LOCATION HAPUNA HI

Established Series
IRD MRK-RTG
05/2012

HAPUNA SERIES

The Hapuna series consists of 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 200 millimeters (8 inches) and the mean annual temperature about 23 degrees C (73 degrees F).

TAXONOMIC CLASS: Medial-skeletal, amorphic, isohyperthermic Petrocalcic Duritorrands

TYPICAL PEDON: Hapuna extremely cobbly medial silt loam, on a west facing, slightly convex, 2 percent slope, under grasses and kiawe shrubs, at an elevation of 165 meters (540 feet). (Colors are for dry soils unless otherwise noted. All textures are apparent field textures. pH measured with meter in 1:1 water: soil. When described on March 11, 1995, 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 6 centimeters (0 to 2 inches); dark yellowish brown (10YR 4/4) extremely cobbly medial silt loam, dark brown (7.5YR 3/3) moist; weak very fine granular and subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; nonsmeary; many very fine and fine roots; many very fine interstitial and few very fine and fine tubular pores; 45 percent angular `a`a gravel, 40 percent angular `a`a cobbles and 5 percent angular `a`a stones; noneffervescent; neutral (pH 7.2); clear smooth boundary. (5 to 7 centimeters {2 to 3 inches} thick)

Bw1/2C2 -- 6 to 17 centimeters (2 to 7 inches); dark brown (7.5YR 3/4) very cobbly medial silt loam, dark brown (7.5YR 3/3) moist; weak very fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; nonsmeary; many very fine and fine, and common medium roots; common very fine to medium tubular and common very fine interstitial pores; 20 percent angular `a`a cobbles and 20 percent angular `a`a gravel; noneffervescent; slightly alkaline (pH 7.4); clear smooth boundary. (9 to 13 centimeters {4 to 5 inches} thick)

Bw2/2C3 -- 17 to 30 centimeters (7 to 12 inches); dark brown (10YR 3/3) very cobbly medial silt loam, black (10YR 2/1) moist; weak very fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; nonsmeary; many very fine and fine, and common medium roots; common very fine to medium tubular and common very fine interstitial pores; 20 percent angular `a`a cobbles and 20 percent angular `a`a gravel; noneffervescent; moderately alkaline (pH 8.0); abrupt wavy boundary. (11 to 15 centimeters (4 to 6 inches) thick)

2C4/Bkqm -- 30 to 43 centimeters (12 to 17 inches); white (10YR 8/1) very strongly cemented material, very pale brown (10YR 8/2) moist; massive; few fine roots; few fine tubular pores; at top of horizon are discontinuous 5 to 10 millimeter thick plates of slightly to strongly effervescent pale yellow (2.5Y 8/2) calcium carbonate and opaline silica; 40 percent angular `a`a gravel and 25 percent angular `a`a cobbles with thin white coatings that are strongly to violently effervescent; strongly alkaline (pH 8.5); clear wavy boundary. (13 to 25 centimeters {5 to 10 inches} thick)

2C5/Bk1 -- 43 to 65 centimeters (17 to 26 inches); brown (10YR 5/3) extremely cobbly medial sand, dark brown (7.5YR 3/3) moist, with yellowish brown (10YR 5/6) clasts, dark brown (7.5YR 3/4) moist; massive; loose, very friable, nonsticky and nonplastic; nonsmeary; few very fine roots; many fine and medium interstitial and few fine tubular pores; 40 percent angular `a`a gravel and 25 percent angular `a`a cobbles; 60 percent of coarse fragments have white (10YR 8/1) carbonate coatings, very pale brown (10YR 8/2) moist; noneffervescent in matrix and violently effervescent on coatings; strongly alkaline (pH 8.5); clear irregular boundary. (22 to 34 centimeters {9 to 13 inches} thick)

2C6/Bk2 -- 65 to 120 centimeters (26 to 47 inches); light brownish gray (10YR 6/2) extremely cobbly sand, brown (10YR 4/3) moist; with brown (10YR 5/3) clasts, dark brown (10YR 3/3) moist; massive; loose, loose, nonsticky and nonplastic; nonsmeary; few very fine and fine roots; many fine and medium interstitial pores; 35 percent angular `a`a gravel, 20 percent angular `a`a cobbles, and 5 percent angular `a`a stones; 50 percent of coarse fragments have white (10YR 8/1) carbonate coatings, very pale brown (10YR 8/2) moist; noneffervescent in matrix and violently effervescent on coatings; strongly alkaline (pH 8.6); clear wavy boundary. (20 to 55 centimeters {8 to 22 inches} thick)

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii. Upslope of Puako, in South Kohala, enter property 0.1 mile north of mile marker 72 on Queen Kaahumanu Hwy. 19; after 10 meters of paved road follow dirt road 1.65 miles upslope to junction with dirt road heading north; turn and drive north 1.0 mile; pedon is located about 50 meters upslope at an elevation of 165 meters (540 feet). Puu Hinai Quadrangle; lat. 19 degrees 57 minutes 11.5 seconds N. and long. 155 degrees 48 minutes 32.5 seconds W. Old Hawaiian Datum.

RANGE IN CHARACTERISTICS:
Depth to bedrock: 102 to 152 centimeters (40 to 60 inches).
Depth to petrocalcic/duripan horizon: 30 to 102 centimeters (12 to 40 inches).
Coarse fragments: 35 to 70 percent of the pedon.
Mean annual soil temperature: 22 to 24 degrees C (72 to 75 degrees F).

A/2C horizon
Hue: 7.5YR or 10YR.
Value: 3 or 4 moist and dry.
Chroma: 3 or 4 moist and dry.
Texture: Cobbly to extremely cobbly medial silt loam and very fine sandy loam.
Structure: weak or moderate granular or subangular blocky.
Some A horizons may be hydrophobic when dry.
Reaction: neutral to slightly alkaline (pH 6.6 to 7.8).

Bw/2C horizon
Hue: 7.5YR or 10YR.
Value: 2 or 3 moist or dry.
Chroma: 1 to 4 moist or dry.
Texture: Cobbly to extremely cobbly medial silt loam and very fine sandy loam.
Structure: weak or moderate subangular blocky.
Reaction: slightly alkaline to strongly alkaline (pH 7.4 to 8.6).

2C/Bkqm horizon
Hue: 7.5YR or 10YR.
Value: 4 to 8 moist or dry.
Chroma: 1 to 6 moist or dry.
Structure: weak subangular blocky or massive.
Reaction: moderately alkaline to strongly alkaline (pH 7.9 to 8.6).

COMPETING SERIES: There are no competing series. Similar soils include Lalamilo and Waikui series.

GEOGRAPHIC SETTING: Hapuna soils are on low elevation, leeward slopes on Mauna Kea Volcano and Kohala Mountain at elevations from sea level to 610 meters (0 to 2,000 feet). The soils are on summit positions of undulating to hilly `a`a flows that are 65,000 to 250,000 years old. Slope gradients range from 2 to 20 percent. The soils formed in basic volcanic ash in `a`a lava. The mean annual rainfall ranges from 178 to 510 millimeters (7 to 20 inches), with most of the rainfall occurring from October through April. The mean annual pan evaporation ranges from 2,286 to 2,540 meters (90 to 100 inches). The mean annual temperature ranges from 21 to 24 degrees C (70 to 75 degrees F). The mean summer soil temperature and the mean winter soil temperature differ by less than 6 degrees C (11 degrees F).

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kiholo, Lalamilo, Puako and Waikui series. Kiholo soils have a lithic contact at 5 to 50 centimeters (2 to 20 inches). Lalamilo soils are not skeletal. Puako soils are alluvial soils with coarse loamy texture in the control section. Waikui soils do not have a petrocalcic horizon.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is high to very high. Permeability is rapid in the soil and very slow in the petrocalcic horizon. Hydrophobic conditions in the surface can reduce infiltration.

USE AND VEGETATION: Used for wildlife habitat and building site development. Vegetation is buffelgrass (Cenchrus ciliaris) and Kiawe (Prosopis pallida).

DISTRIBUTION AND EXTENT: South Kohala District, Island of Hawaii; 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. Proposed 2004.

REMARKS: Soil moisture dry for more than half the year and not moist in any part for as long as 90 cumulative days in most years (aridic moisture regime).
Diagnostic horizons and features recognized in this pedon are:
Andic soil properties: 0 to 65 centimeters (0 to 26 inches) (2C1/A, Bw/2C, and 2C/Bkqm horizons).
Mollic epipedon: 0 to 30 centimeters (0 to 12 inches) (2C1/A and Bw/2C horizons)
Calcic horizon: 65 to 120 centimeters (26 to 47 inches) (2C6/Bk2 horizon).
Petrocalcic/duripan horizon: 30 to 43 centimeters (12 to 17 inches).

ADDITIONAL DATA: NSSL sample S95HI-001-003.

National Cooperative Soil Survey
U.S.A.