La Plata County Area, Colorado
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<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
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