LOCATION LOCHSA                  ID

Established Series
Rev. RJB/GHL/EMM
10/2010

LOCHSA SERIES

The Lochsa series are deep, somewhat excessively drained soils that formed in materials weathered from granited, mica-schist, gneiss, or similar acidic rock. Lochsa soils are along canyon breaks and on mountain slopes and have slopes of 25 to 90 percent. The mean annual precipitation is about 28 inches and the mean annual air temperature is about 46 degrees F.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Pachic Humudepts

TYPICAL PEDON: Lochsa sandy loam, forested. (Colors are for dry soil unless otherwise noted.)

Oi--0 to 1 inch; very slightly decomposed needles, leaves, cones, twigs, and wood; moderately acid (pH 5.6); abrupt irregular boundary. (0 to 2 inches thick)

A1--1 to 9 inches; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky; many very fine and fine and common medium and coarse roots; many very fine interstitial pores; many fine mica flakes; 10 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (3 to 8 inches thick)

A3--9 to 14 inches; brown (10YR 5/3) coarse sandy loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky; many very fine and fine and common medium roots; many very fine interstitial and very fine tubular pores; many fine mica flakes; 10 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (5 to 12 inches thick)

B1--14 to 25 inches; brown (10YR 5/3) gravelly coarse sandy loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky; common very fine and fine and few medium roots; many very fine interstitial pores and many very fine, few fine and medium tubular pores; one wavy horizontal layer 2 millimeters thick that contains clay and clay films; many fine mica flakes; moderately acid (pH 5.8); gradual wavy boundary. (5 to 12 inches thick)

B2--25 to 36 inches; brown (10YR 5/3) gravelly coarse sandy loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky; common very fine and fine and few medium roots; many very fine interstitial and very fine tubular pores; many fine mica flakes; 5 percent cobblestones; one wavy horizontal more clayey band 2 to 3 millimeters thick; moderately acid (pH 5.8); gradual wavy boundary. (10 to 16 inches thick)

C1--36 to 47 inches; light olive brown (2.5Y 5/3) gravelly coarse sandy loam, olive brown (2.5Y 4/3) moist;massive; slightly hard, very friable, slightly stick; few very fine to medium roots; many very fine interstitial and common very fine tubular pores; one wavy horizontal more clayey band that has thin nearly continuous clay films; many fine mica flakes; moderately acid (pH 5.8) gradual wavy boundary. (10 to 15 inches thick)

C2--47 to 57 inches; light olive brown (2.5Y 5/3) gravelly coarse sandy loam, olive brown (2.5Y 4/3) moist; massive; slightly hard, very friable, slightly sticky; few very fine to medium roots; many very fine interstitial and common very fine tubular pores; few thin wavy horizontal clayey bands that have nearly continuous clay films; many fine mica flakes; moderately acid (pH 5.9); abrupt irregular boundary. (0 to 15 inches thick)

R--57 inches; hard mica schist or gneiss that is moderately decomposed; common moderately thick. brown (7.5YR 4/3) clay films in cracks; moderately acid (pH 5.6).

TYPE LOCATION: Idaho County, Idaho; on a 60 percent northeast-facing slopes, about one-eighth mile south of Lolo Creek, in the NE1/4 NE1/4 sec. 17, T.34N., R.4E.

RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 45 degrees to 47 degrees F., and the summer soil temperature, at a depth of 20 inches, ranges from 59 degrees to 62 degrees F. The base saturation is less than 50 percent in the upper part of the profile. The depth to consolidated bedrock ranges from 40 to 60 inches or more.

Oe horizons are present in some pedons.

The A horizon has value of 4 or 5 dry, 1 or 2 moist, and chroma of 2 or 3. It is coarse sandy loam or sandy loam and has up to 5 percent cobblestones and 20 percent gravel.

Very thin wavy horizontal, redder, more clayey bands range from 1 to few in the B and/or C horizons.

COMPETING SERIES: This is the similar Nadeen series. Nadeen soils have moist hue of 5YR in the B2 horizon and average more than 18 percent clay in the 10- to 40-inch control section.

GEOGRAPHIC SETTING: Lochsa soils are along canyon breaks and on mountainous slopes of 25 to 90 percent. They formed in residuum from granite; mica-schist, gneiss, or similar acidic bedrock. Elevations are 2,200 to 4,000 feet. The mean annual precipitation is 25 to 36 inches. The mean annual temperature is 45 degrees to 47 degrees F. The frost-free period ranges from 80 to 100 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Yakus and Suttler soils. Yakus soils are shallow to bedrock. Suttler soils have cryic temperature.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained; medium to very rapid runoff; moderate rapid permeability.

USE AND VEGETATION: Mostly forested. Some areas are used for dryland hay and pasture. Natural vegetation is grand fir, Douglas-fir, western larch, and western white pine.

DISTRIBUTION AND EXTENT: Kooskia Area, Idaho. The soils are inextensive.

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

SERIES ESTABLISHED: Idaho County, Idaho, 1975

REMARKS: Diagnostic horizons and features recognized in this pedon:
Umbric epipedon - the zone from 0 to 35 inches (A1, A3, B1, and B2 horizons).
Particle-size control section - the zone from 10 to 40 inches (A3, B1, B2, and part of the C1 horizons).

The 10/2010 revision reflects a reclassification from Humic Pachic Dystrudepts to Pachic Humudepts subgroup based on revisions to the 11th Edition Keys to Soil Taxonomy. No other changes were made during this revision.

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National Cooperative Soil Survey
U.S.A.