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La Plata County Area, Colorado <br />s~ <br />Exhibit I - B Soil Descriptions <br />denying material is grayish brown barn, and the bwar <br />p to a depth of 60 inches or more is light brownish <br />gr clay loam. <br />cluded in this unit are about t0 percent Shalona <br />loa and small areas of Mikim loam and Harlan cobbty <br />loam <br />Pe eability of this Umbarg soil is moderetety slow. <br />Elf ' e rooting depth is 60 inches or more. Available <br />water pasty is high, Runoff is slow, and the hazard of <br />erosion slight The soil has a fluctuating water table <br />that rises to within about 3 feet of the surface in most <br />places. <br />This unit 's used mainly for inigated field crops, <br />inigeted e, and homesite development and as <br />rangeland. It 's also used for wildlife habitat. <br />In irrigated eas, the main concerns of management <br />are controlling water erosion, maintaining the orgartic <br />matter content rid fertility of the surface layer, and <br />property using ( anon water. Returning crop residue to <br />the sal ins the water intake rate, improves filth, <br />and helps to con I erosion. The use of fertilizer helps <br />to maintain the pr ctivity and fertility of the sal. Grain <br />and grasses respo to nitrogen, and legumes respond <br />to phosphorus. tan smoothing is needed in some areas <br />to achieve a mae tm orm distribution and more efficient <br />use at irrigation water. Irrlgation methods suited to this <br />unit are furrow, corrug n, and spookier systems. <br />Furrow irrigation is suRe to row crops. Corrugation <br />irrigation is well suited to mall grain and pasture. <br />Sprinkler irrgaton is well "dad to most sops. <br />Regardless of the inigatio meltxxl used, water should <br />be applied carefully to prey nt runoff and erosion. <br />The native vegetation on is unit is mainty western <br />wheatgrass, Indian ncegress, eedleantlthread, mountain <br />muhty, servicebeny, big sage sh, and Gambol oak. <br />Proper grazing use as part of planned grazing system <br />helps to maintain the quality an quantity of the <br />rangeland vegetation. Seeding a d deferring grazing <br />facilitate revegetation of areas toted by heavy <br />grazing, cultiva0on, and other dis antes. Mechanical <br />or chemical brush control followed y seeding to <br />adapted grasses improves areas have dense stands <br />of sagebrush. ()eveloping livestock terlng facilities, <br />fencing, and deferting grazing improv the diistrbtion of <br />grazing and help to maintain the cond' "on of the <br />rangeland. <br />Wildfrfe such as mule deer, pheasant, uirrel, <br />cottontail, coyote, and mourning dove u this unit <br />Irtigated areas provide food, and the ar of rangeland <br />provide shelter, nesting areas, and some f .Nearby <br />wooded areas also provide shelter and nos areas. <br />Suitable management for wildlife sixwld loci e <br />protecting the rangeland from overgrazing a wildfire <br />and maintaining adequate plant cover. <br />Wetness and shank-swell potential are the <br />limitations for homesite and urban development The <br />foundations of buildings should be designed to <br />pensate for the shook-swell potential of the sal. <br />that may be needed to overcome the UmitaUOn of <br />wetness. construction of sanitary facilities on This <br />unit poses a of poAUtirtg nearby water. The <br />moderetety slow eability of the soil and the <br />fluctuating water table Quid fte considered when <br />designing septic tank a n fiekts or sewage <br />lagoons. If drainage and prof from seepage are <br />provided, septic tank absorption fie may be suitable if <br />they are made larger than rwrmal. S lagoons can <br />be sealed to reduce seepage. <br />This map unit is in capability subclass Ille, irn d <br />antl nonirrigated. <br />70-UsUc Totriorfhartt~Uatollic.Flaplsrglda <br />caapia;:72.to.88.peegnt.eNpi~This map unit is on <br />terrace edges, rtres8 edge`s; erid'filOsides. Elevation is <br />8,000 to 8,500 feet. The average annual precipitation is <br />about t4 to 19 inches. The average annual air <br />temperature is 45 to 50 degrees F, and the average <br />frost-free period is 100 to 130 days. <br />This unit is 50 percent Ustic Tortiorthents and 30 <br />percent Ustoll'x; Haplargtls. The Ustalic Haplargids are <br />in the less sloping areas. <br />InGuded in this unit are about t5 percent soils that are <br />underlain by bedrock at a depth of 40 inches or less and <br />5 percent shale and sandstone Rock outcrop. <br />Ustic Toniorthems are deep and somewhat <br />excessively drained. These soils formed in outwash. No <br />single profile of Ustic Torriorthenta is typical, but one <br />commonty observed in the survey area has a surface <br />layer of grevelty or cobbty loam or fine sandy loam. The <br />substratum is very gravelty or very cobbty oulwash. <br />Ustollic Haplargids are deep and well drained. They <br />formed in gravelly and cobbly alluvium. No single profile <br />of Ustoilic Haplargids is typical, but one commonty <br />observed in the survey area has a surface layer of <br />gravelly or cobbly loam or fine sandy loam. The subsoil <br />is very cobbly or very gravelty loam, very gravelly or very <br />wbbly sandy clay loam, or very gravelly or very cobbty <br />fine sandy loam. The substratum is very gravelty or very <br />cobbly outwash. <br />Permeability of these Ustic Torrlorthents and Ustollic <br />Haplargids varies depending on the texture of the parent <br />material. Effective rooting depth is 40 inches or more. <br />Available water capacity is low. Runoff is rapid, and the <br />hazard of erosion is high. <br />This unit is used mainy for wildlife habitat, as <br />rangeland, and as a source of construction material. <br />The native vegetation on this unit is mainly western <br />wheatgrass, Indian ncegrass, needteandthread, blue <br />grams, muttongrass, Fendler threeawn, junegrass, big <br />sagebrush, rabbitbrush, pinyon, Rocky Mountain juniper, <br />ponderosa pine, mountainmahogany, sarviceberry, <br />snowbeny, and Gambet oak. Steepness of slaps limits <br />access by livestock and promotes overgrazing of the <br />less soping areas. Proper grazing use as part of a <br />