LOCATION KNAPKE OREstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Entic Ultic Haploxerolls
TYPICAL PEDON: Knapke extremely gravelly loam, on an east, southeast facing concave slope of 68 percent under mixed conifers at 900 feet elevation. (When described the soil was moist below at depth 13 inches. Colors are for moist soil unless otherwise noted.)
0i-1 inch to 0; partially decomposed leaves, needles, and twigs.
A1--0 to 4 inches; very dark brown (10YR 2/2) extremely gravelly loam, black (10YR 2/1) crushed, dark brown (10YR 4/3) dry; weak very fine and fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine roots; many very fine and fine pores; 60 percent gravel, 15 percent cobbles, and 5 percent stones; slightly acid; clear smooth boundary.
A2--4 to 8 inches; very dark grayish brown (10YR 3/2) extremely gravelly loam, dark brown (10YR 4/3) dry; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium, and few coarse roots; many very fine and fine pores; 60 percent gravel. 15 percent cobbles, 5 percent stones; slightly acid; clear smooth boundary. (Combined thickness of A horizon is 7 to 12 inches)
AC--8 to 13 inches; dark brown (10YR 3/3) extremely gravelly loam, dark yellowish brown (10YR 4/4) dry; weak very fine and fine granular structure; soft, very friable, slightly sticky and slightly plastic; common fine and medium and few very fine and coarse roots; many very fine and fine pores; 60 percent gravel; slightly acid; abrupt wavy boundary. (3 to 7 inches thick)
C1--13 to 26 inches; dark brown (7.5YR 3/4) extremely gravelly loam, brown (7.5YR 4/4) dry; massive; soft, friable, slightly sticky and slightly plastic; many fine and medium, and few coarse roots; many very fine and fine pores; 80 percent gravel, 5 percent cobbles; slightly acid; gradual wavy boundary. (10 to 50 inches thick)
C2--26 to 62 inches; dark brown (7.5YR 3/4) extremely gravelly loam, yellowish brown (10YR 5/4) dry; massive; soft, friable, slightly sticky and slightly plastic; common fine and few medium and coarse roots; many very fine and fine pores; 60 percent gravel, 10 percent cobbles, 5 percent stones; slightly acid.
TYPE LOCATION: Josephine County, Oregon; about 12 miles northwest of Selma; 2,280 feet east and 800 feet north of the southwest corner of section 6, T.37S., R.9W.
RANGE IN CHARACTERISTICS: Depth to bedrock is 60 inches or more. The mean annual soil temperature ranges from 47 to 57 degrees F. These soils are usually moist but are dry between depths of 4 and 12 inches for 45 to 80 consecutive days in the 4 months that follow the summer solstice. The particle size control section averages 18 to 27 percent clay and 45 to 85 percent rock fragments of which 5 to 15 percent are cobbles and stones. Rock fragments are dominantly olivine gabbro, but may include gabbro and metagabbro rock types. The mollic epipedon is 10 to 19 inches thick.
The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 1 through 3 moist. It averages 45 to 85 percent rock fragments of which 5 to 20 percent are cobbles and stones.
The C horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 3 or 4 moist and dry. It is very gravelly loam or extremely gravelly loam with 18 to 27 percent clay. It has 35 to 70 percent gravel, 0 to 15 percent cobbles, and 0 to 5 percent stones.
COMPETING SERIES: This is the Takilma series. Takilma soils have 12 to 18 percent clay in the particle-size control section.
GEOGRAPHIC SETTING: Knapke soils are on footslopes and side slopes of mountains. Elevations are 200 to 4,000 feet. Slopes are from 30 to 90 percent. The soils formed in colluvium weathered dominantly from olivine gabbro, but include gabbro and metagabbro rock types. The climate is characterized by warm, wet winters and hot, dry summers. Mean annual temperature is 46 to 56 degrees F. The mean annual precipitation is typically 50 to 70 inches but may range to 100 inches in the interior mountains of Curry County, Oregon. The frost free period is 100 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beekman, Fantz, Josephine, Speaker, and Vermisa soils. All of these soils occur on ridgetops or side slopes of mountains. Beekman, Josephine, Speaker, and Vermisa soils lack a mollic epipedon. Also, Josephine and Speaker soils are fine-loamy. Vermisa soils are 10 to 20 inches deep to a lithic contact.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Knapke soils are used for wildlife habitat, recreation, and timber production. Natural vegetation is Douglas fir, ponderosa pine, Jeffrey pine, Oregon myrtle, tanoak, canyon liveoak, swordfern, forbs, and grasses. In Curry County, Oregon the overstory includes sugar pine, Pacific madrone, and California black oak. The understory includes baldhip rose, California honeysuckle, salal, cascade Oregongrape, western brackenfern, white hawkweed, poison oak, spreading dogbane, red fescue, and bearded fescue.
DISTRIBUTION AND EXTENT: Mountainous areas of southwestern Oregon; MLRA 5. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Josephine County, Oregon, 1979.
REMARKS: A calcium, magnesium imbalance may exist due to high levels of magnesium contributed by the parent material. This situation is reflected in poor vegetation growth and production.
CEC activity class superactive added 1/2000, competing series not updated at that time.
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - from the surface to a depth of 13 inches (A1, A2, AC horizons)
Entic Ultic subgroup - do not have a cambic horizon, and do not in the lower part of the mollic epipedon meet the requirements for a cambic horizon except color, and have a base saturation (by sum of cations) of 75 percent or less in one or more horizons between depths of 10 and 30 inches below the soil surface (C1, C2 horizons).
Particle-size control section - from 10 to 40 inches (part of AC, all of C1 and part of C2 horizons).