LOCATION OROVILLE CAEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Aquic Durixeralfs
TYPICAL PEDON: Oroville gravelly fine sandy loam, on a southeast facing 3 percent slope under a cover of annual grasses and forbs at an elevation of 280 feet, (85 m). When described on 9/26/2001 the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
A--0 to 2 inches, (0 to 5 cm); brown (7.5YR 5/4) gravelly fine sandy loam, dark brown (7.5YR 3/3) moist; 18 percent clay; strong coarse platy parting to moderate fine subangular blocky structure; slightly hard, friable, nonsticky, nonplastic; many very fine roots; few very fine tubular and common very fine irregular pores; 20 percent well rounded mixed gravel; moderately acid, pH 6.0 by Hellige-Truog; abrupt smooth boundary. (2 to 6 inches, (5 to 15 cm) thick)
BAt--2 to 6 inches, (5 to 15 cm); yellowish red (5YR 4/6) gravelly sandy loam, dark reddish brown (5YR 3/4) moist; 20 percent clay; strong medium platy parting to moderate fine subangular blocky structure; very hard, friable, slightly sticky, slightly plastic; few fine, and common very fine roots; few very fine tubular pores; 5 percent discontinuous distinct clay films on vertical faces of peds; 20 percent well rounded mixed gravel; moderately acid, pH 6.0 by Hellige-Truog; abrupt smooth boundary. (0 to 6 inches, (0 to 15 cm) thick)
Bt1--6 to 13 inches, (15 to 33 cm); red (2.5YR 4/6) gravelly clay loam, dark red (2.5YR 3/6) moist; 28 percent clay; strong medium subangular blocky structure; very hard, firm, slightly sticky, moderately plastic; few fine, and common very fine roots; common very fine tubular pores; 30 percent discontinuous distinct clay films on faces of peds; 20 percent well rounded mixed gravel; slightly acid, pH 6.3 by Hellige-Truog; abrupt wavy boundary. (0 to 22 inches, (0 to 56 cm) thick)
2Bt2--13 to 17 inches, (33 to 43 cm); reddish brown (2.5YR 4/4) gravelly clay, dark red (2.5YR 3/6) moist; 50 percent clay; strong fine prismatic parting to moderate fine angular blocky structure; extremely hard, very firm, very sticky, very plastic; few very fine roots; many very fine tubular pores; 5 percent slickensides and 50 percent continuous prominent clay films on faces of peds; 20 percent well rounded mixed gravel; slightly acid, pH 6.3 by Hellige-Truog; clear wavy boundary.
2Btg--17 to 23 inches, (43 to 58 cm); brown (10YR 5/3) gravelly sandy clay, brown (10YR 4/3) moist; 50 percent clay; weak fine angular blocky structure; extremely hard, very firm, very sticky, very plastic; few very fine roots; few very fine tubular pores; 50 percent continuous prominent clay films on faces of peds; 40 percent fine irregular manganese masses; 15 percent fine distinct olive gray (5Y 5/2) iron depletions lining pores; 30 percent well rounded mixed gravel; slightly acid, pH 6.5 by Hellige-Truog; abrupt wavy boundary. (Combined thickness of the 2Bt and 2Btg horizon is 6 to 19 inches, (15 to 48 cm) thick).
3Bqm1--23 to 31 inches, (58 to 79 cm); extremely gravelly indurated duripan; very rigid, cemented by silica, nonsticky, nonplastic; 2 percent well rounded mixed cobbles and 75 percent well rounded mixed gravel; clear wavy boundary.
3Bqm2--31 to 60 inches, (79 to 152 cm); extremely gravelly strongly cemented duripan; rigid, cemented by silica, nonsticky, nonplastic; 2 percent well rounded mixed cobbles and 75 percent well rounded mixed gravel. (Combined thickness of the 3Bqm horizon is 16 to 21 inches, (41 to 53 cm) or more thick).
TYPE LOCATION: Butte County, California, about 0.5 miles north of downtown Oroville in the Fernandez Land Grant, approximately 3200 feet west and 1100 feet south of the northeast corner of projected Section 8, Township 19 N., Range 4 E., 39 degrees, 31 minutes, 20 seconds North latitude and 121 degrees, 33 minutes, 5 seconds West longitude, NAD83 - U.S.G.S. Quad: Oroville, California.
RANGE IN CHARACTERISTICS: Depth to extremely gravelly indurated duripan is 20 to 40 inches, (51 to 102 cm) and depth to 2Bt horizon ranges from 6 to 27 inches, (15 to 69 cm). The mean annual soil temperature is 61 to 64 degrees F, (16 to 18 degrees C). The particle-size control section averages 35 to 50 percent clay and 2 to 35 percent rock fragments, mostly gravel. Mineralogy is mixed. A fluctuating water table can occur from the top of the duripan to the surface of the soil from December through April. Rock fragments on the surface range from 5 to 20 percent gravel.
The A horizon dry color is 7.5YR 5/3, 5/4, 6/3, 6/4, 7/3 or 5YR 3/4. Moist color is 7.5YR 3/3, 3/4, 4/3, 4/4, 5YR 3/4, 4/4 or 2.5YR 3/4. Texture is gravelly sandy loam, fine sandy loam, sandy loam or loam. Clay content ranges from 15 to 24 percent. Organic matter ranges from 0.5 to 2 percent. Rock fragments range from 5 to 20 percent gravel. Redoximorphic features range from 0 to 10 percent soft oxidized iron masses and 0 to 20 percent iron depletions. Reaction ranges from moderately acid to slightly acid.
The BAt horizon dry color is 7.5YR 5/4, 6/3, 6/4, 5YR 4/4, 4/6 or 5/3. Moist color is 7.5YR 4/3, 4/4, 5YR 3/4, 4/4 or 2.5YR 3/4. Texture is gravelly sandy loam, gravelly fine sandy loam, gravelly loam, loam or sandy loam. Clay content ranges from 18 to 25 percent. Organic matter ranges from 0.2 to 0.8 percent. Rock fragments range from 3 to 20 percent gravel. Redoximorphic features range from 0 to 30 percent soft oxidized iron masses, 0 to 15 percent iron depletions, and 0 to 5 percent soft manganese masses. Reaction ranges from moderately acid to neutral.
The Bt horizon dry color is 7.5YR 5/4, 6/4, 7/4, 5YR 5/4, 5/6 or 2.5YR 4/6. Moist color is 7.5YR 4/3, 4/4, 5YR 3/4, 4/4, 4/6, 4/8 or 2.5YR 3/6. Texture is gravelly clay loam, gravelly sandy clay loam, very gravelly sandy clay loam, sandy clay loam or clay loam. Clay content ranges from 22 to 35 percent. Organic matter ranges from 0.1 to 0.5 percent. Rock fragments range from 5 to 40 percent gravel. Redoximorphic features range from 0 to 2 percent soft oxidized iron masses and 0 to 15 percent soft manganese masses. Reaction ranges from moderately acid to neutral.
The 2Bt horizon dry color is 10YR 5/3, 5/4, 7.5YR 5/4, 7/4, 5YR 4/4, 4/6, 5/4, 5/6 or 2.5YR 4/4. Moist color is 10YR 4/3, 4/4, 7.5YR 4/3, 4/4, 5YR 3/3, 3/4, 4/4, 4/6 or 2.5YR 3/6. Texture is gravelly clay, gravelly sandy clay, sandy clay or clay. Clay content ranges from 45 to 52 percent. Organic matter ranges from 0 to 0.3 percent. Rock fragments range from 5 to 45 percent gravel and 0 to 2 percent cobbles. Redoximorphic features range from 0 to 20 percent iron depletions and 0 to 40 percent soft manganese masses. Reaction ranges from moderately acid to neutral.
The 2Btg horizon dry color is 10YR 5/3, 5/4, 5YR 4/4, 4/6, 5/6, 6/4, 7.5YR 5/4 or 7/4. Moist color is 10YR 4/3, 4/4, 5YR 3/3, 4/4, 4/6, 5/4 or 7.5YR 4/4. Texture is gravelly sandy clay, gravelly clay, sandy clay or clay. Clay content ranges from 45 to 55 percent. Organic matter ranges from 0 to 0.3 percent. Redoximorphic features range from iron depletions to manganese masses. Reaction ranges from 6.5 to 7.0 percent.
The 3Bq horizon, when present, dry color is 7.5YR 6/4 or 6/6. Moist color is 7.5YR 4/4, 4/6, 5/4 or 5/6. Texture is very gravelly sandy loam, sandy clay loam or sandy loam. Clay content ranges from 12 to 28 percent. Rock fragments range from 0 to 40 percent gravel. Redoximorphic features range from 0 to 20 percent soft manganese masses. Reaction ranges from slightly acid to neutral.
The 3Bqm horizon is indurated to moderately cemented with silica. A silica and manganese capping 1/16 to 3/8 inch thick may be present. Manganese coatings are found on top of the duripan. Rock fragments range from 15 to 80 percent well rounded gravel and 0 to 5 percent cobbles.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Oroville soils are in swales on intermediate terraces. Slopes range from 0 to 9 percent. These soils formed in alluvium weathered from mixed rocks such as quartz, chert, quartz-diorite, greenschist, diorite, tuff, andesite and basalt. Elevation is 110 to 258 feet, (33 to 79 m). Mean annual precipitation is 20 to 28 inches, (508 to 711 mm). The mean annual temperature is 60 to 62 degrees F, (16 to 17 degrees C). Frost free season is 250 to 255 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fernandez, Thermalito and Thompsonflat soils. Fernandez soils are very deep to weakly to moderately cemented duripan, are fine-loamy, the 2Bt horizon extends to a depth of 60 inches, (152 cm) or more and clay content does not decrease by 20 percent from the maximum at a depth of 60 inches, (152 cm). Thermalito soils are moderately deep to duripan, fine-loamy and are on mounds. Thompsonflat soils are very deep, are fine-loamy, have clay content that decreases by 20 percent from the maximum at a depth of 60 inches, (152 cm), and are on high terraces and high terrace remnants.
DRAINAGE AND PERMEABILITY: Poorly drained; high to very high runoff; moderately rapid to moderate saturated hydraulic conductivity in the A and BAt horizons, moderately slow to slow in the Bt and 2Bt horizons and is impermeable in the 3Bqm horizon. Water frequently ponds up to 3 inches, (8 cm) above the surface for long to very long duration from December through April. A fluctuating water table can occur from the top of the duripan to the surface of the soil from December through April.
USE AND VEGETATION: This soil is used for livestock grazing, wildlife habitat, home site development and in small areas, olive orchards. Vegetation is soft chess, wild oat, medusahead, foxtail barley, filaree, red brome, Italian ryegrass, pepperweed, vinegarweed, goldfields, butter-n-eggs, blue dicks, white brodiae, cowbag clover, tidytips, blow-wives, popcorn flower and some yellow starthistle and coyote thistle.
DISTRIBUTION AND EXTENT: Butte County, California and occurs in the (262Ag) Hardpan Terraces subsection of the (262A) Great Valley section. MLRA: 17 -- Sacramento Valley. The soils are not extensive. Associated with the Laguna formation.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Butte County, California 2005. Source of name from the town of Oroville.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - zone from 0 to 6 inches, (0 to 15 cm) (A, BAt)
Argillic horizon - zone from 6 to 23 inches, (15 to 58 cm) (Bt1, 2Bt2, 2Btg)
Abrupt textural change - zone from 13 to 23 inches, (33 to 58 cm) (2Bt2, 2Btg)
Duripan - zone from 23 to 60 inches, (58 to 152 cm) (3Bqm1, 3Bqm2)
Particle-size control section for this pedon: 6 to 23 inches, (15 to 58 cm)
Aquic conditions zone from 0 to 23 inches, (0 to 58 cm)
The soil moisture control section - zone from 10 to 23 inches, (25 to 58 cm) is dry in all parts from about June to October (about 180 days).
Base saturation by sum of cations is assumed to be less than 75 percent.