for recreation or flood control. Farm ponds are a major source of water for livestock. In most of the area, shallow wells supply water for domestic use, but ground water is scarce in places where sandstone and shale are near the surface.

Soils: (See top of this document for soils descriptions) The major soils are Ustalfs and Ochrepts. They have a thermic temperature regime and an ustic moisture regime. The Ustalfs are loamy and have a loamy or clayey subsoil and siliceous or mixed mineralogy. Well drained, very gently sloping, undulating to sloping or hummocky, moderately deep to deep Haplustalfs (Dougherty, Konawa, Stephenville, and Weatherford series) are on uplands. Well drained and moderately well drained, very gently sloping to steep or rolling, deep Paleustalfs (Chaney, Demona, Duffau, Eufaula, Nimrod, Niotaze, and Windthorst series) are on uplands. Ochrepts are shallow and loamy and have siliceous mineralogy. Well drained to somewhat excessively drained, very gently sloping, shallow Ustochrepts (Darnell series) are on ridge crests and steep valley slopes. Well drained, deep, nearly level Ustifluvents (Bunyan, Pulaski, and Pulexas series) and somewhat poorly drained, nearly level, deep Udifluvents (Tribbey series) are on flood plains.

Potential natural vegetation: This area supports an open stand of trees with an understory of mid and tall grasses, forbs, and low woody plants. Post oak and blackjack oak are the dominant tree species. Big blue stem, little bluestem, indiangrass, sunflower, and lespedezas are the major species in the herbaceous understory.