LOCATION OQUIN CAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, thermic Calcic Haploxerolls
TYPICAL PEDON: Oquin fine sandy loam - on an east facing slope of 20 percent under soft chess, wild oats, red brome, burclover, tarweed, yellow star thistle and other grasses and forbs. The elevation is 400 feet. (Colors are for dry soil unless otherwise stated. When described July 7, l978, the soil was dry to 8 inches and very slightly moist below.)
A1--0 to 8 inches; grayish brown (10YR 5/2) fine sandy loam, very dark grayish brown (10YR 3/2) moist; moderate coarse subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic, many very fine roots; 14 percent clay content; few very fine tubular and common very fine interstitial pores; slightly effervescent with disseminated lime and segregated as few fine soft masses and concretions; moderately alkaline (pH 8.0); clear smooth boundary. (5 to 10 inches thick)
A2--8 to 14 inches; grayish brown (10YR 5/2) fine sandy loam very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; few very fine tubular and common very fine interstitial pores; 18 percent clay content; slightly effervescent with disseminated lime and segregated as few fine soft masses and concretions; moderately alkaline (pH 8.0); clear wavy boundary. (3 to 8 inches thick)
Ak--14 to 24 inches; grayish brown (10YR 5/2) fine sandy loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; few very fine tubular and common very fine interstitial pores; 15 percent clay content; strongly effervescent with disseminated lime and segregated as few fine soft masses and concretions; moderately alkaline (pH 8.0); clear smooth boundary. (7 to 12 inches thick)
Ck--24 to 30 inches; light brownish gray (10YR 6/2) sandy loam, darkbrown (10YR 3/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; few very fine tubular and interstitial pores; 14 percent clay content; strongly effervescent with disseminated lime and segregated as common fine soft masses and concretions; moderately alkaline (pH 8.0); abrupt wavy boundary. (5 to 10 inches thick)
Cr--31 to 37 inches; strongly weathered calcareous sandstone.
TYPE LOCATION: Merced County, California; about 6 miles west southwest of the city of Gustine, 600 feet east and 550 feet north of the SW corner of Section 21, T. 8 S., R. 8 E., Howard Ranch Quadrangle.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 59 degrees to 64 degrees F. The soil temperature is warmer than 47 degrees F from January 30 through December 1. The soil between 8 and 24 inches is moist throughout from about December 1 to May 1 and dry throughout from about July 1 to Novembert 1 in most years. Depth to the paralithic contact ranges from 20 to 40 inches. The soil is mildly alkaline or moderately alkaline throughout. Segregated lime is present in most pedons throughout the profile as soft masses, filaments, or concretions. The A horizon is 15 to 26 inches thick. Organic matter is 1 to 3 percent in the A horizon, but in pedons where the A horizon is over 20 inches thick the organic matter is less than 1 percent below 20 inches. Clay content is 12 to 18 percent throughout the profile.
The A horizon is 10YR 3/2, 3/3, 4/2, 4/3, 5/2 or 5/3. Moist colors are 10YR 2/2, 3/2 or 3/3. The upper A horizon is fine sandy loam. The lower part is fine sandy loam, sandy loam, or loam. It is slightly or strongly effervescent.
The C horizon is 10YR 4/3, 5/3, 5/4, 6/2 or 6/3. Moist colors are 10YR 3/3, 3/4, 4/3 or 4/4. It is sandy loam, fine sandy loam, or loam. It is strongly or violently effervescent.
COMPETING SERIES: These are the Apollo, Oneil, San Timoteo and Wisflat series in other families. Apollo soils are 40 to 60 inches deep and are fine-loamy. Oneil soils are fine-silty. San Timoteo and Wisflat soils do not have a mollic epipedon and in addition Wisflat soils are less than 20 inches deep.
GEOGRAPHIC SETTING: Oquin soils are on hillslopes in foothills and have slopes of 2 to 30 percent. Elevations range from 250 to 500 feet. These soils formed in material weathered from calcareous sandstones of the Panoche formation. The climate is semiarid with hot dry summers and cool moist winters. The mean annual precipitation is 10 to 12 inches. The mean January temperature is 46 degrees F; mean July temperature is 79 degrees F; mean annual temperature is 62 degrees F. Frost-free season is 210 to 280 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Oneil and Wisflat soils and the Ayar soils. Ayar soils are fine and develop wide cracks upon drying.
DRAINAGE AND PERMEABILITY: Well drained; medium and rapid runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used as rangeland and upland wildlife habitat. The vegetation is soft chess, wild oats, red brome, foxtail fescue, filaree, burclover, ripgut brome, tarweed, yellow star thistle and other grasses and forbs.
DISTRIBUTION AND EXTENT: These soils are in the Coast Range of California. They are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Merced County, California 1984. Name is coined.
REMARKS: These soils were mapped as Altamont loam in the Los Banos Area, Series 1939 report. They are being differentiated by being coarse-loamy and moderately deep. pH determined by colormetric method using Thymol Blue and Hellige-Truog Triplex indicators. Texture determined by hydrometer method. Organic matter estimated by comparing with adjacent soils determined by Walkley-Black digestion method. Presence of lime determined by 10 percent HC1.