LOCATION BROWNSCOMBE OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Aridic Argixerolls
TYPICAL PEDON: Brownscombe silt loam, on an 8 percent
south-facing slope on rangeland. (Colors are for dry soil
unless otherwise noted.)
Ap--0 to 5 inches; brown (10YR 5/3) silt loam, very dark
grayish brown (10YR 3/2) moist; weak fine and medium
subangular blocky structure parting to granular; soft,
friable, slightly sticky and slightly plastic; many very
fine and common fine roots; common very fine and fine
tubular and interstitial pores; slightly acid (pH 6.4);
clear smooth boundary. (4 to 10 inches thick)
A--5 to 12 inches; brown (10YR 5/3) silt loam, dark
brown (10YR 3/3) moist; weak fine and medium subangular
blocky structure; soft, friable, slightly sticky and
slightly plastic; common very fine roots; common very fine
tubular and interstitial pores; neutral (pH 7.0); clear
smooth boundary. (5 to 10 inches thick)
2Bt1--12 to 18 inches; dark yellowish brown (10YR 4/4)
sandy clay loam, dark yellowish brown (10YR 3/4) moist; weak
medium subangular blocky structure; hard, firm, slightly
sticky and slightly plastic; common very fine roots; common
very fine tubular pores; many thin clay films on peds; 5
percent gravel; neutral (pH 7.2); clear smooth boundary. (5
to 14 inches thick)
2Bt2--18 to 25 inches; brown (7.5YR 4/4) sandy clay,
dark brown (7.5YR 4/4) moist; moderate medium and coarse
angular blocky structure; very hard, very firm, sticky and
plastic; few very fine roots; few very fine tubular pores;
continuous moderately thick clay films on peds and in pores;
10 percent gravel; neutral (pH 7.2); clear wavy boundary.
(5 to 10 inches thick)
2Cr--25 inches; partially weathered diorite.
TYPE LOCATION: Baker County, Oregon; 100 feet east and 700
feet south of the northwest corner of sec. 36, T. 8 S., R 43
E.
RANGE IN CHARACTERISTICS: The soils are dry in all parts
between depths of 4 to 12 inches for at least half the time (cumulative) during the period the soil temperature is above
41 degrees F and are continuously dry between depths of 4
and 12 inches for more than three months following the
summer solstice. The depth to weathered bedrock is 20 to 40
inches. The mean annual soil temperature is 47 to 52
degrees F. The particle-size control section averages 35 to
45 percent clay. The mollic epipedon is 10 to 20 inches
thick.
The A horizon has value of 4 or 5 dry, 2 or 3 moist and
chroma of 2 or 3 moist and dry. It has 0 to 10 percent
gravel. It is slightly acid to neutral.
The 2Bt horizon has hue of 7.5YR or 10YR, value of 4 or 5
dry, 3 or 4 moist and chroma of 3 or 4 moist and dry. It is
clay loam, sandy clay loam or sandy clay with 0 to 10
percent gravel and 0 to 5 percent cobbles. Carbonates are
present in some pedons but where present they are below 30
inches. It has 30 to 45 percent clay and contains over 15
percent coarse and very coarse sand. It is neutral to
moderately alkaline.
COMPETING SERIES: These are the
Cagle,
Correco,
Northmore,
Perla,
Sherar,
Simpson and
Wicup series. The Cagle series
has 15 to 35 percent rock fragments in the particle-size
control section and 15 to 50 percent or more rock fragments
in the A horizon. Cagle soils have weathered from andesite
and probably contain less than 15 percent coarse and very
coarse sand in the Bt horizon. Correco, Northmore and
Simpson soils are over 40 inches deep to bedrock. Perla
soils are 20 to 40 inches deep to a lithic contact. Sherar
soils have 15 to 35 percent rock fragments dominantly
cobbles throughout the solum. Sherar soils have developed
from clayey sediments and have less than 15 percent coarse
and very coarse sand. Wicup soils have carbonates within 30
inches and have textures of the Bt horizons with less than
15 percent coarse or very coarse sand.
GEOGRAPHIC SETTING: These soils are on hills at elevations
of 2,400 to 3,600 feet. Slopes are 1 to 60 percent. The
soils formed in colluvium and residuum weathered from
diorite with an influence of volcanic ash in the surface.
Winters are cool and moist and summers are warm and dry.
The mean annual precipitation is 9 to 12 inches. The mean
annual temperature is 45 to 50 degrees F. The frost-free
period is 110 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Bakeoven,
Brownlee,
Ruckles and
Ruclick soils. The Bakeoven, Ruckles
and Ruclick soils are skeletal and are located on adjacent
basalt hillslopes. The Brownlee soil is deep and is located
on adjacent hillslopes at higher elevations.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is slow to
medium on the gentle slopes and rapid on the steeper slopes. Permeability is moderately slow.
USE AND VEGETATION: These soils are used for range, dryland
winter wheat, and wildlife habitat. Native vegetation is
bluebunch wheatgrass, Sandberg bluegrass and arrowleaf
balsamroot.
DISTRIBUTION AND EXTENT: Northeastern Oregon. The series
is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Baker County Area, Oregon, 1988.
REMARKS: Diagnostic horizons and features in this pedon
are:
Mollic epipedon - The zone from the surface of the soil to a
depth of 12 inches (Ap, A horizons).
Argillic horizon - the zone from 12 to 25 inches (2Bt1, 2Bt2 horizons).