LOCATION CAPJAC CAEstablished Series
TAXONOMIC CLASS: Medial, glassy, calcareous, mesic Typic Endoaquands
TYPICAL PEDON: Capjac silt loam--on a nearly level slope under irrigated barley at 4,032 feet elevation. (Colors are for dry soil unless otherwise noted. When described on May 16, 1979, the soil was dry from the surface to 5 inches and moist below. A water table was at a depth of 35 inches).
Ap--0 to 10 inches; gray (10YR 5/1) silt loam, black (10YR 2/1) moist; weak fine granular structure; slightly hard, very friable, weakly smeary, slightly sticky and slightly plastic; common very fine roots; common very fine interstitial and tubular pores; slightly alkaline (pH 7.8); clear smooth boundary. (10 to 15 inches thick)
A--10 to 26 inches; gray (10YR 6/1) silt loam, very dark gray (10YR 3/1) moist; moderate fine granular structure; hard, friable, moderately smeary, slightly sticky and slightly plastic; common very fine roots; common very fine tubular pores; slightly effervescent with disseminated carbonates; moderately alkaline (pH 8.0); abrupt smooth boundary. (10 to 20 inches thick)
AC--26 to 35 inches; light gray (5Y 7/1) silt loam, black (5Y 2/1) moist; massive; hard, friable, moderately smeary, moderately sticky and slightly plastic; few very fine roots; common very fine tubular pores; many fine prominent dark yellowish brown (10YR 4/6) moist masses of iron accumulation; slightly effervescent with disseminated carbonates; moderately alkaline (pH 8.0); abrupt smooth boundary. (7 to 12 inches thick)
C1--35 to 55 inches; light gray (5Y 7/1) silt loam, olive gray (5Y 4/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; few very fine tubular pores; many fine prominent dark yellowish brown (10YR 4/6) moist masses of iron accumulation; slightly effervescent with disseminated carbonates; moderately alkaline (pH 8.0); clear wavy boundary. (15 to 25 inches thick)
C2--55 to 65 inches; light gray (5Y 7/1) silt loam, dark olive gray (5Y 3/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many fine prominent dark yellowish brown (10YR 4/6) moist masses of iron accumulation; moderately alkaline (pH 8.0). (8 to 20 inches thick)
TYPE LOCATION: Siskiyou County, California; about 1,200 feet southeast of the Tulelake-Lower Klamath Wildlife Refuge Headquarters of the U.S. Fish and Wildlife Service; about 2,635 feet north and 1,400 feet west of the southeast corner of section 6, T. 26 N., R. 4 E.
RANGE IN CHARACTERISTICS:
Soil moisture - A water table is at a depth of 18 to 36 inches from January to December unless artificially drained.
Mean annual soil temperature - 48 to 52 degrees F.
Effervescence - The soil is calcareous in all parts of depths between 10 and 20 inches.
Moist bulk density - 0.4 to 0.7 g/cc.
Other features - The exchange complex is dominated by amorphous materials.
Reaction - Slightly alkaline or moderately alkaline.
A horizons - Dry color: 10YR 5/1, 4/1, or 6/1.
Moist color: 10YR 2/1 or 3/1.
Salinity (EC): 0 to 2 mmhos/cm.
Sodicity (SAR): 0 to 2.
C horizons - Dry color: 5Y 6/1 or 7/1.
Moist color: 5Y 3/2 or 4/2.
Salinity (EC): 4 to 8 mmhos/cm.
Sodicity (SAR): 2 to 8.
COMPETING SERIES: There are currently no other series in this family.
GEOGRAPHIC SETTING: Capjac soils are on lake basins. The soils formed in alluvium weathered mainly from lacustrine deposits influenced by high amounts of volcanic ash and diatoms. Slopes are 0 to 1 percent. Elevations range from 4,030 to 4,100 feet. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 10 to 12 inches and annual snowfall is 10 to 20 inches. The mean annual temperature is about 46 to 50 degrees F. The frost-free period is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fordney, Laki, and Zuman soils. Fordney soils are sandy, excessively drained, and occur on terraces. Laki soils are fine-loamy, well drained, and occur on calcareous beach deposits. Zuman soils are fine-loamy.
DRAINAGE AND PERMEABILITY: Poorly drained; medium surface runoff; moderate permeability. The soils are artificially drained and have a water table at depths of 18 to 36 inches from January to December. The soil is subject to occasional periods of flooding October to May unless protected.
USE AND VEGETATION: Capjac soils are used for irrigated cropland, wildlife habitat, and rangeland. The vegetation is mainly cattails and bullrush.
DISTRIBUTION AND EXTENT: Northern California. These soils are not extensive. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Siskiyou County (Butte Valley-Tule Lake Area), California, 1986.
REMARKS: This revision of March 2003 updates the taxonomic class from Medial, mesic Typic Endoaquands. The remainder of this document has not been completely updated. More study is needed for this series to confirm the medial substitute class and the placement in the Andisol order.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 10 inches (Ap horizon).
Aquic conditions - The conditions of endosaturation, reduction, and redoximorphic features between 10 and 65 inches at certain times during normal years (parts of the A, AC, C1, and C2 horizons).
Particle-size control section and medial substitute class with glassy mineralogy - The zone from 10 to 40 inches (A and AC horizons and part of the C1 horizon).