LOCATION LAJARA CO+IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, calcareous, frigid Typic Endoaquolls
TYPICAL PEDON: LaJara loam - grassland. (Colors are for dry soil unless otherwise noted.)
A--0 to 10 inches; gray (10YR 5/1) loam, very dark gray (10YR 3/1) moist; common fine prominent yellowish brown (10YR 5/6) mottles; moderate fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many dark magnetic mineral grains; strongly effervescent; moderately alkaline; clear smooth boundary. (8 to 18 inches thick)
Bg1--10 to 25 inches; variegated colors, roughly 50 percent each, yellowish brown (10YR 5/4) and gray (N 5/) loam, dark yellowish brown (10YR 4/4) and gray (N 5/) moist; massive; slightly hard, very friable, slightly sticky, slightly plastic; slightly effervescent in spots; moderately alkaline; gradual smooth boundary. (10 to 20 inches thick)
Bg2--25 to 50 inches; variegated colors, roughly 50 percent each, yellowish brown (10YR 5/4) and gray (N 5/) stratified very fine sandy loam and loam, dark yellowish brown (10YR 4/4) and gray (N 5/) moist; massive; slightly hard, very friable, many dark magnetic mineral grains; slightly alkaline; clear smooth boundary. (15 to 35 inches thick)
2C--50 to 60 inches; multicolored sand; single grain; loose; slightly alkaline.
TYPE LOCATION: Alamosa County, Colorado; approximately 1,200 feet east and 300 feet north of the southwest corner of Sec. 16, R. 36 N., R. 10 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 43 to 47 degrees F. Depth to uniformly calcareous material ranges from 0 to 6 inches. The upper part of the control section is calcareous, but the soils grade to noncalcareous horizons at depths of less than 40 inches. Conductivity ranges from 0 to 14 millimhos in a major part of the control section. Exchangeable sodium ranges from 0 to 15 percent in most of the control section, and there is no subhorizon more than 4 inches thick above depth of 20 inches that exceeds 15 percent. Depth to skeletal materials ranges from 40 to more than 60 inches. The upper part of the control section, ranging in thickness from 10 to 20 inches, is loam or clay loam with clay averaging 18 to 35 percent. This grades to stratified sandy loam and loam at depths shallow enough so that on a weighted average basis the soil is coarse-loamy with clay averaging 5 to 18 percent. Rock fragments range from 0 to 15 percent in the particle-size control section. Hue ranges from 5Y through 7.5YR, with mottles to 2.5Y, and gley hues of N and 5Y.
The A horizon has value of 4 or 5, 2 or 3 moist, and chroma of 1 through 3. It is usually distinctly mottled in at least its lower part. This horizon is neutral through strongly alkaline.
The Bg horizon has value of 5 through 7, 4 through 6 moist, and chroma of 0 through 4. This horizon is neutral through strongly alkaline.
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING: LaJara soils are on flood plains and alluvial fans. Slopes range from 0 to about 6 percent. The soils formed in alluvial materials derived principally from basalt. The average annual precipitation is 7 to 16 inches, with peak periods of precipitation in the late summer. These soils are poorly drained and have fluctuating water tables that stand at or near the surface during part of almost every season. Mean annual air temperature ranges from 46 to 52 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alamosa, Gold creek, LaSauses and Vastine soils. Alamosa soils have argillic horizons with more than 18 percent clay. LaSauses soils lack mollic epipedons and have more than 15 percent exchangeable sodium in their upper horizons. Gold creek soils have wide cracks when dry, and >35% clay in the particle-size control section. Vastine soils have more than 18%, but less than 35% clay in the particle-size control section; and, a strongly contrasting substratum.
DRAINAGE AND PERMEABILITY: Poorly drained; slow runoff; moderate permeability.
USE AND VEGETATION: These soils are used principally as native pastureland or for hay meadows. In some areas where they have been drained, they are used for small grains, but crops requiring cultivation in the summer are not generally grown. Native vegetation is mainly sedges, rushes, wild iris, and other water-tolerant plants.
DISTRIBUTION AND EXTENT: San Luis Valley Area of south-central Colorado, and the Uncompahgre Valley of western Colorado. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Alamosa County, Colorado, 1974.
REMARKS: Last updated by the state 1/95. Diagnostic features include a mollic epipedon from 0 to 10 inches, and a water table above 200 centimeters.
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.