LOCATION STURGILL OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, frigid Fluvaquentic Endoaquolls
TYPICAL PEDON: Sturgill silt loam, cultivated (Colors are for moist soil unless otherwise noted.)
Ap--0 to 8 inches; black (10YR 2/1) silt loam, dark gray (10YR 4/1) dry; moderate medium granular structure; soft, friable, slightly sticky and slightly plastic; many fine roots; common very fine irregular pores; neutral (pH 6.8); clear smooth boundary.
A--8 to 18 inches; black (10YR 2/1) silty clay loam, gray (N 5/ ) dry; weak coarse and medium prismatic structure parting to moderate medium subangular blocky; hard, friable, sticky and plastic; many very fine roots; many very fine and common fine tubular pores; neutral (pH 6.7); clear smooth boundary. (Combined thickness of the A horizon is 11 to 25 inches)
Bw--18 to 23 inches; dark grayish brown (2.5Y 4/2) silty clay loam, grayish brown (2.5Y 5/2) dry; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few fine roots; few fine tubular pores; light olive brown (2.5Y 5/6) masses of iron accumulation; distinct very dark grayish brown (10YR4/3) coatings on faces of peds;neutral (pH 6.8); clear smooth boundary. (4 to 10 inches thick)
C1--23 to 30 inches; dark grayish brown (2.5Y 4/2) silt loam, grayish brown (2.5Y 5/2) dry; massive; hard, friable, slightly sticky and slightly plastic; few fine roots; few fine tubular pores; neutral (pH 6.8); abrupt smooth boundary. (5 to 10 inches thick)
2C2--30 to 38 inches; light brownish gray (10YR 6/2) silt loam (volcanic ash) white (10YR 8/1) dry; massive; soft, very friable, nonsticky and nonplastic; few fine roots; few fine tubular pores; neutral (pH 7.0); abrupt smooth boundary. (0 to 10 inches thick)
3Ab--38 to 44 inches; very dark grayish brown (10YR 3/2) silty clay loam, dark grayish brown (10YR 4/2) dry; massive; firm, friable, moderately sticky and slightly plastic; very few fine roots; few fine tubular pores; neutral (pH 7.2); (0 to 10 inches thick).
3Cg--44 to 60 inches; dark greenish gray (5BG 4/1) silt loam, greenish gray (5GY 6/1) dry; massive; hard, firm, slightly sticky and slightly plastic; few very fine tubular pores; neutral (pH 7.2).
TYPE LOCATION: Wallowa County, Oregon; 1 mile SW of Enterprise, 800 feet north and 1800 feet west of the SE corner of section 3, T. 2 S., R. 44 E. (Latitude 45 degrees, 24 minutes, 44 seconds N, Longitude 117 degrees, 17 minutes, 56 seconds W).
RANGE IN CHARACTERISTICS: The soils are saturated many months of the year. The mean annual soil temperature is 42 to 47 degrees F. The particle-size control section is 18 to 35 percent clay. The mollic epipedon is 14 to 22 inches thick and may include the upper part of the Bw horizon. Depth to moist value of 4 and chroma of 2 or less is 14 to 22 inches. There is an irregular decrease in organic carbon. Depth to bedrock is greater than 60 inches.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 0 or 1 moist and dry. Distinct or prominent redox concentrations as masses are common in the lower part of the A horizon or in the horizon immediately below. Texture is silt loam or silty clay loam in the lower part of the A horizon with 18 to 35 percent clay.
The Bw horizon has hue of 10YR or 2.5Y, value of 3 or 4 moist, 4 to 6 dry, and chroma of 0, 1 or 2 moist and dry. It has distinct to prominent redox concentrations. Texture is silt loam or silty clay loam with 18 to 35 percent clay.
The C1 horizon is silt loam and silty clay loam with 18 to 30 percent clay. It has value of 4 or 5 moist, 5 or 6 dry, and chroma of 2 to 4 moist and dry.
The 2C2 and 3Ab horizons, when present, are at a depth of 30 inches or more. They are silt loam or silty clay loam with 18 to 35 percent clay. Values are 3 to 6 moist, 4 to 8 dry, and chromas are 1 or 2 moist and dry.
The 3Cg horizon, when present, has gleyed colors of 5G or 5BG moist, and 5Y to 5GY when dry. It has similar textures to the 3Ab horizons.
COMPETING SERIES: These are the Seelovers and Vancecreek series. Seelovers soils have a mollic epipedon 10 to 14 inches thick, do not have discontinuities, and are within a 24 to 35 mean annual precipitation zone. Vancecreek soils have a solum depth of 30 to 50 inches and lack buried A horizons within the control section.
GEOGRAPHIC SETTING: The Sturgill soils are on flood plains. Slopes are 0 to 2 percent. Elevations are 3,400 to 4,400 feet. The soils formed in fine-silty, mixed alluvium. The climate is characterized by cold wet winters and hot dry summers. The mean annual precipitation is 13 to 17 inches. The mean annual temperature of 42 to 45 degrees F. The frost-free period is 70 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cheval, Josset, Redmount, and Lostine series. Cheval soils are moderately well drained and fine-loamy in the control sections. Josset, Redmount, and Lostine soils are well drained with a coarse loamy or coarse silty control section.
DRAINAGE AND PERMEABILITY: Poorly drained; moderately slow permeability. An apparent water table is as high as 0.5 to 1.0 feet from the soil surface from March to June. Occasional flooding for brief periods occurs from April through July.
USE AND VEGETATION: The soils are used mainly for pasture. Potential native vegetation includes sedge, tufted hairgrass and rushes.
DISTRIBUTION AND EXTENT: Valleys of northeastern Oregon, MLRA 9. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Wallowa County, Oregon, 1998.
REMARKS: Diagnostic horizons and features in this pedon include:
Mollic epipedon - from the surface to 18 inches with chroma of 1 or less (Ap and A horizons).
Aquic moisture regime - soil is saturated for some period; moist value of 4, chroma of 2, and distinct redox concentrations from 18 to 23 inches (Bw horizon).
Fluvaquentic feature - irregular decrease in organic carbon is inferred based on the nature of the parent material.
Particle-size control section - from 10 to 40 inches (part of A horizon, Bw, C1, 2C2, and upper 3Ab horizons).