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22
<br />SOIL SURvEy
<br />the choice of plants, require special conserva-
<br />tion practices, or both.
<br />Class IV soils have very severe limitations that
<br />reduce the choice of plants, require very care-
<br />ful management, or both.
<br />Class V soils are subject to little or no erosion but
<br />have other limitations, impractical to remove,
<br />that limit their use largely to pasture, range,
<br />woodland, or wildlife habitat.
<br />Class VI soils have severe limitations that make
<br />them generally unsuited to cultivation and limit
<br />their use largely to pasture or range, woodland,
<br />or wildlife habitat.
<br />Class VIII soils and landforms have limitations
<br />that preclude their use for commercial plants
<br />and restrict their use to recreation, wildlife
<br />habitat, or water supply, or to esthetic purposes.
<br />CAPABILITY SUBCLASSES are soil groups within one
<br />class; they are designated by adding a small letter, e,
<br />TV, s, or c, to the class numeral, for example, Ile. The
<br />letter a shows of ero
<br />that the main limitation is risk -
<br />Sion; w shows that water in or on the soil interferes
<br />with plant growth or cultivation (in some soils the
<br />wetness can be partly corrected by artificial drain-
<br />age) ; s shows that the soil is limited m ' 1
<br />The control of erosion and management of w,
<br />are the major concerns in managing these soils.
<br />proving irrigation methods, using crop residue, :
<br />other conservation practices help maintain a high r
<br />of crop production and keep the soil in good conditi
<br />CAPABILITY UNIT 11.-1 (IRRIGATED)
<br />Billings silty clay loam is the only soil in this ca;
<br />bility unit. It is deep, well-drained, and slowly pern
<br />able. The available water capacity is high. The haza
<br />of erosion is moderate. The average annual precipii
<br />tion is about 10 inches, and the frost-free season
<br />165 to 175 days.
<br />This soil is suited to irrigated row crops, grai
<br />pasture, and hay. Under a high level of magemel
<br />the yield per' acre of alfalfa hay is 3 to 5 tons; cor
<br />125 bushels; barley, 90 bushels; and mixed clover ar
<br />grass pasture yield 18 animal-unit-months of grazinj
<br />The low intake rate and the slow percolation rat
<br />are the major concerns in managing these soils. Cor
<br />servation practices, including managing irrigatioi
<br />water, using crop residue, and managing grazing, hell
<br />maintain a high rate of crop production and good soi
<br />condition.
<br />It Is shallow, droughty, or ston alri y because CAPABILITY UNIT IVe-1 (IRRIGATED)
<br />Y; and c, used, in only This unit consists of deep, well-drained, moderately
<br />some parts of the United States, shows that the chief to rapidly permeable sandy loam soils. The slope is 3 to
<br />limitation is climate that is too cold or too dry. 12 percent. The available water capacity is moderate
<br />In class I there are no subclasses, because the soils or high. The hazard of erosion is high or moderate.
<br />of this class have few limitations. Class V can contain, The average annual precipitation is about 16 inches,
<br />at the most, only the subclasses indicated by iv, s, and and the frost-free season is 100 to 125 days. .
<br />c, because the soils in class V are subject to little or no These soils are used for irrigated hay. Under a high
<br />erosion, though they have other limitations that re- level of management
<br />strict their use largely to the yield per acre of alfalfa hay
<br />wildlife habitat, l or recreation.
<br />pasture, range, woodland, is 3 to 4 tons and mixed clover and grass ha
<br />CAPABILITY UNITS are soil 6 tons, y yield 4 to
<br />classes. The soils in one capability. unit aretenough and tillage practices that leave crop residue
<br />alike to be suited to the same crops and pasture plants, surface help control terosionca as contour irrigation
<br />to require similar management, and to have similar on the soil
<br />productivity and other responses to management. and conserve moisture.
<br />Thus, the capability unit is a convenient CAPABILITY UNIT V„?l
<br />This cap
<br />making many statements about management of soils epian poo ly dnsists o Wet alluvial rainedf he slope is 0lto 6?
<br />Capability units are which is de and
<br />generally designated by adding percent. The available water capacity is moderate.
<br />C Arabic numeral to the subclass symbol, for exam- There is no hazard of erosion. The average annual pre moderate.
<br />Ile-1 or VIe- 3. Thus, in one symbol, the Roman cipitation is 16 to 20 inches, and the frost-free season
<br />numeral designates the capability class, or degree of is 50 to 75 days.
<br />limitation; the small letter indicates the subclass, or
<br />Wet alluvial land is used mainly for range and wild-
<br />kind of limitation, as defined in the foregoing Para- life habitat.
<br />graph; and the Arabic numeral specifically identifies
<br />the capability unit within each subclass. CAPABILITY UNIT Via-.1
<br />In the followin This unit consists of deep to shallow, well-drained,
<br />Mesa County Area are described.
<br />g pages the capability units in the moderately to rapidly permeable sandy loam, loam,
<br />and gravelly loam. soils. The slope is 0 to 25 percent.
<br />CAPABILITY UNIT 11x1 (IRRIGATED) The available water capacity is low to high. The haz-
<br />Glenberg sandy loam, 0 to 3 percent slopes, is the and of erosion is slight to high. The average annual
<br />only soil in this capability unit. It is deep, well- precipitation is about 9 to 12 inches, and the frost-free
<br />drained, and rapidly permeable. The available water season is 125 to 175 days.
<br />capacity is low or moderate. The hazard of erosion is
<br />high. The average annual Precipitation These soils are used for range and wildlife habitat.
<br />inches, and the frost-free season is 100 to 125 daoYst 16 This unit consists of shallow to to r2 deep, well-drained,
<br />This soil is used for irrigated hayland and small slowly to very rapidly
<br />grain. Under a high level of management the yield per fine sandy loam, silt loam, clay loam, acre of alfalfa hay is 3 to 5 tons.; mixed clover and loamy sand soils. The slope permeable
<br /> 0 to stony loam, loam,
<br />grass hay, 4 to 6 tons; and barley, 70 to 90 bushels. ? Y m, sandy loam and 40 pe. The
<br />available water capacity is low to high. Therhazard of
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