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<br />16
<br />SOIL SURVEY
<br />management is needed if livestock and wildlife share the
<br />range. Livestock watering facilities also are utilized by
<br />various wildlife species.
<br />This soil has good potential for urban and recreational
<br />developments. Road design can be modified to compen-
<br />sate for the limited..capacity of this soil to support a load.
<br />Capability subclass IVe irrigated, Vle nonirrigated;
<br />Loamy Slopes range site.
<br />18-Colby-Aden loams, 3 to 9 percent slopes. These
<br />gently sloping to moderately sloping soils are on plains,
<br />hills, and ridges at elevations of 4,750 to 4,900 feet. The
<br />Colby soil, which makes up about 55 percent of the map
<br />unit, occupies the steeper, convex parts of the landscape.
<br />The Adena soil, about 30 percent of the unit, occupies the
<br />less steep, slightly concave parts. About 15 percent is
<br />Kim loam and Weld loam.
<br />The Colby soil is deep and well drained. It formed in
<br />calcareous eolian deposits. Typically the surface layer is
<br />pale brown loam about 7 inches thick. The underlying
<br />material to a depth of 60 inches is very pale brown silt
<br />loam.
<br />Permeability is moderate. Available water capacity is
<br />high. The effective rooting depth is 60 inches or more.
<br />Surface runoff is rapid, and the erosion hazard is high.
<br />The Adena soil also is deep and well drained and
<br />formed in calcareous eolian deposits. Typically the surface
<br />layer is brown loam about 6 inches thick. The subsoil is
<br />brown and very pale brown clay loam about 3 inches
<br />thick. The substratum to a depth of 60 inches is very pale
<br />brown silt loam.
<br />Permeability is slow. Available water capacity is high.
<br />The effective rooting depth is 60 inches or more. Surface
<br />runoff is medium, and the erosion hazard is moderate.
<br />This unit is used for nonirrigated cropland and range-
<br />land. It is suited to winter wheat, barley, and sorghum.
<br />Most of the acreage is planted to winter wheat and is
<br />summer fallowed in alternate years to allow. moisture ac-
<br />cumulation. Generally precipitation is too low for benefi-
<br />cial use of fertilizer.
<br />Stubble mulch farming, stripcropping, and minimum til-
<br />lage are needed to control soil blowing and water erosion.
<br />Terracing also may be needed to control water erosion.
<br />The potential native vegetation on this unit is
<br />dominated by blue grama. Sideoats grams, little bluestem,
<br />and western wheatgrass are also prominent. Potential
<br />production ranges from 1,800 pounds per acre in favora-
<br />ble years to 1,100 pounds in unfavorable years. As range
<br />condition deteriorates, the sideoats grama and little
<br />bluestem decrease, forage production drops, and blue
<br />grams, buffalograss, and several perennial forbs and
<br />shrubs increase. Undesirable weeds and annuals invade
<br />the site as range condition becomes poorer.
<br />Management should be based on taking half and leaving
<br />half of the total annual production. Seeding is desirable if
<br />the range is in poor condition. Sideoats grama, little
<br />bluestem, western wheatgrass, bluegrama, pubescent
<br />wheatgrass, and crested wheatgrass are suitable for seed-
<br />ing. The grass selected should meet the seasonal require-
<br />ments of livestock. It can be seeded into a clean, fuzn
<br />sorghum stubble, or it can be drilled into a fuze prepared
<br />seedbed. Plowing and drilling should be on the contour to
<br />minimize runoff and soil losses. Seeding early in spring
<br />has proven most successsful. Capability subclass IVe
<br />nonirrigated; Colby soil in Loamy Slopes range site,
<br />Adena soil in Loamy Plains range site.
<br />19-Colomtio elay,loam, O to 1 percent slopes:` This is
<br />a deep, well drained soil on flood plains and terraces at
<br />elevations of 4,600 to 4,780 feet. It formed in stratified
<br />calcareous alluvium. Included in mapping are small areas
<br />of soils that have a loam surface layer and some small
<br />leveled areas.
<br />Typically the surface layer of this Colombo soil is dark
<br />grayish brown clay loam about 14 inches thick. The upper
<br />7 inches of the underlying material is pale brown
<br />stratified clay loam and loam. The lower part to a depth
<br />of 60 inches is very pale brown loam stratified with thin
<br />lenses of fine sand, medium sand, and clay loam.
<br />Permeability is moderate. Available water capacity is
<br />high. The effective rooting depth is 60 inches or more.
<br />Surface runoff is slow, and the erosion hazard is low.
<br />In irrigated areas this soil is suited to crops commonly
<br />grown in the area, such as corn, sugar beets, beans, alfal-
<br />fa, onions, and potatoes.
<br />All methods of irrigation that are common to the area
<br />are used. Borders are suitable for small grain, alfalfa, and
<br />pasture. Furrow irrigation is used for row crops. Crops
<br />respond to application of nitrogen and phosphorus.
<br />Windbreaks and environmental plantings of trees and
<br />shrubs commonly grown, in the area are generally well
<br />suited to this soil. Cultivation to control competing
<br />vegetation should be continued for as many years as
<br />possible following planting. Trees that are best suited and
<br />have good survival are Rocky Mountain juniper, eastern
<br />redcedar, ponderosa pine, Siberian elm, Russian-olive, and
<br />hackberry. The shrubs best suited are skunkbush sumac,
<br />lilac, Siberian peashrub, and American plum.
<br />Wildlife is an important secondary use of this soil.
<br />Ring-necked pheasant, mourning dove, and many non-
<br />game species can be attracted by establishing areas for
<br />nesting and escape cover. For pheasants, undisturbed
<br />nesting cover is essential and should be included in plans
<br />for habitat development, especially in areas of intensive
<br />agriculture.
<br />Where this soil is on flood plains and is susceptible to
<br />flooding it has poor potential for urban and recreational
<br />development. On the higher terraces the potential is fair.
<br />Dwelling and road designs need to be modified to in-
<br />crease the capacity of the soil to support a load and to
<br />protect it against frost action. Capability subclass IIw ir-
<br />rigated.
<br />20-Colombo clay loam, 1 to 3 percent slopes. This is
<br />a deep, well drained soil on flood plains and terraces at
<br />elevations of 4,600 and 4,780 feet. It formed in stratified
<br />calcareous alluvium. Included in mapping are small areas
<br />of soils that have a loam surface layer. Some small
<br />leveled areas are also included.
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