LOCATION HAPUU HI

Established Series
RTG-MRK
05/2012

HAPUU SERIES

The Hapuu series consists of deep, well drained soils that formed in `a`a lava and basic volcanic ash. Slopes range from 2 to 20 percent. The mean annual rainfall is about 890 millimeters (35 inches), and the mean annual temperature is about 13 degrees C (55 degrees F).

TAXONOMIC CLASS: Sandy-skeletal, isotic, isomesic Udic Ustorthents

TYPICAL PEDON: Hapuu extremely gravelly medial silt loam, on a southwest facing, slightly concave, 20 percent slope under grazed forest at an elevation of 1414 meters (4640 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures." pH measured with organic dyes. When described on July 21, 1997, the soil was slightly moist 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); black (5YR 2.5/1) extremely gravelly medial silt loam, brown (7.5YR 5/2) dry; strong fine granular structure; friable, slightly sticky and slightly plastic; many very fine and fine, and few medium roots; many very fine interstitial pores; 60 percent angular `a`a gravel and 10 percent angular `a`a cobbles; moderately acid (pH 5.9); abrupt wavy boundary. (8 to 15 centimeters {3 to 6 inches} thick)

2C2/Bw--10 to 15 centimeters (4 to 6 inches); very dusky red (2.5YR 2.5/2) extremely gravelly loamy sand, reddish brown (5YR 5/4) dry; moderate very fine granular structure; very friable, nonsticky and nonplastic; many very fine and fine, and few medium root; many very fine interstitial pores; 65 percent angular `a`a gravel and 10 percent angular `a`a cobbles; moderately acid (pH 5.7); clear irregular boundary. (3 to 8 centimeters {1 to 3 inches} thick)

2C3--15 to 36 centimeters (6 to 14 inches); very dusky red (2.5YR 2.5/2) extremely gravelly sand, brown (7.5YR 5/3) dry; single grain; loose, nonsticky and nonplastic; common very fine and fine, and few medium roots; many very fine interstitial pores; 65 percent angular `a`a gravel and 10 percent angular `a`a cobbles; moderately acid (pH 5.7); clear wavy boundary.

2C4--36 to 109 centimeters (14 to 43 inches); very dusky red (2.5YR 2.5/2) extremely gravelly sand, gray (5YR 5/1) dry; single grain; loose, nonsticky and nonplastic; common very fine and fine, and few medium roots; many very fine interstitial pores; 65 percent angular `a`a gravel and 10 percent angular `a`a cobbles; slightly acid (pH 6.4); abrupt irregular boundary.

2R--109 centimeters (43 inches); hard, massive bluerock.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; on Kealia Ranch; from Big Hill Camp road junction at about 1417 meters (4650 feet) elevation, drive north 0.75 miles; pedon is located 8 meters (25 feet) upslope of road; major fenceline that runs up-and-down slope is 69 meters (225 feet) to the north. Kaunene Quadrangle; lat. 19 degrees 24 minutes 46.5 seconds N. and 155 degrees 48 minutes 52.5 seconds W. (GPS/PLGR; Old Hawaiian Datum).

RANGE IN CHARACTERISTICS:
Depth to bedrock: 102 to 152 centimeters (40 to 60 inches).
Mean annual soil temperature: 13 to 15 degrees C (55 to 59 degrees F).
Rock fragments: 35 to 75 percent by volume of the pedon and range in size from gravel to stones, but are primarily gravel and cobble size lava rocks.

2C1/A horizon
Hue: 2.5YR to 10YR.
Value: 2 to 5 moist or dry.
Chroma: 1 or 2 moist, 1 to 4 dry.
Texture: Extremely to very gravelly or cobbly medial silt loam or loamy sand.
Structure: Weak to strong granular.
Wet consistence: Nonsticky or slightly sticky and nonplastic or slightly plastic.
Soil reaction: Moderately acid or slightly acid (pH 5.6 to 6.5).

2C2/Bw horizon
Hue: 2.5YR to 7.5YR.
Value: 2 or 3 moist, 3 to 5 dry.
Chroma: 1 or 2 moist, 1 to 4 dry.
Texture: Extremely gravelly or cobbly sandy loam or loamy sand.
Structure: Weak or moderate granular or subangular blocky.
Soil reaction: moderately acid or slightly acid (pH 5.6 to 6.5).

2C horizon
Hue: 2.5YR to 10YR.
Value: 2 or 3 moist, 3 to 5 dry
Chroma: 1 or 2 moist, 1 to 3 dry.
Soil reaction: Moderately acid or slightly acid (pH 5.6 to 6.5).

COMPETING SERIES: There are no competing series. Similar soils include the Hookena series. Hookena soils are isothermic and have an umbric epipedon.

GEOGRAPHIC SETTING: Hapuu soils are on upper elevation, leeward slopes on the uplands of Mauna Loa Volcano at elevations from 1067 to 2133 meters (3500 to 7000 feet). These soils are on all hillslope positions of constructional landscapes consisting of undulating to hilly `a`a lava flows that are 1,500 to 3,000 years old. Slope gradients range from 2 to 20 percent. The soils formed in sandy material from `a`a lava and from basic volcanic ash. The mean annual rainfall ranges from 510 to 1270 millimeters (20 to 50 inches), with most of the rainfall occurring from April through October. The mean annual pan evaporation ranges from 1020 to 1780 millimeters (40 to 70 inches). The mean annual air temperature ranges from 12 to 14 degrees C (53 to 57 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 Hokukano, Kealoha, Kekake, Manahaa, Mawae, and Puukala series. Hokukano soils are medial. Kealoha and Puukala soils are medial-skeletal. Kekake and Mawae soils are organic soils. Manahaa soils have a lithic contact at 50 to 102 centimeters (20 to 40 inches).

DRAINAGE AND PERMEABILITY: Well drained. Runoff is very low to low. Permeability is rapid.

USE AND VEGETATION: Used for grazing and wildlife habitat. The natural vegetation is kikuyugrass (Pennisetum clandestinum), ohia lehua (Metrosideros polymorpha), and brackenfern (Pteridium aquilinum).

DISTRIBUTION AND EXTENT: South Kona District, Island of Hawaii; MLRA 161B. The series is of small extent.

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

SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii 2008. Proposed in 1997.

REMARKS: Soil moisture - usually moist, but dry in some or all parts for short intermittent periods totaling 90 or more days during the months of October through April in most years (Ustic moisture regime).

Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - from 0 to 15 centimeters (0 to 6 inches) (2C1/A and 2C2/Bw horizons).
Andic properties - from 0 to 10 centimeters (0 to 4 inches) (2C1/A horizon).
Lithic contact - at 109 centimeters (43 inches) (2R horizon).

Removed okinas from name - April 2009.

National Cooperative Soil Survey
U.S.A.