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16
<br />SOIL SURVEY
<br />county. Slopes are less than 3 percent. Some areas are
<br />broad in the larger and more gently sloping drainage-
<br />ways, such as the Badger, San Arroyo, and Muddy
<br />Creeks, attd in places on the South Platte River. All are
<br />subject, in varying degrees, to flooding from adjacent
<br />slopes and main stream chamtels. Included in mapping
<br />are small areas of Satanta loam, Nunn loam, and Sandy
<br />alluvial land and some very small areas of Wet alluvial
<br />land.
<br />or play loamcaboute6 to 10 in hest thck,kIt is normally
<br />noncalcareous. In places sandier materials have been
<br />deposited unevenly on the surface by floodwaters. The
<br />underlying material is stratified loam, silt loam, and
<br />clay loam and contains varying amounts of fine sand,
<br />sand, and fine gravel. It is 20 to more than 60 inches
<br />thick, is brown to dark brown, and in places ha; weak
<br />structure. It is normally calcareous. Sand or sand and
<br />gravel, stratified with thin lenses of silt and loam, are
<br />In some places below a depth of 36 inches.
<br />ratehandltheir available waterscapactyristhigh.dThey
<br />are normally well drained. Natural fertility is high.
<br />The surface layer is easy to work, but the hazard of
<br />water erosion is very severe in all cultivated areas be-
<br />cause gullies form easily if fields are not protected from
<br />flooding. $road areas, more than 200 feet wide, are
<br />suitable for dryland cultivation and are less subject to
<br />gully erosion.
<br />Most of this ]and type is in native grass or in pasture
<br />that has been improved by the use of check dams and
<br />water spreading. Native grasses include western wheat-
<br />grass, blue grams, and switchgrass. A few areas of suit-
<br />able size are used to produce winter wheat, barley, and
<br />forage sorghums. Capability unit VIe-1, nonirrigated;
<br />Overflow range site; tree planting suitability group 5.
<br />Loamy alluvial land, gravelly substratum hvl occurs
<br />as small areas in major drainageways. It is a principal
<br />source of gravel. Nearly all areas are subject to flooding
<br />from streams, and the floods often are damaging.
<br />The soils are shallow and stratified. The strata are
<br />of moderately coarse textured to moderately fine tex-
<br />tared material that is underlain by river sand and
<br />gravel. In some places the soils are slightly influenced
<br />by soluble salts.
<br />The soils of this land type absorb water at a rapid
<br />to slow rate. The available water capacity is low, but
<br />many areas have a high water-table that is beneficial
<br />to plant growth.
<br />Much of this land type is cultivated and irrigated. i
<br />The principal crops are truck crops adapted to the 1
<br />area, mainly celery, melons, sweet corn, tomatoes, lettuce,
<br />carrots, onions, and cabbage. The best growing conditions
<br />can be maintained if the normal water table is con-
<br />trolled so that it remains at a depth of 10 to 20 inches
<br />below the surface during the growing season. Other ir-
<br />rigated crops include pasture mixtures that require some
<br />irrigation but are partly sustained by the water table
<br />in the gravel layers.
<br />Some of this land type is in native grass, mainly
<br />western wheatgrass, saltgrass, blue grams, and s~citch-
<br />grass. The wetter areas produce sedges, rushes, and cat-
<br />tails. This vegetation is largely sustained by the natural
<br />water table and by flooding. Little irrigation is needed.
<br />Capability unit IVw-1, irrigated; not placed in a rani
<br />site; tree planting suitability group 5-
<br />Loamy alluvial land, moderately wet llw] is in man
<br />drainageways throughout the county. It is predominant]
<br />m the broader dratnagervays that have a high wab
<br />table and that formerly had poor drainage. The aret
<br />are broad in the larger and more gently sloping drain
<br />ageways, especially to the South Platte River button
<br />All are subject to damage, in varying degrees, by Root
<br />ins from adjacent slopes and main stream channel:
<br />Included in mapping are small areas of Nunn loan
<br />Satanta loam, Wet alluvial land, and Loam alluvia
<br />land, gravelly substratum. y
<br />The soils are moderately deep, ranging from 20 to 3
<br />inches in depth, over unconsolidated sand and grave.
<br />and generalyrare stratified. Theyoare normally oncal
<br />careous, but they are moderately influenced by solubl
<br />salts in places. Thin lenses of sand, silt, or fine grave
<br />may be m any of the layers.
<br />The soils of this land type absorb water at a moderat
<br />to slow rate, and the available water capacity is high
<br />Artificial drainage is generally needed to grow crops
<br />Natural fertility is high, but under the Intensive man
<br />agement used on these soils, artificial supplements arE
<br />needed.
<br />Most of this Iand type is irrigated. In these areas
<br />crops such as sugar beets, corn, small grains, and vege
<br />tables can be grown. Alfalfa and irrigated pasture are
<br />well adapted. ~Yestern wheatgrass, saltgrass„blue grams.
<br />and switchgrass are grown in some areas. Capability unit
<br />IIIw-1, irrigated; not placed in a range site; tree plant-
<br />ing suitability group 5.
<br />Nunn Series
<br />The Nunn series consists of well-drained, near]Y level
<br />soils on terraces. These soils formed in loamy alluvia]
<br />material.
<br />In a representative profile, the surface layer is gray-
<br />ish-brown loam about 6 inches thick. It is noncalcareous.
<br />The subsoil is dark grayish-brown and grayish-brown
<br />clay about 17 inches thick. It is noncalcareous. The
<br />underlying material, below a depth ~of 23 inches, is
<br />light yellowish-brown and grayish-browla loam and silt
<br />loam. It is highly calcareous and stratified.
<br />Nunn soils absorb water at a moderate rate, and the
<br />available water capacity is high. Permeability is slow
<br />m Nunn soils that have a clay loam snrface layer, and
<br />t is moderately slow in those that have a loam snrface
<br />ayes The entire soil is suitable for plant roots.
<br />Representative profile of Nunn loam, 1 to 3 percent
<br />slopes, in an area of grass, 1,500 feet east and 2,540 feet
<br />north of the southwest corner of section 36, T. 3 S., R.
<br />65 W.:
<br />A1-p to 6 inches, grayish-brown (lOYR 5/2) loam, very dark
<br />grayish brown (lOYR 3/2) when moist and crushed;
<br />weak, fine, granular structure: friable; noncalcareous;
<br />neutral; clear, smooth boundary.
<br />nl-6 [0 9 inches, dark grayish-brown (IOYR 4/2) light clay
<br />loam, very dark grayish brown (lOYR 3/2) when
<br />moist; weak, Coarse, Prismatic Structure parting to
<br />weak, medium, subs ngular blocky structure; slightly
<br />hard, friable; thin patchy clay films on all faces of
<br />pods; noncalcareous; neutral ;clear, smooth boundary.
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