LOCATION RAKU COEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Argiustolls
TYPICAL PEDON: Raku silt loam, on a north facing, nearly level, 1 percent slope in grass at an elevation of 5675 feet. (Colors are for dry soil unless otherwise noted.)
A--0 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate very fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic, neutral; abrupt smooth boundary. (7 to 10 inches thick)
Bt1--8 to 11 inches; brown (10YR 5/3) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate very fine subangular blocky structure; very hard, friable, sticky and plastic; common patchy distinct clay films on all faces of peds; neutral; abrupt smooth boundary.
Bt2--11 to 22 inches; brown (10YR 5/3) silty clay, brown (10YR 4/3) moist and crushed; moderate medium prismatic structure parting to strong medium angular blocks; extremely hard, firm, very sticky and very plastic; common continuous distinct clay films on all faces of peds; slightly alkaline; abrupt smooth boundary.
Bt3--22 to 28 inches; brown (10YR 5/3) silty clay, brown (10YR 4/3) moist and crushed; moderate medium angular blocky structure; very hard, friable, sticky and plastic; common continuous distinct clay films on all faces of peds; violently effervescent (2 percent calcium carbonate equivalent); moderately alkaline; clear smooth boundary. (Combined thickness of the Bt horizons is 18 to 30 inches)
Btk--28 to 45 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 4/3) moist; moderate very fine angular blocky structure; very hard, friable, sticky and plastic; few patchy distinct clay films on all faces of peds; common fine irregular distinct carbonate masses; violently effervescent (4 percent calcium carbonate equivalent); moderately alkaline; gradual smooth boundary. (13 to 18 inches thick)
Bk--45 to 68 inches; very pale brown (10YR 7/3) clay loam, brownish yellow (10YR 6/6) moist; weak coarse subangular blocky structure; slightly hard, friable, sticky and plastic; violently effervescent (17 percent calcium carbonate equivalent); moderately alkaline.
TYPE LOCATION: Las Animas County, Colorado; about 1 mile north of Kim; located about 1,320 feet east and 2,120 feet south of the northwest corner of sec. 15, T. 32 S., R. 53 W.; Kim North USGS quad; lat. 37 degrees 15 minutes 26 seconds N. and long. 103 degrees 21 minutes 00 seconds W., NAD 1927
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is moist April to June, moist intermittently July and August; Ustic moisture regime bordering on aridic.
Mean annual soil temperature: 49 to 53 degrees F
Mean summer soil temperature: 70 to 74 degrees F
Depth to base of the argillic horizon: 40 to 58 inches
Depth to secondary calcium carbonate: 12 to 22 inches
Depth to calcic horizon: 40 to 58 inches
Thickness of the mollic epipedon: 10 to 20 inches
Particle-size control section (weighted average):
Clay content: 40 to 50 percent
Sand content: 0 to 15 percent
Rock fragments: 0 to 5 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3
Texture: silt loam, silty clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 5 percent
Reaction: neutral or slightly alkaline
Bt horizons:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 to 4
Texture: clay, silty clay, silty clay loam
Clay content: 35 to 50 percent
Rock fragments: 0 to 5 percent
Reaction: neutral to moderately alkaline
Btk horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4
Texture: silty clay loam, silty clay, clay
Clay content: 35 to 50 percent
Rock fragments: 0 to 5 percent
Calcium carbonate equivalent: 1 to 5 percent
Bk horizon: (BCk horizon in some pedons)
Hue: 7.5YR or 10YR
Value: 6 to 8 dry, 4 to 6 moist
Chroma: 3 to 6
Texture: silt loam, silty clay loam, clay loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 5 percent
Calcium carbonate equivalent: 5 to 30 percent with at least part of the horizon greater than 15 percent
Gypsum: 0 to 3 percent
Reaction: moderately alkaline or strongly alkaline
COMPETING SERIES: These are the Ashfork(AZ),
Bethune(CO),
Blackpipe(SD),
Boneek(SD),
Boquillas(AZ),
Chapin(CO), Collbran(CO),
Collide(CO),
Emigrant(WY),
Huggins(SD),
Kube(SD),
Leyden(CO),
Loma(CO),
Nuncho(WY),
Nunn(CO),
Querc(WY),
Rednun(CO),
Richfield(KS),
Ryus(Ks),
Savo(SD),
Showlow(AZ),
Standley(CO),
Thunderbird(AZ),
Weld(CO), and
Wormser(WY) series.
Asfork soils: are moist December to February
Bethune, Blackpipe, Boquillas, Emigrant, Huggins, Leyden, and Querc soils: have a paralithic contact at depths of 20 to 40 inches.
Boneek and Kube soils: have a paralithic contact at depths of 40 to 60 inches.
Chapin, Thunderbird and Wormser soils: have a lithic contact at depths of 20 to 40 inches.
Collide and Rednun soils: have hues of 2.5YR or 5YR in the control section.
Loma and Ryus soils: are calcareous throughout.
Nuncho soils: are dry from July 15 through August.
Nunn soils: average 15 to 45 percent sand.
Richfield soils: the depth to the base of the argillic is 12 to 22 inches.
Savo soils: have a mean annual temperature of 48 degrees F. or less.
Showlow soils: average more than 15 percent rock fragments below the Bt horizon.
Standley soils: average 15 to 35 percent rock fragments in the control section.
Weld soils: have less than 15 percent calcium carbonate equivalent throughout.
GEOGRAPHIC SETTING:
Parent material: alluvium and loess derived from mixed sedimentary sources
Landform: plains, depressions, drainageways, terraces
Slopes: 0 to 3 percent
Elevation: 5,000 to 6,000 feet
Mean annual temperature: 50 to 54 degrees F
Mean annual precipitation: 14 to 16 inches
Precipitation pattern: peak periods of precipitation are April through August, driest December through February.
Frost-free period: 125 to 155 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Baca, Calemore, and Wiley series. The Baca and Wiley soils do not have a mollic epipedon and are on plains. The Calemore soils are fine-silty and are on plains.
DRAINAGE AND PERMEABILITY: Well drained, low runoff, slow permeability.
USE AND VEGETATION: This soil is used for rangeland, irrigated and nonirrigated cropland, and wildlife habitat. The native vegetation is mainly western wheatgrass, blue grama, bottlebrush squirreltail and winterfat.
DISTRIBUTION AND EXTENT: southeastern Colorado; LRR G, MLRA 67; the series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES PROPOSED: Las Animas County, Colorado, Las Animas County Area soil survey area, Colorado. The name is coined.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: The zone from 8 to 28 inches. (Bt1, Bt2, and Bt3 horizons)
Mollic epipedon: The zone from 0 to 11 inches. (A and Bt1 horizons)
Argillic horizon: The zone from 8 to 45 inches. (Bt1, Bt2, Bt3, and Btk horizons)
Calcic horizon: The zone from 45 to 68 inches. (Bk horizons)
Other features: Aridic ustic moisture regime.
Remarks:
The assignment of the cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Taxonomic Version: Second Edition, 1999.
ADDITIONAL DATA: