LOCATION NEZ PERCE ID+WAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Xeric Argialbolls
TYPICAL PEDON: Nez Perce silt loam, on a 2 percent slope at 3,465 feet elevation in a cultivated field. When described on May 23, 1962, the soil was moist throughout. (Colors are for dry soil unless otherwise noted.)
Ap--0 to 6 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; strong fine and very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine and few medium roots; many very fine irregular pores; slightly acid (pH 6.3); clear wavy boundary. (4 to 8 inches thick)
A1--6 to 11 inches; dark gray (10YR 4/1) silt loam, black (10YR 2/1) moist; weak fine subangular blocky structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine and few medium roots; many very fine irregular pores; few worm holes and grayish brown (10YR 5/2) casts; slightly acid (pH 6.2); clear wavy boundary. (4 to 7 inches thick)
A2--11 to 14 inches; grayish brown (10YR 5/2) silt loam, very dark brown (10YR 2/2) moist, very dark grayish brown (10YR 3/2) moist, crushed; moderate medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and fine and few medium and coarse tubular pores; slightly acid (pH 6.4); clear wavy boundary. (2 to 5 inches thick)
A3--14 to 17 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium and coarse subangular blocky structure parting to moderate fine and medium angular blocky; slightly hard, friable, slightly sticky and slightly plastic; few very fine and fine roots; many very fine and fine and few medium and coarse tubular pores; few black and dark brown iron and manganese concretions; some mixing of darker A1 material; neutral (pH 6.6); clear wavy boundary. (2 to 4 inches thick)
E--17 to 20 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; very weak medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few very fine roots; many very fine and fine and few medium and coarse tubular pores; few medium faint dark brown (10YR 4/3) moist masses of iron accumulation; common black and dark brown iron and manganese concretions; few very fine (2 to 5 mm.) rounded weathered basalt gravel; few large krotovinas filled with A1 material; neutral (pH 6.6); abrupt smooth boundary. (2 to 6 inches thick)
Btb1--20 to 26 inches; pale brown (10YR 6/3) silty clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to strong medium angular blocky; very hard, firm, sticky and plastic; few very fine roots, mostly between peds; few very fine and fine tubular pores; many distinct grayish brown (10YR 5/2), very dark grayish brown (10YR 3/2) moist, clay films on faces of peds and surfaces of pores; common black and dark brown iron and manganese concretions; few very fine (2 to 5 mm.) fragments of weathered basalt; neutral (pH 7.0); clear wavy boundary. (4 to 8 inches thick)
Btb2--26 to 30 inches; brown (7.5YR 5/3) silty clay, dark brown (7.5YR 4/3) moist; moderate medium and coarse prismatic structure parting to strong fine and medium subangular blocky; extremely hard, very firm, very sticky and very plastic; few very fine roots mostly between peds; few very fine and fine tubular pores; many distinct clay films on faces of peds and surfaces of pores; few black and dark brown iron and manganese concretions; few very fine (2 to 5 mm.) fragments of weathered basalt; slightly alkaline (pH 7.4); clear wavy boundary. (3 to 6 inches thick)
Btkb1--30 to 42 inches; brown (10YR 5/3) silty clay, dark brown (10YR 4/3) moist; moderate medium prismatic structure parting to weak medium subangular blocky; extremely hard, very firm, very sticky and very plastic; few very fine roots, mostly between peds; few very fine and fine tubular pores; many distinct clay films on faces of peds and surfaces of pores; common lime veins and pockets; matrix is noneffervescent; common fine and very fine weathered basalt gravel; slightly alkaline (pH 7.8); clear wavy boundary. (9 to 12 inches thick)
2Btkb2--42 to 69 inches; light brownish gray (10YR 6/2) light silty clay, dark grayish brown (10YR 4/2) moist; moderate medium angular blocky structure; extremely hard, very firm, sticky and plastic; few very fine roots; few very fine and fine tubular pores; many distinct clay films on faces of peds and surfaces of pores; common angular basalt gravel; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (5 to 30 inches thick)
3R--69 inches; lime-coated basalt.
TYPE LOCATION: Idaho County; about 2 miles south of Cottonwood, Idaho; about 120 feet south and 1,400 feet west of the northeast corner of sec. 20, T. 31 N., R.1 E. Latitude - 46 degrees, 01 minutes, 11 seconds north; Longitude - 116 degrees, 21 minutes, 07 seconds west. USGS Cottonwood topographic quadrangle.
RANGE IN CHARACTERISTICS:
Mollic epipedon thickness - 12 to 20 inches
Organic matter content in mollic epipedon (weighted average) - 3 to 6 percent
Depth to perched seasonal water table - 12 to 30 inches
Depth to argillic horizon - 14 to 27 inches
Depth to secondary lime - 20 to 40 inches
Some pedons have few basalt gravel and cobble throughout; however, the rock fragments are usually below the albic horizon
Average annual soil temperature - 47 to 50 degrees F
Average summer soil temperature - 60 to 65 degrees F
Particle-size control section (weighted average)
Clay content - 35 to 55 percent
A horizon or mixed upper 7 inches
Value - 3 or 4 dry, 2 or less moist
Chroma - 1 or 2, dry or moist
Reaction - moderately acid through neutral
AB, BA, or Bw horizons are present in some pedons.
E horizon
Value - 6 or 7 dry, 3 through 6 moist
Chroma - 1 or 2, dry or moist
Textures - SI, SIL
Gravel content - 0 to 3 percent
Contains iron-manganese concretions up to 3mm in diameter
Reaction - slightly acid or neutral
Btb horizons
Hue - 7.5YR or 10YR
Value - 4 through 6 dry, 3 through 5 moist
Chroma - 2 through 4, dry or moist
Textures - SIC, SICL, C
Rock fragments - 0 to 15 percent
Clay content - 35 to 55 percent, 20 to 40 percent more clay (absolute) than E horizon
Iron-manganese concretion content - few or common, up to 3mm in diameter
Reaction - neutral through moderately alkaline
Btkb and 2Btkb horizons (the 2Btkb horizon is not in all pedons)
Hue - 7.5YR or 10YR
Value - 4 through 7 dry, 3 through 6 moist
Chroma - 2 through 4, dry or moist
Textures - SIC, SICL, C
Rock fragments - 0 to 15 percent
Clay content - 30 to 55 percent
Iron-manganese concretion content - few or common, up to 3mm in diameter
Reaction - neutral through strongly alkaline
Sodium absorption ratio - 3 to 10 percent
Calcium carbonate equivalent - 5 to 20 percent
COMPETING SERIES: These are the Chicane, Conley, Kooskia, Lookingglass, and Shebang series. Chicane soils have a mollic epipedon more than 20 inches thick, a cambic horizon above the albic horizon, and lack iron-manganese concretions larger than 2mm in the albic horizon and above a depth of about 40 inches. Conley soils have A1 or Ap horizons 10 inches or less thick, an E horizon that separates horizons making up the mollic epipedon, are somewhat poorly drained, and may have mottles in the E and B2 horizons. Kooskia soils have chroma of 1.5 or more in the upper 7 inches and lack chroma of 2 or mottles or iron-manganese concretions larger than 2mm in the albic horizon. Lookingglass soils do not have accumulations of secondary carbonates in the Bt horizon. Shebang soils have a mollic epipedon 7 to 12 inches thick and are 8 to 14 inches deep to the argillic horizon.
GEOGRAPHIC SETTING: Nez Perce soils are on loess-covered hills and basalt plateaus at elevations of 2,600 to 4,100 feet and have slopes from 0 to 25 percent. They formed in loess, although the lower part may be formed in material weathered from the underlying basalt. The climate is subhumid with an average annual precipitation of 19 to 24 inches including 4 to 7 feet of snow. Peak precipitation is in May and June and minimum precipitation in July and August. The average annual air temperature is 44 to 48 degrees F. The average frost-free season (32 degrees F.) ranges from about 100 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fenn and Ferdinand soils and the competing Chicane soils. Fenn soils lack an E horizon, have many slickensides and wedge-shaped aggregates in the Bt horizon, and lack an abrupt textural change. Ferdinand soils have clayey-skeletal Bt horizons.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium or rapid runoff; slow permeability.
USE AND VEGETATION: Soils are cultivated. Winter wheat, winter peas, barley, hay, and pasture are the principal crops. The natural vegetation is mainly Idaho fescue, bluebunch wheatgrass, sticky geranium, silky lupine, and arrowleaf balsamroot.
DISTRIBUTION AND EXTENT: Northern Idaho and eastern Washington. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Nez Perce and Lewis Counties, Idaho, 1917.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the surface to 17 inches (Ap, A1, A2, and A3 horizons).
Albic horizon - The zone from 17 to 20 inches (E horizon)
Abrupt textural change - at 20 inches (the upper boundary of the Btb1 horizon)
Argillic horizon - The zone from 20 to 69 inches (Bt1b, Bt2b, Btkb1, and 2Btkb2 horizons).
Particle-size control section - The zone from 20 to 40 inches (Btb1, Btb2, and part of Btkb1 horizon).
Secondary carbonate accumulation - The zone from 30 to 69 inches (Btkb1 and 2Btkb2 horizons) (This zone meets the requirements of a calcic horizon in some pedons.
ADDITIONAL DATA: This soil has been sampled for analysis at the NSSL. Laboratory sample numbers 85P 984, 86P 876; Soil survey sample numbers S85ID-069-006, S86ID-061-001.