LOCATION PAJO ID
Established Series
Rev. DJT/ALH/RWL
06/2011
PAJO SERIES
The Pajo series consists of moderately deep, excessively drained soils with rapid permeability that formed in colluvium and residuum from granitic rocks mixed with volcanic ash in the upper part. Slopes range from 35 to 90 percent in mountains and canyons. The average annual precipitation is about 31 inches and the average annual temperature is about 41 degrees F.
TAXONOMIC CLASS: Sandy-skeletal, isotic, frigid Vitrandic Humixerepts
TYPICAL PEDON: Pajo fine gravelly ashy coarse sandy loam, forested -- on a north-facing slope of 80 percent at 4,500 feet elevation. When described on October 26, 1998, the soil was dry throughout. (Colors are for air-dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed forest litter.
A--1 to 8 inches; brown (10YR 4/3) fine gravelly ashy coarse sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine granular structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine, medium and coarse roots; many very fine, fine, medium and coarse irregular pores; 25 percent fine gravel; slightly acid (pH 6.5); clear wavy boundary. (5 to 14 inches thick)
AC--8 to 16 inches; olive brown (2.5Y 4/3) fine gravelly ashy loamy coarse sand, dark olive brown (2.5Y 3/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; many very fine, fine, medium and coarse roots; many very fine, fine, medium and coarse irregular pores; 25 percent fine gravel, 5 percent cobbles; slightly acid (pH 6.4); clear wavy boundary. (3 to 10 inches thick)
2C--16 to 27 inches; light olive brown (2.5Y 5/3) extremely gravelly coarse sand, olive brown (2.5Y 4/3) moist; single grain; loose, nonsticky and nonplastic; many very fine, fine, medium and coarse roots; many very fine, fine, medium and coarse irregular pores; 50 percent gravel, 10 percent cobbles, 20 percent stones; slightly acid (pH 6.3); gradual wavy boundary. (10 to 24 inches thick)
2R--27 inches; moderately fractured granodiorite.
TYPE LOCATION: Boise County, Idaho; about 5 miles north of Banks; 400 feet north and 1,500 feet west of the southeast corner of section 33, T.10 N., R.3 E.; USGS Packer John Mountain Quadrangle; Latitude - 44 degrees, 08 minutes, 57 seconds N. and Longitude - 116 degrees, 06 minutes, 09 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Umbric epipedon thickness - 10 to 20 inches
Vitrandic feature thickness - 10 to 24 inches
Depth to bedrock - 20 to 40 inches
Particle-size control section - 2 to 7 percent clay; 35 to 85 percent rock fragment
Moisture control section - dry 45 to 75 consecutive days following the summer solstice
Average annual soil temperature - 41 to 46 degrees F.
A horizon
Hue - 2.5Y or 10YR
Value - 3 or 4 dry, 2 or 3 moist
Chroma - 1 through 3 dry and moist
Rock fragments - 15 to 35 percent fine gravel
Reaction - slightly acid or neutral
Volcanic glass content - 5 to 20 percent
Acid oxalate extract Al+1/2 Fe - 0.4 to 1.0 percent
AC horizon
Hue - 2.5Y or 10YR
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry or moist
Texture ASHY-SL, ASHY-LS or ASHY-LCOS
Clay content - 3 to 8 percent
Rock fragments - 0 to 10 percent cobbles, 15 to 35 percent gravel and 20 to 45 percent total
Reaction - slightly acid or neutral
Volcanic glass content - 2 to 10 percent
Acid oxalate extract Al+1/2 Fe - 0.2 to 1.0 percent
2C horizon
Hue - 2.5Y or 10YR
Value - 5 or 6 dry, 4 or 5 moist
Chroma - 2 through 4 dry or moist
Texture - LS, LCOS or COS
Clay content - 0 to 3 percent
Rock fragments - 0 to 25 percent stones, 0 to 50 percent cobbles, 25 to 50 percent gravel and 35 to 85 percent total
Reaction - moderately acid or slightly acid
COMPETING SERIES: This is the
Tripod series. Tripod soils are very deep.
GEOGRAPHIC SETTING: Pajo soils are on mountain slopes and canyon walls at elevations of 3,200 to 6,950 feet. These soils formed in colluvium and residuum from granitic rocks mixed with volcanic ash in the upper part. Slopes range from 35 to 90 percent. The average annual precipitation is 26 to 36 inches. The average annual temperature is 39 to 44 degrees F. The frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Kosh,
Packerjohn and
Tripod soils. Kosh soils are on canyon walls and are shallow to bedrock. Packerjohn and Tripod soils are on mountain slopes and are very deep.
DRAINAGE AND PERMEABILITY: Excessively drained; very rapid runoff; rapid permeability.
USE AND VEGETATION: Pajo soils are used mainly for timber production and wildlife habitat. Native vegetation is grand fir, Douglas-fir, ponderosa pine, mountain maple and mallow ninebark.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 43B. Pajo soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Umbric epipedon and vitrandic feature - zone from the mineral soil surface to 16 inches (A and AC horizons)
Particle-size control section - zone from 10 to 26 inches
Soil moisture regime - xeric
All depths related to diagnostic horizons and features listed in the range of characteristics are from the top of the first mineral horizon.
National Cooperative Soil Survey
U.S.A.