LOCATION SMOCREEK CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Fluventic Haploxerolls
TYPICAL PEDON: Smocreek silty clay loam - on a slope of less than 2 percent under basin wildrye, basin big sagebrush, beardless wildrye and mountain brome at about 4440 feet elevation. (When described on 9/27/78 the soil was dry from 0 to 36 inches, and moist below 36 inches. Colors are for dry soil unless otherwise stated).
A1--0 to 2 inches; brown (10YR 5/3) silt loam; very dark grayish brown (10YR 3/2) moist; moderate thick and very thick platy structure; very hard, friable, sticky and plastic; common very fine roots; common very fine interstitial pores; surface 1/4 and 1/2 inch is hard, dry, decomposed organic matter; moderately alkaline (pH 8.0); clear wavy boundary. (2 to 6 inches thick)
A2--2 to 13 inches; grayish brown (10YR 5/2) silty clay loam, black (10YR 2/1) moist; few fine distinct pale brown (10YR 6/3) mottles, brown (10YR 4/3) moist; moderate fine, medium and coarse angular blocky structure; slightly hard, very friable, sticky and plastic; many very fine and common fine roots; many very fine tubular pores; slightly effervescent with disseminated lime, calcium carbonate equivalent is 9 percent; moderately alkaline (pH 8.0); clear wavy boundary. (10 to 14 inches thick)
Bk--13 to 19 inches; light brownish gray (10YR 6/2) silt loam, very dark grayish brown (10YR 3/2) moist; common fine distinct light yellowish brown (10YR 6/4) mottles, dark brown (10YR 3/3) moist; weak fine and medium angular blocky structure; slightly hard, very friable, sticky and plastic; many very fine and common fine roots; strongly effervescent with disseminated lime and lime segregated in few fine filaments and threads, calcium carbonate equivalent is 9 percent; moderately alkaline (pH 8.0); clear wavy boundary. (0 to 8 inches thick)
ABkb--19 to 27 inches; variegated gray (10YR 5/1) and grayish brown (10YR 5/2) silty clay loam, black (N 2/0) and very dark grayish brown (10YR 3/2) moist; common fine distinct light yellowish brown (10YR 6/4) mottles, dark brown (10YR 3/3) moist; moderate fine and medium angular blocky structure; slightly hard, very friable, very sticky and very plastic; many very fine and common fine roots; many very fine and common fine tubular pores; strongly effervescent with disseminated lime and lime segregated in few fine filaments and threads, calcium carbonate equivalent is 11 percent; moderately alkaline (pH 8.0); clear wavy boundary. (2 to 9 inches thick)
Bkb1--27 to 49 inches; light brownish gray (10YR 6/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; common fine distinct light yellowish brown (10YR 6/4) mottles, dark yellowish brown (10YR 4/4) moist; massive, slightly hard, very friable, sticky and plastic; common very fine roots; many very fine tubular pores; many fine organic carbon pieces and stains; strongly effervescent with disseminated lime and lime segregated in few fine filaments and threads, calcium carbonate equivalent is 11 percent; moderately alkaline (pH 8.0); clear wavy boundary. (0 to 22 inches thick)
Bkb2--49 to 60 inches; pale brown (10YR 6/3) silty clay loam, dark grayish brown (10YR 4/2) moist; many fine distinct brownish yellow (10YR 6/6) mottles, dark yellowish brown (10YR 4/4) moist; massive; hard, very friable, sticky and plastic; few very fine roots; many very fine tubular pores; many fine organic carbon pieces and stains; strongly effervescent with disseminated lime and lime segregated in few fine filaments and threads, calcium carbonate equivalent is 7 percent; moderately alkaline (pH 8.0).
TYPE LOCATION: Lassen County, California; in Secret Valley, about 1100 feet W and 150 feet N from the intersection of Hwy 395 and Karlo Road, 900 feet E and 50 feet N of the SW corner section 35, T.35 N., R.15 E.
RANGE IN CHARACTERISTICS: The mollic epipedon is 12 to 20 inches thick. The mean annual soil temperature ranges from 48 degrees to 53 degrees F. The soils are usually moist, but are continuously dry in all parts between the depth of 4 and 15 inches for 80 to 90 days in August through October. The soils are saturated from 40 to 60 inches from January through May. One or more buried A horizons occur within the profile, organic matter decreases irregularly with depth and ranges from 2 to 4 percent. The 10 to 40 inch control section is stratified silt loam or silty clay loam and has a weighed average of 27 to 35 percent clay and 5 to 12 percent material coarser than very fine sand. Few to common distinct to prominent 10YR 5/8, 6/3, 6/4 or 6/6 mottles occur from 2 to 60 inches. It is slightly to strongly effervescent with disseminated lime in the upper part and lime segregated as filaments, threads or seams in the lower part. Calcium carbonate equivalent is 7 to 12 percent in the 10 to 40 inch control section and 5 to 10 percent below 40 inches.
The A horizon dry color is 10YR 5/1, 5/2, or 5/3. Moist color is 10YR 2/1, 3/1, or 3/2. It is loam, silt loam, or silty clay loam. Rock fragments range from 0 to 5 percent. Reaction is mildly or moderately alkaline. E. C. is 0 to 2 in non-alkali phase and 4 to 8 in alkali phase. SAR is 0 to 4 in non-alkali phase and 10 to 20 in alkali phase.
The Bk and Bkb horizons dry color are 10YR 5/1, 6/1, 6/2, 6/3 or 2.5Y 5/2. Moist colors are 10YR 2/2, 3/2, 4/2 and strata of ABkb is 10YR 5/1, 5/2 and N 2/0 through N 4/0 also occur. Reaction is mildly through strongly alkaline. E. C. is 0 to 2 in non-alkali phase and 8 to 16 in alkali phase. SAR is 0 to 4 in non-alkali phase and 20 to 50 in alkali phase.
COMPETING SERIES: This is the Parehat series. Parehat soils have 18 to 27 percent clay in the particle size control section and have formed in alluvium strongly influenced by loess.
GEOGRAPHIC SETTING: Smocreek soils are on nearly level stream terraces. They formed in alluvium from basalt, andesite and tuff. Slopes are 0 to 2 percent. Elevations are 4050 to 5500 feet. The climate is semi-arid with warm dry summers and cold moist winters. The mean annual precipitation is 9 to 16 inches. Snowfall ranges from 10 to 30 inches. The mean annual temperature is 45 degrees to 52 degrees F., mean January temperature is 27 degrees to 32 degrees F., and the mean July temperature is 64 degrees to 68 degrees F. Frost-free season is 60 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Corral, Brubeck, Horsecamp, Gerlach, Ravendale, and Saddlerock soils. Corral soils are less than 20 inches to a paralithic contact and have aridic moisture regimes. Brubeck, Horsecamp, Gerlach and Ravendale soils lack mollic epipedons, are in the fine family and have cracks that open and close each year. Saddlerock soils are in the fine family and have an aquic moisture regime.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff and moderately slow permeability. The alkali phase has slow permeability. A seasonal high water table is at a depth of 40 to 60 inches, and the soils are subject to rare flooding for very brief or brief periods from January through May.
USE AND VEGETATION: Smocreek soils are used mostly for rangeland and to a minor extent are used for irrigated and pasture. Vegetation is basin wildrye, basin big sagebrush, beardless wildrye and mountain brome.
DISTRIBUTION AND EXTENT: Northeastern California. The soils of this series are not extensive.
MLRA OFFICE RESPONSIBLE: Reno, Nevada
SERIES PROPOSED: Lassen County, California, Susanville Area, California 1988.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - zone from the soil surface to 13 inches (A1, A2).
Buried horizons - zone from 19 to 60 inches (ABbk, Bbk1, Bbk2).
Last revised by the state on 4/88.