LOCATION MECLO IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Calciargidic Argixerolls
TYPICAL PEDON: Meclo silt loam -- on a 38 percent convex south-facing slope at 3,500 feet elevation in rangeland. When described on October 10, 1994, the soil was dry throughout. (Colors are for air-dry soil unless otherwise noted.)
A--0 to 4 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, few medium and coarse roots; many very fine and fine irregular pores; slightly acid (pH 6.2); clear smooth boundary. (2 to 8 inches thick)
AB--4 to 8 inches; brown (10YR 5/3) silty clay loam, very dark grayish brown (10YR 3/2) moist; moderate thin and medium platy structure parting to strong medium granular; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine, few medium roots; common very fine and fine tubular pores; about 20 percent of faces of peds covered with bleached silt grains; slightly acid (pH 6.5); abrupt wavy boundary. (0 to 11 inches thick)
Bt1--8 to 13 inches; brown (10YR 5/3) silty clay loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few very fine and fine, few medium and coarse roots; common very fine and fine tubular pores; common distinct clay films on faces of peds and in pores; about 15 percent of faces of peds covered with bleached silt grains; neutral (pH 7.0); clear wavy boundary. (3 to 10 inches thick)
Bt2--13 to 22 inches; pale brown (10YR 6/3) silty clay loam, dark yellowish brown (10YR 4/4) moist; strong fine and medium subangular blocky structure; hard, friable, moderately sticky and very plastic; few very fine, fine and medium roots; common very fine and fine tubular pores; common prominent clay films on faces of peds and in pores; 2 percent gravel; neutral (pH 7.0); gradual wavy boundary. (3 to 14 inches thick)
Btk--22 to 31 inches; pale brown (10YR 6/3) silty clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and very plastic; few very fine, fine and medium roots; common very fine and fine tubular pores; few distinct clay films on faces of peds and in pores; slightly effervescent (about 5 percent calcium carbonate); few carbonate coats on faces of peds and on rock fragments; 5 percent gravel; slightly alkaline (pH 7.4); abrupt smooth boundary. (3 to 14 inches thick)
Crkq--31 to 41 inches; stratified silty and loamy lacustrine deposits; very few discontinuous very thin carbonate and silica coatings on horizontal planes and vertical seams; matted roots at top of horizon.
TYPE LOCATION: Boise County, Idaho; about 7.5 miles south and 3 mile west of Horseshoe Bend; 50 feet north and 950 feet east of the southwest corner of section 31, T.6 N., R.2 E.; USGS Pearl Quadrangle; Latitude - 43 degrees, 48 minutes, 26 seconds N. and Longitude - 116 degrees, 16 minutes, 15 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 7 to 14 inches
Depth to secondary calcium carbonates - 15 to 30 inches
Depth to paralithic contact - 20 to 40 inches
Moisture control section - moist less than 90 consecutive days when the soil temperature is greater than 47 degrees F.
Average annual soil temperature - 51 to 53 degrees F.
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Clay content - 20 to 27 percent
Reaction - slightly acid or neutral
Bt horizon
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 2 through 4 dry or moist
Texture - SICL, SIC or C
Clay content - 35 to 45 percent
Rock fragments - 0 to 5 percent gravel
Pararock fragments - 0 to 25 percent
Reaction - neutral or slightly alkaline
Btk horizon
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 2 through 4 dry or moist
Texture - SICL or CL
Clay content - 27 to 35 percent
Rock fragments - 5 to 10 percent gravel
Pararock fragments - 0 to 35 percent
Calcium carbonate equivalent - 1 to 5 percent
Reaction - neutral or slightly alkaline
COMPETING SERIES: These are the Arzo, Encina, Krebs and Lavey soils. Arzo soils have a calcic horizon. Encina soils are very deep. Krebs soils are 40 to 60 inches deep to a paralithic contact. Lavey soils have a strongly to violently effervescent paralithic contact 3 to 8 inches thick overlying a lithic contact.
GEOGRAPHIC SETTING: Meclo soils are on convex positions of hill backslopes and fan remnants at elevations of 3,300 to 3,800 feet. Slopes range from 4 to 50 percent. The soils formed in colluvium and residuum from silty lacustrine deposits. The average annual precipitation is 14 to 16 inches. The average annual temperature is 49 to 51 degrees F. The frost-free period is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Adaboi and Crawley soils. Adaboi soils are very deep. Crawley soils are shallow to a paralithic contact. Adaboi and Crawley soils are on similar geomorphic positions as the Meclo soils.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; slow permeability.
USE AND VEGETATION: The Meclo soils are used mainly for rangeland. Small areas are used for irrigated hayland and cropland (small grains). Native vegetation is basin big sagebrush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 10. Meclo 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 13 inches (A, AB and Bt1 horizons)
Argillic horizon - zone from 8 to 31 inches (Bt1, Bt2 and Btk horizons)
Particle-size control section - zone from 8 to 28 inches
Paralithic contact - at 31 inches (Crkq horizon)
Soil moisture regime - aridic bordering on xeric
These soils are drier than other Xerolls in the region under similar precipitation due to early runoff and extended period of high evapotranspiration.
ADDITIONAL DATA: This pedon has partial laboratory analysis, reference sample no. - S94ID-015-009 (Pedon no. 97Z169), NSSL, Lincoln, NE.