LOCATION CHICO CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Pachic Argixerolls
TYPICAL PEDON: Chico loam on a less than 1 percent slope under a cover of wheat stubble at an elevation of 186 feet, (57 m). When described on 6/22/94, the soil was moist below 5 inches, (13 cm). (Colors are for dry soil unless otherwise noted).
Ap--0 to 5 inches, (0 to 13 cm); brown (10YR 5/3) loam, very dark grayish brown (10YR 3/2) moist; 23 percent clay; moderate medium and coarse subangular blocky structure parting to moderate very fine and fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and common fine roots; few very fine to medium tubular pores, common fine and medium irregular pores; slightly alkaline, pH 7.5 by Hellige-Truog; clear smooth boundary. 4 to 10 inches, (10 to 25 cm) thick)
Bt1--5 to 10 inches, (13 to 25 cm); brown (10YR 4/3) clay loam, dark brown (7.5YR 3/2) moist; 29 percent clay; moderate medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and fine roots; few very fine to medium tubular and few fine and medium irregular pores; few discontinuous distinct clay films on faces of peds and in pores; slightly alkaline, pH 7.5 by Hellige-Truog; gradual smooth boundary.
Bt2--10 to 21 inches, (25 to 53 cm); brown (10YR 4/3) clay loam, dark brown (7.5YR 3/2) moist; 29 percent clay; moderate medium subangular structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and few fine roots; many very fine to medium tubular pores; common discontinuous distinct clay films on faces of peds and in pores; neutral, pH 7.0 by Hellige-Truog; gradual smooth boundary.
Bt3--21 to 32 inches, (53 to 81 cm); brown (10YR 4/3) clay loam, dark brown (7.5YR 3/2) moist; 29 percent clay; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine roots; common very fine and fine tubular pores; common discontinuous distinct clay films on ped faces and in pores; neutral, pH 7.0 by Hellige-Truog; gradual smooth boundary.
Bt4--32 to 50 inches, (81 to 127 cm); brown (10YR 4/3) loam, dark brown (7.5YR 3/2) moist; 27 percent clay; moderate fine, medium and coarse subangular blocky structure; slightly hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine to medium tubular pores; common discontinuous distinct clay films on ped faces and in pores; neutral, pH 7.0 by Hellige-Truog; gradual smooth boundary.
Bt5--50 to 70 inches, (127 to 178 cm); brown (7.5YR 5/3) loam, k brown (7.5YR 4/3) moist; 25 percent clay; moderate fine, medium and coarse subangular blocky structure; slightly hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine to medium tubular pores; common discontinuous distinct clay films on ped faces and in pores; neutral, pH 7.0 by Hellige-Truog; gradual smooth boundary.
Bt6--70 to 80 inches, (178 to 203 cm); brown (7.5YR 5/4) loam, brown (7.5YR 5/4) moist; 21 percent clay; weak fine and medium subangular blocky structure; slightly hard, firm, slightly sticky and slightly plastic; common very fine roots; common very fine to medium tubular pores; common fine irregularly shaped reddish brown (5YR 4/4) moist, oxidized iron masses and few fine black (N 2/0) moist, soft iron-manganese masses throughout; common discontinuous distinct clay films on ped faces and in pores; neutral, pH 7.0 by Hellige-Truog. (Combined thickness of the Bt horizon is 70 to 76 inches, (178 to 193 cm) thick).
TYPE LOCATION: Butte County, California; about 1 mile south of Chico, approximately 1500 feet north and 250 feet west of the southeast corner of Section 2, Township 21 N., Range 1 E., 39 degrees, 42 minutes, 2 seconds North latitude and 121 degrees, 49 minutes, 27 seconds West longitude, NAD27. U.S.G.S. Quad: Chico, California.
RANGE IN CHARACTERISTICS: Solum thickness is greater than 80 inches, (203 cm). Depth to the argillic horizon is 4 to 24 inches, (10 to 61 cm). The mean annual soil temperature is 62 to 64 degrees F, (17 to 18 degrees C). The soil moisture control section is dry from May to October (140 to 160 days). The particle-size control section averages 25 to 35 percent clay. Mineralogy is mixed. Organic matter ranges from 1 to 5 percent from 0 to 21 inches, (0 to 53 cm) and is less than 1 percent from 21 to 80 inches, (53 to 203 cm). Base saturation by ammonium acetate ranges from 95 to 100 percent throughout. Some pedons have carbonates below 35 inches, (89 cm).
The Ap horizon dry color is 10YR 4/2, 4/3, 5/2, 5/3, 7.5YR 4/2, 4/3, 5/2 or 5/3. Moist color is 10YR 3/2, 3/3 or 7.5YR 3/2. Clay content ranges from 20 to 27 percent. Reaction ranges from slightly acid to slightly alkaline.
The upper Bt horizon dry color is 10YR 4/3, 5/3, 5/4, 7.5YR 4/3, 5/2, 5/3 or 5/4. Moist color is 10YR 3/2, 3/3, 4/3, 7.5 YR 3/2, 3/3 or 3/4. Texture is loam, clay loam or silty clay loam. Clay content ranges from 25 to 35 percent. Reaction ranges from slightly acid to slightly alkaline.
The lower Bt horizon dry color is 10YR 4/3, 5/3, 5/4, 7.5YR 4/2, 4/3, 5/3, 4/4 or 5/4. Moist color is 10YR 4/3, 5/4, 7.5YR 3/2, 3/3, 3/4, 4/3 or 4/4. Texture is loam or clay loam. Clay content ranges from 18 to 35 percent. Below a depth of 70 inches (178 cm) oxidized iron masses and iron-manganese masses occur. Reaction ranges from neutral to slightly alkaline.
COMPETING SERIES: These are the Botella, Saltcanyon, Arujo, McCoy, Kawenga, Sapwi, Tongva, Elkhorn, Havala and Lockwood series. Botella soils have a solum depth less than 65 inches, (165 cm), have neutral and 2.5Y hues, have base saturation ranges from 75 to 95 percent and have a lithologic discontinuity and C horizon. Saltcanyon soils have up to 15 percent coarse fragments, have MAST of 60 to 62 degrees F, (16 to 17 degrees C), lack 7.5YR hue, and lack redoximorphic features in the lower Bt horizon. Arujo soils are underlain by a paralithic contact at 40 to 60 inches, (102 to 152 cm). McCoy soils are underlain by a paralithic contact at 25 to 40 inches, (64 to 102 cm). Elkhorn soils range to moderately acid throughout and the solum is less than 60 inches, (152 cm). Havala soils have a solum that is 30 to 60 inches, (76 to 152 cm) thick. Lockwood soils have greater than 15 percent rock fragments. Kawenga soils are deep to a paralithic contact of sandstone. Sapwi and Tongva soils are moderately deep.
GEOGRAPHIC SETTING: Chico soils are on low fan terraces. Slopes range from 0 to 2 percent. These soils formed in alluvium weathered from mixed rocks. Elevation is 140 to 225 feet, (43 to 69 m). Mean annual precipitation is 22 to 24 inches, (559 to 610 mm). The mean annual temperature is 61 to 62 degrees F, (16 to 17 degrees C). Frost free season is 245 to 255 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Conejo, Vina and Almendra soils. Conejo soils are on distal fans and lack an argillic horizon. Vina soils are on inset fans, lack an argillic horizon and are coarse-loamy. Almendra soils are on mid-fans and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; negligible runoff; moderate saturated hydraulic conductivity in the Ap horizon and moderate to moderately slow in the Bt horizon. A fluctuating water table can occur at depths of 72 to greater than 80 inches, (183 to 203 cm) below the surface of the soil from December through March.
USE AND VEGETATION: This soil is used for almonds, walnuts, row crops residential, commercial and industrial development.
DISTRIBUTION AND EXTENT: Butte County, California. MLRA 17 - Sacramento Valley. The soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - zone from 0 to 21 inches, (0 to 53 cm) (Ap, Bt1, Bt2,)
Argillic horizon - zone from 5 to 32 inches, (13 to 81 cm) (Bt1, Bt2, Bt3).
Soil moisture control section - zone from 6 to 12 inches, (15 to 30 cm).
Particle-size control section - zone from 5 to 25 inches, (13 to 64 cm).
ADDITIONAL DATA: Characterization data from lab pedon number:95P0515, NSSL Lincoln, NE. sampled near the type location. Data did not indicate adequate clay increase for an argillic horizon. However, data from type location showed an adequate increase in clay for an argillic horizon.