LOCATION ARADARAN IDEstablished Series
The Aradaran series consists of very deep, well drained soils with slow permeability that formed in colluvium and alluvium from welded tuff and granitic rocks. Slopes range from 4 to 35 percent in foothills. The average annual precipitation is about 17 inches and the average annual temperature is about 48 degrees F.
TAXONOMIC CLASS: Fine, smectitic, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Aradaran loam -- on a 22 percent convex northwest-facing slope at 3,800 feet elevation in rangeland. When described on August 12, 1995, the soil was dry to 25 inches and slightly moist below. (Colors are for air-dry soil unless otherwise noted.)
A1--0 to 3 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; moderate thin and medium platy structure parting to moderate fine granular; soft, very friable slightly sticky and slightly plastic; common very fine and fine, few medium and coarse roots; common very fine, fine and medium tubular pores; 1 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (2 to 4 inches thick)
A2--3 to 9 inches; dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure parting to moderate fine granular; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium and coarse roots; common very fine and fine tubular pores; 1 percent gravel; slightly acid (pH 6.1); gradual wavy boundary. (2 to 11 inches thick)
BA--9 to 14 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium roots; common very fine and fine tubular pores; 2 percent gravel; moderately acid (pH 5.9); clear wavy boundary. (2 to 11 inches thick)
Bt1--14 to 23 inches; grayish brown (10YR 5/2) clay loam, dark brown (10YR 3/3) moist; strong fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine, fine and medium roots; many very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; 2 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (9 to 19 inches thick)
Bt2--23 to 29 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; weak fine prismatic structure parting to strong fine and medium subangular blocky; very hard, friable, very sticky and very plastic; few very fine, fine and medium roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; 10 to 20 percent of faces of peds are covered with bleached silt grains; 2 percent gravel; slightly acid (pH 6.1); clear smooth boundary. (3 to 11 inches thick)
Bt3--29 to 42 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 3/4) moist; moderate medium prismatic structure; very hard, firm, very sticky and very plastic; few very fine and fine roots; few very fine and fine tubular pores; common prominent clay films on faces of peds and in pores; 5 percent gravel; slightly acid (pH 6.2); gradual wavy boundary. (5 to 15 inches thick)
Bt4--42 to 55 inches; light yellowish brown (10YR 6/4) fine gravelly clay loam, dark yellowish brown (10YR 4/4) moist; strong medium and coarse subangular blocky structure hard, friable, very sticky and moderately plastic; few very fine and fine roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; 15 percent gravel and 10 percent cobbles; slightly acid (pH 6.3); gradual wavy boundary. (7 to 19 inches thick)
Bt5--55 to 60 inches; very pale brown (10YR 7/4) fine gravelly sandy clay loam, brown (10YR 5/3) moist; weak fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine irregular pores; few distinct clay films on faces of peds, in pores and bridging sand grains; 15 percent gravel; slightly acid (pH 6.1).
TYPE LOCATION: Ada County, Idaho; about 6.5 miles north of Camels Back Park in Boise; 2,200 feet south and 1,500 feet west of the northeast corner of section 34, T.5 N., R.2 E.; USGS Boise North Quadrangle; Latitude - 43 degrees, 43 minutes, 42 seconds N. and Longitude - 116 degrees, 11 minutes, 56 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 20 to 30 inches
Depth to bedrock - 60 inches or more
Base saturation (some part between 10 and 30 inches) - 50 to 75 percent
Reaction - moderately acid or slightly acid
Particle-size control section - 35 to 50 percent clay; 0 to 15 percent rock fragments
Moisture control section - dry 60 to 90 consecutive days following the summer solstice
Average annual soil temperature - 49 to 51 degrees F.
A and BA horizons
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Clay content - 20 to 27 percent
Rock fragments - 0 to 15 percent gravel
Bt1, Bt2 and Bt3 horizons
Value - 4 or 5 dry, 3 or 4 moist
Chroma - 2 through 4 dry or moist
Texture - C or CL
Clay content - 35 to 50 percent
Rock fragments - 0 to 15 percent gravel
Bt4 and Bt5 horizons
Value - 5 through 7 dry, 4 or 5 moist
Chroma - 3 or 4 dry or moist
Texture - SCL or CL
Clay content - 25 to 40 percent
Rock fragments - 10 to 20 percent gravel, 0 to 10 percent cobbles and 10 to 30 percent total
COMPETING SERIES: These are the Bogus and Jacket series. Bogus soils have Oi layers and are dry greater than 90 consecutive days in the summer. Jacket soils have Oi layers, are dry 45 to 60 consecutive days following the summer solstice, have 2Bt horizons and contain less than 15 percent medium and coarse sand in the particle-size control section.
GEOGRAPHIC SETTING: Aradaran soils are on hill backslopes, footslopes, summits and shoulders at elevations of 3,400 to 4,200 feet. Slopes range from 4 to 35 percent. These soils formed in alluvium and colluvium from welded tuff and granitic rocks. Average annual precipitation is 15 to 19 inches. Average annual temperature is 47 to 49 degrees F. Frost-free period is 110 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Shafer and Yad soils. Shafer soils have cracks open to the surface, are 20 to 40 inches deep to a lithic contact and occur on structural benches, hill shoulders and summits. Yad soils have cracks open to the soil surface and occur on landslides, butte escarpments, hill backslopes, footslopes, summits and shoulders.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; slow permeability.
USE AND VEGETATION: Aradaran soils are used mainly for rangeland. Small areas are used for nonirrigated hayland/pasture. Native vegetation is Idaho fescue, bluebunch wheatgrass and xeric big sagebrush.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 10. Aradaran soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - zone from the surface to 23 inches (A1, A2, BA, and Bt1 horizons)
Argillic horizon - zone from 14 to 62 inches ( Bt1, Bt2, Bt3, Bt4, and Bt5 horizons)
Particle-size control section - zone from 14 to 34 inches
Linear extensibility - 4.0 to 6.0 cm (assumed) from 0 to 40 inches.
Soil moisture regime xeric