LOCATION CAMPBELL CAEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, thermic Cumulic Haploxerolls
TYPICAL PEDON: Campbell silt loam, protected, 0 to 2 percent slopes, on a south facing 1 percent slope, cultivated, at an elevation of 6 meters. When described the soil was dry to 25 centimeters and moist below. (Colors are for dry soil unless otherwise noted).
Ap--0 to 10 inches, (0 to 25 cm); brown (10YR 5/3) broken face silt loam, very dark grayish brown (10YR 3/2) broken face moist; 24 percent clay; moderate medium subangular blocky and moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine interstitial pores; neutral, pH 7.1 by pH meter 1:1 water; abrupt smooth boundary.
A1--10 to 24 inches, (25 to 60 cm); brown (10YR 5/3) broken face silt loam, very dark grayish brown (10YR 3/2) broken face moist; 26 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, moderately sticky, moderately plastic; few medium roots; common very fine interstitial and many very fine tubular pores; slightly alkaline, pH 7.5 by pH meter 1:1 water; gradual smooth boundary.
A2--24 to 31 inches, (60 to 80 cm); grayish brown (10YR 5/2) broken face silty clay loam, very dark grayish brown (10YR 3/2) broken face moist; 28 percent clay; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky, moderately plastic; few medium roots; common very fine interstitial pores; slightly alkaline, pH 7.7 by pH meter 1:1 water; gradual smooth boundary.
A3--31 to 38 inches, (80 to 97 cm); grayish brown (10YR 5/2) broken face silty clay loam, very dark grayish brown (10YR 3/2) broken face moist; 29 percent clay; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky, moderately plastic; few medium roots; common very fine interstitial pores; slightly alkaline, pH 7.7 by pH meter 1:1 water; gradual smooth boundary.
2A--38 to 51 inches, (97 to 130 cm); dark grayish brown (10YR 4/2) broken face silty clay loam, very dark grayish brown (10YR 3/2) broken face moist; 29 percent clay; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky, moderately plastic; common very fine interstitial pores; 10 percent faint clay films on all faces of peds; strong effervescence, by HCl, 1 normal; slightly alkaline, pH 7.7 by pH meter 1:1 water; clear smooth boundary.
2Bw1--51 to 71 inches, (130 to 180 cm); 50 percent dark grayish brown (10YR 4/2) broken face and 50 percent gray (10YR 5/1) broken face silty clay, 50 percent very dark grayish brown (10YR 3/2) broken face and 50 percent dark gray (10YR 4/1) broken face moist; 40 percent clay; massive; hard, friable, very sticky, moderately plastic; common very fine interstitial pores; violent effervescence, by HCl, 1 normal; slightly alkaline, pH 7.7 by pH meter 1:1 water; gradual smooth boundary.
2Bw2--71 to 79 inches, (180 to 200 cm); 30 percent grayish brown (10YR 5/2) broken face and 70 percent gray (10YR 5/1) broken face silty clay, 30 percent dark grayish brown (10YR 4/2) broken face and 70 percent dark gray (10YR 4/1) broken face moist; 45 percent clay; massive; hard, friable, very sticky, moderately plastic; common very fine interstitial pores; 5 percent carbonate coats; violent effervescence, by HCl, 1 normal; moderately alkaline, pH 7.9 by pH meter 1:1 water;
TYPE LOCATION: Santa Clara County, California, Moitozo Ranch,northwest of the corner of Zanker Road and River Oaks Parkway, San Jose, 25 orange tree rows west of north east corner of orange orchard, between 3 and 4 tree rows south, on north side of orchard., in a nonsectionised area of Township 6S, Range 1W, 4140452 UTM Northing, 0594130 UTM Easting, Zone 10, NAD83. - U.S.G.S Quad: Milpitas, California.
RANGE IN CHARACTERISTICS: The soils are developed in material of mixed mineralogy. Mean soil temperature is between 59 and 62 degrees F. The soils are moist from mid October until about June 15. The textural control section of 25 to 100 centimeters has clay content of 27 to 35 percent clay. Depth to the buried A horizon ranges from 30 to 100 centimeters. Fragments are gravel in size and range from 0 to 2 percent.
The Ap horizon has dry colors of 10YR 5/3, 4/2, 4/1, 3/1 or 2.5Y 5/3. Moist colors are 10YR 3/2, 3/1, 2/2, 2/1 or 2.5Y 3/3. Texture is silt loam or silty clay loam. Clay content ranges from 20 to 35 percent. Reaction is 6.6 to 8.4.
The A horizon has dry colors of 10YR 5/3, 5/2, 4/2, 4/1 or 2.5Y 5/3. Moist colors are 10YR 4/3, 4/2, 3/2, 3/1, 2/2 or 2.5Y 3/3. Texture is silt loam or silty clay loam. Clay content ranges from 25 to 35 percent. Reaction is 6.6 to 8.4. The lower part of the A horizon may contain masses of oxidized iron with color chromas of 4 or 6.
The 2A horizon has dry colors of 10YR 4/2, 3/1 or 2.5Y 5/2. Moist colors are 10YR 3/2, 2/2 or 2.5Y 4/4, 3/2. Oxidized mass of iron may occur and have moist colors of 10YR 5/6 or 5/8. Texture is silty clay loam. Clay content is 27 to 35 percent clay. Reaction is 6.6 to 8.4
The 2Bw horizon has dry colors of 10YR 6/3, 5/2, 4/3, 4/2; 2.5Y 5/4, 5/3, 4/1, 3/2 or 3/1. Moist colors are 10YR 4/2, 3/2, 2/1; 2.5Y 3/3, 3/1, 2/2 or 5Y 2.5/2. Iron depletions may occur with moist color of 10YR 4/1, iron masses may also occur with moist colrs of 10YR 6/4, 5/8, 5/6, 5/4 or 4/4. Texture is silty clay loam or silty clay. Clay content is 35 to 50 percent clay. Reaction is 6.6 to 8.4. The 2Bw horizon is generally calcareous with dissemintated lime and commonly has a few soft lime masses but occasionally is noncalcareous.
COMPETING SERIES: These are the Coyotecreek and the Wisoncreek soils. Coyotecreek and Wilsoncreek soils have less than 27 percent clay in the textural control section and have a difference of more than 30 degrees F. between mean summer and mean winter temperatures in MLRA 17.
GEOGRAPHIC SETTING: Campbell soils occur on nearly level areas on floodplains, the toe of alluvial fans and are marginal to basins. The soils develop in alluvium derived primarily from sedimentary formations. Elevations range from 10 to 400 feet. The climate is subhumid mesothermal with cool moist winters, warm dry summers and a mean annual rainfall of 14 to 18 inches. The average annual air temperature is about 59 degrees F, with a January mean of 48 degrees F, and a July mean of 65 degrees F, the frost-free season is about 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: Campbell soils occur in the same general area as the Clear Lake, Hangerone, Pacheco, and Sunnyvale series. Clear Lake, Hangerone and Sunnyvale are dark gray fine textured soils. Pacheco soils are fine loamy and have clay content in the textural control section of 18 to 35 percent clay.
DRAINAGE AND PERMEABILITY: Originally these soils were somewhat poorly drained under natural conditions. Pumping and general lowering of water tables, and levees has made most areas the equivalent of moderately well drained based on depth to water. Runoff is slow. Permeability is moderately slow and slow.
USE AND VEGETATION: Large areas have been urbanized and othere areas are used for row crops, truck crops, fruit orchards, pasture and hay. Native vegetation was grass-oak.
DISTRIBUTION AND EXTENT: Correlated only in Santa Clara County, California where the soil is moderately extensive. 14,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Santa Clara Area, 1944.
REMARKS: Original classification of Humaquepts and later classification to Xerochrepts was based on an epipedon that is usually massive and hard under cropland, new data does not support this. Classification changed 11/2009 to Haploxerolls. Despite some wetness, mottles are too deep, below 20 inches, for an aquic suborder and chromas are too bright for an aquic extragrade. Major revision of description resulting from moving the type location during mapping of the Santa Clara Valley in 2006-2008 because the old type location was lost to urbanization.