LOCATION MOSCA COEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Typic Natrargids
TYPICAL PEDON: Mosca loamy sand in grassland at an elevation of 7598 feet. (Colors are for dry soil unless otherwise noted.)
A--0 to 3 inches; light brownish gray (10YR 6/2) loamy sand, dark grayish brown (10YR 4/2) moist; weak fine granular structure; soft, very friable; nonsticky, nonplastic; many dark magnetic mineral grains; strongly alkaline (pH 8.6); abrupt smooth boundary. (2 to 4 inches thick)
E--3 to 5 inches; light gray (10YR 7/2) loamy sand, grayish brown (10YR 5/2) moist; weak thin platy structure parting to fine granular; soft, very friable; nonsticky, nonplastic; vesicular; many dark magnetic mineral grains; very strongly alkaline (pH 9.6); abrupt smooth boundary. (0 to 3 inches thick)
Btn--5 to 14 inches; pale brown (10YR 6/3) sandy loam, brown (10YR 4/3) moist; weak to moderate very coarse columnar or prismatic structure parting to moderate medium subangular blocky; slightly hard, firm; slightly sticky, slightly plastic; peds are hard; many thin glossy patches on faces of peds; glossy coatings in pores; wax-like coatings on sand and wax-like bridges between sand grains; many dark magnetic mineral grains; calcareous; very strongly alkaline (pH 9.6); clear smooth boundary. (7 to 16 inches thick)
Bk1--14 to 18 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure; slightly hard, very friable; slightly sticky, slightly plastic; peds are hard; inconsistent wax-like coatings on sand grains and a few wax- like bridges between sand grains; carbonate occurring mostly as coatings on the sand grains; many dark magnetic mineral grains; calcareous; very strongly alkaline (pH 9.6); gradual wavy boundary. (4 to 7 inches thick)
Bk2--18 to 30 inches; light gray (10YR 7/2) sandy loam, grayish brown (10YR 5/2) moist; single grained; soft, very friable; slightly sticky, slightly plastic; visible secondary calcium carbonate occurring as concretions, in thin seams and streaks, and as coatings on the sand grains; many dark magnetic mineral grains; calcareous; very strongly alkaline (pH 9.2); clear wavy boundary. (5 to 25 inches thick)
2C--30 to 60 inches; variegated colors; sand and gravel, 15 percent gravel. (Several feet thick)
TYPE LOCATION: Alamosa County, Colorado; 125 feet south and 1,320 feet west of the E1/4 corner of Sec. 34, T. 40 N., R. 9 E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 41 to 46 degrees F
Mean summer soil temperature: 59 to 64 degrees F
Exchangeable sodium: 15 to 50 percent in a majority of subhorizons in the Bt horizons, but is less than 15 percent in the A horizons of some pedons.
Conductivity: above the C horizon ranges from 0 to 14 dsm/m.
Depth to the sandy or sandy-skeletal 2C horizon: 20 to 40 inches.
Depth to the base of the natric horizon: 10 to 40 inches.
Depth to continuous subhorizons of visible secondary calcium carbonate, calcium sulfate, or other soluble salt accumulation: 10 to 40 inches.
Rock fragments: 0 to 15 percent in a major part of the solum and dominantly range from 1 to 10 inches in diameter. Coarse fragments in the 2C horizon ranges from 5 to 60 percent.
A horizon(s):
Hue: 5Y through 7.5YR
Value: 4 to 7 dry, 3 to 5 moist
Chroma: 2 to 4
Bt or Btn horizon(s):
Hue: 5Y to 7.5YR
Value: 4 to 6 dry, 4 or 5 moist
Chroma: 2 to 4
Texture: sandy loam
Clay content: 10 to 18 percent
Sand content: 52 to 80 percent
Silt content: 0 to 30 percent
Bk, Btk, or Btkn horizon(s):
Hue: 5Y to 7.5YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 2 to 4
Texture: sandy loam, loamy sand
Clay content: 3 to 20 percent
Sand content: 50 to 80 percent fine or coarser sand
Silt content: 0 to 34 percent
2Bk horizon (s):
Hue: 7.5YR or 10YR
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4
Texture: loamy sand
Clay content: 0 to 10 percent
Carbonate clay content: 1 to 4 percent
Sand content: 70 to 82 percent
Silt content: 0 to 30 percent
Fragment content, total: 0 to 10 percent
Fragment size and content: 0 to 10 percent subrounded indurated gravel
Calcium carbonate equivalent: 5 to 15 percent
Electrical conductivity: 4 to 8 mmhos/cm
Sodium adsorption ratio: 5 to 13
Reaction: pH 7.9 to 9.6
Organic matter content: 0.0 to 0.5 percent
2C horizon:
Hue: 5Y or 5YR
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3 or 4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform: alluvial flats, alluvial fans or alluvial terraces
Slopes: 0 to 4 percent
Parent material: alluvium derived from igneous and metamorphic rock
Mean annual precipitation: 6 to 8 inches
Precipitation pattern: Precipitation peaks in July and August occurring as intense summer thunderstorms
Mean annual temperature: 40 to 46 degrees F
Mean summer temperature: 59 to 66 degrees F
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Costilla,
Hooper, and
McGinty soils
Costilla soils: are sandy and lack natric and argillic horizons
Hooper soils: are clayey over sandy or sandy-skeletal.
McGinty soils: are coarse-loamy and lack natric and argillic horizons
DRAINAGE AND PERMEABILITY: Well drained; low runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used as native pastureland or as irrigated cropland where salts are leached successfully for the production of potatoes, alfalfa, barley, oats, and sweet clover. Principal native plants are blue grama, rabbitbrush, snakeweed, sandhill muhly, annual buckwheat, mustard, prickly pear, fringed sage, greasewood, saltgrass, and alkali sacaton.
DISTRIBUTION AND EXTENT: San Luis Valley Area of south-central Colorado. LRR E, MLRA 51. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Grande County, Colorado, 1972.
REMARKS:
Diagnostic horizons and features:
Ochric epipedon: 0 to 5 inches (A, E)
Natric horizon: 5 to 14 inches (Btn)
Calcic horizon: 14 to 30 inches (Bk1, Bk2)
Lithologic discontinuity: 30 to 60 inches (2C)
Last updated by the state: 3/05
At the type location the parent material is derived from mixed sources (igneous and metamorphic rock); volcanic rock only makes up about 30 percent; the original concept for the parent material was basalt, jwb, 4/09. In Costilla County, CO the parent material is derived from granite, gneiss, and mica schist.
Taxonomic version: Tenth edition, 2006