LOCATION DRASCO IDInactive Series
TAXONOMIC CLASS: Fine, smectitic, mesic Ultic Palexerolls
TYPICAL PEDON: Drasco silt loam - on a 12 percent south-facing slope at 2,440 feet elevation in pasture. (Colors are for dry soil unless otherwise stated).
A1--0 to 6 inches; brown (10YR 5/3) silt loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure parting to moderate fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine and fine and common medium tubular pores; 5 percent gravel; slightly acid (pH 6.2); clear smooth boundary.
A2--6 to 15 inches; brown (10YR 5/3) silt loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; hard, friable, sticky and slightly plastic; many very fine and fine roots; many very fine and fine and common medium tubular pores; 5 percent gravel; slightly acid (pH 6.2); clear wavy boundary. (Combined thickness of the A horizons is 8 to 15 inches)
Bw--15 to 24 inches; yellowish brown (10YR 5/4) silt loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; hard, friable, sticky and slightly plastic; common very fine and fine roots; many very fine, fine and medium tubular pores; 5 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (0 to 10 inches thick)
EBt--24 to 27 inches; light yellowish brown (10YR 6/4) silt loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; hard, friable, sticky and plastic; common very fine roots; many very fine and fine tubular pores; few distinct clay films on faces of peds; 5 percent gravel; moderately acid (pH 5.8); abrupt smooth boundary. (3 to 5 inches thick)
Btc--27 to 36 inches; brown (7.5YR 4/4) silty clay, dark brown (7.5YR 3/4) moist; strong medium prismatic structure; extremely hard, very firm, very sticky and very plastic; few very fine roots; common very fine tubular pores; many continuous prominent clay films lining pores and on faces of peds; many, medium iron-manganese concretions; 5 percent gravel; moderately acid (pH 5.6); gradual wavy boundary. (8 to 11 inches thick)
Bt1--36 to 42 inches; brown (7.5YR 4/4) silty clay, dark brown (7.5YR 3/4) moist; strong medium prismatic structure; extremely hard, very firm, very sticky and very plastic; few very fine roots; common very fine and fine tubular pores; many prominent clay films lining pores and on faces of peds; common, fine iron-manganese concretions; 5 percent gravel; moderately acid (pH 5.6); abrupt smooth boundary. (6 to 13 inches thick)
Bt2--42 to 50 inches; brown (7.5YR 4/4) silty clay, dark brown (7.5YR 3/4) moist; moderate fine and medium prismatic structure; extremely hard, very firm, very sticky and very plastic; few very fine roots; common very fine and fine tubular pores; many distinct and common prominent clay films lining pores and on faces of peds; 5 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (8 to 12 inches thick)
R--50 inches; basalt
TYPE LOCATION: Clearwater County, Idaho; about 1 mile northeast of Orofino, Idaho; about 1,550 feet west and 1,030 feet south of the northeast corner of sec. 5, T. 36N., R. 2E.; Latitude - 46 degrees, 29 minutes, 21 seconds, North; Longitude - 116 degrees, 13 minutes, 10 seconds, West.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 47 to 52 degrees F.
Mollic epipedon thickness - 11 to 15 inches
Depth to bedrock - 40 to 60 inches
Soil moisture control section - dry 45 to 60 days in summer and early fall
Depth to seasonally perched water table - 12 to 24 inches from January through April
A horizons:
Hue - 7.5YR or 10YR
Value - 3 through 5 dry
Chroma - 2 or 3 dry or moist
Reaction - moderately acid or slightly acid
Bw horizon:
Reaction - moderately acid or slightly acid
EBt horizon:
Chroma - 3 or 4 dry or moist
Reaction - moderately acid or slightly acid
Coarse fragments - 0 to 5 percent
Btc and Bt horizons:
Hue - 5YR or 7.5YR
Value - 4 or 5 dry and 3 or 4 moist
Chroma - 4 to 6 dry and 3 or 4 moist
Texture - SICL or SIC
Clay percent - 35 to 50 percent
Rock fragments - 0 to 5 percent
Reaction - moderately acid to neutral
COMPETING SERIES: These are the Driscoll, Nawt, Spilyay and Torney (T) series. Driscoll soils are very deep. Nawt and Torney soils have an accumulation of secondary carbonates in the lower part of the profile. Spilyay soils are very deep and are dry 60 to 90 days in summer and early fall.
GEOGRAPHIC SETTING: Drasco soils are on benches, canyon side slopes, and plateaus and have slopes of 3 to 35 percent. They formed in loess and material weathered from basalt. Elevations are 1,600 to 3,200 feet. The average annual precipitation is 20 to 25 inches and the average annual air temperature is 45 to 50 degrees F. The frost free season is 90 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kettenbach, Keuterville, Klickson, Kooskia and Taney series. Kettenbach, Keuterville, and Klickson soils have a loamy-skeletal particle-size control section and are on canyon sides. Kooskia soils have albic horizons and are on plateaus. Taney soils have fine-silty particle-size control sections and are on plateaus.
DRAINAGE AND PERMEABILITY: Moderately well drained; moderately rapid to rapid runoff; slow permeablilty.
USE AND VEGETATION: Used mostly for pasture with some areas of hayland and woodland. Natural vegetation is Idaho fescue, bluebunch wheatgrass, common snowberry, arrowleaf balsamroot, and widely spaced ponderosa pine.
DISTRIBUTION AND EXTENT: North central Idaho. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Clearwater County, Idaho, 1994. The name is coined.
REMARKS: Diagnostic horizons and other features recognized in this pedon are:
Mollic epipedon - the zone from the soil surface to 15 inches (A1 and A2 horizons).
Cambic horizon - the zone from 15 to 24 inches (Bw horizon).
Argillic horizon - the zone from 27 to 50 inches (Btc, Bt1, and Bt2 horizons).
Particle-size control section - the zone from 27 to 47 inches (Btc, Bt1, and part of the Bt23 horizons).