LOCATION ELKHORN CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Pachic Argixerolls
TYPICAL PEDON: Elkhorn fine sandy loam, cultivated. (Colors are for dry soil unless otherwise noted.)
Ap1--0 to 9 inches; brown (10YR 5/3) fine sandy loam, dark brown (10YR 3/3) moist; moderate medium and coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine and few medium roots; few very fine tubular pores; neutral (pH 7.0); clear smooth boundary. (7 to 10 inches thick)
Ap2--9 to 17 inches; brown (10YR 5/3) fine sandy loam, dark brown (10YR 3/3) moist; moderate coarse angular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and few medium roots; few very fine and fine tubular, few very fine interstitial pores; slightly acid (pH 6.5); clear smooth boundary. (7 to 15 inches thick)
A3--17 to 26 inches; brown (10YR 5/3) heavy fine sandy loam, dark brown (10YR 3/3) moist; moderate medium and coarse angular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine, few medium roots; many medium, fine and very fine tubular, many very fine interstitial pores; numerous worm casts; moderately acid (pH 5.8); clear irregular boundary. (6 to 12 inches thick)
B2t--26 to 46 inches; brown (7.5YR 5/4) sandy clay loam, mixed dark brown and reddish brown (7.5YR 4/4, 5YR 4/4) moist; massive; very hard, firm, sticky and slightly plastic; few thin discontinuous clay films lining pores; many medium and coarse weakly cemented shot that are not magnetic but effervescent in solution of H2O2; moderately acid (pH 6.0); gradual wavy boundary. (20 to 40 inches thick)
C--46 to 63 inches; strong brown (7.5YR 5/6) fine sandy loam, mixed strong brown and dark brown (7.5YR 5/6 and 4/4) moist; massive; very hard, firm, slightly sticky and slightly plastic; few very fine and fine roots; few coarse tubular, few very fine interstitial pores; few thin distinct clay films line pores; few medium faint weakly cemented coarse shot are not magnetic, but effervescent in solution of H2O2; slightly acid (pH 6.5).
TYPE LOCATION: Monterey County, California; about 4 miles north of Moss Landing; 2,600 feet west and 3,000 feet north of Springhill Road from intersection of Highway 1.
RANGE IN CHARACTERISTICS: Solum thickness is 42 to 60 inches. The soil between depths of 6 and 18 inches becomes moist in some part in November or early December and remains moist until May. The mean annual soil temperature is between 59 and 60 degrees F. The average summer soil temperature is about 65 degrees F., and the mean winter soil temperature is about 54 degrees F. Base saturation is 75 to 95 percent in all parts. Gravel, shale fragments and other rock fragments are less than 15 percent in the A horizon and B horizon. Organic matter ranges from 2 to 6 percent in the upper 20 inches and decreases regularly to less than 1 percent at 40 inches below the surface.
The A1 horizon is grayish brown, dark grayish brown, very dark grayish brown, brown or dark brown (10YR 5/2, 4/2, 3/2, 5/3, 4/3). It is sandy loam, fine sandy loam or loam. This horizon has granular , subangular blocky or angular blocky structure. Reaction is neutral to medium acid. Some pedons have a few dark reddish brown or brown, coarse shot or concretions in the lower A horizon. A transitional A3 horizon or B1 horizon or both, occurs between the A1 horizon or B2t horizon.
The B2t horizon is dark brown, brown, pale brown, very pale brown, grayish brown, light brownish gray, light gray, dark yellowish brown, or yellowish brown (10YR 4/3, 5/3, 6/3, 6/2,7/2,4/4 5/4) and brown, dark brown, or strong brown (7.5YR 3/2, 4/2, 5/2, 4/4, 5/4, 5/6). It is neutral to medium acid. Few to common firm iron manganese shot, concretions, or flakes are present in some part of this horizon. A buried sandy clay loam or clay layer occurs below the B2t horizon in some pedons.
The C horizon is brown, strong brown or reddish yellow (7.5YR 5/4, 5/6,6/6) and pale brown, yellowish brown, light yellowish brown or brownish yellow (10YR 6/3, 6/4, 5/4, 6/6, 5/6). It is loamy sand, loamy fine sand, sandy loam or fine sandy loam. Reaction is moderately acid to neutral.
COMPETING SERIES: These are the Arujo (t), Botella, Havala (t), Lockwood and McCoy series. Arujo and Havala soils have an average summer-winter soil temperature variance of more than 25 degrees F. Botella and Lockwood soils lack shot or concretions in the solum. Also, Botella soils have chroma of 1 or have neutral colors in the A horizon, and Lockwood soils have 15 to 35 percent shale or other rock fragments in the A horizon. McCoy soils have a paralithic contact of bedrock at depths of 25 to 40 inches.
GEOGRAPHIC SETTING: The Elkhorn soils are on marine terraces with gradients of 0 to 50 percent. They formed in old stablized sandy dune deposits and in soft marine sediments near the coast. The underlying sediments have contrasting textures, some reddish material, and are in part cemented with iron. Elevations are 20 to 800 feet. The climate is subhumid mesothermal with moderately cool, dry somewhat foggy summers and cool, wet winters. The mean annual precipitation is 14 to 35 inches. The average July temperature is 62 to 72 degrees F.; the average January temperature is 46 to 50 degrees F.; and the mean annual temperature is 58 to 60 degrees F. The frost free season is 250 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arnold, Oceano, Pfeiffer, Pinto, Santa Ynez and Watsonville series. Arnold and Oceano soils are sandy in all parts and have less than 1 percent organic matter in the surface 10 inches. Pfeiffer soils have less than 18 percent clay. Pinto soils have an abrupt A/B horizon boundary, and have less than 1 percent organic matter below depth of 20 inches. Santa Ynez soils have more than 35 percent clay in the B2t horizon. Watsonville soils have more than 35 percent clay in the B2t horizon.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: Used for growing special crops such as brussel sprouts, strawberries, artichokes, broccoli, pasture and hay. Uncultivated; dry areas have annual grasses and forbs.
DISTRIBUTION AND EXTENT: Near the coast in central California. The soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Monterey County (Salinas Area), California, 1925.
REMARKS: The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET