LOCATION AMERICANOS CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, semiactive, thermic Mollic Haploxeralfs
TYPICAL PEDON: Americanos silt loam - in an area with a slope of less than 1 percent under a cover of wild oats in an almond orchard at an elevation of about 65 feet. (When described on September 13, l983, the soil was dry to 8 inches and slightly moist below this depth. Colors are for dry soil unless otherwise noted.)
Ap--0 to 8 inches; yellowish brown (10YR 5/4) silt loam, dark brown (10YR 3/3) moist; massive; hard, friable, slightly sticky and slightly plastic; common very fine roots; common very fine and few fine tubular pores, few thin clay films lining pores; slightly acid (pH 6.2); clear smooth boundary. (5 to 18 inches thick)
Bt1--8 to 17 inches; dark yellowish brown (10YR 4/4) silt loam, dark yellowish brown (10YR 3/4) moist; massive; hard, firm, slightly sticky and slightly plastic; few coarse, medium, fine and very fine roots; few very fine and fine tubular and common very fine interstitial pores; few moderately thick clay films lining pores and common thin clay films bridging mineral grains; neutral (pH 6.7); clear smooth boundary.
Bt2--17 to 26 inches; dark yellowish brown (10YR 4/4) silt loam, dark yellowish brown (10YR 3/4) moist; massive, hard, friable, sticky and slightly plastic; few fine and very fine roots; common very fine and few fine tubular and few very fine interstitial pores; many moderately thick clay films bridging mineral grains and lining pores; neutral (pH 6.7); clear smooth boundary.
Bt3--26 to 36 inches; dark yellowish brown (10YR 4/4) silt loam, dark yellowish brown (10YR 3/4) moist; massive; hard, friable, sticky and slightly plastic; few very fine and fine roots; few very fine interstitial and common very fine tubular pores; many thin clay films bridging mineral grains and few moderately thick clay films lining pores; neutral (pH 6.7); clear smooth boundary. (Combined thickness of the Bt horizons is 22 to 35 inches)
BCt--36 to 46 inches; light yellowish brown (10YR 6/4) silt loam, dark yellowish brown (10YR 4/4) moist; massive; hard, very friable, sticky and slightly plastic; few fine and common very fine roots; few very fine interstitial and common fine and few medium tubular pores; common thin clay films bridging mineral grains and few moderately thick clay films lining pores; neutral (pH 6.7); clear smooth boundary. (8 to 20 inches thick)
C--46 to 54 inches; light yellowish brown (10YR 6/4) silt loam, dark yellowish brown (10YR 4/4) moist; massive; hard, very friable, sticky and slightly plastic; few very fine roots; common very fine tubular and interstitial pores; few thin clay films bridging mineral grains and lining pores; neutral (pH 6.7); abrupt smooth boundary. (0 to 15 inches thick)
Cq--54 to 62 inches; light yellowish brown (10YR 6/4) weakly cemented duripan, dark yellowish brown (10YR 4/4) moist; brittle when moist; crushes to sandy loam; 60 percent of horizon (horizontally) is cemented; neutral (pH 6.7)
TYPE LOCATION: Sacramento County, California; about 1 mile northwest of Mather Field, 3,550 feet northeast along Folsom Blvd. from the intersection of Bradshaw Rd. and Folsom Blvd.; and 850 feet north of Folsom Blvd. in an unsectionized area of T. 8 N., R. 6 E., 38 degrees 34' 49" N. Latitude, 121 degrees 19' 30" W. Longitude; Carmichael Quadrangle:
RANGE IN CHARACTERISTICS: The mean annual soil temperature at a depth of 20 inches is 64 to 67 degrees F. The soil between a depth of 6 and 17 inches is dry in most years from mid-May to mid-October and moist in all parts from early December to early May. Where present, depth to duripan ranges from 50 to 72 inches. Weighted average clay content of the family control section is 18 to 27 percent and content of material coarser than very fine sand is less than 15 percent. Reaction is slightly acid to neutral throughout the profile.
The Ap and A horizons have dry color of 10YR 5/4 or 5/3 and moist color of 10YR 3/2, 3/3 or 3/4. Organic matter content is 1 to 3 percent. Content of clay is 12 to 20 percent. Some subhorizon above 8 inches has moist chroma of 4 or is massive and hard.
The Bt horizon has dry color of 10YR 4/4, 5/3, 5/4, 6/4; or 7.5YR 5/4 and moist color of 10YR 3/3, 3/4, 4/4; 7.5YR 3/4 or 4/4. It is silt loam or loam with 18 to 27 percent clay.
Where present, the C horizon has dry color of 10YR 6/4 or 7.5YR 6/4 and moist color of 10YR 4/4 or 7.5YR 4/4. It is loam or silt loam with 8 to 18 percent clay.
Where present, the Cq horizon has dry color of 10YR 6/4 or 7.5YR 6/4 and moist color of 10YR 4/4 or 7.5YR 4/4. Silica cementation is weak. It is discontinuously cemented in 50 to 75 percent of the horizon, horizontally.
COMPETING SERIES: These are the Zamora soils. Zamora soils have 27 to 35 percent clay in the control section.
GEOGRAPHIC SETTING: Americanos soils are on low stream terraces. Slopes are 0 to 2 percent and elevations range from 30 to 200 feet. The soils formed in alluvium derived from mixed rock sources. The climate is subhumid with hot, dry summers and cool, moist winters. Mean annual precipitation is 18 to 23 inches. Mean January temperature is 46 degrees F., mean July temperature is 77 degrees F. and the mean annual temperature is 60 to 62 degrees F. The frost-free season is 275 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Natomas, Rossmoor, and San Joaquin soils. Natomas soils are fine-loamy and are on slightly higher stream terraces. Rossmoor soils are coarse-loamy and are on the high flood plain. San Joaquin soils are fine and are on low terraces.
DRAINAGE AND PERMEABILITY: Well drained, slow runoff; moderate permeability.
USE AND VEGETATION: Used for urban development. Natural vegetation is annual grasses and forbs with scattered oaks.
DISTRIBUTION AND EXTENT: Along the American River in the lower Sacramento Valley, California. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Sacramento County, California, l986.
REMARKS: These soils were mapped as the Honcut soils in the soil survey of the Sacramento Area, California, l954. Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to 8 inches. (Ap horizon) This horizon is massive and hard when dry.
Argillic horizon - the zone from 8 to 26 inches. (Bt1, Bt2 horizons)
Duripan- the zone from 54 to 62 inches. (Cq horizon) This horizon is discontinuous. Brittle areas do not slake in water or acid.
Mollic subgroup - organic carbon is greater than 0.7 percent in the Ap horizon and has moist color value of 3.
Last revised by the state on 6/86.