LOCATION HILEA                   HI

Established Series
Rev. HHS/RCH/MRK/PGN
05/2012

HILEA SERIES

The Hilea series consists of very shallow and shallow, well drained soils that formed in basic volcanic ash over pahoehoe lava. Hilea soils are on uplands and have slopes of 2 to 20 percent. The mean annual rainfall is about 2,540 millimeters (100 inches) and the mean annual temperature is about 18 degrees C. (64 degrees F.)

TAXONOMIC CLASS: Hydrous, ferrihydritic, isothermic Lithic Hydrudands

TYPICAL PEDON: Hilea hydrous silty clay loam on a east facing, 4 percent slope, under forest, at an elevation of 640 meters (2120 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures.")

Oa -- 0 to 1 centimeters (0 to 0.5 inches); highly decomposed plant materials; abrupt smooth boundary.

A -- 1 to 20 centimeters (0.5 to 8 inches); very dark grayish brown (10YR 3/2) hydrous silty clay loam; strong medium and fine subangular blocky structure; friable, slightly sticky, moderately plastic; strongly smeary; many roots; many medium and fine pores; 10 percent cobbles; very strongly acid (pH 4.8); abrupt smooth boundary. (15 to 20 centimeters {6 to 8 inches} thick)

Bw -- 20 to 48 centimeters (8 to 19 inches); dark brown (7.5YR 3/3) hydrous silty clay loam; moderate medium and fine subangular blocky structure; friable, moderately sticky, moderately plastic; strongly smeary; many roots; many very fine and fine pores; thick gelatin-like coatings on surface of peds; strongly acid (pH 5.4); abrupt wavy boundary. (25 to 31 centimeters {10 to 12 inches} thick)

2R -- 48 centimeters (19 inches); hard, massive pahoehoe lava.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; from the village of Naalehu at highway 11 follow Kaalaiki road 2 miles northeast, upslope, past old airstrip. At 2 miles turn left (northwest) and proceed upslope approximately 2.2 miles. Turn right (northeast) and proceed 0.4 miles and park. Hike due north to type location at an elevation of 640 meters (2120 feet) Naalehu Quadrangle; lat. 19 degrees 5 minutes 47.1 seconds N. and long. 155 degrees 35 minutes 53.6 seconds W, Old Hawaiian datum.

RANGE IN CHARACTERISTICS:
Depth to bedrock: 5 to 50 centimeters (2 to 20 inches).
Mean annual soil temperature: 16 to 22 degrees C. (61 to 72 degrees F.)
Rock fragments: 5 to 25 percent by volume of the pedon and range from gravel to cobble size lava rocks.

A horizon
Hue: 5YR to 10YR
Texture: Hydrous silt loam or silty clay loam.
Structure: Moderate to strong granular or subangular blocky.
Stickiness: Slightly sticky to moderately sticky.
Plasticity: Slightly plastic to moderately plastic.
Smeariness: Weakly smeary to strongly smeary.
Rupture resistance: Very friable to firm.

Bw horizon
Hue: 5YR to 10YR.
Value: 2 or 3 moist.
Chroma: 2 or 3 moist.
Texture: Cobbly or noncobbly hydrous silty clay loam.
Smeariness: Moderately smeary to strongly smeary.
Rupture resistance: Friable to firm.

COMPETING SERIES: This is the Kopua series. Kopua soils have a perudic soil moisture regime.

GEOGRAPHIC SETTING: Hilea soils are on mid elevation, windward slopes on the upland of Mauna Loa and Kilauea volcanoes at elevations from 366 to 1,220 meters (1200 to 4000 feet). The soils are on all hill slope positions of constructional landscapes consisting of nearly level to gently sloping pahoehoe lava flows that are about 3,000 to 10,000 years old. Slope gradients range from 0 to 20 percent. The soils formed in basic volcanic ash over pahoehoe lava. The mean annual rainfall ranges from 1,524 to 3048 millimeters (60 to 120 inches), with most of the rainfall occurring from October through April. The mean annual pan evaporation ranges from 640 to 1,270 meters (25 to 50 inches). The mean annual temperature ranges from 15 to 20 degrees C. (59 to 68 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 Akihi, Alapai, and Honuapo soils. Akihi soils are skeletal and over aa lava. Alapai soils are more than 152 centimeters (60 inches) deep. Honuapo soils are 51 to 102 centimeters (20 to 40 inches).

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

USE AND VEGETATION: Used mostly as forest reserve, wildlife habitat, and pasture. The natural vegetation is ohia lehua (Metrosideros polymorpha), hapuu treefern (Cibotium glauca), Hamakua pamakani (Ageratina riparia), and glenwoodgrass (Sacciolepis indica).

DISTRIBUTION AND EXTENT: Ka`u district, Island of Hawaii; MLRA 159B. The series is of small extent.

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

SERIES ESTABLISHED: Island of Hawaii, Hawaii, 1971.

REMARKS:
Soil moisture: Udic moisture regime - moist and not dry in any part for as long as 90 cumulative days in most years.
Diagnostic horizons and features recognized in this pedon are:
Andic properties - 1 to 48 centimeters (0.5 to 19 inches) (A and Bw horizons).
Lithic contact - 48 centimeters (19 inches) (2R horizon).
Umbric epipedon - 1 to 48 centimeters (0.5 to 19 inches) (A and Bw horizons).
Sapric soil materials - 0 to 1 centimeters (0 to 0.5 inches) (Oa horizon).

ADDITIONAL DATA: NASIS User Pedon ID 00HI602004.

Edit log: 11/17/00 Classification revised due to changes in Soil Taxonomy. Old classification: Thixotropic, isothermic Lithic Hydrandepts. Mean annual rainfall changed to 1,524 to 3,810 millimeters (60 to 150 inches).
5/2011 Type location changed from location near Mountain View, Hawaii to location near Naalehu to reflect series concept. MRK

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National Cooperative Soil Survey
U.S.A.