LOCATION JIMBO OREstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, mesic Andic Dystrudepts
TYPICAL PEDON: Jimbo silt loam - forested. (Colors are for moist soil unless otherwise noted.)
A--0 to 8 inches; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; moderate very fine granular structure; soft, friable, nonsticky and nonplastic; weakly smeary; many very fine and fine roots; many irregular pores; 10 percent firm and very firm medium and fine concretions; moderately acid (pH 5.8); clear smooth boundary. (6 to 12 inches thick)
AB--8 to 14 inches; dark brown (7.5YR 3/2) silt loam, brown (10YR 5/3) dry; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; weakly smeary; many very fine and fine roots; many irregular pores; 10 percent fine concretions; moderately acid (pH 5.9); clear smooth boundary. (0 to 8 inches thick)
2Bw--14 to 22 inches; dark yellowish brown (10YR 3/4) loam, brown (10YR 5/3) dry; weak very fine subangular blocky and granular structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; many very fine irregular pores; about 5 percent fine concretions; strongly acid (pH 5.4); clear smooth boundary. (4 to 10 inches thick)
2BC--22 to 31 inches; dark yellowish brown (10YR 3/4) loam, light yellowish brown (10YR 6/4) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine and few fine and medium roots; many very fine irregular pores; strongly acid (pH 5.4); clear smooth boundary. (6 to 11 inches thick)
2C1--31 to 43 inches; dark yellowish brown (10YR 4/4) loam, yellowish brown (10YR 5/4) dry; massive; soft, very friable, nonsticky and nonplastic; few very fine irregular pores; strongly acid (pH 5.2); abrupt wavy boundary. (10 to 20 inches thick)
3C2--43 to 60 inches; multicolored very cobbly sand; single grained; loose; nonsticky and nonplastic; many irregular pores; 30 percent gravel and 25 percent cobbles; strongly acid (pH 5.2).
TYPE LOCATION: Lane County, Oregon; cutbank 40 feet north of Goodpasture Road in the northwest 1/4 southwest 1/4 southwest 1/4, sec. 32, T. 16 S., R. 3 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 47 to 54 degrees F. The soil is usually moist but it is dry in all parts between depths of 4 and 12 inches for less than 45 consecutive days during the 4-month period following the summer solstice. The depth to the very cobbly sand substratum is 40 to over 60 inches and depth to bedrock is more than 60 inches. The umbric epipedon is 10 to 18 inches thick.
The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 and 3 moist and dry. It has 0 to 20 percent concretions of 2 to 10 millimeters in diameter. It is silt loam, loam, or fine sandy loam with 10 to 18 percent clay. It has an estimated acid oxalate extractable aluminum plus one-half iron of 1.0 to 2.0 percent and less than 2.0 cmol per kg fine earth of 1N KCL extractable aluminum. Moist bulk density is 0.85 to 0.95 grams per cubic centimeter.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 5 or 6 dry, and chroma of 3 or 4 moist and dry. It is loam, fine sandy loam or sandy loam and averages 10 to 18 percent clay, with more than 15 percent sand coarser than very fine sand, and 0 to 5 percent concretions of 2 to 10 millimeters in diameter.
The C horizon has value of 5 or 6 dry and chroma of 3 or 4 moist and dry. It is loam or fine sandy loam.
The 2C horizon is multicolored very cobbly sand or very cobbly loamy sand. It has 50 to 60 percent rock fragments.
COMPETING SERIES: This is the Silcox series. Silcox soils have 10 to 35 percent rock fragments within the particle-size control section also including some pumice.
GEOGRAPHIC SETTING: Jimbo soils are on terraces at elevations of 500 to 1,700 feet. Slopes are 0 to 5 percent. These soils formed in ash and mixed alluvium that has been deposited quite uniformly over the first two or three terraces. The climate is characterized by warm wet winters and hot moist summers. The mean annual precipitation is 60 to 95 inches. The mean January temperature is 34 degrees F; mean July temperature is 63 degrees F; and the mean annual temperature is 46 to 52 degrees F. The frost-free period is 80 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cupola, Haflinger, and Saturn soils. Cupola soils have an ochric epipedon and contain more than 35 percent gravel and cobbles in the solum. Haflinger soils are sandy and contain more than 35 percent gravel and cobbles in the control section. Saturn soils have contrasting textures of fine-loamy over fragmental within a depth of 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid over very rapid permeability.
USE AND VEGETATION: These soils are mostly cleared and the major crop is filberts. Other uses include pasture, recreation, and timber production. Native vegetation is mainly Douglas fir, western hemlock, red alder, bigleaf maple, western redcedar, salal, vine maple, trailing blackberry, and western swordfern.
DISTRIBUTION AND EXTENT: Along streams of the western Cascade Range, Oregon; MLRA 3. The series is of small extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lane County Area, Oregon, 1981.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Umbric epipedon - from 0 to 14 inches (A and AB horizons)
Cambic horizon - from 14 to 22 inches (Bw horizon)
Andic feature - from 0 to 14 inches having a moist bulk density of 0.85 to 0.95 grams per cubic centimeter and acid oxalate extractable aluminum plus one-half iron of 1.0 to 2.0 percent.
Particle-size control section - from 10 to 40 inches (upper 4 inches of AB horizon, Bw horizon, Bw, BC, and upper 9 inches of the C1 horizon)
ADDITIONAL DATA: Unpublished laboratory data from Oregon State University sample No. S68 Oregon 20-4.