LOCATION TORSIDO COEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive, frigid Typic Argiaquolls
TYPICAL PEDON: Torsido loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 6 inches; dark gray (10YR 4/1) loam, very dark brown (10YR 2/2) moist; moderate fine granular structure; soft, very friable; many dark colored mineral grains in the sand and silt fractions; neutral (pH 7.0); clear smooth boundary. (4 to 8 inches thick)
B1--6 to 11 inches; dark grayish brown (10YR 4/2) light clay loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure parting to moderate fine granular; slightly hard, very friable; few thin glossy patches on faces of peds and some discontinuous glossy coatings in root channels; many dark colored mineral grains in the sand and silt fractions; neutral (pH 7.0); clear smooth boundary. (0 to 6 inches thick)
B2tg--11 to 19 inches; grayish brown (10YR 5/2) clay loam, very dark grayish brown (10YR 3/2) moist; common medium distinct mottles of yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; slightly hard, very friable; peds are very hard; many wax-like patches on faces of peds; wax-like coatings in root channels; neutral (pH 7.2); gradual smooth boundary. (5 to 30 inches thick)
B3g--19 to 23 inches; grayish brown (10YR 5/2) loam, dark grayish brown (10YR 4/2) moist; many large prominent mottles of brown (7.5YR 4/4) moist and light olive brown (2.5Y 5/4) moist; weak coarse subangular blocky structure; hard, friable; few thin glossy patches on of peds; discontinuous glossy coatings in root channels; neutral (pH 7.2); gradual smooth boundary. (3 to 5 inches thick)
Clg--22 to 30 inches; light brownish gray (10YR 6/2) loam, grayish brown (10YR 5/2) moist; many large prominent brown mottles of brown (7.5YR 4/4) moist and light olive brown (2.5Y 5/6) moist; massive; hard, friable; many dark colored grains in the sand and silt fractions; neutral (pH 7.2); gradual wavy boundary. (0 to 25 inches thick)
IIC-- 30 to 60 inches; very gravelly loamy sand or sand; 35 to 55 percent pebbles and 5 to 15 percent cobble; rock fragments and sand predominated by basalt.
TYPE LOCATION: Rio Grande County, Colorado; 600 feet south and 150 feet east of the N1/4 corner of Sec. 23 T. 38 N., R. 7 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges 41 degrees to 44 degrees F., mean summer temperature ranges from 58 degrees to 60 degrees F. The soils range from slightly acid to moderately alkaline in a majority of subhorizons within the solum. Exchangeable sodium ranges from 0 to 15 percent within the epipedon and the argillic horizon. Depth to the coarse textured IIC horizon ranges from 20 to 40 inches. Depth to the base of the argillic horizon ranges from 17 to 40 inches. Rock fragments range from 0 to 15 percent in the major part of the solum. These are mainly 1 to 10 inches in diameter.
The A horizon has hue of 5Y through 7.5YR, value of 4 or 5, 2 or 3 moist and chroma of 1 or 2.
The B2tg horizon has hue of 5Y through 7.5YR, value of 4 or 5, 2 or 3 moist and chroma of 0 through 2. This horizon ranges from 18 to 35 percent clay and averages 15 to 35 percent sand coarser than very fine sand.
The C1g when present above the IIc horizon has hue of 5Y through 7.5YR, value of 6 or 7, 5 or 6 moist and chroma of 1 through 3. Clay ranges from 18 to 35 percent in any C horizon above the IIC horizon.
The IIC horizon has colors similar to the C horizon.
COMPETING SERIES: There are no know competing series in this family and subgroup. The Vastine soils, in another subgroup lack an argillic horizon. The Sebawa soils have mesic temperatures.
GEOGRAPHIC SETTING: Torsido soils are on fans or terraces. Slopes range from 0 to 10 percent. The soil formed in moderately thin, noncalcareous, medium to moderately fine textured alluvium from basalt and overlying beds of sand and gravel which are also of basalt origin. The average annual precipitation is 7 inches with peak periods of precipitation in the spring and early summer months. Mean annual temperature is 40 to 42 degrees F., mean summer temperature is 56 to 58 degrees F.
GRAPHICALLY ASSOCIATED SOILS: These are the Alamosa and Vastine soils. Alamosa soils lack a sand and gravel substratum above a depth of 40 inches. Vastine soils lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Poorly drained; slow to medium runoff; moderate permeability. The seasonally high water table is 1 to 2 feet from the surface.
USE AND VEGETATION: These soils are used principally as native pastureland or for native hay meadow. Native vegetation is mainly sedges, rushes, and willows.
DISTRIBUTION AND EXTENT: San Luis Valley Area of south-central Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Rio Grande County Area, Colorado, 1972.
REMARKS: OSED scanned and cleaned up by Colorado. Last revised by state on 5/81.
The superactive cation exchange activity class was added in 03/2003 to the taxonomic classification by the National Soil Survey Center on request of the Lakewood MLRA office, without review of the soil series property data. The remainder of this document has not been updated.