LOCATION CHACUACO COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Calcidic Argiustolls
TYPICAL PEDON: Chacuaco loam - range. (Colors are for dry soil unless otherwise noted.)
A--0 to 5 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium granular structure; soft, very friable, slightly sticky and slightly plastic; slightly alkaline (pH 7.5); clear smooth boundary (5 to 7 inches thick).
AB--5 to 10 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure parting to moderate medium granules; soft, very friable, slightly sticky and slightly plastic; strongly effervescent; moderately alkaline (pH 7.9); clear smooth boundary (0 to 5 inches thick).
Bt--10 to 20 inches; yellowish brown (10YR 5/4) clay loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; very hard, firm, sticky and plastic; common continuous distinct clay films on faces of peds; 5 percent pebbles; violently effervescent; few fine masses of calcium carbonate; moderately alkaline (pH 8.0); clear smooth boundary (10 to 18 inches thick).
Bk--20 to 30 inches; very pale brown (10YR 8/3) and very pale brown (10YR 8/4) very gravelly loam, very pale brown (10YR 7/4) moist; massive; soft, very friable, nonsticky and nonplastic; 30 percent pebbles, 10 percent sandstone channers; violently effervescent; 37 percent calcium carbonate equivalent; moderately alkaline (pH 7.9); abrupt wavy boundary (3 to 10 inches thick).
R--30 inches; very strongly cemented Dakota sandstone.
TYPE LOCATION: Las Animas County, Colorado; about 1,000 feet north and 150 feet east of the southwest corner of Sec. 35, T. 34 S., R. 53 W.; Dennis Canyon USGS quadrangle; latitude 37 degrees 2 minutes and 10 seconds N, longitude 103 degrees 20 minutes and 2 seconds W.
RANGE IN CHARACTERISTICS:
Soil moisture: Ustic moisture regime bordering on aridic. Moist in some part April through August. Driest December through February.
Depth to lithic contact: 20 to 40 inches.
Depth to secondary calcium carbonate: 5 to 15 inches.
Thickness of the A and Bt horizons: 17 to 30 inches.
Thickness of the mollic epipedon: 7 to 15 inches.
Some pedons do not have an AB horizon.
Particle sized control section: (weighted average)
Clay content: 20 to 35 percent
Silt content: 5 to 60 percent
Sand content: 20 to 60 percent
Rock fragment content: 5 to 15 percent
The A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3
Reaction: neutral to moderately alkaline.
The Bt horizon:
Hue: 5 YR, 7.5YR, or 10YR Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 4
Texture : clay loam, loam, silty clay loam, or sandy clay loam.
Clay content: 20 to 35 percent
Rock fragment content: 0 to 15 percent
Reaction: slightly alkaline or moderately alkaline.
Calcium carbonate equivalent: 5 to 15 percent.
The Bk horizon:
Hue: 7.5YR or 10YR Value: 6 to 8 dry, 4 to 7 moist
Chroma: 2 to 4
Texture of the fine earth fraction: loam, silt loam
Clay content: 15 to 27 percent
Rock fragment content: 25 to 45 percent
Calcium carbonate equivalent: 15 to more than 40 percent.
COMPETING SERIES: These are the Asparas (NM), Capulin (NM) Rosebud (NE), Ryegate (CO) and Wapiti (CO) series.
Asparas soils: deep to limestone bedrock.
Capulin soils: 40 to 60 inches deep to a lithic contact.
Rosebud soils: paralithic contact at depths of 20 to 40 inches.
Ryegate soils: 35 percent or more fine or coarser sand; deeper than 12 inches to secondary carbonates.
Wapiti soils: very deep.
GEOGRAPHIC SETTING:
Parent material: eolian sediments and residuum derived dominantly from sandstone.
Landform: ridges and interfluves in the plains.
Slope: 0 to 10 percent.
Elevation: 5,000 to 8,000 feet.
Mean annual precipitation: 14 to 16 inches.
Mean annual air temperature: 46 to 53 degrees F.
Frost free period: 120 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Capulin,
Dalerose, and
Torreon series.
Capulin soils: greater than 40 inches to bedrock and are on slightly higher ridges and knolls.
Dalerose soils: less than 20 inches to a lithic contact and are on summits and shoulders.
Torreon soils: do not have bedrock above 60 inches, are in the fine family, and are on more gently sloping areas.
DRAINAGE AND PERMEABILITY: Well drained; runoff is negligible on slopes less than 5 percent and low on 5 to 10 percent slopes; moderate permeability.
USE AND VEGETATION: These soils are used mainly for livestock grazing. Principal native vegetation is blue grama, galleta, sideoats grama, and western wheatgrass.
DISTRIBUTION AND EXTENT: Chacuaco soils occur in southeastern Colorado. LRR G, MLRA's 67 and 70. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES PROPOSED: Las Animas County, Colorado, 1986. The name is from a major drainage in the area.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: 0 to 10 inches. (A and AB horizons)
Argillic horizon: 10 to 20 inches. (Bt horizon)
Calcic horizon: 20 to 30 inches. (Bk horizon)
Lithic contact: bedrock at 30 inches. (top of R layer)
Classified according to Keys to Soil Taxonomy Tenth Edition, 2006.
The soil was previously mapped within the Ryegate soil, but was determined to average less than 45 percent fine and coarser sand in the particle size control section. This soil is pronounced Cha-kwock. Laboratory data S87CO-071-003.
The assignment of cation-exchange activity class is supported by lab samples S87CO-071-003.
ADDITIONAL DATA: None