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<br /> WELD COUNTY, COLORADO, SOUTHERN PART 7
<br /> brief description of the soil profile. In each description, The acreage and proportionate extent of each map unit
<br /> the principal hazards and limitations are indicated, and are given in table 4, and additional information on proper-
<br /> the management concerns and practices needed are ties, limitations, capabilities, and potentials for many soil
<br /> discussed. uses is given for each kind of soil in other tables in this
<br /> The map units on the detailed soil maps represent an survey. (See "Summary of tables.") Many of the terms
<br /> area on the landscape made up mostly of the soil or soils used in describing soils are defined in the Glossary.
<br /> for which the unit is named. Most of the delineations
<br /> shown on the detailed soil map are phases of soil series. Soil descriptions
<br /> Soils that have a profile that is almost alike make up a
<br /> soil series. Except for allowable differences in texture of ( -Altvan loam, 0 to 1 percent slopes. This is a deep,
<br /> the surface layer or of the underlying substratum, all the well drained soil on terraces at elevations of 4,500 to 4,900
<br /> soils of a series have major horizons that are similar in feet. It formed in old alluvium deposited by the major
<br /> composition, thickness, and arrangement in the profile. A rivers. Included in mapping are small areas of soils that
<br /> soil series commonly is named for a town or geographic show evidence of poor drainage. Also included are small,
<br /> feature near the place where a soil of that series was long and narrow areas of sand and gravel deposits.
<br /> first observed and mapped. Olney and Nunn, for example, Typically the surface layer of the Altvan soil is grayish
<br /> are names of two soil series. . brown loam about 10 inches thick. The subsoil is brown
<br /> Soils of one series can differ in texture of the surface and light yellowish brown clay loam and sandy clay loam
<br /> layer or in the underlying substratum and in slope, ero- about 15 inches thick. The substratum is calcareous loamy
<br /> sion, stoniness, salinity, wetness, or other characteristics sand about 6 inches thick over gravelly sand.
<br /> that affect their use. On the basis of such differences, a permeability and available water capacity are
<br /> soil series is divided into phases. The name of a soil phase moderate. The effective rooting depth is 20 to 40 inches.
<br /> commonly indicates a feature that affects use or manage- Surface runoff is slow, and the erosion hazard is low.
<br /> ment. For example, Olney fine sandy loam, 1 to 3 percent This soil is used almost entirely for irrigated crops. It
<br /> slopes, is one of several phases within the Olney series. is suited to all crops commonly grown in the area, includ-
<br /> Some map units are made up of two or more dominant ing corn, sugar beets, beans, alfalfa, small grain, potatoes,
<br /> kinds of soil. Such map units are called soil complexes and and onions. An example of a suitable cropping system is 3
<br /> undifferentiated groups. to 4 years of alfalfa followed by corn, corn for silage,
<br /> A sail complex consists of areas of two or more soils sugar beets, small grain, or beans. The high clay content
<br /> that are so intricately mixed or so small in size that they and the rapidly permeable substratum slightly restrict
<br /> cannot be shown separately on the soil map. Each area in- some crops.
<br /> cludes some of each of the two or more dominant soils, All methods of irrigation are suitable, but furrow ir-
<br /> and the pattern and proportion are somewhat similar in rigat
<br /> is an example. ion is the most common (fig. 4). Proper irrigation
<br /> all areas. Midway-Shingle complex, 5 to 20 percent slopes, water management is essential. Barnyard manure and
<br /> An undifferentiated group is made up of two or more commercial fertilizer are needed for top yields.
<br /> soils that could be mapped individually but are mapped as Windbreaks and environmental plantings of trees and
<br /> one unit because there is little value in separating them. shrubs commonly grown in the area are generally well
<br /> The pattern and proportion of the soils are not uniform. suited to this soil. Cultivation to control competing
<br /> An area shown on the map has at least one of the domi- vegetation should be continued for as many years as
<br /> nant (named) soils or may have all of them. Loup-Boel possible following planting. Trees that are best suited and
<br /> loamy sands, 0 to 3 percent slopes, is an undifferentiated have good survival are Rocky Mountain juniper, eastern
<br /> group in this survey area. redcedar, ponderosa pine, Siberian elm, Russian-olive, and
<br /> Most map units include small, scattered areas of soils hackberry. The shrubs best suited are skunkbush sumac,
<br /> other than those that appear in the name of the map unit. lilac, Siberian peashrub, and American plum.
<br /> Some of these soils have properties that differ substan- This soil can produce habitat elements that are highly
<br /> tially from those of the dominant soil or soils and thus suitable for openland wildlife, including pheasant, cotton-
<br /> could significantly affect use and management of the map tail, and mourning dove. Such crops as wheat, corn, and
<br /> unit. These soils are described in the description of each alfalfa provide suitable habitat for openland wildlife,
<br /> map unit. Some of the more unusual or strongly contrast- especially pheasant. Tree and shrub plantings and
<br /> ing soils that are included are identified by a special sym- undisturbed nesting cover would enhance openland wil-
<br /> bol on the soil map. dlife populations.
<br /> Most mapped areas include places that have little or no This Altvan soil has fair to good potential for urban
<br /> soil material and support little or no vegetation. Such and recreational development. The chief limiting soil fea-
<br /> places are called miscellaneous areas; they are delineated tures for urban development are the shrink-swell poten-
<br /> on the soil map and given descriptive names. Rock out- tial of the subsoil as it wets and dries and the rapid
<br /> crop is an example. Some of these areas are too small to permeability of the sand and gravel substratum. Septic
<br /> be delineated and are identified by a special symbol on tank absorption fields function properly, but in places the
<br /> the soil map. substratum does not contain enough fines to properly
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