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32 SOIL SURVEY These excavations are usually located in areas of sous underlain by gravel at depths of 10 to 40 inches. Included are borrow areas next to roads and major canals that were used as a source of fill materials. Onsite investigations are required on this unit to deter- mine use and management. Where pits are abandoned, reshaping the side slopes. and backfilling with topsoil will aid in revegetation and control of erosion. 32-Haverson loam, 0 to 1 percent slopes. This is a deep, well drained soil on terraces and flood plains. It formed in calcareous, stratified, loamy alluvium derived from sedimentary rocks and deposited by intermittent streams in the western part of the county. The average annual precipitation ranges from 13 to 17 inches. Slopes are nearly level. Included in this unit are small areas of Glenberg sandy loam having 0 to 3 percent slopes. Typically surface layer is grayish brown loam about 4 inches thick. The underlying layer is light brownish gray and light yellowish brown, calcareous loam stratified with thin lenses of fine sandy loam and sandy loam to 60 inches or more. Permeability is moderate. Effective rooting depth is 60 inches or more. Available water capacity is high. Organic matter content in the surface layer is low. Surface runoff is slow, the erosion hazard is slight, and the soil blowing hazard is moderate. This soil is subject to rare flooding during the spring and summer months. This soil is used mainly for irrigated and nonirrigated cropland. In irrigated areas alfalfa, corn, sugar beets and beans are the chief crops. Winter wheat is the main crop in nonirrigated areas. Small isolated areas are used for grazing. Management concerns in irrigated areas are proper ir- rigation water use and maintenance of fertility. This soil is well suited to furrow or border irrigation systems. Land leveling is needed in some areas to obtain more uniform application of water. Good irrigation water management consisting of proper length of run is needed for efficient use of irrigation water. Applications of manure and commercial fertilizers containing nitrogen and phosphorus are needed to maintain fertility. Incor- porating crop residues and maintaining organic matter content increases water infiltration and improves soil tilth. In nonirrigated cropland areas the primary objectives of management are conserving moisture and protecting the soil from erosion. Management practices such as stub- ble mulch tillage and incorporating crop residues are es- sential to protect soil from soil blowing, improve water in- filtration, improve soil tilth, and conserve moisture. Chiseling or subsoiling breaks up tillage pans and im- proves water infiltration. Tillage should be kept to a minimum. Rangeland vegetation of this soil consists mainly of blue grama, buffalograss, western wheatgrass, and sedge. Proper grazing use and planned grazing systems are the most important practices needed to maintain quantity and quality of desirable vegetation. Range seeding will speed the revegetation of areas depleted by heavy grazing, cul- tivation or other disturbances. Combinations of stockwater development, fencing and deferred grazing help improve grazing distribution and maintain range con- dition. Contour furrowing and pitting are practices that improve water infiltration and reduce runoff and are especially effective on rangeland areas in poor and fair condition. Windbreaks and environmental plantings are generally well suited on this soil. They are somewhat hard to establish because of limited precipitation. Special care consisting of summer fallow a year prior to planting, sup- plemental water during plantings and early stages of growth, and continued cultivation for weed control is needed to insure establishment and survival of plantings. Trees best suited and having best survival are Rocky Mountain juniper, eastern redcedar, ponderosa pine, Siberian elm, Russian-olive and hackberry. Shrubs best suited are skunkbush sumac, lilac, Siberian peashrub and American plum. Openland wildlife such as pheasant, cottontail rabbit and mourning dove are suited to this soil. In cropland areas favorable habitat can be developed by establishing nesting and escape cover. For pheasants, undisturbed nesting cover is vital and should be included in plans for habitat development. Tree and shrub plantings along fence lines, irrigation ditches, roadsides and streambanks also help encourage wildlife. Rangeland wildlife, including antelope and jackrabbits, can be encouraged by good water developments and types of fencing to permit un- restricted antelope movement. Where this soil is considered for homesites and other urban developments, the primary limiting soil feature is rare flooding. Special engineering measures such as em- bankments and elevated building pads are needed to minimize this condition. Capability subclass We nonir- rigated, I irrigated. 33-Haverson loam, 1 to 3 percent slopes. This is a deep, well drained soil on terraces, fans and flood plains. It formed in calcareous, stratified, loamy alluvium deposited by intermittent streams in the western part of the county. The average annual precipitation ranges from 13 to 17 inches. Slopes are nearly level to gently sloping. Included in this unit are small areas of Glenberg sandy loam and Bridgeport loam. Typically the surface layer is grayish brown loam about 4 inches thick. The underlying layer is light brownish gray and light yellowish brown calcareous loam stratified with thin lenses of fine sandy loam and sandy loam to 60 inches or more. Permeability is moderate. Effective rooting depth is 60 inches or more. Available water capacity is high. Surface runoff is slow, the erosion hazard is slight, and the soil blowing hazard is moderate. This soil is subject to rare flooding during spring and summer months.