LOCATION CUPPER ORTentative Series
TAXONOMIC CLASS: Ashy over loamy, glassy over mixed, superactive, mesic Typic Vitrixerands
TYPICAL PEDON: Cupper ashy silt loam - cultivated, on a 6 percent slope at an elevation of 2,420 feet. (When described on August 7, 2002, the soil was dry throughout. Colors are for moist soil unless otherwise noted.)
Ap1--0 to 2 inches; very dark gray (10YR 3/1) ashy silt loam, gray (10YR 5/1) dry; moderate very thin platy structure; soft, very friable, nonsticky and nonplastic; few fine and many very fine roots; few fine and very fine tubular pores; neutral (pH 6.9); abrupt smooth boundary.
Ap2--2 to 10 inches; dark grayish brown (10YR 4/2) ashy silt loam, light brownish gray (10YR 6/2) dry; moderate medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; few very fine tubular pores; neutral (pH 6.9); clear smooth boundary. (Combined thickness of the Ap horizon is 6 to 15 inches.)
AC--10 to 14 inches; grayish brown (10YR 5/2) ashy silt loam, light gray (10YR 7/2) dry; moderate medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine roots; few very fine tubular pores; neutral (pH 6.9); gradual smooth boundary. (4 to 10 inches thick)
C--14 to 26 inches; gray (10YR 6/1) ashy silt loam, white (10YR 8/1) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine roots; few very fine tubular pores; neutral (pH 7.3); abrupt smooth boundary. (1 to 25 inches thick)
2Bwb1--26 to 33 inches; brown (10YR 4/3) loam, pale brown (10YR 6/3) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; common very fine tubular pores; slightly alkaline (pH 7.8); clear wavy boundary. (10 to 20 inches thick)
2Bkb1--33 to 41 inches; brown (10YR 4/3) loam, brown (10YR 5/3) dry; strong medium subangular blocky structure; hard, firm, moderately sticky and slightly plastic; common very fine tubular pores; common fine soft seams of carbonates; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary.
2Bkb2--41 to 48 inches; yellowish brown (10YR 5/4) loam, light yellowish brown (10YR 6/4) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine tubular pores; common fine soft seams of carbonates; strongly effervescent; moderately alkaline (pH 8.3); clear wavy boundary.
2Bkb3--48 to 60 inches; light brownish gray (10YR 6/2) loam, light gray (10YR 7/2) dry; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine tubular pores; few fine soft masses of carbonates; strongly effervescent; 5 percent gravel; moderately alkaline (pH 8.3);
TYPE LOCATION: Grant County, Oregon; located about 2 miles east of Monument; 1,000 feet south and 1,700 feet east of the NW corner of section 5, T. 9 S., R. 28 E. (Latitude 44 degrees, 49 minutes, and 22 seconds N. and Longitude 119 degrees, 22 minutes, and 53 seconds W.)
RANGE IN CHARACTERISTICS: These soils are dry in all parts between 8 and 24 inches for 60 to 90 consecutive days following the summer solstice. The mean annual soil temperature is 47 to 52 degrees F. Depth to bedrock is 60 inches or more. The upper 14 to 19 inches of the particle-size control section is silt loam with estimated clay content of 5 to 15 percent, 25 to 40 percent phosphate retention, 0.4 to 0.8 percent acid oxalate extractable aluminum plus one-half iron, 30 to 50 glass and less than 12 percent 15-bar water based on an air-dried sample. The depth to the loamy buried soil material is 20 to 40 inches. The amount of coarse fragment is 0 to 5 percent throughout the soil.
The A horizon has value of 5 or 6 dry, 2 or 3 moist and chroma of 1 or 2 moist and dry. It has subangular blocky or moderate thin or medium platy structure that breaks to weak or moderate fine granular.
The AC and C horizon has value of 6 to 8 dry, 3 to 6 moist and chroma of 1 to 3 moist and dry.
The 2B horizon has value of 4 to 6 dry, 3 or 4 moist and chroma of 2 or 3 moist and dry. It is silt loam or loam with 18 to 27 percent clay. Faint clay films may be present in some pedons. The 2Bk horizon is slightly or strongly effervescent and has 5 to 10 percent calcium carbonate equivalent. Soil reaction is slightly or moderately alkaline.
COMPETING SERIES: This is the Collegecreek series. Collegecreek soils lack secondary carbonates in the lower part of the profile.
GEOGRAPHIC SETTING: Cupper soils are on footslopes and fans at elevations of 2,200 to 4,200 feet. Slopes are 2 to 20 percent. The soils formed in Mt. Mazama volcanic ash in the upper part with colluvium or alluvium in the lower part. The climate is characterized by cool wet winters and hot dry summers. The mean annual precipitation is 12 to 18 inches. The mean annual temperature is 45 to 50 degrees F., mean winter temperature is 30 to 34 degrees F., and mean summer temperature is 66 to 70 degrees F. The frost-free period is 80 to 120 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Exfo, Hack, Ninetysix, Patron, Prill, and Ritter series. Exfo and Ninetysix soils are on adjacent steep, south slopes. Exfo soils are very shallow and are sandy-skeletal. Ninetysix soils are loamy-skeletal and lack vitrandic properties. Hack soils are fine-loamy and are usually found in complex with Cupper soils on fans and broad ridgetops. Patron soils are on adjacent north slopes and are in the fine family. Prill soils are on adjacent south slopes, are in the fine family, and are moderately deep to paralithic contact. Ritter soils are coarse-loamy and are usually found in complex with Cupper soils on fans.
DRAINAGE AND PERMEABILITY: Well drained; permeability is moderate.
USE AND VEGETATION: These soils are used for livestock grazing, dryland small grain and alfalfa. Potential native vegetation is Idaho fescue, Thurber needlegrass, and needleandthread.
DISTRIBUTION AND EXTENT: East-central Oregon; MLRA 10. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Grant County, Oregon, 1959.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon
Andic soil properties - from 0 to 14 inches (Ap1, Ap2, and AC horizons)
Buried soil feature - from 26 to 60 inches (2Bwb, 2Bkb1, 2Bkb2, and 2Bkb3 horizons)
Particle-size control section - from 0 to 40 inches with 0 to 26 inches meeting ashy family and 26 to 40 inches meeting loamy family.
Secondary carbonates - from 33 to 60 inches
Xeric moisture regime
This draft reflects a change in the series type location. The location of the original typical pedon is considered to be frigid.