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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. <br />