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28
<br />Granite bedrock is at a depth of 28 inches. The soil is
<br />slightly acrid.
<br />Permeability of this Woodhall soil is moderate, and the
<br />available water capacity is low. The effective rooting
<br />depth is 20 to 40 inches. Surface runoff is medium, and
<br />the hazarri of erosion is slight.
<br />Most areas of this complex are used as rangeland.
<br />Very steep :;lopes somewhat limit accessibility for
<br />livestock.
<br />The potential native vegetation is mainly Arizona
<br />fescue, mountain muhty, pine dropseed,
<br />mountainnaahogany, and a few ponderosa pines. As the
<br />range deteriorates, blue grams, (ringed sage,
<br />snakeweed, and slimstem muhly increase. The use of a
<br />planned grazing system, cross fencing, and livestock
<br />water dew~fopments helps to prevent range deterioration
<br />and promotes the production of the more desirable
<br />plants. Seeding on this site is inadvisable because of the
<br />large number of rock fragments on the surface, the
<br />outcrops of rock, and the steep slopes.
<br />This soil is poorly suited to use as homesites. Limiting
<br />features are slope, depth to rock, and rock fragments.
<br />They make excavation for roads, utility lines,
<br />foundatioras, and septic tanks difficult. Septic tank
<br />absorption fields will not function properly in most areas
<br />because of steep slopes and shallowness to rock.
<br />This complex is in capability subclass Vlls,
<br />nonirrigated.
<br />32-Silvercliff gravelly sandy loam, 1 to 4 percent
<br />slopes. Tttis is a deep, wet( drained soil on low terraces
<br />and fans. It formed in calcareous alluvium. Elevation is
<br />7,800 to 8,200 feet. The average annual precipitation is
<br />14 to 17 inches, the average annual air temperature is
<br />40 to 44 degrees F, and the frost-free season is 55 to 75
<br />days.
<br />Typically, the surface layer is dark grayish brown
<br />gravelly sandy loam 8 inches thick. The subsoil is light
<br />brown gravelly loam 13 inches thick. The substratum is
<br />reddish brown very gravelly sandy loam in the upper 12
<br />inches, and it is reddish brown very gravelly loamy sand
<br />to a depth of 60 inches or more. The soil is moderately
<br />alkaline and calcareous.
<br />Included with this soil in mapping are areas of Becks
<br />gravelly Loam in low lying positions on the landscape and
<br />along drainageways, They make up about 10 percent of
<br />the map unit. .
<br />Permeability of this Silvercliff soil is moderately rapid,
<br />and the available water capacity is low. The effective
<br />rooting depth is 60 inches or more. Surface runoff is very
<br />slow, and the hazard of erosion is slight.
<br />Most areas are used as rangeland. A few areas are
<br />used for irrigated hay or pasture. Mixtures of brome,
<br />orchardgr.ass, pubescent wheatgrass, and timothy are
<br />commonly grown.
<br />Flooding is a suitable method of irrigating this soil (fig.
<br />8). If the soil is not protected, however, severe water
<br />erosion can result. Land leveling makes irrigation more
<br />• Soil survey -
<br />efficient and reduces erosion. Crops respond well to
<br />nitrogen and phosphorus. With good management, this
<br />soil is capable of producing about 4 tons of grass hay
<br />per irrigated acre.
<br />The potential native vegetation is mainly
<br />needleandthread, western wheatgrass, Arizona fescue,
<br />and junegrass. As the range deteriorates, blue grams,
<br />sleepygrass, slimstem muhly, and rabbitbrush increase.
<br />Renovating and using a planned grazing system and
<br />cross fencing help to prevent range deterioration and
<br />promote the production of the morn desirable plants. In
<br />renovating, seed should be drilled into a well prepared,
<br />firm, weed-free seedbed. Suitable grasses for seeding
<br />are intermediate wheatgrass, pubescent wheatgrass,
<br />western wheatgrass, and Arizona fescue.
<br />This soil is well suited to use as homesites.
<br />Community sewage systems are needed in areas of high
<br />population density because of the hazard of polluting the
<br />ground water. The included areas of Becks soil are
<br />limited for this use by a high water table.
<br />The Silvercliff soil is a suitable source of sand and
<br />gravel and is a good source of roadfill.
<br />This soil is in capability subclasses Vle, nonirrigated,
<br />and Vc, irrigated.
<br />33-Sllvercllff cobbly sandy loam, 15 to 35 percent
<br />slopes. This is a deep, well drained soil on terrace
<br />edges. It formed in calcareous alluvium. Elevation is
<br />8,000 to 9,200 feet. The average annual precipitation is
<br />14 to 17 inches, the average annual air temperature is
<br />40 to 44 degrees F, and the frost-tree season is 55 to 75
<br />days.
<br />Typically, the surface layer is grayish brown cobbly
<br />sandy loam 8 inches thick. The subsoil is brown very
<br />gravelly sandy loam 6 inches thick. The substratum is
<br />stratified very gravelly sandy loam, very gravelly sand,
<br />loamy sand, and cobbly loam to a depth of 60 inches.
<br />The soil is mildly alkaline to a depth of 14 inches,
<br />moderately alkaline and calcareous to a depth of 34
<br />inches, mildly alkaline to a depth of 43 inches, and
<br />moderately alkaline and calcareous below that depth.
<br />Included with this soil in mapping, and making up ~;;•
<br />about 15 percent of the unit, aro areas of Coutis sandy ,
<br />loam along drainageways and on foot slopes.
<br />Permeability oT this Silvercliff soil is moderately rapid; ,^
<br />and the available water capacity is low. The effective ' '
<br />rooting depth is 60 inches or more. Surtace runoff is -.~? , '
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<br />medium, and the hazard of erosion is high. ~ r 9!~
<br />Most areas are used as rangeland (fig. 9).
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<br />The potential native vegetation on this soil is mainly . r
<br />needleandthread, western wheatgrass, and Arizona
<br />fescue. As the range deteriorates, the proportion of the •>
<br />more desirable plants decreases and the proportion of
<br />the less desirable plants such as threeawn, slimstem ~?;,
<br />muhly, sleepygrass, fringed sage, and rabbitbrush '~ii
<br />increases. Undesirable weeds. r.~,rubs, and annu^IS :J~
<br />I
<br />invade and become mares ab:: '.:art as range c:.ndition .>
<br />further deteriorates. A r ~nc~ grazing systen ', ~!os to
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