LOCATION ACASCO COEstablished Series
TAXONOMIC CLASS: Clayey over sandy or sandy-skeletal, smectitic, frigid Typic Endoaquolls
TYPICAL PEDON: Acasco clay loam. Colors are for dry soil unless otherwise noted.
Ap--0 to 6 inches; grayish brown (10YR 5/2) clay loam, very dark brown (10YR 2/2) moist; moderate medium granular structure; soft, very friable; 10 percent pebbles; many dark colored magnetic mineral grains of sand and silt size; neutral (pH 7.0); clear wavy boundary. (3 to 9 inches thick)
A2g--6 to 14 inches; grayish brown (10YR 5/2) clay loam, very dark brown (10YR 2/2) moist; common medium distinct mottles of dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure parting to moderate medium granular; slightly hard, friable; many dark colored magnetic grains of sand and silt size; 10 percent pebbles; neutral (pH 7.0); gradual wavy boundary. (4 to 14 inches thick)
Bg--14 to 24 inches; light brownish gray (10YR 6/2) gravelly clay loam, dark grayish brown (10YR 4/2) moist; many large prominent mottles of dark yellowish brown (10YR 4/4) moist, and dark gray (2.5Y 4/1) moist; weak medium subangular blocky structure; hard, friable; 20 percent pebbles; many dark colored mineral grains of sand and silt size; neutral (pH 7.0); gradual wavy boundary. (13 to 17 inches thick)
2C--24 to 60 inches; sand and pebbles.
TYPE LOCATION: Rio Grande County, Colorado; 1,300 feet south and 1,200 feet east of the NW corner of Sec. 1, T. 37 N., R. 7 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 41 degrees to 45 degrees F., and mean summer soil temperature ranges from 59 degrees to 62 degrees F. Thickness of the solum and depth to sand and gravel ranges from 20 to 36 inches. Rock fragments in the particle-size control section above the discontinuity range from 10 to 35 percent. Fine or coarser sand in the control section above the discontinuity ranges from 15 to 35 percent and clay ranges from 35 to 45 percent. Hue ranges from 5Y through 7.5YR in most pedons, but thin subhorizons of 5YR are in some pedons.
The A horizon has value of 3 through 5, 2 or 3 moist, and chroma of 0 through 2. It has faint through prominent mottles. It is 27 to 40 percent clay. This horizon is slightly acid through moderately alkaline.
The B horizon has value of 5 or 6 dry, 4 or 5 moist, and chroma of 1 or 2. It has distinct or prominent mottles. This horizon is gravelly clay loam or gravelly clay with 35 to 45 percent clay.
COMPETING SERIES: This is the McDonaldsville series. McDonaldsville soils have a zone of lime accumulation, and have less than 15 percent pebbles in the particle size control section and 2C horizon.
GEOGRAPHIC SETTING: Acasco soils are on old lake terraces and alluvial fans. Slopes are typically less than 1 percent but range from 0 to 6 percent. These soils formed in alluvial materials derived principally from basalt. At the type location, the average annual precipitation is about 7 inches. Mean annual temperature ranges from 39 degrees to 43 degrees F. and mean annual summer temperature is 59 degrees to 64 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gerrard and Platoro soils. Gerrard soils have a fine-loamy particle-size class in the upper part of the control section. Platoro soils are well drained and have an argillic horizon.
DRAINAGE AND PERMEABILITY: Poorly drained; moderate runoff; slow permeability.
USE AND VEGETATION: These soils are used principally as native pastureland or for irrigated hay meadows. In some places they are used for irrigated cropland. Principal native vegetation consists of sedges and western wheatgrass.
DISTRIBUTION AND EXTENT: San Luis Valley 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: Diagnostic horizons and features recognized are:
This soil has not been reviewed since 1980. The typical pedon section line was added and the classification was updated from Typic Haplaquolls to Typic Endoaquolls 2/1999.