LOCATION SANTIAM OREstablished Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Aquultic Haploxeralfs
TYPICAL PEDON: Santiam silt loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 6 inches; dark brown (10YR 3/3) silt loam, pale brown (10YR 6/3) dry; moderate medium and fine granular structure; slightly hard, friable, moderately sticky and moderately plastic; many roots; many very fine and fine irregular pores; moderately acid (pH 5.6); abrupt smooth boundary. (4 to 7 inches thick)
AB--6 to 13 inches; dark brown (10YR 3/3) silt loam, pale brown (10YR 6/3) dry; weak very coarse prismatic structure parting to moderate medium and fine subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many roots; many fine and very fine tubular pores, common fine and very fine faint brown (10YR 4/3) masses of iron accumulation; 5 percent gravel; moderately acid (pH 5.6); abrupt smooth boundary. (6 to 11 inches thick)
Bt1--13 to 22 inches; dark yellowish brown (10YR 4/4) silty clay loam, pale brown (10YR 6/3) dry; weak very coarse prismatic parting to moderate medium and fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common roots; many fine and very fine tubular pores; many medium and fine faint brown (10YR 4/3) masses of iron accumulation; few faint clay films; faint silt and sand coatings on faces of peds; common fine black manganese films and common iron-manganese concretions; strongly acid (pH 5.4); gradual wavy boundary. (7 to 12 inches thick)
Bt2--22 to 30 inches; dark yellowish brown (10YR 4/4) silty clay loam, light yellowish brown (10YR 6/4) dry; common black stains; weak fine prismatic parting to moderate fine and medium subangular and angular blocky structure; very hard, firm, moderately sticky and moderately plastic; few roots; many medium, fine and very fine tubular pores; common distinct clay films; prominent grayish brown (10YR 5/2), light gray (10YR 7/2) dry, silt coatings on faces of peds; common black manganese films; common fine and medium distinct very dark grayish brown (10YR 3/2) iron depletions; 5 percent gravel; strongly acid (pH 5.2); clear smooth boundary (5 to 14 inches thick).
2C--30 to 60 inches; dark grayish brown (10YR 4/2) and brown (10YR 4/3) silty clay, pale brown (10YR 6/3) and light gray (10YR 7/1) dry; massive; very hard, firm, very sticky and very plastic; few very fine roots; common fine and very fine pores; few fine prominent yellowish brown (10YR 5/8) masses of iron accumulation; 10 percent paragravel; strongly acid (pH 5.2).
TYPE LOCATION: Marion County, Oregon; 15 feet south of the center of gravel road and 475 feet east of road corner; about 1,400 feet west and 2,500 feet north of the SE corner of section 1, T. 10 S., R. 3 W.;Willamette Meridian, Crabtree, Oregon; 7.5 minute quad; Latitude 44 degrees, 43 minutes, 47 seconds N. and Longitude 122 degrees, 59 minutes, 41 seconds W.; NAD 27.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry for 45 to 60 consecutive days within the four month period following the summer solstice. The mean annual soil temperature is 52 to 55 degrees F. Depth to bedrock is greater than 60 inches. Depth to aquic conditions with chroma of 2 or less, with or without redox concentrations is 20 to 30 inches. The pscs has 35 to 45 percent clay, 0 to 5 percent rock fragments and 0 to 15 percent pararock fragments. The soil reaction is moderately acid or strongly acid.
The A horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 5 or 6 dry and chroma of 2 to 4 moist and 2 or 3 dry. It has 18 to 27 percent clay and 0 to 5 percent gravel.
The AB or BA horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 5 or 6 dry and chroma of 2 to 4 moist and dry. It has weak prismatic parting to moderate subangular blocky structure. Texture is silt loam or silty clay loam with 20 to 35 percent clay and 0 to 5 percent gravel.
The Bt horizon has hue of 10YR or 7.5YR, value of 3 to 5 moist, 5 to 7 dry and chroma of 2 to 4 moist and 2 to 6 dry. It has weak prismatic parting to moderate to strong subangular or angular blocky structure. Texture is silty clay loam, silty clay or clay with 35 to 45 percent clay. It has 0 to 5 percent gravel and 0 to 15 percent paragravel.
The 2C horizon has hue of 10YR or 2.5Y, value of 4 or 5 moist, 6 or 7 dry and chroma of 2 to 6 moist and 1 to 6 dry. It has weak prismatic structure or is massive. The fine-earth texture is silty clay or clay with 40 to 50 percent clay. It has 0 to 5 percent gravel and 5 to 25 percent paragravel.
COMPETING SERIES: These are the Dupee, Linslaw and Zing soils. The Dupee soils have angular siltstone and sandstone paragravel in the lower particle-size control section, and lack a discontinuity. Linslaw soils have loam A and B horizon with greater than 15 percent fine sand and coarser, and has a 2C horizon with sandy loam or sandy clay loam textures. Zing soils have an umbric epipedon, a mean annual soil temperature of 47 to 52 degrees F, and a hue of 2.5Y or 5Y in the B horizon.
GEOGRAPHIC SETTING: The Santiam soils are on high terrace remnants or foot slopes of low hills at elevations from 250 to 400 feet. Slope gradients range from 2 to 20 percent. The soils formed in silty glaciolacustrine deposits over older weathered clayey alluvium or weathered basalt or sediments. The climate is characterized by warm, wet winters and hot, dry summers. The mean annual precipitation of 40 to 60 inches. The mean annual temperature is 50 to 54 degrees F. The mean July temperature is 65 to 67 degrees F. and the mean January temperature is 39 to 40 degrees F. The frost-free period is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bellpine, Hazelain, Jory, Noti, Pengra, Salkum, Steiwer, and Willakenzie soils and the competing Linslaw soils. Bellpine, Steiwer and Willakenzie soils are moderately deep and occur on adjacent convex hills. Hazelair soils are moderately deep and very fine and occur on adjacent foot slopes. Jory and Salkum soils lack aquic conditions with chroma of 2 or less within 40 inches and occur on convex hills and terraces. Pengra soils are fine-silty over clayey and occur on adjacent foot slopes. Noti soils have aquic conditions with chroma of 2 or less above 10 inches and occur in depressions on terraces. Linslaw soils occur on depressions on terraces.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium to slow runoff; moderately slow permeability in the Bt horizon and slow in the 2C horizon. A perched water table is at its uppermost limit from December to March.
USE AND VEGETATION: The Santiam soils are used principally for small grains, grass seed, orchard, Christmas trees, pasture, vegetables, berries, and woodland. The native vegetation is Douglas-fir, ponderosa pine, Pacific poison-oak, western hazel, creambush oceanspray, trailing blackberry, strawberry, thimbleberry, brackenfern, and grasses.
DISTRIBUTION AND EXTENT: These soils are distributed along the margins of the Willamette Valley, Oregon; MLRA 2. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Marion County, Oregon, 1972.
REMARKS: Diagnostic horizons and features include:
Ochric epipedon
Argillic horizon - the zone from 13 to 30 inches (Bt1 and Bt2 horizons)
Aquultic feature - chroma of 2 or less (redox depletions) within 20 to 30 inches of the surface and at least some part of the argillic horizon within 30 inches having a base saturation (sum) of less than 75 percent.
Particle-size control section - the zone from 13 to 30 inches.