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HomeMy WebLinkAbout1.03 Soil featuresPart VI Soil Features The United States Department of Agriculture Soil Conservation Service Soil Survey of Rifle Area, Colorado provides the following information about the soils and environment in the area of the facility: 45-Morval-Tridell complex, 6 to 25 percent slopes. These moderately sloping to hilly soils are on alluvial fans and sides of mesas. Elevation ranges from 6,500 to 8,000 feet. The soils formed in reworked alluvium derived from basalt and sandstone. The average annual precipitation is about 15 inches, the average annual air temperature is about 44 degrees F, and the average frost -free period is about 100 days. The Morval soil makes up about 55 percent of the unit, and the Tridell soil makes up about 30 percent. The Morval soil is on the less sloping parts of the landscape, and the Tridell soil is on the sides of mesas. The Morval soil is deep and well drained. Typically, the surface layer is brown loam about 5 inches thick. The upper part of the subsoil is brown and light brown clay loam and stony clay loam about 12 inches thick, and the lower part is light brown stony clay loam about 10 inches thick. The substratum is pink stony loam. Permeability of the Morval soil is moderate, and available water capacity is moderate. Effective rooting depth is 60 inches. Surface runoff is medium, and the erosion hazard is moderate. The Tridell soil is deep and well drained. Typically, the surface layer is brown stony loam 10 inches thick. The upper part of the underlying material is brown very stony loam 11 inches thick, and the lower part is pinkish white very stony loam to a depth of 60 inches. Permeability of the Tridell soil is moderately rapid, and available water capacity is low. Effective rooting depth is 60 inches. Surface runoff is medium, and the erosion hazard is moderate. Included with these soils in mapping are small areas of Villa Grove and Zoltay soils on the steeper parts of the landscape. These areas make up about 15 percent of the map unit. These soils are used mainly for grazing. The native vegetation on the Morval soil is mainly needleandthread, wheatgrass, and sagebrush. The native vegetation on the Tridell soil is mainly pinyon, Utah juniper, and some Rocky Mountain juniper and an understory mostly of wheatgrass, Indian ricegrass, needleandthread, junegrass, serviceberry, bitterbrush, mountainmahogany, and big sagebrush. When range condition deteriorates, forbs and shrubs increase. Properly managing grazing maintains and improves range condition. Seeding improves range in poor condition on gently sloping Morval soils. Bluebunch wheatgrass, western wheatgrass, and needleandthread are suitable for seeding. Preparing a seedbed and drilling the seed are good practices. Reducing brush improves range that is producing more shrubs than are normally found in the potential plant community. Properly managing the vegetation on the Tridell soil maintains wood production and grazing. Selectively thinning pinyon and juniper improves grazing and provides firewood, posts, and Christmas trees. The Tridell soil is suited to production of pinyon and Utah juniper. It can produce 8 cords of wood per acre when trees more than 4.5 feet tall reach an average diameter (at one foot) of 5 inches. Special care is needed to prevent erosion during harvest. The low avail- able water capacity affects survival of seedlings. Mule deer, wild turkey, and squirrel find habitat on these soils. Community development is limited by large stones. Cut slopes are difficult to revegetate because of the stones and because of the shrink -swell potential and frost action of the Morval soil. This complex is in capability subclass VIe, nonirrigated. 3 -Arvada loam, 1 to 6 percent slopes. 4 -Arvada loam, 6 to 20 percent slopes. This deep, well drained, sloping soil is on fans and high terraces. Elevation ranges from 5,100 to 6,200 feet. This soil formed in highly saline alluvium derived from sandstone and shale. The average annual precipitation is about 12 inches, average annual air temperature is about 48 degrees F, and the average frost -free period is about 120 days. Typically, the surface layer is moderately alkaline, pale brown loam about 3 inches thick. The subsoil is brown silty clay loam about 14 inches thick. The substratum is light brown or brown silty clay loam to a depth of 60 inches. Included with this soil in mapping are small areas of Limon, Kim, and Heldt soils. Permeability is very slow, and available water capacity is high. Effective rooting depth is 60 inches or more. Organic matter content of the surface layer is low. Surface runoff is moderately rapid, and the erosion hazard is severe. This soil is used mainly for wildlife habitat and limited grazing. The native vegetation on this soil is mainly sagebrush, greasewood, and wheatgrass. When range condition deteriorates, grasses decrease and weedy forbs, cheatgrass, big sagebrush, and greasewood increase. Properly managing grazing maintains and improves range condition. Seeding improves range in poor condition. Western wheatgrass and tall wheatgrass are suitable for seeding. Preparing a seedbed and drilling the seed are good practices. Irrigating new seedings is necessary for successful establishment. Brush should not be reduced because grass production is low and some desirable native shrubs could be destroyed. Cottontail and pheasants find shelter on this soil if they can obtain food in surrounding areas. Use of this soil for sanitary facilities and as a source of construction material is limited by the large amounts of clay and salts. This soil is corrosive to steel and concrete. High shrink -swell potential, salinity, and steep slopes limit community development. This soil is in capability subclass VIIs, nonirrigated. 67-Torriorthents-Rock outcrop complex, steep. This broadly defined unit consists of exposed sandstone and shale bedrock and stony soils that are shallow to moderately deep over sandstone and shale and stony basaltic alluvium. Areas of this complex occur throughout the survey area. The soils and outcrops are moderately steep to very steep. Slope ranges from 15 to 70 percent. Torriorthents make up about 60 percent of this complex, and Rock outcrop makes up 25 percent. The Torriorthents are on foothills and mountainsides below the Rock outcrop. Torriorthents are generally clayey to loamy and contain variable amounts of gravel, cobbles, and stones. The surface is normally covered with stones weathered from the higher -lying Rock outcrop. South of the Colorado River, stones and cobbles of basalt are on the surface. The Rock outcrop is mainly Mesa Verde sandstone and Wasatch shale. Some areas are covered with basaltic boulders and stones. Small areas of limestone out- crops and exposed gypsum are in the eastern part of the survey area. Included in mapping are small isolated areas of Ildefonso, Lazear, Ansari, Gaynor, Tridell, and Nihill soils. These intermittent areas make up 10 to 15 percent of this map unit. This complex is used for limited grazing, wildlife habitat, and recreation. Because of the stones on the surface, the Rock outcrop, and the steep slope, this complex is unsuited to crops. The native vegetation includes wheatgrass, bluegrass, Indian ricegrass, needlegrass, bitterbrush, sagebrush, mountain mahogany and an overstory of pinyon and juniper. The vegetation should be managed to maintain wood production and limited grazing. Selectively thinning the pinyon and juniper improves grazing and provides firewood and posts. Steep slopes, moderate to severe erosion hazard, and slow regrowth of trees affect harvesting and management. Most of this complex is a prime wintering area for deer. Rabbits, coyote, and a few elk also find food and cover on this complex. Community development is limited by the Rock outcrop, steep slopes, and stoniness. These limitations can be overcome by appropriate design and construction. This complex is in capability subclass VIIe, nonirrigated. 34-Ildefonso stony loam, 25 to 45 percent slopes. This deep, well drained, hilly to steep soil is on mesa breaks, sides of valleys, and alluvial fans. A small portion of this unit is on very steep to extremely steep mesa escarpments. Elevation ranges from 5,000 to 6,500 feet. This soil formed in mixed alluvium derived primarily from basalt. This soil has a thin intermittent cap of reddish eolian material. The average annual precipitation is about 14 inches, the average annual air temperature is about 46 degrees F, and the average frost -free period is about 125 days. Typically, the surface layer is brown stony loam about 8 inches thick. The underlying material is white, very strongly calcareous very stony loam to a depth of 60 inches. Included with this soil in mapping are small areas of Potts and Ascalon soils on less steep and depressional positions. These areas make up about 5 to 15 percent of the map unit. Permeability is moderately rapid, and available water capacity is low. Effective rooting depth is more than 60 inches. Surface runoff is medium, and the erosion hazard is severe. Ildefonso soil is used mainly for grazing and wildlife habitat. The native vegetation on this soil is mainly pinyon and Utah juniper. The understory consists of Indian ricegrass, wheatgrass, junegrass, serviceberry, bitterbrush, and big sagebrush. When the understory vegetation deteriorates, grasses almost disappear and forbs and shrubs increase. Properly managing the vegetation maintains wood production and ground cover. The value for grazing is low because of steep slopes and tree cover. Firewood, posts, and Christmas trees can be harvested on the more gently sloping areas. This soil is suited to production of pinyon and Utah juniper. It can produce 9 cords of wood per acre when trees more than 4.5 feet tall reach an average diameter (at one foot) of 5 inches. The low available water capacity affects survival of tree seedlings. Steep slopes and severe erosion hazard affect harvesting. Mule deer, chukar, wild turkey, gray squirrel, and cot- tontail rabbit find habitat on this soil. Community development is limited by large stones and steep slopes. Structures to divert runoff are needed for roads. This soil is in capability subclass Vile, nonirrigated. 50 -Olney loam, 3 to 6 percent slopes. 51 -Olney loam, 6 to 12 percent slopes. This deep well drained, moderately sloping to rolling soil is on alluvial fans and sides of valleys. Elevation ranges from 5,000 to 6,500 feet. This soil formed in alluvium derived from sandstone and shale. The average annual precipitation is about 14 inches. the average annual air temperature is about 48 degrees F, and the frost -free period is about 125 days. Typically, the surface layer is grayish brown loan about 12 inches thick. The subsoil is grayish brown am light gray sandy clay loam about 21 inches thick. The substratum is light gray gravelly sandy clay loam am very gravelly sandy loam to a depth of 60 inches. Included with this soil in mapping are small areas of Heldt, Potts, and Kim soils that have slopes of 6 to 12 percent. These areas make up 5 to 15 percent of the map unit. Permeability is moderate, and available water capacity is moderate. Effective rooting depth is 60 inches or more. Surface runoff is medium, and the erosion hazard is moderate. This soil is used mainly for irrigated hay, fruits, and grazing. Grass -legume mixtures and apples, peaches, and apricots are grown. This soil is irrigated by furrows and flooding. Sprinklers are also suitable. Drop structures in irrigation ditches help to control water and prevent excessive ditch erosion. Keeping a grass or legume cover on this soil at least three-fourths of the time controls erosion. The native vegetation on this soil is mainly wheat- grass, needleandthread, and sagebrush. When range condition deteriorates, forbs and shrubs increase. When the range is in poor condition, undesirable weeds and annual plants are numerous. Properly managing grazing maintains and improves range condition. Reducing brush improves the range. Seeding improves range in poor condition. Crested wheatgrass, western wheatgrass, and Russian wildrye are suitable for seeding. Preparing a seedbed and drilling the seed are good practices. Cottontail rabbit, squirrel, pheasant, and some mule deer find habitat on this soil. Community development and recreation are limited by steep slopes and low strength. This soil is in capability subclass IVe, irrigated and nonirrigated. 55 -Potts loam, 3 to 6 percent slopes. This deep, well drained, moderately sloping soil is on mesas, benches, and sides of valleys. Elevation ranges from 5,000 to 7,000 feet. This soil formed in alluvium derived from sandstone, shale, or basalt. The average annual precipitation is about 14 inches, the average annual air temperature is about 46 degrees F, and the average frost -free period is about 120 days. Typically, the surface layer is brown loam about 4 inches thick. The subsoil is reddish brown clay loam about 24 inches thick. The substratum is pinkish white loam to a depth of 60 inches. Included with this soil in mapping are small areas of Olney, Kim, and Ildefonso soils that have slopes of 3 to 6 percent. These areas make up 1 0 to 15 percent of the map unit. Permeability is moderate, and available water capacity is high. Effective rooting depth is 60 inches or more. Surface runoff is slow, and the erosion hazard is moderate. This soil is used mainly for irrigated crops and hay and for dryland farming (fig. 10). Alfalfa, small grains, and grass -legume hay are grown. Small areas are used for grazing. These soils are usually irrigated by flooding. Drop structures in irrigation ditches, grassed waterways, and minimum tillage prevent serious erosion. Irrigation water should be carefully managed to avoid piping and erosion. Cover crops or stubble mulching also help to limit erosion in dryfarmed areas. The native vegetation on this soil is mainly wheatgrass, needleandthread, and sagebrush. When range condition deteriorates, forbs and shrubs increase. When the range is in poor condition, undesirable weeds and annual plants are numerous. Properly managing grazing maintains and improves range condition. Reducing brush improves the range. Seeding improves range in poor condition. Crested wheatgrass, western wheatgrass, and Russian wildrye are suitable for seeding. Preparing a seedbed and drilling the seed are good practices. Pheasant, mourning dove, cottontail rabbit, some mule deer, and squirrel find habitat on this soil. Community development and recreation are limited by low strength and the shrink -swell potential. Dwellings and roads can be designed to overcome these limitations. Community sewage systems will be needed if the population density increases. This soil is in capability subclasses IIIe, irrigated, and IVe, nonirrigated. 58-Potts-lldefonso complex, 12 to 25 percent slopes. These strongly sloping to hilly soils are on mesas, alluvial fans, and sides of valleys. Elevation ranges from 5,000 to 6,500 feet. The Potts soil formed in alluvium derived from sandstone, shale, or basalt. The Ildefonso soil formed in very strongly calcareous, basaltic alluvium and small amounts of eolian material. The aver- age annual precipitation is about 14 inches, the average annual air temperature is about 46 degrees F, and the average frost -free period is about 120 days. The Potts soil makes up about 60 percent of this unit, and the Ildefonso soil makes up about 30 percent. The Potts soil is in slightly concave positions, and the Ildefonso soil is on the breaks of steeper slopes. The Potts soil is deep and well drained. Typically, the surface layer is brown loam about 4 inches thick. The subsoil is reddish brown clay loam about 24 inches thick. The substratum is pinkish white loam to a depth of 60 inches. Permeability of the Potts soil is moderate, and available water capacity is high. Effective rooting depth is 60 inches or more. Surface runoff is medium, and the erosion hazard is moderate. The Ildefonso soil is deep and well drained. Typically, the surface layer is brown stony loam about 8 inches thick. The underlying material is white, calcareous very stony loam to a depth of 60 inches. Permeability of the Ildefonso soil is moderately rapid, and available water capacity is low. Effective rooting depth is about 60 inches. Surface runoff is medium, and the erosion hazard is moderate. Included with this soil in mapping are small areas of Morval and Lazear soils. The Morval soils are at the higher elevations. The Lazear soils are shallow and are on ridge crests and steep mountainsides. These areas make up 10 to 18 percent of the map unit. These soils are used mainly for limited grazing and wildlife habitat. The native vegetation on the Potts soil is mainly wheatgrass, needleandthread, and sagebrush. The native vegetation on the Ildefonso soil is mainly pinyon and Utah juniper and an understory of Indian ricegrass, wheatgrass, junegrass, serviceberry, bitterbrush, and sagebrush. When the understory vegetation deteriorates, grasses almost disappear and forbs and shrubs increase. Properly managing grazing maintains and improves range con- dition on both soils. Seeding improves range in poor condition in less sloping areas of the Potts soil. Blue- bunch wheatgrass, western wheatgrass, and needleandthread are suitable for seeding. Preparing the seedbed and drilling the seed are good practices. Controlling brush on the Potts soil improves range that is producing more shrubs than are normally found in the potential plant community. Properly managing the understory vegetation on the Ildefonso soil maintains wood production and grazing. Selectively thinning pinyon and juniper improves grazing and provides firewood, posts, and Christmas trees. The Ildefonso soil is suited to production of pinyon and Utah juniper. It can produce 9 cords of wood per acre when trees more than 4.5 feet tall reach an average diameter (at one foot) of 5 inches. The low available water capacity affects survival of tree seedlings. Mule deer, wild turkey, chukar, gray squirrel, cottontail rabbit, and some pheasant find habitat on these soils. The steep slopes limit community development. Structures are needed to divert runoff to minimize gullying and erosion. This complex is in capability subclass VIe, nonirrigated.