LOCATION BELLPINE OREstablished Series
TAXONOMIC CLASS: Fine, mixed, active, mesic Xeric Haplohumults
TYPICAL PEDON: Bellpine silty clay loam, cultivated. (Colors are for moist soil unless otherwise noted.)
Ap--0 to 6 inches; dark reddish brown (5YR 3/3) silty clay loam, reddish brown (5YR 5/4) dry; moderate fine and medium subangular blocky and weak very fine to medium granular structure; hard, friable, slightly sticky and moderately plastic; many very fine roots; many very fine irregular pores; moderately acid (pH 5.6); clear smooth boundary. (4 to 9 inches thick)
BA--6 to 10 inches; dark reddish brown (5YR 3/4) heavy silty clay loam, reddish brown (5YR 4/4) dry; moderate very fine and fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine roots; many very fine and fine tubular pores; 3 percent gravel at lower boundary; moderately acid (pH 5.6); abrupt wavy boundary. (4 to 12 inches thick)
Bt1--10 to 20 inches; dark red (2.5YR 3/6) silty clay, red (2.5YR 4/6) dry; moderate fine and medium subangular blocky structure; extremely hard, very firm, very sticky and very plastic; common very fine roots; many very fine and fine tubular pores; common distinct clay films on faces of peds and along pores; 3 percent fine gravel; 5 percent yellowish brown paragravel; strongly acid (pH 5.4) gradual wavy boundary. (6 to 15 inches thick)
Bt2--20 to 26 inches; dark red (2.5YR 3/6) paragravelly clay, red (2.5YR 4/6) dry; moderate medium subangular blocky structure; very hard, very firm, very sticky and very plastic; few very fine roots; many very fine tubular pores; common distinct clay films; 20 percent yellowish brown paragravel; strongly acid (pH 5.2); abrupt wavy boundary. (4 to 11 inches thick)
Crt--26 inches; pinkish gray (7.5YR 7/2) and reddish brown (5YR 5/4) weakly to moderately cemented sandstone with many prominent reddish brown (5YR 4/4) and dark red (2.5YR 3/6) clay films on fragments. There are also thin tongues of the Bt horizon extending into the horizon.
TYPE LOCATION: Benton County, Oregon; about 700 feet west and 600 feet north of the SE corner of section 34, T. 12 S., R. 6 W. Willamette Meridian. Flat Mountain, Oregon USGS 7.5 minute topographic quadrangle. Latitude 44 degrees, 28 minutes, 41 seconds N. and Longitude 123 degrees, 23 minutes, 45 seconds W. NAD 27.
RANGE IN CHARACTERISTICS: The soils are usually moist but are dry for 45 to 60 consecutive days during the summer between depths of 4 and 12 inches within MLRA 2 but ranges to 90 days in MLRA 5. The mean annual soil temperature ranges from 52 to 55 degrees F. Depth to a paralithic contact ranges from 20 to 40 inches. Coarse fragments of sedimentary paragravel range from few to 50 percent with a weighted average of less than 35 percent in the particle-size control section, the amount increasing with increasing depth. Up to 5 percent hard rock fragments commonly occur at the horizon boundary of the BA and Bt1 horizons. The particle-size control section has 40 to 55 percent clay.
The A horizon has hue of 7.5YR or 5YR, value of 2 or 3 moist, 4 or 5 dry and chroma of 2 to 4 moist and 3 or 4 dry. It has 0 to 10 percent gravel and 0 to 15 percent cobbles. Reaction is moderately acid to strongly acid.
The BA horizon has hue of 7.5YR or 5YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 3 to 6 moist and dry. In some pedons this horizon is replaced with an AB horizon. It has 0 to 5 percent gravel. Texture is silty clay loam or silty clay with 35 to 45 percent clay. Reaction is moderately acid or strongly acid.
The Bt horizon has hue of 2.5YR or 5YR, value of 3 or 4 moist, 4 or 6 dry and chroma of 4 to 6 moist and dry. It has 0 to 5 percent gravel and 5 to 20 percent paragravel in the upper part and 5 to 50 percent paragravel in the lower part. Texture is silty clay or clay with 40 to 55 percent clay. Clay films range from common faint to common or many distinct. Reaction is very strongly acid to moderately acid.
Some pedons have a thin BC horizon above the paralithic contact.
COMPETING SERIES: These are the Gelderman, Nekia, and Windygap series. Gelderman soils have an umbric epipedon and contain basalt pararock fragments. Nekia soils have a lithic contact at a depth of 20 to 40 inches. Windygap soils have a paralithic contact at 40 to 60 inches.
GEOGRAPHIC SETTING: The Bellpine soils occur in the smooth convex foothills adjacent to the Willamette Valley terraces and in southwest Oregon. Elevations are 300 to 3,000 feet. The soils formed in colluvium and residuum derived from sandstone and siltstone. Slopes are 2 to 75 percent. The winters are warm and wet and the summers are hot and dry. The average January temperature is 39 to 40 degrees F. and average July temperature is 65 to 67 degrees F. The average annual temperature is 50 to 55 degrees F. The average annual precipitation is 30 to 60 inches. The frost-free period is 160 to 235 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Dupee, Jory, Rickreall, Willakenzie, and the competing Nekia soils. Dupee soils have aquic conditions and chroma of 2 or less at a depth of 20 to 30 inches and occur on footslopes and in depressions on hills. Jory soils have bedrock at depths greater than 60 inches and occur on concave or linear hills. Rickreall soils have bedrock at depths of less than 20 inches and occur on ridges, shoulder slopes and other convex parts of the hillslope. Willakenzie soils are fine-loamy and occur at lower elevations. Nekia soils occur over lithic volcanic bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for timber production, cropland, Christmas trees and homesite development. Vegetation is Douglas-fir, Oregon white oak, wild rose, Pacific poison-oak, snowberry, brackenfern, and grasses.
DISTRIBUTION AND EXTENT: These soils occur on the low foothills along the Williamette Valley in Oregon; MLRA 2, 5. 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 in the pedon include:
Ochric epipedon - the zone from 0 to 6 inches (Ap horizon)
Argillic horizon - the zone from 10 to 26 (Bt1 and Bt2 horizons)
Base saturation is less than 35 percent thoughtout the lower part of the argillic horizon.
Xeric soil moisture regime.