LOCATION LEMHI IDEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive Cumulic Cryaquolls
TYPICAL PEDON: Lemhi loam -- on a nearly level flood plain at 5,200 feet elevation in ryegrass pasture. (Colors are for dry soi unless otherwise noted. When described on August 14, 1991, the soil was moist from the surface to 16 inches, wet from 16 to 43 inches and saturated below 43 inches. A water table was present at 43 inches.)
Oi--0 to 3 inches; slightly decomposed roots, leaves and stems; abrupt, smooth boundary. (0 to 3 inches thick)
A--3 to 9 inches; dark gray (10YR 4/1) loam, black (10YR 2/1) moist; moderate medium granular structure; slightly hard, friable, slightly sticky and plastic; many very fine and fine and common medium roots; many very fine tubular pores; slightly effervescent (5 percent calcium carbonate equivalent); moderately alkaline (pH 8.4); clear smooth boundary. (4 to 6 inches thick)
Bk--9 to 16 inches; dark gray (10YR 4/1) loam, black (10YR 2/1) moist; moderate fine and medium subangular blocky structure; hard, friable, slightly sticky and moderately plastic; common very fine and fine, and few medium roots; many very fine tubular pores; slightly effervescent (4 percent calcium carbonate equivalent); common fine and medium soft masses and seams of segregated lime; moderately alkaline (pH 8.4); clear smooth boundary. (7 to 10 inches thick)
Bg--16 to 24 inches; grayish brown (2.5Y 5/2) loam, very dark grayish brown (2.5Y 5/2) moist; common medium faint masses of iron depletions black (2.5Y 2/2) moist; moderate medium subangular blocky structure; very hard, friable, slightly sticky and moderately plastic; few very fine, fine and medium roots; many very fine tubular pores; thin discontinuous strata of dark grayish brown (2.5Y 4/2) loamy sand with common fine and medium prominent masses of iron depletions very dark brown (10YR 2/2) and dark yellowish brown (10YR 3/4) moist; neutral (pH 7.3); abrupt wavy boundary. (8 to 18 inches thick)
2Cg1--24 to 27 inches; grayish brown (2.5Y 5/2) loamy sand, dark grayish brown (2.5Y 4/2) moist; common medium prominent masses of iron depletions olive (5Y 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine irrgular pores; 5 percent gravel; neutral (pH 7.3); abrupt wavy boundary. (3 to 6 inches thick)
2Cg2--27 to 63 inches; multicolored, dominantly olive gray (5Y 5/2) extremely gravelly coarse sand, olive gray (5Y 4/2) moist; single grain; loose; few very fine and fine roots; many very fine irregular pores; 60 percent gravel, 20 percent cobbles; neutral (pH 6.7).
TYPE LOCATION: Lemhi County, Idaho; approximately 2 miles southeast of Lemhi, Idaho, about 100 feet west and 200 feet south of the northeast corner of sec. 9, T. 17N. R. 24E. Latitude - 44 degrees North, 49 minutes, 30 seconds; Longitude - 113 degrees West, 36 minutes, 0 seconds.
RANGE IN CHARACTERISTICS:
Profile:
Average annual soil temperature - 36 to 42 degrees F.
Average summer soil temperature - 49 to 55 degrees F. (Classified without an O horizon as it is not always present)
Mollic epipedon thickness - 20 to 30 inches
Depth to water table - 12 to 18 inches (April through June)
Depth to sand and gravel - 20 to 40 inches
Particle-size control section:
Clay content: 18 to 26 percent in the upper part and 5 to 10 percent in the lower part
Rock fragments - 0 to 5 percent in the upper part and 5 to 80 percent in the lower part
A and Bk horizons
Value - 2 or 3 moist
Chroma - 1 or 2 moist
Reaction - slightly or moderately alkaline
Calcium carbonate equivalent - 2 to 10 percent
Bg horizon
Hue - 10YR or 2.5Y
Value - 4 or 5 dry, 3 or 4 moist
Chroma - 1 or 2 dry and moist
Texture - L or SIL
Clay content - 18 to 26 percent
2Cg1 horizon
Hue - 2.5Y or 5Y
Value - 4 or 5 dry and moist
Texture - LS or GR-LS
Coarse fragments - 5 to 20 percent
2Cg2 horizon
Hue - 2.5Y or 5Y
Value - 4 or 5 dry and moist
Texture - GRX-COS, GRX-LCOS
Rock fragments - 60 to 80 percent
COMPETING SERIES: This is the Hovarka series. Hovarka soils are noncalcareous to depth of more than 40 inches and do not have a Bk horizon.
GEOGRAPHIC SETTING: Lemhi series are on flood plains. These soils formed in medium textured alluvium over flood deposited sand and gravel. Slopes are 0 to 2 percent. Elevation ranges from 5,000 to 5,600 feet. The climate is cold and moist in winter and spring and cool in summer. The average annual precipitation is 10 to 14 inches. Average annual air temperature is 38 to 42 degrees F. Frost-free period is 50 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Copperbasin and Lilylake series. Copperbasin soils are on convex positions on valley flats, are somewhat poorly drained and have sandy-skeletal particle-size control sections. Lilylake soils are in concave positions in old slough channels on floodplains, are very poorly drained and have histic epipedons.
DRAINAGE AND PERMEABILITY: Poorly drained; slow runoff; moderate permeability in the upper part of the profile and very rapid permeability in the lower part. This soil floods occasionally for brief periods in January through June.
USE AND VEGETATION: Moistly cultivated under flood irrigation for grass hay and pasture. The principle native vegetation is basin wildrye, slender wheatgrass and sedges.
DISTRIBUTION AND EXTENT: East-central Idaho. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lemhi County, Idaho, 1999.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from 3 to 24 inches (A, BK and Bg horizons)
Particle-size control section - the zone from 13 to 43 inches (part of the Bk, the Bg, 2Cg1 and the 2Cg2 horizons)
All depths to diagnostic horizons and other features are measured from the top of the first mineral horizon.