LOCATION APT OREstablished Series
TAXONOMIC CLASS: Fine, isotic, mesic Typic Haplohumults
TYPICAL PEDON: Apt silty clay loam, woodland, on an 18 percent northeast-facing slope at an elevation of 1,000 feet. (Colors are for moist soil unless otherwise noted. When described in June 1969, the soil was moist throughout.)
Oi--0 to 1 inch; slightly decomposed plant material; clear smooth boundary.
A--1 to 6 inches; very dark brown (10YR 2/2) silty clay loam, dark grayish brown (10YR 4/2) dry; strong fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; moderately smeary; many very fine roots; many very fine irregular pores; very strongly acid (pH 4.8); NaF pH 10.8; clear smooth boundary. (5 to 13 inches thick)
AB--6 to 11 inches; very dark grayish brown (10YR 3/2) silty clay loam, grayish brown (10YR 5/2) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine, and common medium roots; many very fine tubular pores; few very dark brown (10YR 2/2) organic coatings on ped faces; few fine black (7.5YR 2/1) manganese masses and common fine dark brown (7.5YR 3/3) iron-manganese nodules, spherical in the matrix, very weakly cemented; very strongly acid (pH 4.8); NaF pH 9.5; clear smooth boundary. (0 to 7 inches thick)
Bt1--11 to 18 inches; dark brown (10YR 3/3) silty clay, brown (10YR 5/3) dry; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many very fine, fine, and medium roots; many very fine and fine tubular pores; few distinct clay films along surfaces of pores; very strongly acid (pH 5.0); NaF pH 9.0; abrupt smooth boundary.
Bt2--18 to 27 inches; dark yellowish brown (10YR 3/4) silty clay, light yellowish brown (10YR 6/4) dry; moderate fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine, fine, and medium roots; common very fine tubular pores; few distinct clay films on ped faces and along surfaces of pores; very strongly acid (pH 5.0); NaF pH 8.4; clear smooth boundary.
Bt3--27 to 37 inches; strong brown (7.5YR 4/6) clay, light brown (7.5YR 6/4) dry; moderate fine and very fine subangular blocky structure; very hard, firm, moderately sticky and very plastic; few fine and medium roots; many very fine tubular pores; common distinct clay films on ped faces and common prominent clay films along surfaces of pores; very strongly acid (pH 5.0); NaF pH 8.0; clear smooth boundary.
Bt4--37 to 51 inches; strong brown (7.5YR 4/6) clay, reddish yellow (7.5YR 6/6) dry; weak fine and medium subangular blocky structure; very hard, firm, moderately sticky and very plastic; few fine, medium and coarse roots; many very fine tubular pores; common distinct clay films on ped faces and common prominent clay films along surfaces of pores; very strongly acid (pH 5.0); NaF pH 8.0; clear smooth boundary. (Combined thickness of the Bt horizon is 20 to 40 inches)
BCt--51 to 66 inches; strong brown (7.5YR 5/6) silty clay loam, reddish yellow (7.5YR 7/6) dry; weak medium and coarse subangular blocky structure; very hard, firm, moderately sticky and very plastic; few fine, medium and coarse roots; many very fine tubular pores; few faint clay films on ped faces and along surfaces of pores; very strongly acid (pH 5.0); NaF pH 8.0.
TYPE LOCATION: Benton County, Oregon; about 10 feet north and 10 feet east of the southwest corner of section 23, T. 10 S., R. 7 W., about 1 mile northwest of Bonner Mountain. (Latitude 44 degrees, 40 minutes, 50 seconds N.; Longitude 123 degrees, 31 minutes, 10 seconds W.; Summit, OR 7.5 minute USGS Quad; NAD 1927).
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 55 degrees F. The soil is usually moist and is dry between depths of 4 and 12 inches for less than 45 consecutive days in the four-month period following the summer solstice in most years. Solum thickness and depth to bedrock is greater than 60 inches. The umbric epipedon is 10 to 20 inches thick, and may include the upper part of the Bt horizon. The pscs has 45 to 60 percent clay, 0 to 10 percent gravel, 0 to 35 percent paragravel, and 0 to 5 percent paracobbles. Hue is 10YR or 7.5YR. Reaction is very strongly acid or strongly acid.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. Texture is silty clay loam in the upper part, and silty clay loam or paragravelly silty clay loam in the lower part with 27 to 35 percent clay. It has 0 to 10 percent gravel and 0 to 20 percent paragravel.
The Bt horizon has value of 3 or 4 moist, 5 or 6 dry, and chroma of 3 to 6 moist and dry. Texture is silty clay, paragravelly silty clay, very paragravelly silty clay, clay, paragravelly clay or very paragravelly clay with 45 to 60 percent clay. It has 0 to 10 percent gravel, 0 to 35 percent paragravel, and 0 to 5 percent paracobbles.
The BCt horizon has value of 3 or 4 moist, 5 to 7 dry, and chroma of 3 to 6 moist and dry. Texture is silty clay, paragravelly silty clay, very paragravelly silty clay, extremely paragravelly silty clay, clay, paragravelly clay, very paragravelly clay, extremely paragravelly clay, silty clay loam, or very gravelly silty clay loam with 30 to 45 percent clay. It has 0 to 40 percent gravel, 0 to 50 percent paragravel, and 0 to 10 percent paracobbles.
COMPETING SERIES: These are the McDuff, Peavine, and Wintley soils in the same family, and the Absaquil, Hazelcamp, and Skookumhouse series in a similar family. Peavine soils have Bt horizons with hue of 5YR and range to 2.5YR. McDuff and Peavine soils have solum thickness and/or depth to paralithic bedrock contact of 20 to 40 inches. .Wintley soils have 35 to 50 percent clay in the Bt horizon and a very gravelly 2C horizon at a depth of 40 inches or more. Absaquil, Hazelcamp, and Skookumhouse series are currently in a mixed mineralogy class. Absaquil and Skookumhouse soils are 40 to 60 inches deep to a paralithic bedrock contact. Absaquil soils have hue yellower than 5YR in the particle-size control section .Hazelcamp and Skookumhouse soils have 35 to 45 percent clay in the particle-size control section. Hazelcamp soils are 20 to 40 inches deep to a paralithic contact and lack rock fragments throughout the solum.
GEOGRAPHIC SETTING: Apt soils occur on summits, footslopes, and toeslopes of mountains. Elevations are 300 to 2,400 feet. Where these soils are mapped in the Oregon Coast Range mountains elevations are 300 to 1,400 feet; where they are mapped in the Oregon Cascade Range elevations are 700 to 2,400 feet. Slopes are 2 to 50 percent. The soils formed in clayey colluvium and residuum derived from sandstone and siltstone. The climate is characterized by warm, wet winters and hot, moist summers. The mean annual precipitation is 60 to 90 inches. The mean annual air temperature is 45 to 55 degrees F. The frost-free period is 110 to 220 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing McDuff and Peavine series, and the Honeygrove, Bohannon, Preacher, and Slickrock soils. All of these soils occur on mountains. Bohannon, Preacher, and Slickrock soils have less than 35 percent clay in the textural control section. Bohannon, McDuff, and Peavine soils are moderately deep. Bohannon, Preacher, and Slickrock soils have andic properties associated with the surface horizons of their solums. Slickrock soils have a strongly contrasting particle-size class (medial over loamy).
DRAINAGE AND PERMEABILITY: Well drained. The permeability is moderately slow.
USE AND VEGETATION: The Apt soils are used for timber production, recreation, wildlife habitat, and watersheds, with minor acreage used for Christmas tree production. The potential native vegetation is Douglas-fir, bigleaf maple, red alder, creambush oceanspray, salal, western hazel, vine maple, cascade Oregongrape, western swordfern, western brackenfern, baldhip rose, Pacific dogwood, violet, and trailing blackberry. A minor amount of western hemlock and western redcedar may also be present in some areas.
DISTRIBUTION AND EXTENT: Central and north Coast Range and western foot slopes of the Cascade Range in Oregon; MLRA 1, 3. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benton County (Benton Area), Oregon, 1970.
REMARKS: Diagnostic horizons and features included in this pedon are:
Umbric epipedon - from the mineral soil surface to 18 inches (A , AB , and Bt1 horizons).
Argillic horizon - from 11 to 66 inches (Bt1, Bt2, Bt3, Bt4, and BCt horizons) with 0.9 percent organic carbon in the upper part.
Particle-size control section - the zone from 11 to 31 inches.
Depths to diagnostic horizons and features are measured from the top of the first mineral layer.
Revision 9/03, represents a relocation of the type location. The original series type location for the Apt series was established in the initial soil survey of the Alsea Area, Oregon (published 1973). The modal concept was represented with a clay surface texture. Adjacent survey areas using the Apt series recognized a silty clay loam surface texture as the representative pedon. Over 55,000 acres of the Apt series have been mapped with a silty clay loam surface texture, while only about 5,000 acres were recognized as having a clay surface texture (all of those acres were in the outdated Alsea Area, Oregon survey). With the recent update mapping of Benton County, Oregon Soil Survey the typical pedon for this soil was relocated based on further field observations and documentation to reflect a modal concept which has a silty clay loam surface texture and an isotic mineralogy class. The classification was changed to Fine, isotic, mesic Typic Haplohumults based on changes in the Keys to Soil Taxonomy, 8th edition.