LOCATION APTOS CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Pachic Ultic Argixerolls
TYPICAL PEDON: Aptos fine sandy loam, forested. (Colors are for dry soil unless otherwise noted.)
0--1 inch to 0; twigs and leaves of vegetative cover; slightly acid (pH 6.3); abrupt smooth boundary. (0 to 4 inches thick)
A11--0 to 9 inches; dark grayish brown (10YR 4/2) fine sandy loam, dark brown (7.5YR 3/2) moist; medium coarse angular blocky structure; slightly hard, friable, nonsticky and nonplastic; many medium and coarse, common fine and very fine roots; many medium, common fine and very fine tubular, common very fine interstitial pores; slightly acid (pH 6.3); clear wavy boundary. (7 to 9 inches thick)
A12--9 to 18 inches; brown (7.5YR 5/2) fine sandy loam, dark brown (7.5YR 3/2) moist; weak coarse angular blocky structure; slightly hard, friable, nonsticky and nonplastic; many medium and coarse, common fine and very fine roots; many very fine and fine tubular, common very fine interstitial pores; few worm casts in pores; slightly acid (pH 6.1); clear wavy boundary. (8 to 12 inches thick)
A13--18 to 23 inches; grayish brown (10YR 5/2) fine sandy loam, dark brown (7.5YR 3/2) moist; weak coarse angular blocky structure; hard, friable, slightly sticky and slightly plastic; many medium and coarse, common fine and very fine roots; common fine and very fine tubular, many fine interstitial pores; moderately acid (pH 5.9); clear wavy boundary. (0 to 8 inches thick)
B2t--23 to 29 inches; brown (10YR 5/3) clay loam, dark brown (7.5YR 3/2) moist; moderate medium and coarse angular blocky structure; hard, friable, sticky and plastic; many medium and coarse, common fine and very fine roots; many very fine, common fine tubular, few very fine interstitial pores; common thin clay films, lining pores and coating faces of peds; very strongly acid (pH 5.0); pockets of this horizon penetrate to 36 inches deep in rock fractures; gradual irregular boundary. (5 to 15 inches thick)
Cr--29 to 39 inches; highly weathered fine grained sandstone, cut with moderate difficulty with tile spade; very strongly acid (pH 4.8). Soil in fractures similar to above horizon making up less than 10 percent of volume to 36 inches depth, decreasing to nil at 39 inches depth.
TYPE LOCATION: Santa Cruz County, California; about 0.1 mile up Love Creek Road from Woodland Way and about 350 feet uphill east of Love Creek Road; NE1/4 NW1/4 section 33, T.9S., R.2W.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact of fine grained sandstone or shale is 20 to 40 inches. The soil between depths of 7 and 21 inches is usually dry between mid-July and mid-October and usually moist between the end of December and the end of April. The mean annual soil temperature is about 56 to 58 degrees F. Organic matter content is more than 1 percent at a depth of 20 to 30 inches. Base saturation is more than 50 percent in all parts and less than 75 percent in some or all parts of the profile to a depth of 30 inches. Pebbles range from 0 to 15 percent by volume.
The A horizon is very dark grayish brown, dark gray, dark grayish brown, grayish brown, or brown (10YR 3/2, 4/1, 4/2, 5/2, 5/3; 7.5YR 5/2). It is sandy loam, fine sandy loam. This horizon ranges from medium acid to neutral.
The B2t horizon is dark gray, gray, grayish brown, brown or yellowish brown (10YR 4/1, 5/1, 5/2, 5/3, 5/4) and in places, at a depth greater than 20 inches, pale brown (10YR 6/3). It is loam, sandy clay loam or clay loam and has 20 to 35 percent clay. This horizon ranges from very strongly acid to slightly acid. In some pedons a 3 to 5 inch thick C horizon underlies the B2t horizon.
COMPETING SERIES: These are the Nisene (t) and Roseburg series in the same family and the Felton, Lompico and Soquel series in other families. Nisene soils have a paralithic contact at depths of 40 to 60 inches or more. Roseburg soils have a mean annual soil temperature of 52 to 55 degrees F. Felton and Lompico soils have a moist chroma of 4 or more within 10 to 20 inches of the surface. Soquel soils have an irregular decrease in organic matter to a depth of more than 20 inches.
GEOGRAPHIC SETTING: Aptos soils are on uplands and have slopes of 15 to 75 percent. They formed in material weathered from fine grained sandstone and shale at elevations from 400 to 3,000 feet. The climate is humid mesothermal having warm, dry but foggy summers and cool, moist winters. The mean annual precipitation is 35 to 60 inches. The average January temperature is about 45 degrees F.; the average July temperature is about 65 degrees F.; and the mean annual temperature is 54 to 57 degrees F. The frost free season is 220 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Felton, Lompico, Nisene, and Soquel soils, and the Ben Lomond, Catelli and Sur soils. Ben Lomond and Catelli soils lack B2t horizons and have less than 18 percent clay. Sur soils have more than 35 percent rock fragments and a base saturation of more than 75 percent throughout.
DRAINAGE AND PERMEABILITY: Well drained; rapid to very rapid runoff; moderate permeability.
USE AND VEGETATION: Used for timber production, recreation, wildlife, watershed, and in some areas, homesites and orchards. Vegetation is redwoods, Douglas fir, madrone, tanoak, ferns and poison oak.
DISTRIBUTION AND EXTENT: Central part of the Coast Range of California. The soils are not extensive.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Santa Cruz County, California, 1976.
REMARKS: The activity class was added to the classification in January of 2003. Competing series were not checked at that time. - ET
Activity class updated to superactive after reviewing lab data from similiar adjacent soils. WR/KP