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2.04.9 <br />Soil Map Unit No. 3 <br />Pinon loam, 3 to 50 percent slopes. This shallow and well <br />drained soil is formed in residuum derived dominantly from inter- <br />bedded sandstone and shale. This unit is on edges of mesas, <br />benches and escarpments. The native vegetation is mainly Pinyon <br />pine, and Utah juniper with sparse grass and shrub understories. <br />Elevation is 5400 to 6800 feet. The average annual precipitation <br />is 10 to 14 inches, the average annual air temperature is 46 to <br />48 degrees F. , and the average frost-free period is 110 to 130 <br />days. <br />Typically the surface layer is brown loam about 5 inches <br />thick. The underlying material to a depth of 16 inches is pink- <br />ish white loam. Hard sandstone is at a depth of 16 inches. In <br />some areas the surface layer is gravelly loam, gravelly sandy <br />loam, sandy loam or cobbly loam. <br />Included in this unit is 15 to 20 percent of Progresso, <br />Bo~adlisk, and small areas of Bares and Paradox soils. .41so in- <br />cluded are small areas of similar soils having greater than 35 <br />percent rock fragments in the control section and soils that lack <br />a calcic horizon. Also found are small areas of sandstone and <br />shale rock outcrops. The included components of this unit are so <br />intricately intermingled that is not practical to map them sepa- <br />rately. <br />• Permeability of this Pinon soil is moderate. Available <br />water capacity is very low. Effective rooting depth is 10 to 20 <br />inches. Runoff is medium and the hazard of water erosion is <br />high. <br />This unit is used for limited livestock grazing and wildlife <br />habitat. <br />The potential plant community on this unit is mainly Pinyon <br />pine and Utah juniper with an understory of Indian ricegrass, <br />Salina wildrye, galleta, and big sagebrush. The average annual <br />production of air-dry vegetation is about 300 to 800 pounds per <br />acre. <br />If the condition of the understory deteriorates, Fendler <br />threeawn, hairy goldaster, broom snakeweed, and prickly pear <br />cactus increase. Where the understory is in poor condition, <br />these plants are dominant. Grazing should be managed so that the <br />desirable balance of species is maintained in the plant communi- <br />ty. <br />• 2.04-23 <br />