LOCATION ARBURUA            CA
Established Series
Rev. MAV/CAF
12/2002

ARBURUA SERIES


The Arburua series consists of moderately deep, well drained soils on foothills, hills and mountains. These soils formed in material weathered from sandstone and shale. Slope is 2 to 75 percent. The mean annual precipitation is about 11 inches and the mean annual temperature is about 62 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, thermic Typic Xerorthents

TYPICAL PEDON: Arburua loam - on a slightly convex, north northeast facing slope of 29 percent under soft chess, wild oats, red brome and other annual grasses and forbs at 840 feet elevation. (Colors are for dry soil unless otherwise stated. When described on May 2, 1978, the soil was slightly moist throughout).

A1--0 to 4 inches; brown (10YR 5/3) loam, brown (10YR 4/3) moist; moderate coarse subangular blocky structure; soft, friable, moderately sticky and moderately plastic; many very fine roots; few very fine, fine and medium tubular pores; violently effervescent, carbonates disseminated and segregated as few fine soft masses; moderately alkaline (pH 8.0); clear smooth boundary. (2 to 5 inches thick)

A2--4 to 10 inches; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, moderately sticky and moderately plastic; common very fine roots; common very fine, fine and medium tubular pores; violently effervescent, carbonates disseminated and segregated as few fine soft masses; moderately alkaline (pH 8.0); gradual smooth boundary. (4 to 12 inches thick)

Bk1--10 to 17 inches; pale brown (10YR 6/3) loam, dark yellowish brown (10YR 4/4) moist; massive; soft, very friable, moderately sticky and moderately plastic; common very fine roots; few very fine, fine and medium tubular pores; violently effervescent, carbonates disseminated and segregated as few fine soft masses; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 10 inches thick)

Bk2--17 to 27 inches; brown (10YR 5/3) loam, dark yellowish brown (10YR 4/4) moist; massive; soft, very friable, moderately sticky and moderately plastic; few very fine roots; few very fine and fine tubular pores; violently effervescent, carbonates disseminated and segregated as few fine and medium soft masses; moderately alkaline (pH 8.0); abrupt irregular boundary. (6 to 14 inches thick)

Cr--27 to 32 inches; strongly weathered calcareous shale. (1 to 6 inches thick)

R--32 to 33 inches; hard, massive, nonfractured calcareous shale.

TYPE LOCATION: Merced County, California; approximately 11 miles south southwest of the city of Los Banos and 900 feet south southwest of the intersection of Arburua and San Carlos Roads; 1,400 feet north and 300 feet east of the southwest corner of section 2, T. 12 S., R. 9 E., MDB&M; Latitude 36 degrees, 54 minutes, 52 seconds north and Longitude 120 degrees, 57 minutes, 43 seconds west; USGS Ortigalita Peak NW Topographic Quadrangle, NAD 27.

RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 20 to 40 inches. Depth to a lithic contact is 24 to 41 inches. The mean annual soil temperature is 59 to 65 degrees F. and is more than 47 degrees F from February 15 to December 15. The moisture control section of 6 to 18 inches is moist throughout from about December 1 to May 1 and dry throughout from about July 1 to October 31 of each year, about 120 days. Accelerated erosion has resulted in the loss of 25 to 75 percent of the original surface in some pedons.

The A horizon has color of 10YR 4/2, 5/2, 5/3, 5/4, 6/3, 6/4, 7/3; 2.5Y 5/2, 5/3, 6/2 or 6/4. Moist color is 10YR 4/2, 4/3, 4/4, 5/4; 2.5Y 4/2, 4/4 or 5/4. Organic matter content is less than 1 percent. Texture is loam or clay loam. Clay percent is 18 to 30 percent. It is strongly or violently effervescent. Some pedons do not have soft masses of carbonates. Calcium carbonate equivalent is 1 to 5 percent. Gravel content is 0 to 10 percent. Reaction is neutral to moderately alkaline.

The Bk horizon has color of 7.5YR 5/4; 10YR 5/2, 5/3, 6/2, 6/3, 7/2, 7/4; 2.5Y 6/2, 6/4 or 7/4. Moist color is 10YR 4/2, 4/3, 4/4, 5/2, 5/3, 5/4; 2.5Y 4/2, 4/4, 5/4, 6/2or 6/4. Texture is loam or clay loam. Clay content is 18 to 30 percent. Soft masses of carbonates are few or common. Calcium carbonate equivalent is 2 to 5 percent. Gravel content is 0 to 15 percent. Cobble content is 0 to 5 percent.

COMPETING SERIES: These are the Kilmer (CA), and Mendi (CA) series. Kilmer soils (MLRA 15), on foothills and mountains, have a xeric moisture regime bordering on aridic and have a lithic contact at a depth of 20 to 40 inches. Mendi soils (MLRA 15), on hills, have a paralithic contact at a depth ofmore than 60 inches.

GEOGRAPHIC SETTING: Arburua soils are on the mountain side slopes, ridge tops and escarpments of foothills, hills and mountains. Slope is 2 to 75 percent. Soils with slopes of 2 to 15 percent are commonly on strath terraces. The underlying sandstone or shale of the Moreno and Panoche Formation is soft and fractured for 1 to 6 inches becoming extremely hard with increasing depth. The fractures are up to 1.5 inches wide and filled with soil and root material. The rock is too hard to dig with hand tools within 40 inches of the surface. Elevation is 200 to 3,670 feet. The climate is dry, mesothermal with hot dry summers and cool moist winters. The mean annual precipitation is 9 to 15 inches. Mean January temperature is 44 degrees F; mean July temperature is 73 degrees F; mean annual temperature is 59 to 64 degrees F. Frost-free season is 190 to 280 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Apollo, Ayar, Bapos, Conosta, Los Banos, Oneil, San Timoteo and Wisflat soils. Apollo soils, on low foothills, have a mollic epipedon and a paralithic contact at a depth of 40 to 60 inches. Ayar soils, on foothills, have a fine particle-size control section and have wide deep cracks when dry. Bapos soils, on terraces and fan remnants, are very deep and have a fine particle-size control section. Conosta soils, on foothills, have an argillic horizon and a fine particle-size control section. Los Banos soils, on terraces and fan remnants, have an argillic horizon and a fine particle-size control section. Oneil soils, on foothills, have a mollic epipedon and a fine-silty particle-size control section. San Timoteo soils, on low foothills, have a coarse-loamy particle-size control section. Wisflat soils, on foothills, hills and mountains, have a lithic contact at a depth of 10 to 20 inches.

DRAINAGE AND PERMEABILITY: Well drained; low to high runoff; moderate permeability.

USE AND VEGETATION: These soils are used mostly for livestock grazing of sheep and cattle. Vegetation is soft chess, wild oats, red brome, filaree, tarweed and other annual grasses and forbs.

DISTRIBUTION AND EXTENT: Eastern edge of the Diablo Range in the California Coast Ranges bordering the western edge of the Central San Joaquin Valley of California. They are moderately extensive. MLRA-15.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Merced County, California, 1980.

REMARKS: These soils were formerly mapped as Kettleman soils but are being differentiated by having a xeric rather than an aridic moisture regime.
CEC/Clay ratio estimated from similar soils with laboratory data in the W. Stanislaus Soil Survey Area.


National Cooperative Soil Survey
U.S.A.