2005-07-13_REVISION - M2000016 (34)

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The Colby soil also is deep and well drained and formed in calcareous eolian deposits. Typically the surface layer is pale brown loam about 7 inches thick. The underlying material is very pale brown silt loam to a depth of 60 inches. Permeability is moderate. Available water capacity is high. The effective rooting depth is 60 inches or more. Surface runoff is medium, and the erosion hazard is moderate. This map unit is used for irrigated and nonirrigated cropland and for rangeland, wildlife habitat, and urban development. In irrigated azeas these soils are suited to all crops commonly grown in the area, including corn, sugar beets, beans, alfalfa, small grain, and onions. An example of a suitable cropping system is 3 to 4 years of alfalfa followed by com, corn for silage, sugar beets, small grain, or beans. Land leveling, ditch lining and installing pipelines may be needed for proper water applications. All methods of irrigation are suitable but furrotiv irrigation is the most common. Barnyard manure and commercial fertilizer are needed for top yields. In nonirrigated areas these soils are suited to winter wheat, barley, and sorghum. Most of the acreage is planted to winter wheat. The predicted average yield is 28 bushels per acre. The soil is summer fallowed in alternated years to allow moisture accumulation. Generally precipitation is too low for beneficial use of fertilizer. Stubble mulch farming, stripcropping, and minimum tillage are needed to control soil blowing and water erosion. Terracing also may be needed [o control water erosion. The potential native vegetation is dominated by blue grama. Several mid grasses such as western wheatgrass and needleandthread are also present. Potential production ranges from 1600 pounds per acre in favorable years to 1000 pounds in unfavorable years. As range condition deteriorates, the mid grasses decrease; blue grama, buffalograss, snakeweed, yucca, and fringed sage increase; and forage production drops. Undesirable weeds and annuals invade the site as range condition becomes poorer. Management of vegetation on this soil should be based on taking half and leaving half of the total annual production. Seeding is desirable if the range is in poor condition. Sideoats grama, little bluestem, western wheatgrass, blue grama, pubescent wheatgrass, and crested wheatgrass are suitable for seeding. The grass selected should meet the seasonal requirements of livestock. It can be seeded into a clean, firm sorghum stubble or it can be drilled into a firm prepared seedbed. Seeding early in spring has proven most successful. Windbreaks and environmental plantings are generally well suited to these soils. Cultivation to control competing vegetation should be continued for as many years as possible following planting. Trees that are best suited and have good survival aze Rocky F[ Laptan Pit DMG l /2 Permit Page 5! of 8!