LOCATION LATAH WA+ID
Established Series
Rev. ND/RJE/SHB
06/2016
LATAH SERIES
Landscape--Columbia basalt plateau
Landform--low terraces along drainageways
Slope--0 to 3 percent
Parent material--loess and alluvium from surrounding loess hills
Mean annual precipitation--about 510 mm
Mean annual air temperature--about 9 degrees C
Depth class--deep
Drainage class--somewhat poorly drained
Soil moisture regime--xeric
Soil temperature regime--mesic
Soil moisture subclass--typic
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Xeric Argialbolls
TYPICAL PEDON: Latah silt loam, grassland
A1--0 to 15 cm; silt loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; moderate fine and medium granular structure; slightly sticky and slightly plastic; many roots; many very fine pores; neutral (pH 6.8); abrupt smooth boundary
A2--15 to 25 cm; silt loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; weak coarse prismatic structure breaking to moderate fine and medium subangular blocky; slightly hard, very friable, slightly sticky and slightly plastic; many roots; neutral (pH 6.8); clear wavy boundary
A3--25 to 48 cm; silt loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; moderate fine and medium prismatic structure; slightly hard, very friable, slightly sticky and slightly plastic; many roots; many very fine pores, neutral (pH 6.8); clear wavy boundary
E1--48 to 61 cm; silt loam, light brownish gray (10YR 6/2) dry, dark grayish brown (10YR 4/2) moist; weak fine and medium prismatic structure; slightly hard, very friable, slightly sticky and slightly plastic; common roots; common very fine pores; neutral (pH 6.8); clear irregular boundary
E2--61 to 76 cm; silt loam, light gray (10YR 7/1) dry, gray (10YR 5/1) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; common roots; many very fine pores; neutral (pH 6.8); abrupt smooth boundary
Bt1--76 to 91 cm; silty clay loam, brown (10YR 5/3) dry, brown (10YR 4/3) moist; strong fine and medium subangular blocky structure; hard, very firm, sticky and plastic; few flattened roots in cracks, no roots in peds; common very fine pores; thick continuous clay films on all faces of peds; few fine and medium light brown (7.5YR 6/4) and light gray (2.5Y 7/2) mottles on peds; organic matter stains along fracture planes; neutral (pH 6.6); clear smooth boundary
Bt2--91 to 150 cm; silty clay loam, brown (10YR 5/3) dry, brown (10YR 4/3) moist; strong fine and medium subangular blocky structure; hard, very firm, sticky and plastic; few flattened roots in cracks, no roots in peds; many very fine pores; thin continuous clay films on all faces of peds; common medium reddish yellow (7.5YR 6/6) and common medium and coarse light gray (2.5Y 7/2) mottles on peds; organic matter stains along fracture planes; neutral (pH 6.6)
TYPE LOCATION: Whitman County, Washington; about 790 m south and 185 m west of the northeast corner of section 7, T. 15 N., R. 46 E.; latitude 46.8004722, longitude -117.0559722, datum WGS 84 (coordinates estimated from PLSS details)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature at a depth of 50 cm--8 to 10 degrees C
Moisture control section--usually moist, but dry between depths of 10 and 30 cm 45 to 60 consecutive days following summer solstice
Thickness of mollic epipedon--45 to 80 cm
Thickness of solum--100 to 150 cm or more
A horizon
Value--4 or 5 dry, 2 or 3 moist
Chroma--1 or 2 dry or moist
Estimated content of organic matter in A1 horizon--3 to 8 percent
Reaction--6.1 to 8.4
Combined thickness--35 to 80 cm
A BA horizon is in some pedons.
E horizon
Value--5 to 7 dry, 4 or 5 moist
Chroma--1 or 2 dry or moist
Structure--prismatic, massive
Mottles--in some pedons below A3 horizon
Manganese concretions--few very fine and fine in some pedons
Reaction--6.6 to 8.4
Combined thickness--8 to 45 cm
Bt horizon
Value--4 to 6 dry, 3 to 5 moist
Chroma--2 to 4 moist or dry
Texture--silty clay loam, silty clay, clay
Content of clay--35 to 60 percent
Manganese concretions--few very fine and fine in some pedons
Reaction--6.6 to 8.4
Combined thickness--13 to 25 cm or more
A Btgb horizon is in some pedons.
COMPETING SERIES:
Quicksell--20 to 40 percent sand in particle-size control section
Setnum--50 to 100 cm to hard bedrock
Tilma--no mottles; low chroma associated with saturation and reduction
GEOGRAPHIC SETTING:
Elevation--550 to 975 m
Climate--warm, dry summers; cool, moist winters
Mean annual precipitation--460 to 635 mm
Mean January air temperature--about -2 degrees C
Mean July air temperature--20 degrees C
Mean annual air temperature--9 degrees C
Frost-free season--100 to 140 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Caldwell,
Snow--less than 35 percent clay; irregular decrease in organic matter
Garfield--ochric epipedon
Naff,
Palouse--no E horizon
Thatuna--less than 35 percent clay in argillic horizon
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--somewhat poorly drained
Saturated hydraulic conductivity (Ksat)--moderately high in A horizon; low in Bt horizon
USE AND VEGETATION:
Use--production of small grain
Native vegetation--tufted hairgrass, sedge, rose, redosier dogwood, cow parsnips, willows, black hawthorn, Saskatoon serviceberry, potentilla, rush, scattered hardwood
DISTRIBUTION AND EXTENT: Eastern Washington, northeastern Oregon, northern Idaho; MLRA 9; moderate extent
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benewah County, Idaho; 1930
REMARKS:
Diagnostic horizons and other features in this pedon
*Mollic epipedon--zone from surface to a depth of 48 cm
*Albic horizon--zone from 48 to 76 cm
*Argillic horizon--zone from 76 to 150 cm
MLRA-wide investigation is needed to evaluate the influence and extent of volcanic ash in the Latah series.
6/2016--This official series description (OSD) was updated as part of the final correlation of the Spokane County, Washington, soil survey. The formatting was updated according to SSR1 Technical Note 11--Content and Format of Official Series Descriptions (revised 12/2015).
National Cooperative Soil Survey
U.S.A.