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<br />covered with a mat of partially decomposed leaves and
<br />twigs 3 inches thick. The upper part of the surface layer
<br />is dark reddish gray loam about 11 inches thick, and the
<br />lower part is reddish gray loam about 4 inches thick. The
<br />upper 15 inches of the subsoil is reddish brown loam,
<br />and the lower 12 inches is reddish brown clay loam. The
<br />substratum to a depth of 60 inches or more is reddish
<br />brown cobbly clay loam. The rock fragments are angular
<br />in shape.
<br />Permeability of the Tampico soil is moderate. Available
<br />water capacity is high. Effective rooting depth is 60
<br />inches or more. Runoff is medium, and the hazard of
<br />water erosion is moderate to very high.
<br />The Miracle soil is moderately deep and well drained.
<br />It formed in colluvium and residuum derived dominantly
<br />from red-bed sandstone. Typically, the upper part of the
<br />surtace layer is dark reddish gray fine sandy loam about
<br />B inches thick. The lower part is reddish brown loam
<br />about 7 inches thick. The upper 7 inches of the subsoil
<br />is reddish brown loam, and the lower 5 inches is reddish
<br />brown sandy clay loam. Highly weathered and fractured
<br />sandstone that breaks down easily is at a depth of 27
<br />inches. Hard sandstone is at a depth of 32 inches. Depth
<br />to hard sandstone ranges from 20 to 40 inches. In some
<br />areas the surface layer is loam.
<br />Permeability of the Miracle soil is moderate. Available
<br />water capacity is moderate. Effective rooting depth is 20
<br />to 40 inches. Runoff is medium, and the hazard of water
<br />erosion is moderate to high.
<br />This unit is used for livestock grazing and wildlife
<br />habitat.
<br />The potential plant community on the Tampico soil is
<br />mainly Gambel oak, serviceberry, mountain brome, elk
<br />sedge, snowberry, and slender wheatgrass. Smaller
<br />amounts of chokecherry, Columbia needlegrass, and
<br />rose commonly are also present in the potential plant
<br />community. The potential plant community on the
<br />Miracle soil is mainly Idaho fescue, Letterman
<br />needlegrass, mountain brome, big sagebrush, low
<br />rabbitbrush, and serviceberry. Smaller amounts of
<br />Columbia needlegrass, slender wheatgrass, and
<br />snowberry commonly are also present in the potential
<br />plant community. The average annual production of air-
<br />dry vegetation is about 2,000 pounds per acre.
<br />If the range is overgrazed, the proportion of preferred
<br />forage plants decreases and the proportion of less
<br />preferred forage plants increases. Therefore, livestock
<br />grazing should be managed so that the desired balance
<br />of preferred species is maintained in the plant
<br />community.
<br />Management practices suitable for use on this unit are
<br />proper range use, deterred grazing, and rotation grazing:
<br />Slope limits access by livestock and results in
<br />overgrazing of the less sloping areas. Trails or walkways
<br />can be constructed in places to encourage livestock to
<br />graze in areas where access is limited. Grazing should
<br />be delayed until the soil in this unit is firm and the more
<br />• Soil survey
<br />desirable forage plants have achieved sufficient growth
<br />to withstand grazing pressure.
<br />Brush management and seeding are suitable practices
<br />where slopes are less than 15 percent. The main
<br />limitations for seeding are a short growing season,
<br />competition from brush and shrubs, and steepness of
<br />slope. For successful seeding, prepare a seedbed and
<br />drill in the seed. The plants selected for seeding should
<br />meet the seasonal requirements of livestock or wildlife,
<br />or both.
<br />This map unit is in capability subclass Vlle,
<br />nonirrigated. The Tampico soil is in Brushy Loam range
<br />site, and the Miracle soil is in Mountain Loam range site.
<br />89-Tlsworth fine sandy loam, 0 to 5 percent
<br />slopes. This deep, well drained soil is on valley floors
<br />and broad tans. It formed in alluvium derived dominantly
<br />from sedimentary rock with a high content of gypsum
<br />and alkaline salt. Areas are elongated and are 30 to 300
<br />acres. The native vegetation is mainly salt-tolerant
<br />shrubs and grasses. Elevation is 5,600 to 7,000 feet. The
<br />average annual precipitation is 13 to 15 inches, the
<br />average annual air temperature is 42 to 45 degrees F,
<br />and the average frost-free period is 80 to 105 days.
<br />Typically, the surtace layer is pale brown fine sandy
<br />loam 4 inches thick. The subsoil is light yellowish brown
<br />clay loam 7 inches thick. The upper 9 inches of the
<br />underlying material is very pale brown Tine sandy loam
<br />that has fine crystals and seams of gypsum and calcium
<br />carbonate, and the lower part to a depth of 60 inches or
<br />more is very pale brown fine sandy loam. In some areas
<br />the surface layer is loam or clay loam.
<br />Included in this unit are small areas of Absher and
<br />Havre loams, Kobar sihy clay loam, Moyerson clay loam,
<br />and Patent and Trembles loams. Also included are small
<br />areas of soils that are similar to this Tisworth soil but are
<br />severely Bullied and soils that have slightly steeper
<br />slopes. Included areas make up about 15 percent of the
<br />total acreage. The percentage varies from one area to
<br />another.
<br />Permeability of this Tisworth soil is slow. Available
<br />water capacity is moderate. Effective rooting depth is 60
<br />inches or more. Runoff is rapid, and the hazard of water
<br />erosion is moderate.
<br />This unit is used for livestock grazing, irrigated hay and
<br />pasture, and wildlife habitat.
<br />The potential plant community on this unit is mainly
<br />greasewood, big sagebrush, Nevada bluegrass, western
<br />wheatgrass, bottlebrush squirreltail, and shadscale.
<br />Smaller amounts of winterfat and rabbitbrush commonly
<br />are also present in the potential plant community. The
<br />production of forage is limited by low precipitation, rapid
<br />runoff, alkalinity, and a short growing season. The
<br />average annual production of air-dry vegetation is about
<br />600 pounds per acre.
<br />If the range is overgrazed, the proportion of preferred
<br />forage plants decreases and the proportion of less
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