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LOGAN COUNTY, COLORADO
<br />where the soil is used for homesites or urban develop-
<br />ments. Special 'sewage systems must be anticipated. Sep-
<br />tic -tank absorption fields , will not function ,properly
<br />because of ,slow; ;permeability and a high water ;table.
<br />Compensating engineering designs and measures such as
<br />%ackfilling with materials with low shrink - "swell ,potential
<br />,and offsetting structural_ construction are needed for
<br />roads and 'dwellings in order to - minimize the slirinkswell
<br />potential. Wetness affects dwellings with basements and
<br />requires special designs. Capability subclass IIIs nonir-
<br />rigated, Its irrigated.
<br />83—Nunn-,clay loam, wet. This is a deep, wet sod on
<br />terraces aind flood plains. It formed in calcareous, loamy
<br />alluvium. The average annual precipitation ranges from
<br />13 to 19 inches. Slopes are nearly level.
<br />Included in this unit" are small areas of Satanta loam,
<br />wet, and Nunn clay loam, water table. Small localized
<br />areas, of "strongly saline -alkali affected Nunn clay 'loam
<br />commonly occur.
<br />Typically the surface layer is grayish brown •heavy clay
<br />loam about 10 inches thick. The subsoil is grayish brown
<br />heavy clay loam about 13 inches thick over grayish
<br />brown, calcareous clay 'loam about 13 inches thick. The
<br />substratum is 'light gray and slight grayish brown. clay
<br />loam and loam .extending to Winches.- Mottles and visible
<br />salts occur . -in the "lower ,part of the subsoil' and
<br />throughout the substratum.
<br />Permeability 'is slow. Effective rooting depth is 60
<br />inches. Available 'water capacity Is high. Surface runoff is
<br />slow, and the erosion hazard •is slight. This soil is, affected
<br />by a'high water =table caused mainly by loss 'of irrigation
<br />water and overirrigation on adjacent soils.
<br />This soil is'used"mainly for irrigated cropland. `Some
<br />areas 'are used for,grazing. Corn,.alfalfa, sugar beets and
<br />wheat are the -principal crops. Crop yields are affected by
<br />the high water table.
<br />Management concerns in irrigated areas are .proper -ir-
<br />rigation water' use, maintaining - fertility and .minimizing
<br />wetness. This soil is well suited to furrow and border ir-
<br />rigation methods. _Land 'leveling is needed in -some ,areas
<br />to obtain more uniform application of water. Good irriga-
<br />tion .water management such as proper -length of run is
<br />needed to compensate for the slow ,permeability and to
<br />avoid raising the water table. Tile drain systems and "open
<br />drainage ditches are essential to lower the water table.
<br />Subsoiling is effective in improving water infiltration "and
<br />allowing salts to leach downward. Applications of manure
<br />and - commercial fertilizers containing nitrogen and
<br />phosphorus, "are,needed to maintain fertility. Incorporating
<br />crop residues into the soil increases water infiltration and
<br />improves soil tilth. '
<br />`Rangeland vegetation consists mainly of alkali sacaton,
<br />inland saltgrass, switchgrass, western wheatgrass, ;sedge,
<br />and rush. -Key forage ,grasses need to "be ,maintained, -by
<br />proper grazing use -and grazing.management.that includes
<br />deferment during the .growing - season at well-timed inter-
<br />vals. 'This soil -can be seeded to rangeland. - species or
<br />adapted introduced grasses such as tall wheatgrass. Fenc-
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<br />ing -and .watering developments are effective in obtaining
<br />more uniform distribution of grazing.
<br />Windbreaks and environmental plantings are tgenerally
<br />well suited to this "soil. -The 'high water table and abun-
<br />dant competing vegetation are the - principal concerns in
<br />establishing tree and 'shrub plantings. Summer fallow,
<br />continued 'cultivation for weed control and selection ' of
<br />adapted plants are needed to insure ,establishment and
<br />survival off plantings. Trees best suited 'and having good
<br />survival ,are plains cottonwood, golden willow, Colorado
<br />blue •spruce, Rocky ,-Mountain juniper and eastern
<br />redeedar. Shrubs ,best suited are American plum,':purple
<br />willow, common chokecherry and redosier dogwood.
<br />'Openland wildlife such !as ,pheasant, cottontail, mourn -
<br />ing'dove and miscellaneous songbirds are favored on this
<br />soil -because of Its high "potential for growing habitat util-
<br />ized 'by these kinds of wildlife. Under irrigation a great
<br />variety of crops and cover types can be grown. Some of
<br />the .primary practices that would enhance openland wil-
<br />dlife populations include "tree and shrub plantings and
<br />undisturbed nesting cover. 'Rangeland wildlife, including
<br />antelope and jackrabbit, can. be encouraged by grazing
<br />management, fencing and water developments.
<br />Wetness, slow permeability, and -high "shrink -swell
<br />potential -are the 'principal limiting features where this
<br />soil is used for homesites and other urban developments.
<br />Special sewage systems must be `anticipated., Septic tank
<br />absorption fields will not - function properly because of the
<br />slow permeability and high water table. Compensating en-
<br />gineering designs and_ measures such -as backfilling with
<br />materials w_ ith low ,shrink-swell potential and offsetting
<br />structural construction are .needed for -roads and
<br />dwellings •in order ton *u*miz'e -the shrink -swell potential.
<br />The high water table seepage affects dwellings with base-
<br />ments and requires special designs. Capability subclass
<br />IIIw nonirrigated, IIw irrigated.
<br />84 =01ney sandy -loam, 3 to 5 percent slopes. This is a
<br />deep, well drained "soil on .upland ridges and hills. It
<br />formed -in calcareous, loamy eolian and alluvial materials.
<br />The 'average annual precipitation ranges from 13 to 15
<br />inches. Slopes are "gently sloping.
<br />Included in ;this unit are small areas of Stoneham loam
<br />and Vona sandy 'loam soils.
<br />'Typically the surface layer is grayish brown sandy loam
<br />about 3 inches .thick. The subsoil is .grayish brown sandy
<br />clay loam about 112 ,inches thick and is calcareous in the
<br />lower part. The substratum pis pale yellow and light brown -
<br />isli gray, calcareous sandy loam extending to'60 inches or
<br />more. -
<br />Permeability -is moderate. Effective rooting depth is 60
<br />inches or more. Available water capacity is moderate.
<br />Surface runoff is medium, the erosion hazard is moderate,
<br />and 'the soil blowing hazard 'is moderate.
<br />This soil is used for irrigated and aonirrigated cropland:
<br />Some areas are used for grazing. Corn, alfalfa, sugar
<br />beets and "small grains are the principal crops grown in ir-
<br />Tigated areas. Whea£ is the main crop :grown in nonir-
<br />rigated areas.
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