LOCATION NAKARNA ID+WAEstablished Series
TAXONOMIC CLASS: Ashy over loamy, amorphic over paramicaceous, frigid Typic Udivitrands
TYPICAL PEDON: Nakarna ashy silt loam, forest; on a northwest-facing slope of 35 percent at 3,500 feet elevation. When described on June 5, 1984, the soil was moist throughout. (Colors are for dry soil unless otherwise stated.)
Oi--0 to 1 inch; slightly decomposed needles, leaves, and twigs.
Oe--1 to 2 inches; decomposed organic matter mixed with Mt. St. Helens volcanic ash. (O horizons 0.5 to 3.5 inches thick)
A--2 to 4 inches; pale brown (10YR 6/3) ashy silt loam, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine, and common medium roots; many very fine and fine tubular pores; neutral (pH 6.8); clear wavy boundary. (2 to 8 inches thick)
Bw1--4 to 16 inches; light yellowish brown (10YR 6/4) ashy silt loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; common very fine, fine and, medium and few coarse roots; common very fine and fine tubular pores; neutral (pH 7.0); abrupt wavy boundary. (10 to 17 inches thick)
2Bw2--16 to 24 inches; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; common very fine, fine, and medium roots; common very fine and fine tubular pores; many very fine and fine mica flakes; 10 percent decomposed schist parafragments; 5 percent gravel; slightly acid (pH 6.5); clear wavy boundary. (8 to 19 inches thick)
2BC--24 to 36 inches; very pale brown (10YR 7/4) paragravelly fine sandy loam, yellowish brown (10YR 5/4) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; common very fine, fine, and few medium roots; many very fine and fine irregular pores; many very fine and fine mica flakes; 25 percent decomposed schist parafragments; 10 percent gravel; slightly acid (pH 6.3); gradual wavy boundary. (0 to 12 inches thick)
2C--36 to 49 inches; very pale brown (10YR 7/4) cobbly fine sandy loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, nonsticky and slightly plastic; few very fine roots; common very fine and fine irregular pores; common medium and coarse strong brown (7.5YR 4/6) moist iron stains; many very fine and fine mica flakes; 25 percent decomposed schist parafragments; 10 percent gravel and10 percent cobbles; slightly acid (pH 6.3); clear wavy boundary. (8 to 24 inches thick)
2Cr--49 inches; highly weathered soft micaceous schist.
TYPE LOCATION: Shoshone County, Idaho; approximately 2 miles southeast of Clarkia, about 2,200 feet west and 1,000 feet north of the southeast corner of section 17, T. 42 N., R. 2 E.; Latitude - 46 degrees, 58 minutes, 52 seconds North; Longitude - 116 degrees, 14 minutes, 04 seconds West. USGS Anthony Peak quadrangle.
RANGE IN CHARACTERISTICS:
Soil moisture - usually dry for 25 to 35 consecutive days August to mid-September, moist mid-September through July (udic moisture regime)
Average annual soil temperature - 39 to 46 degrees F
Average summer soil temperature - 47 to 50 degrees F with an O horizon (frigid temperature regime)
Depth to soft bedrock - 40 to 60 inches
Average mica content in control section - greater than 35 percent by volume
Solum thickness - 24 to 40 inches
Volcanic ash mantle - 14 to 27 inches thick
Estimated properties of the volcanic ash influenced layer:
Volcanic glass content in the 0.02 to 2.0 mm fraction - 30 to 65 percent
Acid-oxalate extractable Al plus 1/2 Fe - 1.0 to 3.0 percent
Phosphate retention - 60 to 70 percent
15-bar water retention on air dried samples - 7 to 12 percent
A horizon
Hue - 10YR or 7.5YR dry or moist
Value - 4 to 6 dry, 2.5 to 4 moist
Chroma - 2 to 4 dry and moist
Texture - Ashy-SIL, Ashy-L
Clay content - 3 to 9 percent
Rock fragments - 0 to 15 percent gravel
Mica content - 0 to 5 percent fine mica by volume
Bulk density - 0.65 to 0.85 grams/cc
Reaction - moderately acid to neutral
Bw horizon
Hue - 10YR or 7.5YR dry or moist
Value - 4 to 6 dry, 3 or 4 moist
Chroma - 3 to 6 dry or moist
Texture - Ashy-SIL, Ashy-L
Clay content - 3 to 9 percent
Rock fragments - 0 to 15 percent gravel
Mica content - 0 to 5 percent fine mica by volume
Bulk density - 0.65 to 0.85 grams/cc
Reaction - moderately acid to neutral
2Bw horizon
Hue - 10YR or 7.5YR dry or moist
Value - 4 to 7 dry, 3 to 5 moist
Chroma - 3 to 6 dry or moist
Texture - L, VFSL, FSL, SL, SIL, GR-L, GR-VFSL, GR-FSL, GR-SL, GR-SIL, CB-L, PGR-SL
Clay content - 4 to 18 percent
Rock fragments - 0 to 25 percent gravel, 0 to 15 percent cobbles, 0 to 30 percent total fragments
Micaceous schist parafragments - 0 to 30 percent
Mica content - 10 to 50 percent fine mica by volume
Reaction - strongly acid to neutral
Clay bands - few present in some pedons (2E&Bt horizon), 1/8 to 3/4 inch thick
2C horizon (and 2BC horizon when present)
Hue - 10YR or 2.5Y dry, 7.5YR or 10YR moist
Value - 5 to 8 dry, 4 to 7 moist
Chroma - 3 to 6 dry or moist
Texture - CB-FSL, GR-FSL, GR-SL, CB-SL, FSL, SL, LFS, GRV-SL, L, GR-LS, LS, PGR-FSL, PGR-SL
Clay content - 2 to 15 percent
Rock fragments - 3 to 35 percent gravel, 0 to 25 percent cobbles, 3 to 60 percent total fragments
Micaceous schist parafragments - 0 to 60 percent
Mica content - 35 to 70 percent fine mica by volume
Reaction - very strongly acid to neutral
COMPETING SERIES: This is the Rettig series. Rettig soils are greater than 60 inches to bedrock.
GEOGRAPHIC SETTING: Nakarna soils are on mountain slopes and ridges. These soils formed in weathered material derived dominantly from decomposed micaceous schist and have a thick mantle of volcanic ash. Slopes are 5 to 75 percent. Elevation ranges from 1,600 to 5,000 feet. The climate is cool, humid with warm, moist summers and cool, wet winters. The average annual precipitation is 30 to 50 inches, and the average air temperature is 38 to 44 degrees F. The frost-free season is 50 to 110 days (9 in 10 years to 1 in 10 years, respectively).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ahrs, Bouldercreek, Helmer, Hobo, Honeyjones, and Sly soils. Ahrs soils are on east and west-facing mountain slopes, and are very deep and loamy-skeletal. Bouldercreek and Honeyjones soils are on north-facing mountain slopes, and are ashy over loamy-skeletal. Helmer soils are on dissected terraces and have a fragipan at depths of 10 to 20 inches. Hobo and Sly soils are on dissected terraces and foothills, and are very deep and have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; runoff is medium to rapid; permeability is moderate.
USE AND VEGETATION: These soils are used mainly for timber production, livestock grazing, wildlife habitat, recreation, and watershed. The potential natural vegetation is mainly western hemlock, western redcedar, western white pine, grand fir, Douglas-fir, and western larch, with an understory of queencup beadlily, goldthread, longtube twinflower, myrtle pachystima, oneleaf foamflower, sweetscented bedstraw, starry false-Solomons-seal, big blueberry, and western rattlesnake plantain.
DISTRIBUTION AND EXTENT: Northern Idaho and northeastern Washington. MLRA 43. The soils are moderately extensive.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Benewah County, Idaho, 1975.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 2 to 4 inches (A horizon)
Cambic horizon - the zone from 4 to 36 inches (Bw1, 2Bw2, and 2BC horizons)
Volcanic ash mantle - the zone from 2 to 16 inches (A and Bw1 horizons)
Particle-size control section - the zone from 2 to 42 inches (A, Bw1, 2Bw2, 2BC, and part of the 2C horizon)
The ranges of values listed under the Range in Characteristics for the soil properties Bulk density, Volcanic glass content, Acid-oxalate Al +1/2 Fe, Phosphate retention and 15-bar water retention are estimates only.
Lamella, when present, are less than 15 cm in cumulative thickness.
Diagnostic horizons and features are measured from the top of the first mineral layer.