LOCATION COBURG OR
Established Series
Rev. WRP/JGM/EED
04/2019
COBURG SERIES
Landscape--valleys
Landform--stream terraces
Slope--0 to 5 percent
Parent material--mixed alluvium
Mean annual precipitation--about 1150 mm
Mean annual air temperature--about 11 degrees C
Depth class--very deep
Drainage class--moderately well drained
Soil moisture regime--xeric
Soil temperature--mesic
Soil moisture subclass--oxyaquic
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Oxyaquic Argixerolls
TYPICAL PEDON: Coburg silty clay loam in a cultivated field, on a slope of 1 percent at an elevation of 104 m
Ap--0 to 18 cm; silty clay loam, dark grayish brown (10YR 4/2) dry, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to moderate medium granular; hard, friable, moderately sticky and moderately plastic; many very fine roots; common very fine and few fine and medium tubular pores; moderately acid (pH 5.6); abrupt smooth boundary
AB--18 to 46 cm; silty clay loam, dark grayish brown (10YR 4/2) dry, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to moderate fine subangular blocky; hard, friable, moderately sticky and moderately plastic; many very fine roots; common very fine and few fine and medium tubular pores; moderately acid (pH 5.6); abrupt smooth boundary
Bt1--46 to 71 cm; silty clay, dark grayish brown (10YR 4/2) dry, dark brown (10YR 3/3) moist; weak medium subangular blocky structure parting to moderate fine subangular blocky; very hard, firm, moderately sticky and moderately plastic; few very fine roots; many very fine and fine tubular pores; common distinct very dark grayish brown (10YR 3/2) clay films on faces of peds and in pores; few black concretions 1 to 3 mm in size; slightly acid (pH 6.2); clear wavy boundary
Bt2--71 to 104 cm; silty clay loam, brown (10YR 4/3) dry, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; very hard, firm, moderately sticky and moderately plastic; few very fine roots; many very fine and fine tubular pores; many prominent very dark grayish brown (10YR 3/2) clay films in pores and few distinct clay films on faces of peds; common fine prominent strong brown (7.5YR 5/6) masses of iron accumulation; few small black manganese films on peds; slightly acid (pH 6.3); clear wavy boundary
Bt3--104 to 135 cm; silty clay, brown (10YR 4/3) dry, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; very hard, friable, moderately sticky and moderately plastic; few very fine roots; many very fine and fine tubular pores; many prominent very dark grayish brown (10YR 3/2) clay films in pores; common fine prominent strong brown (7.5YR 5/6) masses of iron accumulation; few small black manganese films on peds; neutral (pH 6.6); clear wavy boundary
2C--135 to 165 cm; fine sandy loam, pale brown (10YR 6/3) dry, brown (10YR 4/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few fine roots; many very fine and common fine pores; common medium prominent strong brown (7.5YR 5/6) masses of iron accumulation; neutral (pH 6.8)
TYPE LOCATION: Lane County, Oregon, about 5.4 km south of Junction City; about 365 m west and 30 m south of the northeast corner of section 19, T. 16 S., R. 4 W.; latitude 44.1712694, longitude -123.2132806, datum WGS 84 (coordinates estimated from PLSS details)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--11 to 13 degrees C
Moisture control section--usually moist, but dry 45 to 70 consecutive days in summer
Thickness of mollic epipedon--50 to 75 cm
Depth to seasonal high water table--70 to 100 cm
Depth to top of argillic horizon--25 to 50 cm
Depth to lithologic discontinuity--100 to 150 cm
Particle-size control section
*Clay content--35 to 45 percent
*Total fragment content--0 to 5 percent
A horizon
Hue--10YR, 7.5YR
Value--2 or 3 moist, 3 to 5 dry
Chroma--2 or 3 moist or dry
Clay content--27 to 35 percent
Sand content--10 to 20 percent
Total fragment content--0 to 5 percent
Gravel content--0 to 5 percent
Reaction--5.6 to 6.5
Thickness--15 to 28 cm
AB horizon
Hue--10YR, 7.5YR
Value--2 or 3 moist, 4 or 5 dry
Chroma--2 or 3 moist or dry
Fine-earth texture--silty clay loam, silty clay
Clay content--35 to 45 percent
Sand content--10 to 20 percent
Total fragment content--0 to 5 percent
Gravel content--0 to 5 percent
Reaction--5.6 to 6.5
Thickness--13 to 38 cm
Bt horizon
Hue--10YR, 7.5YR
Value--3 to 5 moist, 4 to 6 dry
Chroma--2 to 4 moist or dry
Fine-earth texture--silty clay loam, silty clay
Clay content--35 to 45 percent
Sand content--10 to 20 percent
Total fragment content--0 to 5 percent
Gravel content--0 to 5 percent
Reaction--5.6 to 7.3
Thickness--25 to 100 cm
BC horizon (where present)
Hue--10YR, 7.5YR
Value--3 to 5 moist, 4 to 6 dry
Chroma--2 to 4 moist or dry
Clay content--35 to 45 percent
Sand content--20 to 35 percent
Total fragment content--0 to 10 percent
Gravel content--0 to 10 percent
Reaction--5.6 to 7.3
Thickness--0 to 30 cm
2C horizon
Hue--10YR, 7.5YR
Value--3 or 4 moist, 4 to 6 dry
Chroma--3 or 4 moist or dry
Fine-earth texture--fine sandy loam, loam, sandy clay loam, clay loam
Clay content--15 to 30 percent
Sand content--35 to 55 percent
Total fragment content--0 to 10 percent
Gravel content--0 to 10 percent
Reaction--6.1 to 7.3
COMPETING SERIES:
Coolyork--mollic epipedon less than 50 cm thick; pararock fragments throughout profile
GEOGRAPHIC SETTING:
Elevation--30 to 305 m in MLRA 2, 30 to 335 m in MLRA 5
Climate--warm, dry summer; cool, moist winters
Mean annual precipitation--1000 to 1500 mm in MLRA 2, 750 to 1500 mm in MLRA 5
Mean annual air temperature--10 to 12 degrees C in MLRA 2, 10 to 13 degrees C in MLRA 5
Mean January air temperature--4 degrees C
Mean July air temperature--18 to 19 degrees C
Frost-free period--165 to 210 days in MLRA 2, 160 to 235 days in MLRA 5
GEOGRAPHICALLY ASSOCIATED SOILS:
Awbrig--aquic conditions at the surface to a depth of 25 cm; in depressions of stream terraces in MLRA 2
Clackamas--aquic conditions at a depth of 25 to 50 cm; extremely gravelly C horizon; on stream terraces in MLRA 2
Conser--aquic conditions at the surface to a depth of 25 cm; in depressions of stream terraces
Courtney--aquic conditions at the surface to a depth of 25 cm; in depressions in MLRA 2
Darby--no aquic conditions within 100 cm of the surface; on terraces in MLRA 5
Malabon--no aquic conditions within 100 cm of the surface; on terraces
Oxley--aquic conditions at a depth of 25 to 50 cm; loamy-skeletal; on terraces in MLRA 2
Redbell--aquic conditions at a depth of less than 75 cm; on terraces in MLRA 5
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well drained
Saturated hydraulic conductivity (Ksat)--moderately high
Flooding--rare or occasional, brief periods in December through March in some areas
Apparent water table--uppermost limit in December through March
USE AND VEGETATION:
Use--production of small grain, hay, pasture, and grass seed
Potential natural vegetation--Douglas-fir, Oregon white oak, Pacific poison oak, grasses
DISTRIBUTION AND EXTENT: Willamette Valley, Oregon, MLRA 2; Umpqua Valley, Oregon, MLRA 5; moderate extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benton Area, Benton County, Oregon; 1970
REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 46 to 96 cm
*Mollic epipedon--zone from the surface to a depth of 71 cm
*Argillic horizon--zone from 46 to 135 cm
*Redoximorphic concentrations--zone from 71 to 165 cm
*Depth to lithologic discontinuity--135 cm
The Coburg soils are on high and low Winkle geomorphic surfaces as recognized in the Willamette Valley of Oregon. The soils associated with the low Winkle surfaces are subject to flooding.
2/2000--Classification changed from Pachic Ultic Argixerolls to Oxyaquic Argixerolls based on revision of Soil Taxonomy that included addition of the Oxyaquic subgroup.
8/2017--This official series description was updated according to SSR01 Technical Note 11--Content and Format of Official Series Descriptions (revised 11/2017). Most of the changes were in formatting; some involved an update of competing series. No major technical changes were made.
National Cooperative Soil Survey
U.S.A.