LOCATION RUBSON ID+MTEstablished Series
TAXONOMIC CLASS: Coarse-silty, mixed, superactive, frigid Vitrandic Hapludalfs
TYPICAL PEDON: Rubson silt loam, forested; on a 1 percent slope at 2,280 feet elevation. When described on October 18, 1972, the soil was moist throughout. Pedon was redescribed on August 30, 1995. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 2 inches; needles, leaves, and twigs.
Oe--2 to 3 inches; partially decomposed needles, leaves, and twigs mixed with Mt. St. Helens volcanic ash.
A--3 to 5 inches; pale brown (10YR 6/3) ashy silt loam, brown (7.5YR 4/2) moist; moderate fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine, medium, and coarse roots; many very fine pores; slightly acid (pH 6.1); clear wavy boundary. (1 to 4 inches thick)
Bw1--5 to 11 inches; pale brown (10YR 6/3) ashy silt loam, brown (7.5YR 5/4) moist; weak fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine, medium, and coarse roots; many very fine and few fine and medium pores; slightly acid (pH 6.2); clear wavy boundary. (5 to 8 inches thick)
Bw2--11 to 17 inches; pale brown (10YR 6/3) ashy silt loam, brown (7.5YR 5/4) moist; weak fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many fine, medium, and coarse roots; many very fine pores; moderately acid (pH 5.9); clear wavy boundary. (6 to 8 inches thick)
Bt1--17 to 26 inches; very pale brown (10YR 7/3) silt loam, pale brown (10YR 6/3) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine, medium, and coarse roots; many very fine and fine pores; few faint clay films on faces of peds and lining pores; few thin lamellae 2 to 4 mm thick; slightly acid (pH 6.1); clear wavy boundary. (8 to 12 inches thick)
Bt2--26 to 32 inches; very pale brown (10YR 7/3) silt loam, pale brown (10YR 6/3) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine, medium, and coarse roots; many very fine pores; few faint clay films on faces of peds and lining pores; common thin yellowish brown (10YR 5/4) lamellae .25 to .5 inch thick; slightly acid (pH 6.3); abrupt wavy boundary. (3 to 6 inches thick)
Bt3--32 to 35 inches; reddish yellow (7.5YR 6/6) silt loam, yellowish brown (10YR 5/4) and dark yellowish brown (10YR 3/4) moist; weak coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine roots; many very fine and fine pores; many faint clay films on faces of peds and lining pores; moderately acid (pH 5.7); abrupt wavy boundary. (3 to 6 inches thick)
Bt4--35 to 53 inches; very pale brown (10YR 7/3) very fine sandy loam, pale brown (10YR 6/3) moist; weak coarse subangular blocky structure; hard, friable, nonsticky and nonplastic; few fine, medium, and coarse roots; many very fine pores; few faint clay films on faces of peds and lining pores; common wavy and discontinuous yellowish brown (10YR 5/4) lamellae about 0.5 to 2 inches thick; slightly acid (pH 6.3); abrupt wavy boundary. (14 to 25 inches thick)
Bt5--53 to 58 inches; yellowish brown (10YR 5/4) very fine sandy loam, dark yellowish brown (10YR 4/4) moist; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine pores; few faint clay films and lamellae; slightly acid (pH 6.4); abrupt wavy boundary. (3 to 6 inches thick)
C--58 to 68 inches; light gray (10YR 7/2) loamy very fine sand, grayish brown (2.5Y 5/2) moist; massive; soft, very friable, nonsticky and nonplastic; many fine pores; slightly alkaline (pH 7.7).
TYPE LOCATION: Boundary County, Idaho; about one mile northeast of the junction of U. S. 2/95 and Paradise Valley Road; about 3.5 miles south of Bonners Ferry Ranger Station; about 200 feet west and 300 feet north of the southeast corner sec. 16, T.61N., R.1E.
Latitude - 48 degrees, 37 minutes, 53 seconds North
Longitude - 116 degrees, 19 minutes, 37 seconds West
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 42 to 45 degrees F.
Average summer soil temperature - 52 to 56 degrees F. with an O horizon.
Moisture control section - dry 15 to 30 days (August to mid September), moist mid September through July; Udic moisture regime.
Volcanic ash influence - 12 to 20 inches thick
Volcanic glass content - 5 to 20 percent
Acid-oxalate extractable Al + 1/2 Fe - 0.4 to 1.0 percent
Moist bulk density - 1.0 to 1.2 g/cc
Phosphate retention - 25 to 55 percent
A and Ap horizons
Value - 4 to 6 dry, 2 to 4 moist
Chroma - 2 or 3 dry or moist
Texture - ashy SIL, ashy VFSL
Clay content - 5 to 10 percent
Reaction - moderately acid to neutral
Bw horizons
Value - 5 to 7 dry, 3 to 5 moist
Chroma - 3 or 4 dry or moist
Texture - ashy SIL, ashy VFSL
Clay content - 5 to 10 percent
Reaction - moderately acid to neutral
Bt horizons
Hue - 10YR, 7.5YR, 2.5Y
Value - 5 to 7 dry, 3 to 6 moist
Chroma - 3 to 6 dry or moist
Texture - SIL, VFSL
Clay content - 5 to 17 percent
Lamellae - 1/16 to 2 inches thick, 10YR or 7.5YR 4/4, 4/6, 5/4 moist, clay content 16 to 25 percent
Reaction - moderately acid to neutral
2C horizon
Chroma - 2 or 3 dry or moist
Texture - LVFS, VFSL
Clay content - 0 to 5 percent
Reaction - neutral to slightly alkaline
Effervescence (calcium carbonate) - none to strongly
COMPETING SERIES: This is the Frycanyon series. Frycanyon soils have a Bk horizon.
GEOGRAPHIC SETTING: Rubson soils are on terraces. Slopes range from 0 to 20 percent. These soils formed in glaciolacustrine sediments with minor amounts of volcanic ash in the surface layers. The climate is subhumid with cold wet winters and warm relatively dry summers. Elevation is 2100 to 2700 feet. The average annual precipitation is 25 to 32 inches, and average annual air temperature is 42 degrees to 45 degrees F. The average frost-free period is 100 to 135 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Artnoc, Caboose, Crash, Elmira, Frycanyon, Porthill, Selle, and Wishbone soils. Artnoc, Caboose, Crash, and Wishbone soils are on terrace escarpments, have hues of 5Y in the solum and are not vitrandic. Elmira and Selle soils are on dumes and terraces and are sandy. Frycanyon soils are on terraces and have Bk horizons. Porthill soils are on terraces and are fine textured in the argillic horizon.
DRAINAGE AND PERMEABILITY: Well-drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: Woodland, wildlife habitat, recreation and dry cropland. The principal crops are small grains, alfalfa hay, clover seed and pasture. Some areas are used for Christmas tree plantations and homesites. Natural vegetation is mainly western hemlock, western redcedar, western white pine, Douglas-fir, grand fir, and western larch with an understory of myrtle pachystima, baldhip rose, longtube twinflower, queencup beadlily; starry false Solomons seal, common princes pine, darkwoods violet, and western rattlesnake plantain.
DISTRIBUTION AND EXTENT: Northern Idaho, Montana, and possibly northeastern Washington. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Boundary County, Idaho, 1974.
Remarks: Classification changed from Psammentic Haploxeralfs to Vitrandic Glossoboralfs in 1994. Vegetation indicates udic moisture regime. Classification changed to coarse-silty, mixed, superactive, frigid Vitrandic Hapludalfs in 1998 due to revision in soil taxonomy.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the mineral soil surface to 7 inches (A and part of the Bw1 horizons)
Argillic horizon - the zone from 17 to 58 inches (2Bt1, 2Bt2, 2Bt3, 2Bt4 and 2Bt5 horizons)
Volcanic ash influence - the zone from 3 to 17 inches (A, Bw1, and Bw2 horizons)
Particle-size control section - the zone from 17 to 37 inches (2Bt1, 2Bt2, 2Bt3, and part of the 2Bt4 horizons)