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30 SOIL SURVEY of the county. It formed in calcareous, loamy materials weathered from Brule Siltstone. The average annual precipitation ranges from 13 to 17 inches. Slopes are gently sloping to moderately sloping. Included in this unit are small areas of Keota loam, 3 to 5 percent slopes. Typically the surface layer is light brownish gray loam about 3 inches thick. The underlying layer is very pale brown and light gray, calcareous loam that is about 8 inches thick and contains weathered fragments of Silt- stone. Below this is a eery pale brown, calcareous Brule Siltstone at a depth of 11 inches. Permeability is moderate. Effective routing depth is '. to 20 inches. Available water ~. ~~acity is low'. Surface ru- noff is rapid, and the erosion hazard is high. This soil is used almost entvely for grazing. It is not suited for cultivation because of its shallow depth. Small areas once used as nonirr gated cropland are now seeded back to grass. Rangeland vegetation on this soil consists mainly of blue grama, western whextgrass, winterfat, threadleaf sedge, and sideoats grama. Proper grazing use and planned grazing systems must be designed to limit stocking and degree of use to maintain a protective plant cover on this soil. Periodic deferment of grazing during the summer months benefits the vegetation by permitting forage plants to complete growth and mature seed. Mechanical rangeland treatment practices are not recom- mended. Stock water is usually difficult to find in areas of this soil. Windbreak and environmental plantings are generally ,not suited to this soil because of the shallow depth. Onsite investigation is needed to determine if plantings are feasible. Rangeland wildlife such as antelope and scaled quail could best be encouraged by proper livestock grazing management and installation of watering facilities. Depth to bedrock is the primary limiting soil feature for homesites or other urban developments. Special sewage systems must be designed. Septic tank absorption fields will not function properly because of the depth to rock. Compensating building and road designs must be utilized in order to offset the shallow bedrock condition. Capability subclass VIe nonirrigated. 28-Fluvaquentic Haplaquolls. Fluvaquentic Haplaquolls consist of deep, dark-colored, poorly drained soils formed in recent alluvial deposits underlain by sand and gravel at depths less than 20 inches. These nearly level soils are on bottomlands along the South Platte River and have a braided pattern of old meandering chan- nels. They are extremely variable in texture within short distances, ranging from sandy loam to clay. Included are small areas of Westplain silty clay loam and Alda loam. These soils have a fluctuating water table during most of the year and are subject to frequent flooding during spring and summer months. A moderate saline condition is also common. These soils are used mainly for grazing (fig. 8). A few small areas bordering areas of more productive soils are used for irrigated cropland. These soils are best suited for grazing. Irrigated cropland areas require intensive management. Special care is requu•ed on this soil in applying irrigation water. Sprinkler irrigation is best suited, but border or furrow methods can be used. Land IeveGng is difficult because these soils may be shallow over sand and gravel. Short irrigation runs and frequent light irrigations are needed. Applications of manure and commercial fertilizer containing nitrogen and phosphorus are important to naintain fertility. Rangeland veget:,[ion consists mainly of alkali sacaton, inland saltgrass, switchgrass, western whextgrass, sedge, and rush. hey forage grasses should be maintained by proper grazing use and grazing management systems that include deferment during the growing season at well- timed intervals. These soils can be seeded to rangeland species or adapted introduced grasses such as tall wheat- grass. Fencing and livestock water developments are ef- fective in obtaining mare uniform distribution of grazing. Windbreak and environmental plantings are generally difficult to establish on these soils because of frequent flooding and the high water [able. Onsite investigation is needed to determine feasibility of plantings and adapted plants. Wetland wildlife, especially waterfowl, utilize these soils. The high water table allows production of wetland plants that provide nesting and protective cover, as well as some food for waterfowl. Because these soils provide cover for wrildlife and are near irrigated cropland where the wildlife species obtain much of their food, they are valuable for openland, wetland and rangeland wildlife. Openland wildlife, especially pheasants, use these areas far cover and nesting. They also provide excellent cover for rangeland wildlife, especially deer. Management for wildlife should include prevention of overgrazing by livestock and protection from unplanned fire. Where livestock are present, these valuable wildlife areas should be fenced to prevent unwanted encroachment and overuse. Frequent flooding and a fluctuating water table at 10 to 40 inches limit these soils for use as homesites or other urban developments. Intensive and costly engineering design and measures are needed in order to overcame these limiting soil features. Capability subclass Viw nonirrigated, IVw irrigated. 29-Fluvaquents. Fluvaquents are deep, somewhat poorly drained and poorly drained sails formed in recent alluvial deposits bordering the South Platte River Chan- nel. They are nearly level. The area is dissected by old river channels and by smaller intermittent streams. This unit is extremely variable from place to place. The surface layer ranges from loamy sand to clay overlying sand and gravel at depths of 4 to 20 inches. These soils have a fluctuating water table ranging from 10 to 60 inches during winter and summer months. They