LOCATION HEBO OREstablished Series
TAXONOMIC CLASS: Fine, isotic, acid, isomesic Typic Humaquepts
TYPICAL PEDON: Hebo silty clay loam - pastureland. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 4 inches; very dark gray (10YR 3/1) silty clay loam, dark gray (10YR 4/1) dry; moderate fine and medium granular structure; hard, firm, moderately sticky and moderately plastic; many very fine roots; many very fine tubular pores; few fine prominent strong brown (7.5YR 5/6) iron-manganese masses lining pores; very strongly acid (pH 4.7); clear smooth boundary. (4 to 9 inches thick)
BA--4 to 10 inches; very dark gray (10YR 3/1) silty clay, dark gray (10YR 4/1) dry; weak medium prismatic and moderate very fine and fine angular blocky structure; very hard, very firm, moderately sticky and very plastic; many very fine roots; common fine pores; many fine prominent strong brown (7.5YR 5/6) and dark reddish brown (5YR 3/4) iron-manganese masses on peds; very strongly acid (pH 4.7); clear smooth boundary. (6 to 12 inches thick)
Bg1--10 to 18 inches; dark gray (5Y 4/1) clay, gray (5Y 6/1) dry; weak medium prismatic and moderate coarse and medium angular blocky structure; very hard, very firm, very sticky and very plastic; common very fine roots; many coarse prominent strong brown (7.5YR 5/8) iron-manganese masses on peds and light brownish gray (10YR 6/2) iron depletions on peds, few coarse prominent black (N 2.5/0) manganese coatings on peds, and few medium prominent black (N 2.5/0) iron-manganese concretions in the matrix; very strongly acid (pH 4.6); gradual smooth boundary.
Bg2--18 to 26 inches; gray (5Y 5/1) clay, light gray (5Y 7/1) dry; moderate medium prismatic and strong fine and medium angular blocky structure; very hard, very firm, very sticky and very plastic; few very fine roots, along ped faces; few very fine pores; many coarse prominent strong brown (7.5YR 5/8) iron-manganese masses on peds ,many coarse prominent black (N 2.5/0) manganese coatings on peds, and common medium prominent black (N 2.5/0) iron-manganese concretions in the matrix; very strongly acid (pH 4.6); gradual smooth boundary. (combined Bg horizon is 11 to 26 inches thick)
BCg--26 to 35 inches; gray (5Y 5/1) and dark gray (5Y 4/1) silty clay, light gray (5Y 7/1, 6/1) dry; weak fine and medium subangular and angular blocky structure; hard, firm, very sticky and very plastic; very few roots; many coarse prominent strong brown (7.5YR 5/8) iron-manganese masses on peds and few medium prominent black (N 2.5/0) manganese coatings on peds; very strongly acid (pH 4.6); gradual smooth boundary. (0 to 20 inches thick)
2Cg--35 to 60 inches; olive gray (5Y 4/2) clay loam, light olive gray (5Y 6/2) dry; massive; hard, firm, moderately sticky and moderately plastic; many coarse prominent strong brown (7.5YR 5/8) iron-manganese concentrations on peds and many coarse distinct gray (10YR 5/1) iron depletions on peds; 5 percent rounded gravel; 2 percent rounded paragravel; very strongly acid (pH 4.8). 6 to 12 inches thick)
TYPE LOCATION: Tillamook County, Oregon, about 1/4 mile northwest of Johnson Bridge; about 1,700 feet south and 200 feet west of the northeast corner of section 33, T. 1 S., R. 9 W;USGS Tillamook topographic quadrangle; latitude 45 degrees 26 minutes 40 seconds N. and longitude 123 degrees 46 minutes 55 seconds W. NAD 27.
RANGE IN CHARACTERISTICS: The soil is saturated from November to June unless artificially drained. The profiles are over 60 inches thick but the rooting depth is limited dominantly to less than 20 inches. The umbric epipedon is 10 to 15 inches thick. Thickness of the solum is 24 to 48 inches. The mean annual soil temperature is 48 to 54 degrees F. The difference between the mean summer soil temperature and the mean winter temperature varies from 5 to 9 degrees F. Soil reaction is extremely acid to strongly acid above 40 inches and extremely acid to moderately acid below.
The Ap or A and BA horizon has value of 2 or 3 moist, 4 or 5 dry and chroma of 1 or 2 moist and dry. Redox features are few to many and faint to distinct in hue 7.5YR and 5YR.
The BA horizon is silty clay loam or silty clay with 35 to 45 percent clay.
The Bg, Bw, or BCg horizon has hue of 5Y or 2.5Y, value of 4 to 6 moist, 5 to 7 dry and chroma of 1 or less moist and dry. Redox features have hue of 7.5YR or 5YR. Texture is silty clay or clay with 40 to 60 percent clay. Occasional thin sand and gravel lenses occur in the lower B horizons.
The 2Cg or 2C horizon has hue of 10YR, 2.5Y or 5Y, value of 4 to 6 moist, 5 to 7 dry and chroma of 1 or 2 moist and dry. Texture is clay loam, silty clay loam or silty clay with 35 to 45 percent clay. It has 0 to 10 percent rounded gravel and 0 to 5 percent pararock fragments.Occasional thin sand and gravel lenses may occur.
COMPETING SERIES: This is the Sekiu and similar Chetco series. Sekiu soils have a solum thickness of 14 to 18 inches. Chetco soils are nonacid.
GEOGRAPHIC SETTING: Hebo soils are on nearly level to depressional areas on terraces at elevations of 20 to 300 feet. Slopes are 0 to 7 percent. The soils formed in mixed fine textured alluvium. The climate is humid, characterized by cool wet winters and cool moist summers with fog. A strong marine influence limits the diurnal and annual range of temperature. The mean annual precipitation is 70 to 100 inches. The mean annual temperature is 48 to 53 degrees F. The frost-free season is 160 to 300 days. These soils are on the Whiskey Run geomorphic surface.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chitwood, Knappa and Walluski soils. Chitwood and Walluski soils are somewhat poorly drained and moderately well drained respectively and lack redox depletions with chroma of 2 or less above 20 inches. Knappa soils are well drained and have less than 35 percent clay in the particle-size control section. All of these soils are on terraces.
DRAINAGE AND PERMEABILITY: Poorly drained; permeability is very slow. A perched high water table is at its uppermost limit from November through June.
USE AND VEGETATION: These soils are used for improved pasture, watershed, and wildlife habitat when artificially drained. Native vegetation is Sitka spruce, Douglas fir, grand fir, western hemlock and red alder. Understory species include rushes, sedges, skunk cabbage, salmonberry, salal, and western swordfern.
DISTRIBUTION AND EXTENT: Terraces in the coastal area of Oregon; MLRA 4A. The soil is inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Astoria Area, Clatsop County, Oregon, 1938.
REMARKS: Diagnostic features and horizons in this pedon include:
Umbric epipedon - from 0 to 10 inches (Ap and BA horizons)
Cambic horizon - 10 to 26 inches (Bg1 and Bg2 horizons)
Redox depletions with chroma of 2 or less occur throughout the profile.
Particle-size control section - from 10 to 40 inches
ADDITIONAL DATA: Reference laboratory sample number 83T7159-7166; NSSL, Lincoln, NE.