LOCATION COWBONE                 ID

Established Series
Rev. KL/HBM/CLM
08/2021

COWBONE SERIES

The Cowbone series consists of very deep, poorly drained soils that formed in alluvium on flood plains. Permeability is moderate in the subsoil and rapid in the substratum. Slopes are 0 to 3 percent. Average annual precipitation is about 300 mm and average annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Aeric Calciaquolls

TYPICAL PEDON: Cowbone silt loam--on a 2 percent slope at 1410 meters with Black cottonwood, Woods rose, Basin wildrye and bluegrass. (Colors are for dry soil unless otherwise noted. When described on August 12, 1987 the soil was dry to 28 cm, moist from 28 to 99 cm, and wet below 99 cm.)

Oe--0 to 1 cm; moderately decomposed leaves and twigs; abrupt wavy boundary.

Ak1--1 to 10 cm; grayish brown (10YR 5/2) silt loam, very dark brown (10YR 2/2) moist; moderate medium and coarse granular structure; hard, firm, slightly sticky and slightly plastic; common very fine and few medium coarse and very coarse roots; many very fine and fine irregular pores; slightly effervescent; (6 percent calcium carbonate equivalent); moderately alkaline (pH 7.9); abrupt wavy boundary.

Ak2--10 to 25 cm; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium and coarse granular structure; hard, firm, slightly sticky and slightly plastic; common very fine and few medium, coarse and very coarse roots; many fine and very fine irregular pores; slightly effervescent; (7 percent calcium carbonate equivalent); slightly alkaline (pH 7.8); clear wavy boundary. (Combined thickness of the Ak horizons is 15 to 30 cm)

Bkg--25 to 41 cm; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; common fine distinct yellowish brown (10YR 5/6) redox concentrations; moderate, medium and fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and few fine, medium and coarse roots; many fine and very fine irregular pores; strongly effervescent; (16 percent calcium carbonate equivalent); moderately alkaline (pH 7.9); abrupt wavy boundary. (15 to 20 cm thick)

Bg1--41 to 61 cm; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; common fine distinct yellowish brown (10YR 5/6) redox concentrations; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine, medium and coarse roots; many fine and very fine irregular pores; slightly alkaline (pH 7.8); abrupt wavy boundary. (10 to 25 cm thick)

Bg2--61 to 99 cm; light brownish gray (10YR 6/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; common, fine and medium distinct yellowish brown (10YR 5/6) redox concentrations; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few roots; many fine and very fine irregular pores; slightly alkaline (pH 7.6); clear wavy boundary. (0 to 51 cm thick)

Cg1--99 to 117 cm; light brownish gray (10YR 6/2) very fine sandy loam, very dark grayish brown (2.5Y 3/2) moist; many fine and medium prominent dark yellowish brown (10YR 4/6) and few , medium prominent very dusky red (2.5YR 2.5/2) redox concentrations and depletions; massive, soft, very friable, nonsticky and nonplastic; few very fine, fine, medium, coarse and very coarse roots; many fine and very fine irregular pores; slightly alkaline (pH 7.5); abrupt wavy boundary.

Cg2--117 to 137 cm; light brownish gray (10YR 6/2) fine sandy loam, dark grayish brown (10YR 4/2) moist; many large prominent dark grayish brown (2.5Y 4/2) redox depletions; massive; soft, friable, nonsticky and nonplastic; few fine and very fine roots; few fine and very fine irregular pores; slightly alkaline (pH 7.5); clear wavy boundary. (Combined thickness of the Cg horizons is 25 to 75 cm)

2Cg3--137 to 150 cm; light olive gray (5Y 6/2) very cobbly loamy very fine sand, dark olive gray (5Y 3/2) moist; many fine and medium yellowish red (5YR 4/6) redox concentrations; massive; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; common fine irregular pores; 10 percent gravel, 25 percent cobbles; slightly alkaline (pH 7.5).

TYPE LOCATION: Lemhi County, Idaho; about 1.6 km north of Ellis, Idaho; about 395 meters north and 135 meters east of the southwest corner from section 24, T.16N, R.20E.

RANGE IN CHARACTERISTICS:

Average annual soil temperatures - 4 to 7 degrees C
Mollic epipedon thickness - 30 to 50 cm
Depth to contrasting material - 115 to 150 cm
Depth to calcic horizon - 15 to 30 cm
Depth to seasonal high water table - 15 to 45 cm March to July

Control section - Percent clay: averages 5 to 15
Coarse fragments: 0 to 10 percent

Ak horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 or 2 dry or moist
Calcium carbonate equivalent - 5 to 10 percent
Reaction - slightly or moderately alkaline

Bkg horizon
Calcium carbonate equivalent - 15 to 20 percent

Bg and Cg horizons
Hue - 10YR or 2.5Y
Value - 4 to 6 dry, 2 to 4 moist
Texture - VFSL, FSL
Coarse fragments - 0 to 10 percent
Reaction - slightly or moderately alkaline

2Cg horizons
Coarse fragments - 35 to 60 percent
Reaction - neutral or slightly alkaline

COMPETING SERIES: These are the Fram and Wyndmere series. These soils lack the contrasting sand and gravel material between 115 and 150 cm.

GEOGRAPHIC SETTING: Cowbone soils are on flood plains at elevations of 1130 to 1525 meters. The soils formed in alluvium. Slopes range from 0 to 3 percent. The climate is cold and moist in winter and spring and dry in summer. Average annual precipitation is 200 to 355 millimeters. Average annual air temperatures are 6 to 8 degrees C. The frost-free period is 60 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bartonflat, Bock, Bromaglin, Bursteadt, Dawtonia, Sprabat, and Tohobit series. Bartonflat, Bock, and Bromaglin soils are on terraces and are well drained. Bartonflat and Bromaglin soils have sandy-skeletal particle-size control sections. Bock soils are on terraces, are well drained and have thin mollic epipedons. Bursteadt soils are on valley flats, are moderately well drained and have a xeric moisture regime. Dawtonia soils are on mountains and fan terraces, are well drained and have argillic horizons. Sprabat soils are on fan terraces, are well drained and lack mollic epipedons. Tohobit soils are on valley flats, are moderately well drained and have sandy-skeletal particle-size control sections.

DRAINAGE AND PERMEABILITY: Poorly drained. Slow runoff. Moderate permeability in the subsoil and rapid or very rapid permeability in the substratum. These soils are frequently flooded from April to June for brief periods of about 3 to 5 days.

USE AND VEGETATION: Wildlife habitat. The native vegetation is Black cottonwood, woods rose, Basin wildrye and bluegrass.

DISTRIBUTION AND EXTENT: East-central, Idaho. These soils are 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 the surface to 41 cm (the Ak1, Ak2 and Bkg horizons).

Calcic horizon - The zone from 25 to 41 cm (Bkg horizon).

Particle-size control section - The zone from 25 to 100 cm (Bkg, Bg1, Bg2, and part of Cg1 horizon)

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National Cooperative Soil Survey
U.S.A.