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Yuma County, Colorado
<br />use as septic tank filter fields because of the difficulty of
<br />laying leach lines. If areas of suitable soils can not be
<br />located nearby, a pad of suitable soil material can be
<br />constructed and leach lines placed in it.
<br />Capability subclass VIe, nonirrigated and irrigated.
<br />9— Canyon -Rock outcrop complex, 9 to 25 percent
<br />slopes. This complex consists of Rock outcrop and an
<br />undulating to moderately steep soil on the rim of the
<br />valleys of the Republican and Arikaree Rivers. The areas
<br />are elongated and are up to 1,000 acres in size.
<br />Canyon soil makes up 50 percent of the map unit,
<br />Rock outcrop 20 percent, Bayard fine sandy loam 20
<br />percent, and Valent sand and Eckley gravelly sandy
<br />loam 5 percent each. Bayard and Valent soils are on
<br />slopes below outcroppings of caprock. The Eckley soil is
<br />on top of the caprock. In places, shale outcrops on the
<br />steep slopes of canyons below caprock.
<br />The Canyon soil is shallow and well drained. It formed
<br />in sandstone that caps the Ogallala Formation. Typically,
<br />the surface layer is grayish brown, calcareous loam
<br />about 8 inches thick. The layer below that is light
<br />brownish gray, calcareous loam about 4 inches thick.
<br />White, calcareous sandstone is at a depth of 12 inches.
<br />Permeability is moderate. The available water capacity
<br />is very low. The effective rooting depth is 6 to 20 inches.
<br />Surface runoff is medium. Water erosion and soil blowing
<br />are moderate hazards.
<br />Rock outcrop consists of areas of barren, exposed,
<br />highly calcareous sandstone.
<br />This complex is used as rangeland. The main concern
<br />of management is maintaining range in good condition.
<br />The potential native vegetation on the Canyon soil is
<br />little bluestem, threadleaf sedge, prairie sandreed,
<br />sideoats grama, and blue grama. Continuous heavy
<br />grazing will cause an increase in the population of mat
<br />plants, yucca, sedges, fringed sagebrush, and blue
<br />grama and a decrease of the taller grasses.
<br />Management of grazing on this soil can maximize the
<br />amount of forage on rangeland. Because of the steep
<br />slopes and rock outcrops, the use of machinery and
<br />seeding normally are not feasible.
<br />This complex is relatively unproductive of vegetation,
<br />especially in times of drought when production may be
<br />as low as 625 pounds per acre per year. Rangeland
<br />wildlife, for example, the antelope and scaled quail, can
<br />be encouraged by developing livestock watering
<br />facilities, by proper livestock grazing management, and
<br />by range seeding, if needed.
<br />This complex generally is not suited to windbreaks and
<br />environmental plantings. Onsite investigation is needed if
<br />plantings are contemplated.
<br />This complex is not well suited to use as homesites
<br />because shallow soil, rockiness, and steep slopes cause
<br />severe construction problems. The Canyon soil is very
<br />poorly suited to use as septic tank filter fields. However,
<br />it is possible to find areas of included soils that may be
<br />suitable if downstream pollution can be avoided. In spite
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<br />of construction difficulties, attractive sites for houses can
<br />be developed with careful site selection and design.
<br />Capability subclass Vlls, nonirrigated.
<br />10 —Colby silt loam, 3 to 6 percent slopes. This is a
<br />deep, well drained, gently undulating soil. It formed in
<br />loess on plains. The areas of this soil are mainly in the
<br />southeastern part of the county. They are as much as
<br />400 acres in size.
<br />Included in mapping and making up about 15 percent
<br />of this map unit are areas of Kuma silt loam and Keith
<br />silt loam. These soils are at the base of slopes and in
<br />narrow swalelike areas.
<br />Typically, the surface layer is light brownish gray,
<br />calcareous silt loam about 8 inches thick. The underlying
<br />material, to a depth of 60 inches or more, is very pale
<br />brown, calcareous silt loam. In places, the surface layer
<br />is fine sandy loam. In some areas, it is darker and
<br />thicker than is typical.
<br />Permeability is moderate. The available water capacity
<br />is high. Surface runoff is medium. Water erosion and soil
<br />blowing are moderate hazards.
<br />About 80 percent of the acreage is nonirrigated
<br />cropland used for winter wheat. The wheat is grown in a
<br />crop - fallow sequence to conserve moisture. About 10
<br />percent of the acreage is irrigated cropland, and about
<br />10 percent is rangeland.
<br />The main concerns in managing irrigated cropland are
<br />controlling water erosion and soil blowing and
<br />maintaining soil fertility and tilth. Soil blowing can be
<br />controlled by incorporating crop residue into the surface
<br />layer. Incorporating residue into the surface layer can
<br />also improve soil tilth and water intake and reduce
<br />erosion. Minimum tillage helps to maintain tilth and
<br />reduce erosion. This soil is low in nitrogen, and fertilizer
<br />is needed. Grasses and legumes in rotation about one -
<br />fourth of the time help to maintain tilth and fertility and
<br />improve water intake.
<br />This soil is suited to sprinkler irrigation. Water must be
<br />applied slowly to reduce runoff, and enough water must
<br />be applied to moisten the soil fairly deep.
<br />The main concerns in managing nonirrigated cropland
<br />are controlling water erosion and soil blowing and
<br />conserving soil moisture. The essential conservation
<br />practices are stubble mulch tillage and striperopping.
<br />Where soil slopes are long enough to permit their use,
<br />terracing and farming on the contour help to reduce
<br />runoff. Because of the weak structure and low organic
<br />matter content, this soil is very susceptible to soil
<br />blowing during windy and droughty periods. Emergency
<br />tillage that leaves ridges on the surface at right angles to
<br />the prevailing wind can be effective temporarily. The best
<br />erosion - control practice is maintaining a protective cover
<br />throughout the year.
<br />The potential native vegetation includes blue grama,
<br />buffalograss, western wheatgrass, sedges, and green
<br />needlegrass. Continuous heavy grazing causes western
<br />wheatgrass and green needlegrass to decrease and
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