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<br />can be overcome by increasing the size of the
<br />absorption field.
<br />This soil is in capability subclasses Ille, irrigated, and
<br />Vlle, nonirrigated. It is in the Mountain Outwash range
<br />site.
<br />49-Morval clay loam, 3 to 6 percent slopes. This
<br />deep, well drained soil is on valley side slopes and fans.
<br />Elevation is 7,700 to 8,400 feet. The soil formed in
<br />moderately fine textured alluvium derived from igneous
<br />rocks. The average annual precipitation is about 15
<br />inches; the average annual air temperature is about 41
<br />degrees F; and the frost-free period is about 85 days.
<br />Included in this unit are a few small areas of Rock
<br />River gravelly loam, Garita gravelly loam, and Derrick
<br />very gravelly loam.
<br />Typically, the surface layer of this Morval soil is dark
<br />reddish gray clay loam about 5 inches thick. The subsoil
<br />is reddish gray and reddish brown clay loam about 22
<br />inches thick. The substratum to a depth of 60 inches is
<br />light reddish brown light clay loam and brown gravelly
<br />clay loam.
<br />Permeability is moderate. Effective rooting depth is 60
<br />inches or more. Available water capacity is high. Surface
<br />runoff is medium, and the hazard of erosion is moderate.
<br />This soil is used principally as range and wildlife
<br />habitat with some recreation uses.
<br />The potential natural vegetation on this Morval soil is
<br />dominated by western wheatgrass, needleandthread, and
<br />fourwing saltbush. If the range condition deteriorates, the
<br />proportion of more desirable species, such as western
<br />wheatgrass and needleandthread, decreases and that of
<br />the less desirable species, such as blue grama, rubber
<br />rabbitbrush, (orbs, and annuals increases. Undesirable
<br />weeds and annual plants invade and become more
<br />abundant as the range condition declines.
<br />Establishing rangeland seedlings on this soil is difficult
<br />because of low rainfall and cold climate. Species suitable
<br />for seeding are Russian wildrye, Nordan crested
<br />wheatgrass, Siberian wheatgrass, and pubescent
<br />wheatgrass. Seedbed preparation should be done on the
<br />contour to minimize soil erosion. Late summer seedings
<br />have proven most successful. Deferred grazing,
<br />stockwater developments, brush control, and erosion
<br />control structures help prevent range deterioration.
<br />Wildlife such as antelope, cottontail, jackrabbit, and
<br />coyote are adapted to the habitat supported by this soil.
<br />Forage production is low, and livestock grazing
<br />management can help maintain wildlife habitat. Livestock
<br />water developments are beneficial for both livestock and
<br />wildlife.
<br />Recreation on this unit is mainly hunting, hiking, and
<br />sightseeing.
<br />This soil is suited to homesite development. The main
<br />limitation is shrink-swell potential. The effects of
<br />shrinking and swelling can be minimized by using proper
<br />engineering designs and by backfilling with material that
<br />Soil Survey
<br />has low shrink-swell potential. The designs of roads built
<br />on areas of this soil must offset the soil's low load-
<br />bearing strength. Erosion is a hazard in the steeper
<br />areas. Only the part of the site that is used for
<br />construction should be disturbed.
<br />This soil is in capability subclass Vle, nonirrigated. It is
<br />in the Foothill Loam range site.
<br />50-Mosca loamy sand, 0 to 3 percent slopes. This
<br />deep, well drained soil is moderately affected by alkali. It
<br />is on fans and flood plains on alluvial valley floors.
<br />Elevation is 7,600 to 7,800 feet. The soil formed in
<br />alluvium derived mainly from basalt. The average annual
<br />precipitation is about 7 inches; the average annual air
<br />temperature is about 41 degrees F; and the average
<br />frost-free period is about 90 days.
<br />Included in this map unit are small areas of Hooper
<br />loamy sand and McGinty sandy loam.
<br />Typically, the surface layer of this Mosca soil is very
<br />pale brown and brown loamy sand about 8 inches thick.
<br />The subsoil, about 6 inches thick, is brown sandy loam
<br />that is affected by alkali. The upper part of the
<br />substratum is brown calcareous loamy sand about 18
<br />inches thick. The lower part to a depth of 60 inches is
<br />sand and very gravelly sand.
<br />Permeability is moderate above the substratum.
<br />Effective rooting depth is about 60 inches. Available
<br />water capacity is low. Surface runoff is slow, and the soil
<br />blowing hazard is high.
<br />This soil is used for irrigated potatoes, alfalfa, and
<br />small grains and for range. Applications of gypsum,
<br />commercial Tertilizers, crop residue, and manure are
<br />generally needed. Gypsum helps leach alkali from the
<br />soil. Generally, small grains and potatoes respond to
<br />phosphate fertilizers. Use of minimum tillage practices
<br />and high-residue crops helps prevent soil blowing.
<br />The sprinkler and furrow systems of irrigation are well
<br />suited to potatoes. Border and sprinkler irrigation
<br />systems are suited to alfalfa and small grains. Where
<br />border and furrow irrigation systems are used, land
<br />leveling and adjusted lengths of run are necessary to
<br />conserve water and prevent seepage and buildup of
<br />salts in the soil surface.
<br />The potential natural vegetation on this soil is
<br />dominated by Indian ricegrass, blue grama, alkali
<br />sacaton, and thickspike wheatgrass. Black greasewood,
<br />rubber rabbitbrush, and founving saltbush are prominent
<br />but widely spaced. If the range deteriorates, the
<br />proportion of the more desirable grasses, such as Indian
<br />ricegrass, alkali sacaton, and thickspike wheatgrass,
<br />decreases, and that of black greasewood, rubber
<br />rabbitbrush, and blue grama increases. Undesirable
<br />weeds and annual plants invade and become more
<br />abundant as the range condition declines.
<br />Establishing rangeland seedlings is very difficult
<br />because of the low rainfall, low available water capacity,
<br />and alkali conditions. Deferred grazing, cross fencing,
<br />
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