LOCATION THATUNA ID+OR WA
Established Series
Rev. JCC/TWH/CLM
06/2016
THATUNA SERIES
Landscape--Columbia basalt plateau
Landform--loess hills
Slope--about 0 to 55 percent; dominantly north-facing slopes and other slopes that receive runoff from higher lying areas or additional moisture from snow drifts
Parent material--recent loess over an older age of loess
Mean annual precipitation--535 mm
Mean annual air temperature--about 9 degrees C
Depth class--very deep
Drainage class--moderately well drained
Soil moisture regime--xeric
Soil temperature regime--mesic
Soil moisture subclass--oxyaquic
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Oxyaquic Argixerolls
TYPICAL PEDON: Thatuna silt loam, cultivated
Ap--0 to 13 cm; silt loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; very weak thin platy structure parting to moderate fine and very fine granular; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine irregular pores; neutral (pH 6.8) clear smooth boundary
A1--13 to 30 cm; silt loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; moderate fine and very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine irregular and tubular pores; neutral (pH 6.6); clear smooth boundary
A2--30 to 48 cm; silt loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; neutral (pH 6.6); clear smooth boundary
Bw--48 to 69 cm; silt loam, brown (10YR 5/3) dry, dark brown (10YR 3/3) moist; moderate medium and fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common fine roots; many very fine tubular pores; slightly acid (pH 6.5); abrupt smooth boundary
E--69 to 94 cm; silt loam, very pale brown (10YR 7/3) and pale brown (10YR 6/3) dry, brown (10YR 4/3) moist; some streaks of brown B-like material; massive; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; common very fine tubular pores; many black concretions less than 1 mm in diameter; slightly acid (pH 6.5); abrupt smooth boundary
Btb1--94 to 114 cm; silt loam, light yellowish brown (10YR 6/4) dry, brown (7.5YR 4/4) moist; weak medium and fine prismatic structure parting to weak medium subangular blocky; very hard, very firm, moderately sticky and moderately plastic; white speckling in interior of peds, mainly in upper 3 cm; few fine roots; many very fine tubular pores; many fine black concretions; continuous prominent dark yellowish brown (10YR 4/4) clay films on faces of peds; some uncoated light brownish gray (10YR 6/2) silt grains on faces of peds; slightly acid (pH 6.4); clear smooth boundary
Btb2--114 to 142 cm; silty clay loam, light yellowish brown (10YR 6/4) dry, brown (7.5YR 4/3) moist; weak medium prismatic structure; very hard, very firm, moderately sticky and moderately plastic; few fine roots; many very fine tubular pores; many fine iron-manganese concretions; continuous distinct clay films on faces of peds; some light speckling in interior of peds; slightly acid (pH 6.5); clear smooth boundary
Btb3--142 to 163 cm; silt loam, yellowish brown (10YR 5/4) dry, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; few fine roots; many very fine tubular pores; many fine iron-manganese concretions; many distinct clay films on faces of peds; neutral (pH 6.7)
TYPE LOCATION: Benewah County, Idaho, on east side of state line road, on a
10-percent, northwest-facing slope; about 370 m north of the NW1/4SW1/4 of section 24, T. 44 N., R. 6 W; latitude 47.1378200, longitude -117.0396000, datum WGS 84 (coordinates estimated from PLSS details)
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon--45 to 90 cm
Depth to Btb horizon--75 to 100 cm
Depth to seasonal perched water table--60 to 120 cm
Consecutive days moist--60 to 90 late in winter and in spring
Consecutive days dry--60 to 80 late in summer and early in fall
Depth to calcareous material--105 to 150 cm or more
Mean summer soil temperature--17 to 18 degrees C
Mean annual soil temperature--8 to 10 degrees C
Ap horizon
Thickness--13 to 25 cm
A horizon
Value--3 to 5 dry, 2 or 3 moist
Chroma--2 or 3 dry, 1 to 3 moist
Content of organic matter in upper 20 cm--3 to 6 percent
Carbon to nitrogen ratio in upper 20 cm--11.5 to 13
Reaction--5.6 to 7.3
Combined thickness--35 to 60 cm
Bw horizon
Value--3 to 5 dry
Chroma--3 or 4 dry, 2 to 4 moist
Reaction--5.6 to 7.3
Content of clay--18 to 25 percent
Thickness--18 to 35 cm
E horizon
Hue--10YR, 7.5YR
Value--6 or 7 dry, 3 to 5 moist
Chroma--2 or 3 dry or moist
Iron-manganese concretions--few or common, fine
Reaction--5.6 to 7.3
Thickness--15 to 35 cm
Btb horizon
Hue--10YR, 7.5YR
Value- 5 or 6 dry, 4 or 5 moist
Chroma--3 or 4 dry or moist
Texture--silt loam, silty clay loam
Content of particles coarser than very fine sand--0 to 10 percent
Iron-manganese concretions--few or common, fine
Reaction--6.1 to 7.3
Content of clay--24 to 35 percent
Combined thickness--40 to 55 cm or more
COMPETING SERIES:
Southwick--dry 45 to 60 days late in summer and early in fall
GEOGRAPHIC SETTING:
Elevation--550 to 975 m
Climate--subhumid
Mean annual precipitation--430 to 585 mm
Mean annual air temperature--7 to 10 degrees C
Frost-free season--100 to 160 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Caldwell--aquic conditions with chroma of 2 or less; redoximorphic concentrations at a depth of 75 to 100 cm; mollic epipedon 50 to 95 cm thick; in drainageways and on flood plains
Garfield,
Naff,
Palouse,
Staley--no E horizon; on loess hills
Schumacher--fine-loamy particle-size control section; on hills
DRAINAGE AND PERMEABILITY:
Drainage class--moderately well drained
Saturated hydraulic conductivity (Ksat)--moderately low
Depth to seasonal perched water table--60 to 120 cm in February through April
USE AND VEGETATION:
Use--cultivated crop production
Major crops--wheat, barley, hay, pasture, lentils, peas
Dominant vegetation in uncultivated areas--Idaho fescue, wild rose, snowberry, small forbs, other shrubs
DISTRIBUTION AND EXTENT: Loess region in prairies of northern Idaho, eastern Washington, and northeastern Oregon; MLRA 9; moderate extent
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: South Palouse River Project; Whitman County, Washington, and Latah County, Idaho; 1940
REMARKS:
Diagnostic horizons and other features in this pedon
*Mollic epipedon--zone from 0 to 69 cm
*Albic horizon--zone from 69 to 94 cm
*Argillic horizon--zone from 94 to 163 cm
*Oxyaquic feature--zone beginning at 69 cm that is saturated with water 30 cumulative days or more
*Particle-size control section--zone from 94 to 145 cm
5/2000--The classification of this series was changed from fine-silty, mixed, mesic Boralfic Argixerolls to fine-silty, mixed, superactive, mesic Oxyaquic Argixerolls
6/2016--This official series description (OSD) was updated as part of the final correlation of the Spokane County, Washington, soil survey. The soils may have volcanic ash above the Btb horizon; further investigation is required. The formatting of the OSD was updated according to SSR1 Technical Note 11--Content and Format of Official Series Descriptions (revised 12/2015).
ADDITIONAL DATA:
Chemical and physical data--profiles 65IDA 0502-Modal and 6IDA 0513
National Cooperative Soil Survey
U.S.A.