LOCATION CAPAY CA

Established Series
Rev. GWH/CAF/JJJ/KP/SBS/AEC
03/2018

CAPAY SERIES

The Capay series consists of very deep, moderately well and somewhat poorly drained soils that formed in fine textured alluvium derived from mostly sandstone and shale. Capay soils are on flood basins, alluvial fans, interfan basins and basin rims. Slopes are 0 to 15 percent. The mean annual precipitation is about 21 inches(541 mm)and the mean annual air temperature is about 61 degrees F (16 degrees C).

TAXONOMIC CLASS: Fine, smectitic, thermic Typic Haploxererts

TYPICAL PEDON: Capay silty clay, cultivated. (Colors are for dry soil unless otherwise stated.)

Ap--0 to 5 inches (0 to 13 cm); dark grayish brown (2.5Y 4/2) silty clay, very dark grayish brown (10YR 3/2) moist; strong medium granular structure in upper 1 or 2 inches and strong coarse prismatic structure below; very hard, very firm, sticky and very plastic; many fine roots; common very fine tubular pores; neutral (pH 7.1); clear smooth boundary. (5 to 8 inches thick).

Bk1--5 to 21 inches (13 to 53 cm); dark grayish brown (2.5Y 4/2) silty clay, very dark grayish brown (10YR 3/2) moist; few fine prominent strong brown (7.5YR 5/6) masses of oxidized iron, moist; strong very coarse prismatic structure; very hard, very firm, sticky and very plastic; few fine roots; common very fine tubular pores; strongly effervescent, fine soft masses of lime in lower 4 inches; moderately alkaline (pH 7.9); clear wavy boundary. (12 to 16 inches thick).

Bssk1--21 to 32 inches (53 to 81 cm); brown (10YR 5/3) silty clay, dark brown (10YR 3/3) moist; strong coarse prismatic structure; very hard, very firm, sticky and very plastic; many fine roots; common very fine tubular pores; prominent intersecting slickensides; strongly effervescent, fine soft masses of lime; moderately alkaline (pH 8.4); clear wavy boundary. (8 to 12 inches thick).

Bssk2--32 to 40 inches (81 to 102 cm); brown (10YR 5/3) silty clay, dark yellowish brown (10YR 4/4) moist; faces of peds dark brown (10YR 3/3) moist; moderate medium prismatic structure; hard, firm, sticky and very plastic; few fine roots; many very fine tubular pores; distinct intersecting slickensides; slightly effervescent, fine soft masses of lime; moderately alkaline (pH 8.3); gradual smooth boundary. (8 to 10 inches thick).

B'k2--40 to 50 inches (102 to 127 cm); pale brown (10YR 6/3) silty clay loam, dark yellowish brown (10YR 4/4) moist; faces of peds dark brown (10YR 3/3); moist; weak coarse angular blocky structure; hard, firm, sticky and very plastic; few fine roots, many very fine tubular pores; slightly effervescent; fine soft masses of lime; moderately alkaline (pH 8.3); diffuse boundary. (8 to 10 inches thick).

B'k3--50 to 62 inches (127 to 157 cm); yellowish brown (10YR 5/6) silty clay loam, dark yellowish brown (10YR 4/4) moist; faces of peds dark brown (10YR 3/3); few fine distinct strong brown (7.5YR 5/6) mottles, yellowish brown (10YR 5/6) moist; weak fine and medium angular blocky structure; hard, firm, sticky and very plastic; many very fine tubular pores; slightly effervescent, fine soft masses of lime; moderately alkaline (pH 8.2); diffuse boundary.

2B'k4--62 to 81 inches (157 to 206 cm); pale brown (10YR 6/3) clay loam, dark yellowish brown (10YR 4/4) moist; 1 percent fine distinct (7.5YR 5/6) and 1 percent fine faint (10YR 5/6) masses of oxidized iron; massive parting to weak fine and medium angular blocky structure; hard, firm, moderately sticky, very plastic; very few roots; many tubular pores; 3 percent carbonate concretions and few fine masses of lime; slightly effervescent; moderately alkaline (pH 8.3); clear smooth boundary.

2B'k5--81 to 88 inches (206 to 224 cm); pale brown (10YR 6/3) sandy clay loam, dark yellowish brown (10YR 4/4) moist; 3 percent medium distinct (7.5YR 6/6) and 3 percent medium distinct (7.5YR 5/6) masses of oxidized iron; massive parting to weak fine and medium angular blocky structure; hard, firm, moderately sticky, moderately plastic; very few roots; very few fine irregular and common very fine tubular pores; few fine masses of lime; slightly effervescent; moderately alkaline (pH 8.3); clear wavy boundary.

2B'k6--88 to 102 inches (224 to 259 cm); yellowish brown (10YR 5/4) fine sandy loam, dark yellowish brown (10YR 4/4) moist; massive; few fine masses of lime; slightly effervescent; moderately alkaline (pH 8.1).

TYPE LOCATION: Solano County, California; about 2 1/2 miles northeast of Elmira; about 200 feet east and 50 feet north of the SW corner of section 16, T.6 N., R.1 E., MDB&M. 38 degrees 21 minutes 33 seconds North, 121 degrees 52 minutes 38 seconds West, NAD83.

RANGE IN CHARACTERISTICS: The mean annual soil temperature is estimated to range from 60 degrees to 66 degrees F. Some pedons are saline-sodic throughout. The soils have 1 to 2 cm wide cracks that open and close at least once each year and remain open for 150 days or less in the summer.

The A horizon is 10YR 5/2, 4/2, 3/2, 5/3, 4/3; 7.5YR 5/2, 5/4, 4/2; 2.5Y 5/2, 4/2 or 3/2, moist values are commonly one unit lower. Texture is clay, silty clay, silty clay loam or clay loam. Reaction is moderately acid to moderately alkaline becoming more alkaline with increasing depth. Some pedons have a few mottles in the A horizon. These are commonly associated with rice culture. The lower part of the A horizon may have intersecting slickensides.

The Bssk and B'k horizons are 10YR 7/2, 6/4, 6/3, 5/4, 4/2, 4/3, 4/4, 5/2, 5/3; 2.5Y 6/2, 5/2, 5/4, 5/6, 4/4; 5Y 6/4, 6/3, 5/3, 5/2 or 4/3. Moist values are the same or 1 to 2 units darker. Texture is clay, silty clay, silty clay loam or clay loam. Some pedons have loam textures in the lower part of the profile. Reaction is neutral to strongly alkaline. Lime is in concretions, soft masses and disseminated throughout the horizon.

COMPETING SERIES: These are the Ayar, Bosquejo and Maxwell series. Ayar soils are well drained and have slopes of more than 9 percent. Bosquejo soils have redoximorphic features and no secondary carbonates below the lithologic discontinuity. Maxwell soils are 24 to 56 inches deep to carbonates and have a chroma of 1.5 in the A horizon.

GEOGRAPHIC SETTING: Capay soils are on flood basins, alluvial fans, interfan basins at elevations below 1,200 feet. They formed in fine textured alluvium derived from sandstone and shale or other mixed rock sources. Slopes are 0 to 15 percent. The soils are in a dry climate of relatively hot dry summers and cool moist winters. Mean annual precipitation ranges from 9 to 28 inches. Mean January temperature is 47 degrees F, mean July temperature is 72 degrees F, mean annual temperature ranges from 58 degrees to 63 degrees F. Frost-free season is 185 to 300 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Clear Lake, Myers, San Ysidro, Yolo and Zamora soils. Clear Lake soils are on lower positions and have chroma of less than 1.5. Myers soils have dry value of more than 5.5. San Ysidro and Zamora soils have argillic horizons. Yolo soils have less than 35 percent clay in the series control section.

DRAINAGE AND PERMEABILITY: Moderately well and somewhat poorly drained; negligible to high runoff, slow to very slow permeability. Also some pedons have a water table between depth of 4 and 6 feet. Some areas are subject to rare, occasional or frequent flooding.

USE AND VEGETATION: Used for growing irrigated crops such as tomatoes, sugar beets, beans or grain sorghum, dry farmed to small grains, and irrigated and dryland pasture. Native vegetation is a dense stand of annual grasses and forbs.

DISTRIBUTION AND EXTENT: Western edge of the Sacramento Valley and intermountain valleys of the Coast Range of northern California. The soil is extensive in MLRA-17 and has been mapped in MLRA 15 in some places

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Woodland Area, California, 1909.

REMARKS: Redoximorphic features in the A horizon are associated with rice culture.

Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from the surface to a depth of 21 inches (Ap, Bssk1).

Cracking - it is assumed from the cracking statement in the RIC that the soil does not meet Aridic subgroup criteria.

Series reclassified May 1996.

Runoff terminology adjusted 5/96 to the adjective criteria of the Soil Survey Manual, 10/93.

The previous horizonation Ap, Ak, Bssk1, Bssk2, Bssk3, Bk is updated. The suffix k indicated an accumulation of carbonates making the Ak a B horizon. The RIC stated that "The lower part of the A horizon has intersecting slickensides" but the Type Location does not have them. Thus Ak is changed to Bk and the last horizon is changed to B'k. (KP) 6/2003

Edits made after SDJR projects and additional horizons and lab textures and pH were incorporated from lab pedon ID S1964CA095002. The additional horizons show a lithologic discontinuity at 157 cm that is likely due to sea level rise between 20 to 6 thousand years ago and the associated stream gradient change.-AEC

ADDITIONAL DATA: NSSL pedons: S64CA-095-002 (40A-385); S64CA-113-013 (40A-3086); S91CA-099-003 (91P-344); S67CA-065-001; S64CA-113-013; S91CA-099-003 and -004 (partial pedons); S92CA-099-005 (county type location).

National Cooperative Soil Survey
U.S.A.