LOCATION HOOKENA HI

Established Series
RTG-MRK
05/2012

HOOKENA SERIES

The Hookena 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 1650 millimeters (65 inches), and the mean annual air temperature is about 19 degrees C (66 degrees F).

TAXONOMIC CLASS: Sandy-skeletal, isotic, isothermic Eutric Fulvudands

TYPICAL PEDON: Hookena very cobbly medial silt loam, on a southwest facing, slightly convex, 20 percent slope under forest at an elevation of 573 meters (1880 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures." pH measured with organic dyes. When described on July 17, 1997, the soil was slightly moist throughout.) The 2C part of these horizons consist of unconsolidated `a`a lava fragments of variable size.

A1/2C1--0 to 13 centimeters (0 to 5 inches); black (5YR 2.5/1) very cobbly medial silt loam; strong very fine and fine granular structure; friable, slightly sticky and slightly plastic; many very fine and fine, common medium, and few coarse roots; many very fine interstitial pores; 20 percent angular `a`a cobbles and 15 percent angular `a`a gravel; moderately acid (pH 5.6); abrupt smooth boundary.

A2/2C2--13 to 31 centimeters (5 to 12 inches); black (7.5YR 2.5/1) very gravelly medial silt loam; strong very fine and fine granular; friable, slightly sticky and slightly plastic; common very fine and fine, few medium, and very few coarse roots; many very fine interstitial pores; 20 percent angular `a`a gravel and 15 percent angular `a`a cobbles; moderately acid (pH 5.6); abrupt wavy boundary. (Combined thickness of the A horizon ranges from 25 to 36 centimeters {10 to 14 inches}.)

2C3/Bw--31 to 43 centimeters (12 to 17 inches); black (7.5YR 2.5/1) extremely gravelly medial sandy loam; appears massive, but parts to weak very fine and fine subangular blocky structure; loose, nonsticky and nonplastic; common very fine and fine, and few medium roots; many very fine interstitial pores; 50 percent angular `a`a gravel and 15 percent angular `a`a cobbles; moderately acid (pH 5.8); clear wavy boundary. (10 to 15 centimeters {4 to 6 inches} thick)

2C4--43 to 76 centimeters (17 to 30 inches); dark reddish brown (5YR 2/2) extremely gravelly sand; massive; loose, nonsticky and nonplastic; few very fine, fine, and medium roots; many very fine interstitial pores; 55 percent angular `a`a gravel and 20 percent angular `a`a cobbles; moderately acid (pH 6.0); clear wavy boundary.

2C5--76 to 152 centimeters (30 to 60 inches); very dusky red (2.5YR 2.5/2) extremely gravelly sand; massive; loose, nonsticky and nonplastic; few very fine, fine, and medium roots; many very fine interstitial pores; 55 percent angular `a`a gravel and 15 percent angular `a`a cobbles; slightly acid (pH 6.2).

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; on Kaimalino Ranch, turn north on ranch road that approximately follows the 549 meters (1,800 feet) elevation contour; drive north to main upslope/downslope ranch road and follow road upslope about 91 meters (300 feet) to fork in the road; walk 9 meters (30 feet) downslope and then 6 meters (20 feet) to a north facing roadcut; the pedon is located 5 meters (17 feet) at 145 degrees magnetic at about 573 meters (1,880 feet) elevation in the forest. Kaunene Quadrangle; lat. 19 degrees 23 minutes 42.8 seconds N. and long. 155 degrees 51 minutes 53.4 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: 17 to 22 degrees C (63 to 71 degrees F).
Rock fragments: 35 to 70 percent by volume of the pedon and range in size from gravel to stones, but are primarily gravel and cobble size lava rocks.

A/2C horizon
Hue: 5YR to 10YR.
Value: 2 or 3 moist or dry.
Chroma: 1 or 2 moist or dry.
Texture: Very cobbly or very gravelly medial silt loam.
Structure: Moderate or strong granular or subangular blocky.
Soil reaction: strongly acid or moderately acid (pH 5.1 to 6.0).

2C/Bw horizon
Hue: 5YR or 7.5YR.
Value: 2 or 3 moist, 2 to 4 dry.
Chroma: 2 to 4 moist or dry.
Texture: Very or extremely gravelly medial sandy loam or loam.
Structure: Massive, single grain or weak subangular blocky.
Soil reaction: strongly acid or moderately acid (pH 5.1 to 6.0).

2C horizon
Hue: 2.5YR or 5YR.
Value: 2 or 3 moist or dry.
Chroma: 2 or 3 moist or dry.
Texture: Extremely gravelly or very gravelly loamy sand or sand.
Structure: Massive or single grain.
Soil reaction: Moderately acid or slightly acid (pH 5.6 to 6.5).

COMPETING SERIES: There are no competing series. Similar soils include the Hapuu series. Hapuu soils are isomesic.

GEOGRAPHIC SETTING: Hookena soils are on mid elvation, leeward slopes of Mauna Loa Volcano at elevations from 305 to 1067 meters (1000 to 3500 feet). These soils are on all hillslope positions of constructional landscapes consisting of undulating to hilly `a`a 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 1270 to 2030 millimeters (50 to 80 inches), with most of the rainfall occurring from April through October. The mean annual pan evaporation ranges from 640 to 1020 millimeters (25 to 40 inches). The mean annual air temperature ranges from 16 to 22 degrees C (61 to 71 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 Honaunau, Honuaulu, Hua, Kealakekua, Kona, Napoopoo, and Puna series. Honaunau, Hua, and Kealakekua soils are hydrous. Honuaulu and Napoopoo soils are hydrous-skeletal. Kona soils are organic over pahoehoe lava. Puna soils are organic soils over `a`a lava.

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

USE AND VEGETATION: Used primarily for grazing and to a lesser extent orchard crops. The natural vegetation is christmasberry (Schinus terebinthifolius), ohia lehua (Metrosideros polymorpha), ginger (Zingiber), 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 2012. Proposed 1996.

REMARKS: Soil moisture - moist and not dry in any part for as long as 90 cumulative days (Udic moisture regime).
Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon - from 0 to 31 centimeters (0 to 12 inches) (A1/2C1 and A2/2C2 horizons).
Cambic horizon - from 31 to 43 centimeters (12 to 17 inches) (2C3/Bw horizon).
Andic properties - from 0 to 43 centimeters (0 to 17 inches) (A1/2C1, A2/2C2, and 2C3/Bw horizons).

ADDITIONAL DATA: Hookena NSSL sample S97HI-001-010.

National Cooperative Soil Survey
U.S.A.