LOCATION SPROULISH CATentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, isomesic Typic Dystrustepts
TYPICAL PEDON: Sproulish loam on a northwest facing 34 percent slope under Douglas-fir, tan oak, Pacific madrone, coast redwood, evergreen huckleberry, and salal, at an elevation of 378 meters. (Colors are for dry soil unless otherwise noted.) When described on 06/14/06, the soil was moist to 200 cm.
Oi--0 to 3 centimeters; 75 percent very dark brown (7.5YR 2.5/2) and 25 percent pinkish gray (7.5YR 6/2), slightly decomposed plant material; black (7.5YR 2.5/1) rubbed; about 80 percent fiber, 50 percent rubbed; 2 percent gravel; moderately acid (pH 6.0); abrupt smooth boundary. (0 to 10 centimeters thick)
A--3 to 10 centimeters; brown (10YR 5/3) paragravelly loam, dark brown (7.5YR 3/3) moist; moderate very fine and fine subangular blocky structure; moderately hard, friable, moderately sticky and slightly plastic; many very fine and common fine and medium roots throughout; few very fine, fine, and medium tubular pores; 10 percent mudstone paragravel, 10 percent mudstone gravel; moderately acid (pH 6.0); clear smooth boundary. (5 to 30 centimeters thick)
ABt--10 to 25 centimeters; yellowish brown (10YR 5/4) silty clay loam, brown (7.5YR 4/4) dry; moderate fine subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; common very fine and fine, many medium, and common coarse and very coarse roots throughout; common very fine, fine, and medium tubular pores; few faint clay films on all faces of peds; 5 percent mudstone paragravel, 5 percent mudstone gravel; moderately acid (pH 5.6); gradual wavy boundary. (0 to 25 centimeters thick)
Bt1--25 to 43 centimeters; pale brown (10YR 6/3) paragravelly silty clay loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; few very fine and fine and common medium, coarse, and very coarse roots throughout; common very fine and fine tubular pores; few distinct clay films on all faces of peds; 10 percent mudstone paragravel, 5 percent mudstone gravel; moderately acid (pH 5.6); gradual wavy boundary.
Bt2--43 to 82 centimeters; light yellowish brown (10YR 6/4) gravelly silty clay loam, dark yellowish brown (10YR 4/4) moist; moderate very fine and fine subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; common very fine, few fine, common medium, coarse, and very coarse roots throughout; common very fine and few fine tubular pores; few faint clay films on all faces of peds; 20 percent mudstone paragravel, 20 percent mudstone gravel; strongly acid (pH 5.4); gradual wavy boundary.
Bt3--82 to 142 centimeters; light yellowish brown (10YR 6/4) gravelly silty clay loam, dark yellowish brown (10YR 4/4) moist; moderate fine and very fine subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; common very fine, few fine, and common medium, coarse, and very coarse roots throughout; common very fine and few fine tubular pores; few faint clay films on all faces of peds; 20 percent mudstone paragravel, 20 percent mudstone gravel; strongly acid (pH 5.4); clear wavy boundary. (Combined thickness of the Bt horizons is 100 to 195 centimeters thick)
BCt--142 to 180 centimeters; light yellowish brown (10YR 6/4) paragravelly silty clay loam, dark yellowish brown (10YR 4/4) moist; weak fine subangular blocky structure; moderately hard, friable, moderately sticky and moderately plastic; few very fine and fine and common medium, coarse, and very coarse roots throughout; few very fine and fine tubular pores; few faint clay films on rock fragments and few faint clay films on all faces of peds; 20 percent mudstone paragravel; strongly acid (pH 5.4). (0 to 75 centimeters thick)
TYPE LOCATION: Humboldt County, California; about 8 kilometers southwest of the town of Weott, CA, USGS quadrangle Bull Creek, CA; 40 degrees 16 minutes 44 seconds north latitude and 123 degrees 59 minutes 37 seconds west; zone 10 415526mE, 4459176mN; NAD 83.
RANGE IN CHARACTERISTICS:
Particle size control section (weighted average):
Rock fragments: 0 to 35 strongly cemented mudstone and sandstone gravel, 0 to 5 percent strongly cemented sandstone cobbles
Pararock fragments: 2 to 50 percent moderately cemented mudstone and sandstone gravel
Clay content: 20 to 35 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 4 to 6, 2 to 4 moist
Chroma: 1 to 4, dry and moist
Texture of fine earth: loam
Clay content: 15 to 27 percent
Rock fragments: 0 to 10 percent strongly cemented mudstone and sandstone gravel
Pararock fragments: 0 to 14 percent moderately cemented mudstone and sandstone gravel
Reaction: moderately to slightly acid
Upper Bt horizons:
Hue: 7.5YR or 10YR
Value: 5 or 6, 2 to 4 moist
Chroma: 3 or 4, dry or moist
Texture of fine earth: loam, silt loam, clay loam, or silty clay loam
Clay content: 20 to 35 percent
Rock fragments: 0 to 35 percent strongly cemented mudstone and sandstone gravel
Pararock fragments: 2 to 50 percent moderately cemented mudstone and sandstone gravel
Reaction: slightly to strongly acid
Lower Bt horizons:
Hue: 7.5YR, 10 YR, or 2.5Y
Value: 5 or 6, 3 or 4 moist
Chroma: 3 to 6, dry or moist
Texture of fine earth: loam, silt loam, clay loam, or silty clay loam
Clay content: 25 to 40 percent
Rock fragments: 0 to 50 percent strongly cemented mudstone and sandstone gravel
Pararock fragments: 2 to 70 percent moderately cemented mudstone and sandstone gravel
Reaction: strongly to moderately acid
Some pedons have C horizons below 150 centimeters
Hue: 7.5YR, 10 YR, or 2.5Y
Value: 5 to 7, 3 or 4 moist
Chroma: 4 to 6, dry or moist
Texture of fine earth: sandy loam, loam, silt loam
Clay content: 10 to 20 percent
Rock fragments: 0 to 90 percent strongly cemented mudstone and sandstone gravel
Pararock fragments: 2 to 90 percent moderately cemented mudstone and sandstone gravel
Reaction: strongly to moderately acid
COMPETING SERIES: These are the Crispin, Gibsoncreek (T), Ornbaun, and Redwohly (T) series. Crispin soils are moderately deep to consolidated marine sediments, Gibsoncreek soils lack a Bt horizon or do not have an increase of 1.2 times the percent clay in the Bt horizon, Ornbaun soils have a paralithic contact within 200 centimeters, Redwohly soils have a C horizon between 50 and 100 centimeters composed of highly fractured bedrock.
GEOGRAPHIC SETTING: Sproulish soils are on linear to concave or slightly convex positions on summits, shoulders, and backslopes of mountain slopes and ridges. Slopes are 15 to 75 percent. Elevations are 185 to 730 meters. These soils formed in colluvium and residuum derived from sandstone or mudstone. The climate is subhumid with warm, dry summers and cool, moist winters. Mean annual precipitation is 1525 to 2500 millimeters. The mean annual temperature is 11 to 13 degrees C. Frost free season is about 240 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Canoecreek (T) and Redwohly (T) soils. Canoecreek soils contain more than 35 percent rock fragments and do not have an increase of 1.2 times the percent clay in the Bt horizon. Canoecreek soils are found on linear to concave or convex positions on summits, shoulders and backslopes. Redwohly soils have a C horizon composed of highly fractured bedrock between 50 and 100 centimeters and are found on convex to strongly convex positions on shoulders and summits.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; high or very high runoff; moderately high to moderately low saturated hydraulic conductivity.
USE AND VEGETATION: This soil is used for timber production, wildlife habitat, and watershed. Natural vegetation includes Douglas fir, tan oak, and Pacific madrone, and evergreen huckleberry. When present, coast redwood is less than 50 percent
DISTRIBUTION AND EXTENT: California Coastal Belt; MLRA 4B. The series is moderately extensive.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES PROPOSED: Southern Humboldt County Soil Survey, California. The name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 0 to 10 centimeters.
Argillic horizon: The zone from 10 to 180 centimeters.
3. Particle-size control section: The zone from 10 to 60 centimeters (ABt, Bt1, and Bt2 horizons)
ADDITIONAL DATA:
Keys to Soil Taxonomy, 10th edition