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<br />.))!S98
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<br />been delineated on the generalized soil and vegetation map, with numbers
<br />corresponding to the numbers assigned to the following names: 1. Desert-
<br />Sierozem, 2. Brown-Chestnut, 3. Mountain Prairie-Chestnut, 4. Gray
<br />Wooded-Brown Podzolic-Mountain Prairie, and 5. Alpine Meadow-Alpine Bog.
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<br />. .
<br />
<br />',.
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<br />Within the five climatic soil groupings are soils that do not exhibit the
<br />influence of climate in profile characteristics. These are the young
<br />soils (Alluvials and Regoso1s), soils shallow to parent rock (Lithoso1s),
<br />poorly drained soils (Humic G1eys), high sodium soils (Solonetz) and
<br />miscellaneous land types (rockland, rock outcrops and rock slides). Kinds
<br />or species of vegetation change with the major soil groupings. These
<br />changes may be sharp or they may be broad transitions.
<br />
<br />.' .
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<br />Soils presently irrigated are primarily Humic G1ey, Alluvial, Sierozem,
<br />Brown and Chestnut. There is also an additional acreage of soils suitable
<br />for irrigation, primarily in the Brown, Chestnut and Alluvial groups.
<br />Acreage of great soils groups, by major groupings, and distribution of
<br />this acreage by irrigated land and vegetative types for the Gunnison River
<br />Basin is given in table 1.
<br />
<br />1. Desert Sierozem
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<br />Soils of this grouping have developed under 10\1 effective precipitation,
<br />on gently to moderately undulating floodplains and strongly to steeply
<br />sloping, severely eroded low rolling shale hills, in a11uvirun and residuum
<br />from sandstone and saline shale, at elevations ranging from 5,000 to 6,000
<br />feet. They are deep, generally slowly permeable, moderately coarse to fine
<br />textured soils which have an alkaline reaction, a horizon of high lime
<br />accumulation in the solum and may have some disseminated lime at or near
<br />the surface. TI1is grouping also includes about 3 percent Solonetz (high
<br />sodium) soils; 6 percent of deep, moderately fine textured Regoso1s; 15
<br />percent of deep, medium to fine textured Alluvial soils; 22 percent mis-
<br />cellaneous land types; and 17 percent moderately coarse to moderately fine
<br />textured Lithosols.
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<br />There are about 94,200 acres of irrigated land in this grouping, primarily
<br />on the Sierozem and Alluvial soil groups. Salinity is a major problem and
<br />is reflected in the spotty crop growth observed on these soils. The common
<br />natural vegetation consists of shadscale, mat salt bush, gardner salt bush,
<br />greasewood, rabbit brush, winter fat, cactus, ga11eta, three awn and squirrel
<br />tail.
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<br />2. Brown-Chestnut
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<br />Soils of this grouping have developed under slightly higher effective pre-
<br />cipitation than the Desert-Sierozem soils, on gently sloping stream terraces,
<br />outwash fans and valley fills, and moderately to steeply sloping uplands,
<br />in glacial till, alluvium and residuum from sandstone and shale, at eleva-
<br />tions ranging from 6,000 to 8,000 feet. They are deep, moderately coarse
<br />to moderately fine textured soils, which are nearly neutral in reaction and
<br />have lime leached deeper in the soil profile than grouping number I. This
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