LOCATION GELDERMAN OREstablished Series
TAXONOMIC CLASS: Fine, mixed, active, mesic Xeric Haplohumults
TYPICAL PEDON: Gelderman silty clay loam - grassland, on a 6 percent west-facing slope at an elevation of 500 feet. (When described on September 4, 1997 the soil profile was dry throughout. Colors are for moist soil unless otherwise noted.)
A1--0 to 5 inches; dark reddish brown (5YR 3/3) silty clay loam, reddish brown (5YR 4/4) dry; strong fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, and common fine, medium, and coarse roots; many very fine tubular pores; moderately acid (pH 5.7); clear smooth boundary.
A2--5 to 10 inches; dark reddish brown (5YR 3/3) silty clay loam, reddish brown (5YR 4/4) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine, and common fine, medium, and coarse roots; many very fine tubular pores; strongly acid (pH 5.4); clear smooth boundary. (Combined thickness of the A horizon is 10 to 14 inches)
Bt1--10 to 24 inches; dark reddish brown (5YR 3/4) clay, reddish brown (5YR 4/4) dry; moderate coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine, fine, medium and coarse roots; many very fine and fine, and common medium tubular pores; common faint clay films on faces of peds and surfaces of pores; 5 percent paragravel and 5 percent gravel; strongly acid (pH 5.1); clear wavy boundary.
Bt2--24 to 30 inches; dark reddish brown (5YR 3/4) paragravelly clay, yellowish red (5YR 4/6) dry; moderate medium and coarse subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; few very fine, fine, medium and coarse roots; many very fine and fine, and few medium tubular pores; many distinct clay films on faces of peds and surfaces of pores; 25 percent paragravel and 5 percent gravel; strongly acid (pH 5.1); abrupt wavy boundary. (Combined thickness of the Bt horizon is 10 to 26 inches)
Cr--30 inches; highly weathered basalt.
TYPE LOCATION: Marion County, Oregon; 1.5 miles northeast of the community of Sunnyside; located about 1200 feet south and 800 feet west of the northeast corner of section 23, T. 8 S., R. 3 W., Willamette Meridian. Sidney, Oregon USGS 7.5 minute topographic quadrangle. (Latitude 45 degrees, 51 minutes, 55
seconds N. Longitude 123 degrees, 00 minutes, 43 seconds W. NAD 27)
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 52 to 57 degrees F. The soil is usually moist but is dry for 45 to 60 consecutive days in all parts of the soil between depths of 4 and 12 inches following the summer solstice. The particle-size control section is 40 to 50 percent clay, and has 5 to 30 percent pararock fragments and 5 to 10 percent total rock fragments. The rock fragments are weathered basalt or tuffaceous materials. The depth to bedrock and solum thickness is 20 to 40 inches. The umbric epipedon is 10 to 14 inches thick.
The A1 horizon has hue of 7.5YR or 5YR, value of 2 or 3 moist, 3 or 4 dry and chroma of 2 or 3 moist and 3 or 4 dry. Texture is silty clay loam or silt loam with 20 to 40 percent clay. It has 0 to 3 percent cobbles, 0 to 10 percent gravel and 0 to 10 percent paragravel. Reaction is strongly acid or moderately acid.
The A2 horizon, when present, has hue of 7.5YR or 5YR, value of 2 or 3 moist, 3 or 4 dry and chroma of 2 or 3 moist and 3 or 4 dry. Texture is silty clay loam or silt loam with 27 to 40 percent clay. It has 0 to 3 percent cobbles, 0 to 10 percent gravel and 0 to 10 percent paragravel. Reaction is strongly acid or moderately acid.
The AB or BA horizons have hue of 7.5YR or 5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 3 or 4 moist and dry. Texture is a silty clay loam, clay or silty clay with 35 to 45 percent clay. It has 0 to 3 percent cobbles, 0 to 10 percent gravel and 0 to 10 percent paragravel. Reaction is strongly acid or moderately acid.
The Bt horizon has hue of 5YR or 2.5YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist and 4 to 6 moist and dry. It is silty clay or clay with 40 to 50 percent clay. It has 0 to 5 percent cobbles and 0 to 10 percent gravel. It has 5 to 15 percent paragravel. Reaction is very strongly acid to moderately acid.
The BCt horizon has hue of 5YR or 2.5YR, value of 3 or 4 moist, 4 or 5 dry and chroma of 3 or 4 moist and 4 to 6 moist and dry. It is silty clay or clay with 40 to 50 percent clay. It has 0 to 10 percent cobbles and 5 to 15 percent gravel. It has 5 to 50 percent parafragments. Reaction is very strongly acid to moderately acid.
COMPETING SERIES: These are the Bellpine, Nekia, Tullycreek (T), and Windygap soils. All of these soils have an ochric epipedon. Bellpine soils have an ochric epipedon and has rock and pararock fragments and a paralithic contact that are from sedimentary origin. Nekia soils are 20 to 40 inches deep to a lithic contact from igneous origin. Tullycreek soils are greater than 60 inches deep to bedrock and are dry for more than 90 consecutive days following the summer solstice. Windygap soils are 40 to 60 inches deep to a paralithic contact from sedimentary origin.
GEOGRAPHIC SETTING: Gelderman soils occur on summit (interfluve component) and shoulder positions (nose slope component) of hills and foothills. The summit position typically has a linear-convex or convex-linear slope shape, and the shoulder position typically has a convex-convex slope shape. Slopes are 2 to 30 percent. Elevation is 250 to 2200 feet. The soils formed in residuum and colluvium derived from the Columbia River Basalt Formation, Siletz River Volcanics, and tuffaceous materials from the Sardine Formation. The climate is characterized by warm, wet winters and hot, dry summers. The mean annual precipitation is 40 to 60 inches. The mean annual temperature is 50 to 54 degrees F. The frost-free season is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cottrell, Jory, MacDunn, Price, Ritner, Witzel, and the competing Nekia soils. Cottrell soils have redox depletions in the upper part of the argillic horizon and occur on concave positions. Jory soils are greater than 60 inches to bedrock and occur on linear or concave parts of the hillslope. MacDunn soils are clayey-skeletal. Price soils do not have an argillic horizon. MacDunn and Price soils occur on the more steeply sloping parts of the hillslope. Ritner soils are clayey-skeletal and are 20 to 40 inches to hard bedrock. Witzel soils are 12 to 20 inches to hard bedrock. Ritner and Witzel soils occur on convex parts of the hillslope.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: These soils are used for home sites, Christmas trees, vineyards, grass seed production, orchards, pastures, wildlife habitat and watersheds. Native vegetation is Douglas fir and Oregon white oak with an understory of poison oak, western hazel, common snowberry, and western brackenfern.
DISTRIBUTION AND EXTENT: Willamette Valley, Oregon; MLRA 2. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Benton County, Oregon, 2004. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Umbric epipedon - from the soil surface to a depth of 10 inches (A1, A2 horizons)
Argillic horizon - from a depth of 10 to 30 inches (Bt1, Bt2 horizons)
Particle-size control section - from 10 to 30 inches (Bt1, Bt2 horizons)
Paralithic contact - weathered basalt at 30 inches.
Humults suborder - based on lab data from associated soils, the Gelderman series is assumed to have 12 kg/m2 or more organic carbon between the mineral soil surface and the paralithic contact.
This soil was separated from the Nekia series concept based on the presence of a paralithic contact with basalt bedrock instead of a lithic contact, and the resulting interpretation differences for use and management.
ADDITIONAL DATA: Characterization data on one profile (S60 Oreg. 24-8) reported in Riverside Soil Survey Lab. Report soils for Marion County, Oregon, sampled in July, 1960. The Soil Survey Laboratory soil survey sample number is S60OR-047-008. At the time of sampling the soil was called Aiken. Correlation was made to the Gelderman series concept at a later date.