LOCATION SHAWA CO+MT NM UTEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Pachic Haplustolls
TYPICAL PEDON: Shawa loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 8 inches; dark grayish brown (10YR 4/2) loam, black (10YR 2/1) moist; strong medium granular structure; slightly hard, very friable; neutral; clear smooth boundary. (3 to 10 inches thick)
A2--8 to 25 inches; gray (10YR 5/1) loam, very dark gray (10YR 3/1) moist; weak medium subangular blocky structure parting to moderate medium granular; slightly hard, very friable; moderately alkaline; gradual smooth boundary. (8 to 20 inches thick)
A3--25 to 40 inches; gray (10YR 5/1) loam, very dark gray (10YR 3/1) moist; massive; slightly hard, very friable; moderately alkaline; gradual smooth boundary. (6 to 24 inches thick)
C--40 to 60 inches; grayish brown (10YR 5/2) loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, very friable; neutral.
TYPE LOCATION: Rio Grande County, Colorado; about 2 miles east of South Fork, Colorado; located approximately 2,640 feet west and 2,000 feet south of the northeast corner of Sec. 35, T. 40 N., R. 3 E; South Fork East USGS quad; latitude 37 degrees, 40 minutes, 24 seconds N. and longitude 106 degrees, 36 minutes, 47 seconds W, NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture regime: ustic
Mean annual soil temperature: 41 to 47 degrees F (5.0 to 8.3 degrees C)
Mean summer soil temperature: 59 to 66 degrees F (15.0 to 18.9 degrees C)
Thickness of the mollic epipedon: 16 to 45 inches (41 to 114 centimeters)
Depth to secondary calcium carbonate: 40 to 60 inches (102 to 152 centimeters) or more
Particle size control section:
Clay content: 18 to 35 percent
Sand content: 20 to 52 percent
Rock fragments: 0 to 30 percent that are dominantly 1 to 10 inches (3 to 25 centimeters) in diameter.
A horizon(s):
Hue: 7.5YR to 5Y
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3
Texture: loam, clay loam, silty clay loam, and fine sandy loam
Reaction: slightly acid to moderately alkaline
C horizon:
Hue: 7.5YR to 5Y
Value: 4 to 7 dry, 2 or 4 moist
Chroma: 1 to 3
Texture: loam, clay loam, sandy clay loam, sandy loam, gravelly sandy loam, and very gravelly sandy loam
Rock fragment content: 0 to 35 percent
Reaction: slightly acid to moderately alkaline
COMPETING SERIES: These are the
Arnegard (ND),
Beman (CO),
Bowery (MT),
Falkirk (ND),
Garlips (CO),
Garza (WY),
Lonecone (CO),
Molinaro (CO)
Obrien (MT),
Roseglen (ND),
Sheckle (T) (UT) and
Yeoman (MT) series.
Arnegard, Falkirk, Roseglen, and Yeoman soils: have cambic horizons and horizons with visible calcium carbonate accumulations.
Bowery soils have cambic horizon.
Beman and Garza soils: have secondary carbonates above a depth of 15 inches.
Garlips soils have a calcic horizon at depths of 18 to 35 inches and are dry in July.
Molinaro soils: have cambic horizon and visible secondary calcium carbonate of fine filaments of lime at 30 to 56 inches.
Sheckle soils: are dominantly sandy clay loam in the particle-size control section and have chroma of 4 through 6.
Lonecone soils: have paralithic bedrock at depths of 20 to 40 inches.
Obrien soils: have free carbonates above a depth of 30 inches and bulk density greater than 1.55.
GEOGRAPHIC SETTING:
Parent material: alluvium, slope alluvium and colluvium derived from sedimentary, igneous and metamorphic rock, and granite, gneiss, and mica schist.
Landform: alluvial fans, fan remnants, stream terraces, structural benches, hills and mountain slopes.
Slopes: 0 to 65 percent
Elevation: 6,000 to 10,000 feet (1,829 to 3,048 meters). In Montana elevation ranges from 3,500 to 5,000 feet.
Mean annual air temperature: 37 to 46 degrees F (4.4 to 7.8 degrees C)
Mean annual precipitation: 12 to 22 inches (30 to 56 centimeters)
Precipitation pattern: The soil moisture control section is affected by snow melt in early spring and peak precipitation occurring in the form of thunderstorms from June to September.
Wettest months: July and August
Driest months: January and February
Frost-free period: about 75 to 115 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Empedrado and
Jodero soils.
Empedrado soils: have an argillic horizon.
Jodero soils: have an irregular decrease in organic carbon.
DRAINAGE AND PERMEABILITY: Well to moderately well drained; slow to rapid runoff; moderate and moderately slow permeability.
USE AND VEGETATION: These soils are used for rangeland or native hay meadows and for irrigated crops. Native vegetation consists of western wheatgrass, needleandthread, blue grama, cactus, snakeweed, and Wyoming big sage.
DISTRIBUTION AND EXTENT: Colorado, Montana, New Mexico and Utah; LLR E, MLRA 48A and 51. 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 features include:
Mollic epipedon: the zone from 0 to 40 inches. (A1, A2, and A3 horizons)
Particle-size control section: the zone from 10 to 40 inches. (Part of the A2 horizon and A3 horizon)
Series last updated by state 7/02.
Activity class is presumed based on the general trend of other soils in the area.
The range in characteristics of this series has become much too broad over the years, and needs to be narrowed back to the original concept. The original concept of the series is in alluvial parent material, on fan remnants and stream terraces, with an aridic ustic moisture subclass, about 11 to 15 inches of precipitation, and sagebrush grass vegetation. The original slope range was 0 to 15 percent slopes. It appears that the original concept did not include a cambic horizon.
Taxonomic Version: Tenth edition, 2006