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Yuma County, Colorado
<br />are needed where substratum material has been
<br />exposed by land leveling or erosion.
<br />The main concerns in managing nonirrigated cropland
<br />are controlling soil blowing and conserving soil moisture.
<br />Soil blowing can be controlled and moisture conserved
<br />by stubble mulch tillage and striperopping. Light
<br />applications of nitrogen fertilizer normally will result in
<br />larger amounts of crop residue, which helps reduce soil
<br />blowing and trap snow. Nonirrigated cropland can be
<br />converted to grass by seeding a mixture selected from
<br />sand bluestem, sideoats grama, prairie sandreed,
<br />switchgrass, and indiangrass in a prepared seedbed or
<br />into the clean, firm stubble of sorghum or millet. After
<br />seeding, grazing should be deferred until the end of the
<br />second growing season.
<br />This soil generally is suited to windbreaks and
<br />environmental plantings. Soil blowing is the principal
<br />limitation to establishing trees and shrubs. This limitation
<br />can be overcome by cultivating only in the tree row and
<br />by leaving a strip of vegetation between the rows.
<br />Supplemental irrigation is necessary at the time of
<br />planting and during dry periods. The trees that are best
<br />adapted and that have a good chance of survival are
<br />Rocky Mountain juniper, ponderosa pine, Siberian elm,
<br />Russian- olive, and hackberry; the shrubs are skunkbush
<br />sumac, lilac, and Siberian peashrub.
<br />This soil is well suited to use as sites for septic tank
<br />filter fields and houses. However, because of the low
<br />bearing strength of the soil, foundation footings need to
<br />be sufficiently wide to provide a safety margin of support
<br />for the weight of buildings.
<br />Capability subclass Ile, nonirrigated and irrigated.
<br />20— lliff loam. This is a moderately deep, well drained
<br />oil in th orthwestern part of the county. It formed in
<br />ess overly • limestone. The areas of this soil generally
<br />are rounded or . al and range to 300 acres in size.
<br />, ,Included in map.'. • and making up as much as 20
<br />ercent of this map u ' are Canyon loam and Dioxice
<br />nesandy loam, which a = .long the perimeter of the
<br />teas of this Iliff soil. A few s •r. II slickspots are included
<br />,p areas of the Iliff soil.
<br />Typically, the surface layer is gra ' brown loam
<br />bout 6 inches thick. The subsoil is da • rayish brown
<br />IIty clay and pale brown silty clay loam a• : t 12 inches
<br />tack. The substratum is very pale brown loa bout 8
<br />3ohes thick. Limestone bedrock is at a depth of out
<br />D , iqT/o/V 7-7 ®f /9
<br />n nonirrigated cropland used for wheat, soil blowing
<br />can controlled by stubble mulching and striperopping.
<br />Chiseling and minimum tillage help to maintain soil tilth.
<br />Con.ervation practices on irrigated cropland include
<br />irrigatio management, leaving crop residue on the
<br />surface, hiseling and subsoiling, minimum tillage, and
<br />growing • asses and legumes in rotation at least one -
<br />fourth of t - time. Fertilizers that add nitrogen and
<br />phosphorus to the soil, applied at rates determined by
<br />soil tests, no ally increase the yield of irrigated crops.
<br />The potential native vegetation is dominantly blue
<br />grama, buffalo • ass, western wheatgrass, and green
<br />needlegrass. Co tinuous heavy grazing will cause
<br />western wheatgr -_ s and green needlegrass to decrease;
<br />blue grama and b alograss will increase, forming a sod.
<br />Continued overuse ill result in the invasion of red three -
<br />awn, broom snakew: ed, cactus, fringed sagebrush, and
<br />others. Deferred graz g is effective in maintaining the
<br />condition of the range.
<br />Badly depleted range : nd can be improved by
<br />interseeding with a mixtu selected from western
<br />wheatgrass, sideoats gra a, little bluestem, blue grama,
<br />and crested, pubescent, or 'ntermediate wheatgrass.
<br />Seeds should be planted in - prepared seedbed early in
<br />spring.
<br />Wildlife habitat, especially f• openland and rangeland
<br />wildlife, is an important second- use for this soil.
<br />Habitat favorable for ring- necke• pheasant, mourning
<br />dove, and many nongame specie can be developed on
<br />cropland by establishing nesting a • escape cover.
<br />Undisturbed nesting cover is vital fo pheasants and
<br />needs to be established, especially i areas of intensive
<br />agriculture. Wildlife can be encourage by planting
<br />skunkbush sumac, lilac, Siberian peash ub, Rocky
<br />Mountain juniper, Russian - olive, and ha berry in
<br />selected areas. Rangeland wildlife, for ex mple, the
<br />pronghorn antelope, can be encouraged b developing
<br />livestock water facilities, by properly grazin livestock,
<br />and by range seeding, where needed.
<br />This soil generally is poorly suited to windb -aks and
<br />environmental plantings because of restricted •oting
<br />depth and the low water - holding capacity. Onsit
<br />investigations are needed if plantings are conte • lated.
<br />This soil is not well suited to use as homesites
<br />because of the high shrink -swell potential and the
<br />moderate depth to bedrock. The bedrock is rippable,
<br />using construction machinery. Backfilling foundations
<br />with coarser textured material will reduce the shrink -s ell
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