LOCATION BLAVO CAEstablished Series
TAXONOMIC CLASS: Very-fine, smectitic, thermic Xeric Duraquerts
TYPICAL PEDON: Blavo clay on a less than 1 percent slope under a cover of rice at an elevation of 87 feet, (26 m). When described on 5/7/1992, the soil was moist throughout, water table was at 51 inches, (130 cm). (Colors are for dry soil unless otherwise noted)
Ap--0 to 5 inches, (0 to 13 cm); dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; 65 percent clay; strong very coarse prismatic structure parting to strong fine and medium angular blocky; hard, friable, very sticky and very plastic; many very fine roots; vertical cracks 0.5 to 1.5 inches, (1.3 to 3.8 cm) wide, 6 to 12 inches, (15 to 30 cm) apart; common fine and medium brown (7.5YR 4/4) moist, oxidized iron masses; noneffervescent; slightly acid, pH 6.5 by Hellige-Truog ; abrupt smooth boundary. (5 to 16 inches, (13 to 41 cm) thick)
Bssg1--5 to 16 inches, (13 to 41 cm); dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; 65 percent clay; strong very coarse prismatic structure parting to strong coarse angular blocky; extremely hard, firm, very sticky and very plastic; many very fine roots; common very fine tubular pores; vertical cracks 0.5 to 1.5 inches, (1.3 to 3.8 cm) wide, 6 to 12 inches, (15 to 30 cm) apart; many 4 to 6 inch, (10 to 15 cm) wide wedge shaped aggregates; many slickensides; common fine brown (7.5YR 4/4) moist, oxidized iron masses; noneffervescent; moderately alkaline, pH 8.0 by Hellige-Truog; clear wavy boundary.
Bssg2--16 to 24 inches, (41 to 61 cm); dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; 65 percent clay; moderate coarse prismatic structure parting to strong medium and coarse angular blocky; extremely hard, firm, very sticky and very plastic; common very fine roots; common very fine tubular pores; many 4 to 6 inch, (10 to 15 cm) wide wedge shaped aggregates; many slickensides; noneffervescent; moderately alkaline, pH 8.0 by Hellige-Truog; clear wavy boundary. (Combined thickness of the Bss horizon is 6 to 20 inches (15 to 51 cm) thick).
Bkssg--24 to 30 inches, (61 to 76 cm); dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; 60 percent clay; moderate medium and coarse angular blocky structure; very hard, friable, very sticky and very plastic; few very fine roots; many very fine tubular pores; many 1 to 3 inch, (2.5 to 7.6 cm) wide wedge shaped aggregates; many slickensides; disseminated carbonates; strongly effervescent; moderately alkaline, pH 8.0 by Hellige-Truog; clear wavy boundary. ( 4 to 18 inches (10 to 46 cm) thick).
Bkg--30 to 36 inches, (76 to 91 cm); gray (10YR 6/1) clay loam, dark gray (10YR 4/1) moist; 38 percent clay; strong fine and medium angular blocky structure; hard, friable, very sticky and very plastic; few very fine roots; many very fine tubular pores; many 1 to 2 inch, (2.5 to 5 cm) wide wedge shaped aggregates common fine and medium irregular carbonate masses; violently effervescent; strongly alkaline, pH 8.5 by Hellige-Truoug; abrupt wavy boundary. (4 to 8 inches (10 to 20cm) thick)
2Bkqm--36 to 60 inches, (91 to 152 cm); Indurated duripan very pale brown (10YR 8/2) brown (10YR 4/3) moist; massive; extremely hard, extremely firm; continuous indurated silica cemented 15 to 25 mm thick laminar cap; alternating layers of strongly cemented to indurated duripan to 60 inches; does not slake in HCl; many medium and coarse carbonate masses and many fine plate like black (N 2/0) moist, manganese masses at top of horizon; violently effervescent.
TYPE LOCATION: Butte County, California; about 3.2 miles southwest of Richvale, approximately 600 feet west and 2350 feet north of the southeast corner of Section 31, Township 19 N., Range 2 E.; 39 degrees, 29 minutes, 24 seconds North latitude and 121 degrees, 46 minutes, 57 seconds West longitude, NAD27. U.S.G.S. Quad: West of Biggs, California.
RANGE IN CHARACTERISTICS: Depth to duripan is 20 to 40 inches, (51 to 102 cm). The mean annual soil temperature is 62 to 66 degrees F, (17 to 19 degrees C). The soil moisture control section is dry from June to October (120 to 125 days). The particle-size control section averages 60 to 70 percent clay. Mineralogy is smectitic. The soil is calcareous from 15 to 34 inches, (38 to 86 cm). Reversible surface-initiated cracks 1 to 2 inches, (2.5 to 5 cm) wide extend to a depth of 29 inches, (74 cm) from May 15 to October 15 (150 days) when the soil is not irrigated. Intersecting slickensides range from few to common in the Bssg and Bsskg horizons from 7 to 29 inches, (18 to 74 cm). A fluctuating, water table can occur between the top of the duripan and the surface of the soil from December through May. Redoximorphic features such as manganese nodules and oxidized iron masses with colors of 7.5YR 4/4 moist, and reduced matrix with chromas of 1 moist, occur in horizons above the duripan. Some pedons have silt loam overwash from 6 to 20 inches, (15 to 51 cm) thick.
The Ap horizon dry color is 10YR 3/1 or 4/1. Moist color is 10YR 2/1 or 3/1. Clay content ranges from 60 to 70 percent. Organic matter ranges from 1 to 2 percent. Reaction is moderately acid to neutral.
The Bssg horizon dry color is 10YR 3/1, 4/1 or 5/1. Moist color is 10YR 3/1 or 4/1. Clay content ranges from 65 to 70 percent. Organic matter ranges from 0.5 to 2 percent. Reaction ranges from neutral to moderately alkaline.
The Bkssg dry color is 10YR 3/1, 4/1 or 5/1. Moist color is 10YR 3/1, 4/1 or 4/2. Clay content ranges from 65 to 70 percent. Organic matter ranges from 0.5 to 1 percent. Reaction ranges from slightly alkaline to moderately alkaline.
The Bkg horizon dry color is 10YR 5/1, 5/2, 6/1, 6/2 or 6/3. Moist color is 10YR 4/1, 4/2, 5/2 or 2.5Y 4/2. Texture is clay loam or clay. Clay content ranges from 35 to 60 percent. Organic matter ranges from 0.1 to 0.5 percent. Reaction ranges from moderately alkaline to strongly alkaline.
The 2Bkqm horizon dry color is 10YR 5/2, 6/2, 7/2, 7/3 or 8/2. Moist color is 10YR 4/2, 4/3 or 5/2. Rupture resistance ranges from indurated to strongly cemented with alternating weak and moderately cemented layers cemented with silica and lime.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Blavo soils are in flood basins. Slopes range from 0 to 1 percent. These soils formed in alluvium from mixed rocks. Elevation is 60 to 110 feet, (18 to 34 m). Mean annual precipitation is 18 to 20 inches, (457 to 508 mm). The mean annual temperature is 59 to 60 degrees F, (15 to 16 degrees C). Frost free season is 240 to 245 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lofgren, Esquon and Neerdobe soils. Lofgren soils are deep to a duripan. Esquon soils are fine and deep to a duripan. Neerdobe soils are fine and moderately deep to a duripan.
DRAINAGE AND PERMEABILITY: Poorly drained; high runoff ; very slow saturated hydraulic conductivity in the Ap, Bssg and Bkssg horizons, moderately slow in the Bkg horizon and impermeable in the 2Bkgm horizon. The soils are rarely to occasionally flooded for very brief to brief periods in December through March. Water ponds frequently up to 6 inches, (15 cm) above the surface for very long duration from December through April. A fluctuating water table can occur between the top of the duripan and the surface of the soil from December through May. Dams, Levees, drainage ditches, and leveling for agriculture have altered the frequency and duration of saturation, ponding and flooding.
USE AND VEGETATION: This soil is used for rice production, wildlife habitat and watershed.
DISTRIBUTION AND EXTENT: Butte County, California. MLRA 17 - Sacramento Valley. The soils are moderately extensive
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from a stop along the Southern Pacific Railroad east of Nelson.
REMARKS: These soils were previously mapped as Stockton clay adobe in the Soil Survey of Oroville Area, California 1926.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 16 inches, (0 to 41 cm), (Ap, Bssg1)
Cambic horizon - 16 to 36 inches, (41 to 91 cm), (Bssg2, Bkssg, Bkg)
Duripan - 36 to 60 inches, (91 to 152 cm), (2Bkqm)
Lithologic discontinuity at 36 inches, (91 cm), (2Bkqm)
Particle-size control section - 10 to 36 inches, (25 to 91 cm).
Moisture control section- 7 to 22 inches, (18 to 56 cm).
ADDITIONAL DATA: Grab samples from UCD (Lab #1757) University of California unpublished.