LOCATION SMOCREEK CA

Established Series
Rev. DCE-SJB-DJE-JBF
11/2016

SMOCREEK SERIES

The Smocreek series consists of very deep, somewhat poorly drained soils formed in alluvium derived from volcanic rocks. The Smocreek soils are on stream terraces and have slopes of 0 to 2 percent. The mean annual precipitation is about 300 mm and the mean annual temperature is about 8 degrees C.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Fluventic Haploxerolls

TYPICAL PEDON: Smocreek silty loam - on a slope of less than 2 percent under basin wildrye, basin big sagebrush, beardless wildrye and mountain brome at about 1,353 meters elevation. (When described on 9/27/78 the soil was dry from 0 to 90 cm, and moist below 90 cm. Colors are for dry soil unless otherwise stated).

A1--0 to 5 cm; brown (10YR 5/3) silt loam; very dark grayish brown (10YR 3/2) moist; moderate thick and very thick platy structure; very hard, friable, moderately sticky and moderately plastic; common very fine roots; common very fine interstitial pores; surface 0.6 and 1.2 cm is hard, dry, decomposed organic matter; moderately alkaline (pH 8.0); clear wavy boundary. (5 to 15 cm thick)

A2--5 to 33 cm; grayish brown (10YR 5/2) silty clay loam, black (10YR 2/1) moist; few fine distinct pale brown (10YR 6/3) redox concentations, brown (10YR 4/3) moist; moderate fine, medium and coarse angular blocky structure; slightly hard, very friable, moderately sticky and moderately 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. (25 to 36 cm thick)

Bk--33 to 48 cm; 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) redox concentations, dark brown (10YR 3/3) moist; weak fine and medium angular blocky structure; slightly hard, very friable, moderately sticky and moderately 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 20 cm thick)

ABkb--48 to 69 cm; 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) redox concentations, 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. (5 to 23 cm thick)

Bkb1--69 to 124 cm; 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) redox concentrations, dark yellowish brown (10YR 4/4) moist; massive, slightly hard, very friable, moderately sticky and moderately 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 56 cm thick)

Bkb2--124 to 152 cm; pale brown (10YR 6/3) silty clay loam, dark grayish brown (10YR 4/2) moist; many fine distinct brownish yellow (10YR 6/6) redox concentrations, dark yellowish brown (10YR 4/4) moist; massive; hard, very friable, moderately sticky and moderately 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.32 N., R.15 E.; latitude 40 degrees 35 minutes 6 seconds N and longitude 120 degrees 15 minutes 12 seconds W; NAD 83.

RANGE IN CHARACTERISTICS:
Soil moisture: Usually moist, but are continuously dry in all parts between the depth of 10 and 38 cm for 80 to 90 days in August through October. The soils are saturated from 100 to 150 cm from January through May.
Mean annual soil temperature: 9 to 12 degrees C.
Mollic epipedon: 30 to 50 cm thick.
Calcium carbonate equivalent: 7 to 12 percent in the 25 to 100 cm particle-size control section and 5 to 10 percent below 100 cm.
Carbonates: Slightly effervescent through strongly effervescent with disseminated lime in the upper part and lime segregated as filaments, threads or seams in the lower part.
Other features: One or more buried A horizons occur within the profile, organic matter decreases irregularly with depth and ranges from 2 to 4 percent. Few to common distinct to prominent 10YR 5/8, 6/3, 6/4 or 6/6 redox features occur from 5 to 150 cm.

Particle-size control section - Clay content: Average of 27 to 35 percent Sand content: 5 to 12 percent material coarser than very fine sand.

A horizon
Value: 2 or 3 moist.
Chroma: 1 through 3 dry, 1 or 2 moist.
Reaction: Slightly alkaline or moderately alkaline.
Electrical conductivity (EC): 0 to 2 in non-alkali phase and 4 to 8 in alkali phase.
Sodicity (SAR): 0 to 4 in non-alkali phase and 10 to 20 in alkali phase.

Bk and Bkb horizons
Hue: 10YR or 2.5Y.
Value: 5 or 6 dry, 2 through 4 moist.
Chroma: 1 through 3 dry.
Texture: Stratified silt loam or silty clay loam.
Electrical conductivity (EC): 0 to 2 in non-alkali phase and 8 to 16 in alkali phase.
Sodicity (SAR): 0 to 4 in non-alkali phase and 20 to 50 in alkali phase.

ABkb
Hue: 10YR or N.
Value: 2 through 5.
Chroma: 0 through 2.
Reaction: Slightly alkaline through strongly alkaline.
Electrical conductivity (EC): 0 to 2 in non-alkali phase and 8 to 16 in alkali phase.
Sodicity (SAR): 0 to 4 in non-alkali phase and 20 to 50 in alkali phase.

COMPETING SERIES: This is the Maytown series. Maytown soils lack Bk horizons with secondary lime.

GEOGRAPHIC SETTING: Smocreek soils are on stream terraces. They formed in alluvium from basalt, andesite and tuff. Slopes are 0 to 2 percent. Elevations are 1,230 to 1,680 meters. The climate is semi-arid with warm dry summers and cold moist winters. The mean annual precipitation is 230 to 400 mm. Snowfall ranges from 250 to 760 mm. The mean annual temperature is 7 to 11 degrees C. 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 50 cm 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 SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained; slow runoff; moderately slow saturated hydraulic conductivity. The alkali phase has slow permeability. A seasonal high water table is at a depth of 100 to 150 cm, 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 SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES PROPOSED: Lassen County, California, Susanville Area, California 1988.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 33 cm (A1, A2).
Buried horizons - The zone from 33 to 150 cm (ABbk, Bbk1, Bbk2).
Particle-size control section - The zone from 25 to 100 cm (Bk, ABbk and part of the A2 and Bkb1 horizons).

ADDITIONAL DATA: User Pedon ID: 2015CA035001.

National Cooperative Soil Survey
U.S.A.