LOCATION LATOUR ID+MT

Established Series
Rev. CJW-SHB-EMM
07/2013

LATOUR SERIES

The Latour series consists of very deep, well drained soils on mountains and ridgetops. They formed in talus and colluvium from metasedimentary rock with a thick mantle of volcanic ash. Permeability is moderate. Slopes are 15 to 75 percent. The average annual precipitation is about 48 inches and the average annual air temperature is about 40 degrees F.

TAXONOMIC CLASS: Medial-skeletal, glassy Typic Haplocryands

TYPICAL PEDON: Latour gravelly silt loam, forest; on a northwest-facing concave slope of 49 percent at 5,360 feet elevation. When described on September 8, 1981, the soil was dry throughout. (Colors are for dry soil unless otherwise stated.)

Oi--0 to 1 inch; slightly decomposed needles, leaves, and twigs.

Oe--1 to 2 inches; decomposed organic matter.

A--2 to 4 inches; grayish brown (10YR 5/2) gravelly medial silt loam, very dark grayish brown (10YR 3/2) moist; weak very fine and fine granular structure; soft, very friable, nonsticky and slightly plastic; common very fine, fine, and few medium and coarse roots; many very fine, fine, and few medium tubular and irregular pores; 10 percent gravel, 5 percent cobbles; moderately acid (pH 5.8); clear wavy boundary. (2 to 6 inches thick)

Bw1--4 to 13 inches; yellowish brown (10YR 5/4) gravelly medial silt loam, dark yellowish brown (10YR 3/4) moist; weak medium and coarse subangular blocky structure; soft, very friable, nonsticky and slightly plastic; common very fine, fine, and few medium and coarse roots; common very fine, fine, and few medium tubular and irregular pores; 10 percent gravel, 5 percent cobbles; slightly acid (pH 6.5); gradual wavy boundary. (4 to 12 inches thick)

Bw2--13 to 20 inches; light yellowish brown (10YR 6/4) very gravelly medial silt loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; common very fine, few fine and medium roots; common very fine, fine, and few medium tubular and irregular pores; 25 percent gravel, 10 percent cobbles; slightly acid (pH 6.5); gradual wavy boundary. (6 to 12 inches thick)

Bw3--20 to 44 inches; light yellowish brown (10YR 6/4) extremely cobbly medial silt loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; common very fine, few fine, medium and coarse roots; common very fine, fine, and few medium tubular and irregular pores; 30 percent gravel, 30 percent cobbles, 10 percent stones; slightly acid (pH 6.5); abrupt wavy boundary. (10 to 26 inches thick)

2C--44 to 60 inches; light yellowish brown (10YR 6/4) extremely cobbly loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, friable, nonsticky and slightly plastic; few very fine roots; few very fine irregular pores; 30 percent gravel, 40 percent cobbles, 15 percent stones; slightly acid (pH 6.5).

TYPE LOCATION: Benewah County, Idaho; about 0.75 mile northeast of St. Joe Baldy; about 2,300 feet west and 300 feet north of the southeast corner of sec. 36, T 47 N., R. 1 W.

RANGE IN CHARACTERISTICS:

Soil moisture - usually dry for 20 to 30 consecutive days August to mid-September, moist in the fall through mid-summer (udic moisture regime)
Average annual soil temperature - 39 to 42 degrees F
Average summer soil temperature - 44 to 46 degrees F with an O horizon
Depth to bedrock - more than 60 inches
Solum thickness - 30 to 56 inches

Volcanic ash mantle - 20 to 42 inches thick
Volcanic glass content in the 0.02 to 2.0 mm fraction - 30 to 70 percent
Acid-oxalate extractable Al + 1/2 Fe - 2.0 to 4.5 percent
Phosphate retention - 55 to 100 percent
15-bar water retention on air dried samples - 15 to 18 percent
Reaction - moderately acid or slightly acid

A horizon
Hue - 10YR or 7.5YR
Chroma - 2, 3, or 4, dry or moist
Texture - medial silt loam
Rock fragments - 10 to 35 percent
Bulk density - 0.65 to 0.85 g/cc

Bw horizon
Chroma - 3 or 4 dry and moist
Texture - medial silt loam
Rock fragments - 15 to 45 percent in the upper part and 35 to 70 percent in the lower part (average greater than 35 percent)
Bulk density - 0.65 to 0.85 g/cc

2C horizon
Value - 6 or 7 dry, 4 or 5 moist
Texture - silt loam, loam or sandy loam
Rock fragments - 55 to 85 percent

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Latour soils are on all aspects of mountains and ridgetops at higher elevations, but mainly occupy northerly aspects at lower elevations. These soils formed in talus and colluvium from metasedimentary rock with a thick mantle of volcanic ash. Slopes are 15 to 75 percent. Elevations are 4,800 to 6,200 feet. The climate is cold, humid, with cool, moist summers and cold, wet winters. The average annual precipitation is 38 to 55 inches, and the average annual air temperature is 38 to 42 degrees F. The frost-free season is 30 to 75 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ahrs (T), Bouldercreek (T), Honeyjones (T), and Marblecreek (T) soils. Ahrs and Marblecreek soils are on southerly-facing mountains at lower elevation, and are loamy skeletal and frigid. Honeyjones and Bouldercreek soils are on northerly-facing mountains at lower elevations, and are ashy over loamy-skeletal and frigid.

DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability.

USE AND VEGETATION: These soils are used for timber production, wildlife habitat, recreation, limited grazing, and watershed. Potential natural vegetation is mainly subalpine fir, Engelmann spruce, mountain hemlock, lodgepole pine, western larch and Douglas-fir, with an understory of common beargrass, big blueberry, myrtle pachystima, rustyleaf menziesia, common snowberry, low Oregon-grape, western fescue, and mountain brome.

DISTRIBUTION AND EXTENT: Northern Idaho. This soil is moderately extensive. MLRA 43A.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Shoshone County, Idaho, 1993.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 4 inches (Oi, Oe and A horizons)

Cambic horizon - the zone from 4 to 44 inches (Bw1, Bw2, Bw3 horizons)

Volcanic ash mantle - the zone from 2 to 44 inches (A, Bw1, Bw2, and Bw3 horizons)

Particle-size control section - the zone from 2 to 42 inches (A, Bw1, Bw2 and part of the Bw3 horizon)

ADDITIONAL DATA: There is laboratory data for a Latour pedon other than the type location in the St. Joe survey area. NSSL Pedon Number 89P746; Soil Survey Sample Number S89ID-079-002.

National Cooperative Soil Survey
U.S.A.