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A1,--0 to 8 inches, light b~sh-gray (lOYR 6/2)
<br />'sand, dark grayish brain (lOYR 4/2) when moist
<br />single grain; loose; slightly calcareous; pH
<br />9.8; gradual, smooth boundary.
<br />C1--8 to 24 inches, light brownish-gray (lOYR 6/2)
<br />sand, brown (lOYR 5/3) when moist; single
<br />grain; loose; slightly calcareous; pH 9.8;
<br />gradual, smooth boundary.
<br />C2--24 to 36 inches, Light brownish-gray (lOYR 6/2)
<br />sand, grayish brown (IOYR 5/2) when moist;
<br />single grain; loose; slightly calcareous; pH
<br />10.2; gradual, smooth boundary.
<br />C3--36 to 60 inches, pale-brown (lOYR 6/3) sand,
<br />brown (lOYR S/3) when moist; single grain;
<br />loose; slightly calcareous; pH 10.0.
<br />Corlett soils are nearly uniform in the upper 3
<br />feet. Texture is sand or loamy sand, pH values range
<br />from 9.0 to more than 10.0, and content of exchange-
<br />able sodium ranges from 15 to 75 percent. These
<br />soils commonly contain a buried soil or finer tex-
<br />tured material in the lower part of the profile that
<br />contributes to restricted drainage and very strong
<br />alkalinity. The depth to this buried soil or finer
<br />textured material depends on the height of the dunes
<br />or ridges.
<br />Corlett sand, hilly (COE),--This soil occupies
<br />low dunes and ridges on the valley floor in the
<br />central and north-central parts of the survey area.
<br />The dunes range from 1/4 acre to 10 acres in size
<br />and from 5 to 15 feet in height. The surface layer
<br />commonly has a crust of white salt in low-lying
<br />areas. This soil has the profile described as rep-
<br />resentative for the Corlett series. Surface runoff
<br />is slow from the dune areas. The hazard of soil
<br />blowing is very severe if vegetative cover is not
<br />adequate.
<br />Included in mapping, in some low areas between
<br />the dunes, are soils that contain mottles and have a
<br />seasonal high water table at a depth of 20 to 40
<br />inches.
<br />This soil is used for range and is grazed by cat-
<br />tle and sheep. Capability unit VIIe-3 (non-
<br />irrigated); Sand Hummocks range site.
<br />Corlett-Hooper complex, undulating (CpB).--This
<br />complex occurs mainly in the central and north-cen-
<br />tral parts of the county. A small area occurs west
<br />of Alamosa near the Rock Creek drainageway. Corlett
<br />sand occupies the sand dunes and has the profile
<br />described as representative for the Corlett series.
<br />These dunes range from 2 feet to 15 feet in height
<br />and from a few square yards to 5 or 30 acres in size.
<br />The Corlett soil generally is in intricate patterns
<br />with the Hooper soils, and mapping them separately
<br />was not feasible. Corlett sand represents 30 to 70
<br />percent of this complex. The Hooper soils occupy
<br />the low areas between the dunes. These soils in-
<br />clude Hooper clay loam and Hooper loamy sand. They
<br />make up 30 to 70 percent of the total acreage in the
<br />complex. There are many areas of eroded Hooper
<br />soils.
<br />Depth to the underlying water table varies large-
<br />ly with the topography. Some of the lake basins have
<br />water near ~urface, and this generally is the
<br />level of the water under the entire complex. The
<br />water table commonly is several feet below the tops
<br />of dunes and near the surface in the lake basin
<br />areas. Surface runoff is slow. The hazard of soil
<br />blowing is very severe on the Corlett soil but is
<br />only slight to moderate on the Hooper soils.
<br />Included in mapping are areas of Arena loam and
<br />Hapney loam that make up as much as 10 percent of
<br />the acreage in some places. There also are some
<br />inclusions of Space City loamy fine sand. Many of
<br />the smaller lake basins are included in this complex.
<br />The vegetation is nearly all greasewood on Hooper
<br />clay loam, but some saltgrass, sedges, and alkali
<br />sacaton grow in the wetter areas and on Hooper loamy
<br />sand. Large areas of the complex are bare. The
<br />vegetation on the Corlett soil is greasewood, rabbit-
<br />brush, four-wing sal tbush, and small amounts of salt-
<br />grass and alkali sacaton. The small inclusions of
<br />Space City soils have Indian ricegrass, blue grama,
<br />and spiry muhly. None of this complex is irrigated,
<br />and range is the main use. Capability unit VIIs-5
<br />(noni rri gated); Corlett soil in Sand Hummocks range
<br />site; Hooper loamy sand in Salt Flats range site.
<br />Costilla Series
<br />The Costilla series consists of somewhat exces-
<br />sively drained, coarse-textured, nearly level to
<br />gently sloping soils on alluvial flood plains. These
<br />soils occur mainly in the eastern half of the county.
<br />In a representative pm file, the surface layer is
<br />dark grayish-brown gravelly loamy sand about 4 inches
<br />thick. It is noncalcareous and is mildly alkaline.
<br />The next layer is dark-brown loamy sand about
<br />inches thick. It is moderately calcareous and
<br />strongly alkaline in the Lower part. The substratum,
<br />to a depth of 60 inches, is brown mainly gravelly
<br />loamy sand and gravelly sand that is highly calcare-
<br />ous and strongly alkaline.
<br />Costilla soils have very low available water
<br />holding capacity and are very droughty. Permeabil-
<br />ity is rapid. Plant roots can penetrate to a depth
<br />of 60 inches or more.
<br />The vegetation consists of blue grams, ring
<br />muhly, little rabbitbrush, and Greens rabbitbrush.
<br />These soils are used for range, pasture, and irri-
<br />gated crops.
<br />Representative profile of Costilla loamy sand, 0
<br />to 2 percent slopes, 1,050 feet west and 1,850 feet
<br />south of the northeast corner of sec. 11, T. 36 N.,
<br />R. 11 E.:
<br />Al--0 to 4 inches, grayish-brown (lOYR 5/2) gravelly
<br />loamy sand, dark grayish brown (IOYR 4/2) when
<br />moist; single grain; loose; 15 percent gravel;
<br />noncalcareous; pH 7.8; clear, smooth boundary.
<br />AC--4 to 13 inches, brown (lOYR S/3) loamy sand,
<br />dark brown (lOYR 3/3) when moist; very weak,
<br />medium, sub angular blocky structure parting to
<br />very weak, fine, granular; slightly hard when
<br />dry, very friable when moist; pH 8.7; noncal-
<br />careous; about 8 percent gravel; clear, smooth
<br />boundary.
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