LOCATION BLACKWELL ID+CO MT NV WYEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Typic Cryaquolls
TYPICAL PEDON: Blackwell clay loam, pasture. (Colors are for air dry soil unless otherwise stated.)
A1--0 to 1.5 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; weak fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine, fibrous roots; moderately acid (pH 6.0); clear smooth boundary. (0 to 2 inches thick)
A2--1.5 to 2.5 inches; dark grayish brown (10YR 4/2) clay loam, very dark brown (10YR 2/2) moist; weak medium and thin platy and moderate medium granular structure; hard, firm, moderately sticky and moderately plastic; many fibrous, fine roots, most roots extend horizontally; moderately acid (pH 6.0); clear smooth boundary. (0 to 2 inches thick)
A3--2.5 to 11 inches; very dark gray (10YR 3/1) clay loam, black (10YR 2/1) moist; weak medium and coarse subangular blocky structure parting to moderate fine subangular blocky; hard, firm, moderately sticky and moderately plastic; many fibrous, fine roots; moderately acid (pH 6.0); gradual smooth boundary. (5 to 15 inches thick)
A4--11 to 19 inches; dark gray (10YR 4/1) sandy clay loam that approaches sandy loam or loam, black (10YR 2/1) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few fine roots; slightly acid (pH 6.3); gradual smooth boundary. (6 to 12 inches thick)
Cg--19 to 27 inches; gray (10YR 6/1) sandy clay loam, dark gray (10YR 4/1) moist; massive; hard, friable, slightly sticky and slightly plastic; few fine roots; few fine distinct masses of iron accumulation; slightly acid (pH 6.3); clear smooth boundary. (5 to 40 inches thick)
2C--27 to 60 inches; light brownish gray (10YR 6/2) stratified loamy coarse sand and sandy clay loam, brown (10YR 4/3) moist; single grain and massive; hard, very friable; few roots; slightly acid (pH 6.4)
TYPE LOCATION: Valley County, Idaho; about 8 miles south of Donnelly; 1,160 feet north and 1,700 east of the southwest corner of section 24, T. 15 N., R. 3 E.
RANGE IN CHARACTERISTICS:
Soil moisture control section - usually saturated
Average annual soil temperature - 41 to 44 degrees F.
Average summer soil temperature - 51 to 55 degrees F.
Mollic epipedon thickness - 13 to 20 inches
Particle-size control section - CL, SIL, L, SCL, or GR-SCL;
and averages 18 to 34 percent clay
Depth to redoximorphic features - 15 to 25 inches
High water table - 0 to 30 inches from March through July
Depth to stratified sandy material - 20 to 40 inches
Reaction (pH) - neutral to moderately acid
Base saturation - 50 to 65 percent
A horizon
Hue - 10YR or 2.5Y
Value - 3 or 4 dry, 1 through 3 moist
Chroma - 1 or 2 dry or moist
Cg horizon
Hue - 10YR through 5Y
Value - 5 through 8 dry, 3 through 6 moist
Chroma - 1 or 2 dry or moist
COMPETING SERIES: These are the Foolhen, Furniss, Haydenfork, and Vensora series. Foolhen and Haydenfork soils do not have lithologic discontinuity. Furniss soils are slightly or moderately alkaline. Vensora soils have skeletal textures within 40 inches.
GEOGRAPHIC SETTING: The Blackwell soils are on bottomlands, stream terraces and alluvial fans and have slopes of 0 to 5 percent. Elevations range from 3,800 to 9,000 feet and range from 9,100 to 10,600 feet in Colorado. These soils formed in alluvium derived from basic igneous and acid igneous rocks. Average annual precipitation is 15 to 30 inches. Average annual temperature is 39 to 42 degrees F. The frost free season is 50 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gestrin, Girardot, and Melton soils. Gestrin soils have an argillic horizon. Girardot soils lack a mollic epipedon and are calcareous. Melton soils have a fine-loamy over sandy or sandy-skeletal control section. Gestrin and Melton soils are on alluvial fans. Girardot soils are on floodplains.
DRAINAGE AND PERMEABILITY: Poorly drained; slow runoff; moderately slow permeability. This soil commonly floods for brief periods from April through June.
USE AND VEGETATION: Blackwell soils are used mainly for pasture and wild hay. Vegetation is principally sedges, redtop, bluegrass, and willows.
DISTRIBUTION AND EXTENT: Mountainous areas of Colorado, Idaho, and Nevada. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jackson County, Colorado, l973.
REMARKS: Diagnostic horizons and other features recognized in this pedon:
Mollic epipedon - zone 0 to 19 inches (Al, A2, A3, and A4 horizons)
Redoximorphic features - masses of iron accumulation at 19 to 27 inches (Cg horizon)
Aquic moisture regime - water table at 2 to 30 inches