LOCATION AUWAIAKEAKUA            HI

Established Series
RTG-MRK
05/2012

AUWAIAKEAKUA SERIES

The Auwaiakeakua series consists of moderately deep, well drained soils that formed in basic volcanic ash in `a`a lava. Slopes range from 2 to 20 percent. The mean annual rainfall is about 360 millimeters (14 inches), and the mean annual temperature is about 28 degrees C (82 degrees F).

TAXONOMIC CLASS: Clayey-skeletal, isotic, isohyperthermic Typic Haplocambids

TYPICAL PEDON: Auwaiakeakua extremely cobbly silt loam, on a west facing, 7 percent slope, in desert at an elevation of 113 meters (370 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures". pH measured with electrode in 1:1 water. When described on September 7, 1993, the soil was dry throughout.) The 2C part of these horizons consist of unconsolidated `a`a lava fragments of variable size.

2C1/A--0 to 10 centimeters (0 to 4 inches); very dark grayish brown (10YR 3/2) extremely cobbly silt loam, grayish brown (10YR 5/2) dry; weak very fine granular structure; loose, very friable, slightly sticky and slightly plastic; nonsmeary; many very fine and fine roots; 25 percent subangular `a`a gravel, 30 percent angular `a`a cobbles, and 15 percent angular `a`a stones; slightly acid (pH 6.4); clear wavy boundary. (8 to 13 centimeters {3 to 5 inches} thick)

2C2/Bw1--10 to 50 centimeters (4 to 20 inches); dark brown (7.5YR 3/2) extremely cobbly silt loam, dark yellowish brown (10YR 4/4) dry; weak very fine and fine granular structure; loose, friable, slightly sticky and slightly plastic; nonsmeary; many very fine and fine roots; 45 percent subangular `a`a gravel, 30 percent angular `a`a cobbles, and 10 percent angular`a`a stones; slightly alkaline (pH 7.4); gradual wavy boundary. (20 to 50 centimeters {8 to 20 inches} thick)

2C3/Bw2--50 to 84 centimeters (20 to 33 inches); dark brown (7.5YR 3/3) extremely cobbly silt loam, yellowish brown (10YR 5/4) dry; massive; loose, friable, slightly sticky and slightly plastic; nonsmeary; common very fine and fine roots; slightly effervescent on common patchy white coatings on cobbles; 40 percent subangular `a`a gravel, 35 percent angular `a`a cobbles, and 10 percent angular `a`a stones; neutral (pH 7.2); abrupt irregular boundary. (0 to 46 centimeters {0 to 18 inches} thick)

2R--84 centimeters (33 inches); hard `a`a blue rock.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; from Highway 19 turn east on access road opposite Waikaloa Resort, then travel south about 0.3 miles; at the power substation drive 1.8 miles east along road that follows the three parallel powerlines, then along the double powerlines; turn north at access road along `a`a flow and continue about 0.3 miles to a roadcut 2 meters (6 feet) high, near a scarp 8 meters (25 feet) high between `a`a and pahoehoe flows; soil pit is located 3 meters (10 feet) east of the roadcut. Puu Hinai Quadrangle; lat. 19 degrees 54 minutes 39 seconds N. and long. 155 degrees 51 minutes 10 seconds W.

RANGE IN CHARACTERISTICS:
Depth to bedrock: 50 to 102 centimeters (20 to 40 inches).
Mean annual soil temperature: 24 to 31 degrees C (76 to 87 degrees F).
Rock fragments: 55 to 85 percent by volume of the pedon and range in size from gravel to stones, but are primarily gravel and cobble size.

2C/A horizon
Hue: 5YR to 10YR.
Value: 2 or 3 moist, 3 to 5 dry.
Chroma: 2 or 3 moist or dry.
Texture: Extremely cobbly silt loam or loam.
Consistency: Loose or soft; very friable or friable; nonsticky or slightly sticky; and nonplastic or slightly plastic.
Soil reaction: Slightly acid or neutral (pH 6.1 to 7.3).

2C/Bw horizon
Hue: 5YR to 10YR.
Value: 2 or 3 moist, 3 to 5 dry.
Chroma: 2 or 3 moist, 2 to 4 dry.
Texture: Extremely cobbly or stony silt loam or loam.
Structure: Weak or moderate granular or subangular blocky.
Consistency: Loose or soft; very friable or friable; nonsticky or slightly sticky; and nonplastic or slightly plastic.
Soil reaction: Neutral or slightly alkaline (pH 6.6 to 7.8).

COMPETING SERIES: There are no competing series. Similar soils include the Akahipuu series. Akahipuu soils are medial-skeletal and isothermic.

GEOGRAPHIC SETTING: Auwaiakeakua soils are on west slopes on the undissected uplands of Mauna Loa and Hualalai volcanoes at elevations from sea level to 457 meters (0 to 1500 feet). These soils are on all hillslope positions of constructional landscapes consisting of rolling to hilly `a`a flows that are 5,000 to 15,000 years old. Slope gradients range from 2 to 20 percent. The soils formed in basic volcanic ash over `a`a lava. The mean annual rainfall ranges from 180 to 510 millimeters (7 to 20 inches), with most of the rainfall occurring from December through April. The mean annual pan evaporation ranges from 2030 to 2540 millimeters (80 to 100 inches). The mean annual air temperature ranges from 24 to 30 degrees C (76 to 86 degrees F). The mean summer and the mean winter soil temperatures differ by less than 6 degrees C (11 degrees F).

GEOGRAPHICALLY ASSOCIATED SOILS: These are Kiholo and Nanuku series. Kiholo soils are non-skeletal and have a lithic contact at 5 to 25 centimeters (2 to 10 inches.) Nanuku soils are sandy-skeletal.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is very low. Permeability is very rapid in the soil and very slow in the underlying bedrock.

USE AND VEGETATION: Used primarily for recreation and wildlife habitat. Natural vegetation is fountaingrass (Pennisetum setaceum) and kiawe (Prosopis pallida).

DISTRIBUTION AND EXTENT: Island of Hawaii, North Kona District; MLRA 157. The series is of small extent.

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

SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii 2012.

REMARKS: Soil moisture - dry, but moist in some or all parts for less than 90 cumulative days in most years (Aridic moisture regime).
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - from a depth of 0 to 84 centimeters (0 to 33 inches) (2C1/A, 2C2/Bw1, and 2C3/Bw2 horizons).
Lithic Contact - at a depth of 84 centimeters (33 inches) (2R horizon).

Edit Log: 11/99 Classification changed to clayey-skeletal (from loamy-skeletal) based on 2.5 x 15 bar water. RTG

ADDITIONAL DATA: Auwaiakeakua NSSL sample S94HI-001-004.

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National Cooperative Soil Survey
U.S.A.