LOCATION LATAHCO                 ID

Established Series
Rev. AEK/CLM/BG/GAH
09/2013

LATAHCO SERIES

The Latahco series consists of very deep, somewhat poorly drained soils that formed in alluvium from the surrounding loessal uplands. Latahco soils are on low terraces, flood plains and drainageways. Slopes are 0 to 3 percent. The mean annual precipitation is about 20 inches and the mean annual temperature is about 44 degrees F.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Argiaquic Xeric Argialbolls

TYPICAL PEDON: Latahco silt loam-cultivated; originally described on August 21, 1963 on a 2 percent slope at 2,559 foot elevation (Colors are for dry soil unless otherwise noted.)

Ap--0 to 8 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; weak thin or medium platy structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; many very fine irregular pores; few uncoated silt grains; slightly acid (pH 6.5); abrupt smooth boundary. (6 to 10 inches thick)

A--8 to 13 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; many fine and very fine tubular pores; few uncoated silt grains; neutral (pH 6.6); clear irregular boundary. (4 to 12 inches thick)

E1--13 to 17 inches; gray (10YR 5/1) silt loam, black (10YR 2/1) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and very fine roots; many very fine tubular pores; many uncoated silt grains; few noncemented fine (less than 1 mm.) manganese masses; neutral (pH 6.8); clear wavy boundary.

E2--17 to 20 inches; gray (10YR 6/1) silt loam (high in coarse silt), very dark gray (10YR 3/1) moist; massive; soft, very friable, slightly sticky and slightly plastic; few fine roots; many fine and very fine tubular pores; many uncoated silt grains; few fine masses of iron accumulation; common noncemented fine (less than 1 mm.) manganese masses; neutral (pH 7.0); abrupt wavy boundary. (Combined E horizon thickness is 3 to 15 inches)

E/B--20 to 21 inches; horizon consisting of material like that in the E2 and Bt horizons. (0 to 2 inches thick)

Bt--21 to 26 inches; grayish brown (2.5Y 5/2), light brownish gray (2.5Y 6/2) silty clay loam, dark gray (2.5Y 4/1) dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate medium angular blocky; very hard, firm, moderately sticky and moderately plastic; few fine roots; many very fine and fine tubular pores; continuous distinct very dark gray (10YR 3/1) clay films that are darker moist; many noncemented fine (less than 1 mm.) manganese masses; slightly alkaline (pH 7.4); clear smooth boundary. (5 to 7 inches thick)

Btk1--26 to 32 inches; grayish brown (2.5Y 5/2) light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium prismatic structure parting to moderate medium angular blocky; very hard, firm, moderately sticky and moderately plastic; few fine roots on peds; many fine and very fine tubular pores; continuous distinct very dark grayish brown (10YR 3/2) clay films, very dark gray (10YR 3/1) moist; many noncemented fine (less than 1 mm.) manganese masses; noncalcareous matrix with thin seams and old root channels coated with white (10YR 8/1) lime; moderately alkaline (pH 7.9); clear smooth boundary. (0 to 8 inches thick)

Btk2--32 to 42 inches; grayish brown (2.5Y 5/2) light brownish gray (2.5Y 6/2) silty clay loam, dark grayish brown (2.5Y 4/2) moist; moderate medium and coarse prismatic structure parting to moderate coarse angular blocky; very hard, firm, moderately sticky and moderately plastic; common fine and medium tubular pores; continuous distinct clay films on faces of peds and continuous prominent clay films in pores; few fine black (10YR 2/1) concretions; thin white (10YR 8/1) lime and seams and masses in cracks and in channels, matrix is noncalcareous; moderately alkaline (pH 8.2); clear smooth boundary. (0 to 11 inches thick)

Btb--42 to 51 inches; light brownish gray (2.5Y 6/2) silt loam, grayish brown (2.5Y 5/2) moist; weak very coarse prismatic structure; very hard, firm, moderately sticky and moderately plastic; few fine and medium tubular pores; continuous faint clay films on faces of peds, continuous prominent clay films in pores; few fine distinct masses of iron accumulation; slightly alkaline (pH 7.8); abrupt wavy boundary. (8 to 14 inches thick)

Cc--51 to 62 inches; light gray (2.5Y 7/2) silt loam, grayish brown (10YR 5/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium pores; many fine and medium distinct yellowish brown (10YR 5/6) and yellowish brown (10YR 5/4) masses of iron accumulation, dark yellowish brown (10YR 4/4) and brown (10YR 4/3) moist; many fine and medium black (10YR 2/1) concretions; moderately alkaline (pH 8.0).

TYPE LOCATION: Benewah County, Idaho; about 4 miles northwest of Tensed, 300 feet west of Highway 95 at Benewah Creek road intersection; 1,540 feet north and 2,020 feet wesy of the southeast corner of section 27, T.45N., R.5W.; (Latitude 47 degrees, 12 minutes, 40 seconds North and Longitude 116 degrees, 56 minutes, 48 seconds West; USGS Tensed Quadrangle).

RANGE IN CHARACTERISTICS:

Mean annual soil temperature - 41 to 47 degrees F.
Soil moisture control section - usually moist but are dry for 45 to 60 days in late summer and fall.
Mollic epipedon thickness - 11 to 22 inches
Depth to the argillic horizon - 17 to 35 inches
Depth to aquic features with chroma of 2 or less with redox concentrations is 17 to 27 inches

Ap and A horizon
Value - 2 to 5 dry, 1 to 3 moist
Chroma - 1 or 2 dry or moist
Textures - SIL, SICL
Clay content - 15 to 30 percent
Reaction - moderately acid to neutral

E horizon (EB horizon, when present)
Hue - 10YR or 2.5Y dry or moist
Value - 5 to 8 dry, 2 to 7 moist
Chroma - 1 to 3 dry, 1 to 4 moist
Texture - SIL or VFSL
Clay content - 7 to 22 percent
Redoximorphic features - few to common
Iron-manganese concretions - few to common
Reaction - moderately acid to neutral

Bt and Btb (Btk and Btc horizons, when present)
Hue - 2.5Y, 10YR or 7.5YR
Value - 4 to 6 dry, 3 to 5 moist
Chroma - 1 to 4 dry or moist
Texture - SIL, SICL
Clay content - 24 to 38 percent
Redoximorphic features - few to many
Iron-manganese concretions - few to many
Reaction - slightly acid to moderately alkaline
Btk horizon has seams, veins, and segregations of lime, but the matrix is always noncalcareous.

Some pedons have a Btg horizon and some pedons lack a Cc horizon.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Latahco soils are on low terraces, flood plains, and drainageways associated with loess covered uplands. Slopes are 0 to 3 percent. The soils formed in alluvium from the surrounding loessal uplands. Elevation is 1,600 to 4,200 feet. The mean annual precipitation is 18 to 35 inches. The frost-free period is 80 to 135 days. The mean annual temperature is 40 to 46 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cald, Lovell, Southwick and Thatuna soils. Cald soils lack albic and argillic horizons. Lovell soils have an ochric epipedon. Southwick soils have fragic properties in the lower part of the profile are moderately well drained with oxyaquic conditions and lack redox features. Thatuna soils lack redox depletions within the upper 30 inches and are dry for 60 to 80 consecutive days in late summer and early fall.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; saturated hydraulic conductivity is moderately high in the surface and moderately low in the subsurface. Occasional, brief flooding occurs from February to April. Typically a perched water table is present from December through June. An apparent water table is also present.

USE AND VEGETATION: These soils are used mainly for cropland. Crops are wheat, barley, hay, pasture, and grass seed. Native vegetation includes perennial forbs and grasses, black hawthorn, common chokecherry, and ponderosa pine.

DISTRIBUTION AND EXTENT: Northwestern Idaho, MLRA 9. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Benewah County, Idaho, 1975.

REMARKS: Diagnostic horizons and features recognized in the pedon:

Mollic epipedon - The zone from the soil surface to 17 inches (Ap, A, and E1 horizons)

Albic horizon - The zone from 17 to 20 inches (E2 horizon)

Argillic horizon - The zone from 21 to 51 inches (Bt, Btk1, Btk2 and Btb horizons)

Particle-size control section - 21 to 41 inches (Bt and Btk1 and part of the Btk2 horizons)

Soil moisture regime - aquic/xeric

Soil temperature regime - frigid

CEC activity class based on associated soils.

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National Cooperative Soil Survey
U.S.A.