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Custer County Area, Colorado
<br />of rolling uplands. They make up about 5 percent of the
<br />unit.
<br />Permeability of this Martinsdale soil is moderately
<br />slow, and the available water capacity is moderate. The
<br />effective rooting depth is 60 inches or more. Surface
<br />runoff is medium, and the hazard of erosion is high to
<br />very high.
<br />This soil is used as irrigated hayland, irrigated pasture,
<br />and rangeland. Mixtures of brome, orchardgrass,
<br />pubescent wheatgrss, and timothy are commonly grown.
<br />Where this soil is irrigated, the main management
<br />concerns are the efficient use and distribution of water,
<br />maintenance of soil fertility, and reduction of soil erosion.
<br />Flooding is the common method of irrigation. Contour
<br />ditches and sprinklers are also suitable methods. The
<br />land needs to be leveled and irrigation water managed to
<br />obtain uniform distribution of water, control erosion, and
<br />prevent large losses of tailwater. Applications of manure
<br />and commercial fertilizer containing nitrogen and
<br />phosphorus help maintain soil fertility. With good
<br />management this soil is capable of producing 4.5 tons of
<br />grass hay per irrigated acre.
<br />The potential native vegetation is mainly
<br />needleandthread, western wheatgrass, jnegrass, and
<br />Indian ricegrass. As the range deteriorates, blue grams,
<br />sleepygrass, snakeweed, pingue, and rabbitbrush
<br />increase. Renovating and using a planned grazing
<br />system, cross fencing, erosion control structures, and
<br />livestock water developments help to prevent range
<br />deterioration and promote the production of the more
<br />desirable plants. In renovating, seed should be drilled
<br />into a well prepared, firm, weed-free seedbed. Suitable
<br />grasses for seeding are intermediate wheatgrass,
<br />pubescent wheatgrass, western wheatgrass, Nordan
<br />crested wheatgrass, and Russian wildrye.
<br />This soil is well suited to use as homesites.
<br />This soil is in capability subclasses Vle, nonirrigated,
<br />and Vle, irrigated.
<br />21-Norriston very cobbly sandy loam, 2 to 6
<br />percent slopes. This is a deep, somewhat excessively
<br />drained soil on terraces and fans. It formed primarily in
<br />glacial outwash. Elevation is 7,900 to 8,600 feet. The
<br />average annual precipitation is 16 to 20 inches, the
<br />average annual air temperature is 40 to 44 degrees F,
<br />and the frost-free season is 55 to 75 days.
<br />Typically, the surface layer is brown very cobbly sandy
<br />loam 6 inches thick. The subsoil extends to a depth of
<br />23 inches. It is brown extremely cobbly sandy loam in
<br />the upper 5 inches, light brown extremely gravelly sandy
<br />loam in the middle 7 inches, and light brown extremely
<br />gravelly loamy sand in the lower 5 inches. The
<br />substratum is light brown extremely cobbly loamy sand in
<br />the upper 11 inches and is light brown extremely cobbly
<br />sand to a depth of 60 inches or more. The soil is neutral.
<br />Included with this soil in mapping are areas of
<br />Alvarado very cobbly sandy loam in depressions and
<br />Libeg extremely cobbly sandy loam in the less sloping
<br />21
<br />areas. Each of the included soils makes up about 10
<br />percent of the map unit.
<br />Permeability of this Norriston soil is rapid, and the
<br />available water capacity is very low. The effective rooting
<br />depth is 60 inches or more. Surface runoff is slow, and
<br />the hazard of erosion is slight.
<br />Most of the acreage is rangeland. A few areas where
<br />the cobbles have been removed from the surface are
<br />used as irrigated pasture.
<br />Where this soil is irrigated, management concerns are
<br />the proper use of water and maintenance of soil fertility.
<br />Flooding is the common method of irrigation. Sprinklers
<br />and contour ditches are also suitable methods. Frequent
<br />light irrigation is needed because the available water
<br />capacity is low. Applications of manure and commercial
<br />fertilizer containing nitrogen and phosphorus help
<br />maintain soil fertility. With good management, this soil is
<br />capable of producing 3 tons of pasture per irrigated acre.
<br />The potential native vegetation is mainly Arizona
<br />fescue, needleandthread, and mountain muhly. As the
<br />range deteriorates, slimstem muhly, blue grams,
<br />Kentucky bluegrass, sun sedge, granite gilia, and
<br />rabbitbrush increase. The use of a planned grazing
<br />system, cross fencing, and livestock water developments
<br />helps to prevent range deterioration and promotes the
<br />production of the more desirable plants. Seeding, other
<br />than broadcasting, is inadvisable because many small
<br />stones are near the surface.
<br />This soil is well suited to use as homesites. Excavation
<br />for foundations, roads, utility lines, and septic tanks is
<br />difficult because of the high content of small stones.
<br />Cutbanks are unstable. Effluent from septic tank
<br />absorption fields rapidly penetrates the substratum and
<br />there is a risk of polluting the ground water. This soil is a
<br />good source of roadfill.
<br />This soil is in capability subclasses Vlls, nonirrigated,
<br />and Vlls, irrigated.
<br />22-Norriston extremely cobbly sandy loam, 6 to
<br />15 percent slopes. This is a deep, somewhat
<br />excessively drained soil on terraces and fans. It formed
<br />primarily in glacial outwash. Elevation is 7,900 to 8,600
<br />feet. The average annual precipitation is 16 to 20 inches,
<br />the average annual air temperature is 40 to 44 degrees
<br />F, and the frost-free season is 55 to 75 days.
<br />Typically, the surface layer is brown extremely cobbly
<br />sandy loam 6 inches thick. The subsoil extends to a
<br />depth of 23 inches. It is brown extremely cobbly sandy
<br />loam in the upper 5 inches, light brown extremely
<br />gravelly sandy loam in the middle 7 inches, and light
<br />brown extremely gravelly loamy sand in the lower 5
<br />inches. The substratum is light brown extremely cobbly
<br />loamy sand in the upper 11 inches and is light brown
<br />extremely cobbly sand to a depth of 60 inches or more.
<br />The soil is neutral.
<br />Included with this soil in mapping are areas of
<br />Alvarado very cobbly sandy loam in depressions and
<br />Libeg extremely cobbly sandy loam along the base of
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