LOCATION HONUAPO                 HI

Established Series
Rev. MRK
05/2012

HONUAPO SERIES

The Honuapo series consists of moderately deep, well drained soils that formed in basic volcanic ash over pahoehoe lava. Slopes range from 0 to 20 percent. The mean annual rainfall is about 2540 millimeters (100 inches) and the mean annual temperature about 18 degrees C. (64 degrees F.)

TAXONOMIC CLASS: Hydrous, ferrihydritic, isothermic Typic Hydrudands

TYPICAL PEDON: Honuapo hydrous silt loam, on a southeast facing, slightly concave, 1 percent slope, under pasture, at an elevation of 617 meters (2,025 feet). (Colors are for moist soils unless otherwise noted. All textures are apparent field textures. pH measured with organic dyes. When described on February 14, 2001, the soil was very moist throughout.)

Ap -- 0 to 48 centimeters (0 to 19 inches); 90 percent very dark brown (10YR2/2) and 10 percent dark brown (7.5YR3/4) hydrous silt loam; strong very fine and fine granular structure; very friable, slightly sticky, slightly plastic; weakly smeary; common very fine, fine, and medium roots; many very fine and fine vesicular and interstitial pores; very strongly acid (pH 4.8); abrupt wavy boundary. (31 to 51 centimeters {12 to 20 inches} thick)

Bw1 -- 48 to 66 centimeters (19 to 26 inches); dark brown (7.5YR 3/4) hydrous silty clay loam; moderate fine and medium subangular blocky structure; very friable, moderately sticky, moderately plastic; moderately smeary; few very fine and fine roots; common very fine and fine irregular pores; 5 percent dark reddish brown (5YR 3/3) paragravel; strongly acid (pH 5.2); clear smooth boundary. . (15 to 20 centimeters {6 to 8 inches} thick)

Bw2 -- 66 to 76 centimeters (26 to 30 inches); very dark brown (7.5YR 2.5/3) very paragravelly hydrous silty clay loam; strong fine and medium subangular blocky structure; friable, moderately sticky, moderately plastic; moderately smeary; few very fine and fine roots; common very fine and fine irregular pores; 50 percent dark reddish brown (5YR 3/3) paragravel; strongly acid (pH 5.4); clear smooth boundary. (8 to 10 centimeters {3 to 4 inches} thick)

Bw3 -- 76 to 99 centimeters (30 to 39 inches); dark brown (7.5YR 3/4) hydrous silty clay loam; moderate fine and medium subangular blocky structure; friable, moderately sticky, moderately plastic; moderately smeary; common very fine and fine irregular pores; 5 percent dark reddish brown (5YR 3/3) paragravel; strongly acid (pH 5.4); abrupt wavy boundary. (20 to 25 centimeters {8 to 10 inches} thick)

2R -- 99 centimeters (39 inches); hard, massive pahoehoe lava.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; from Naalehu town, drive 1.9 miles north on Kaalaiki Road, turn west at intersection and drive upslope 2.1 miles to elevation 640 meters (2100 feet), turn northeast and drive 1.6 miles. Pedon is located 6 meters (20 feet) north of road at an elevation of 617 meters (2,025 feet). Naalehu Quadrangle; lat. 19 degrees 6 minutes 0.2 seconds N. and long. 155 degrees 35 minutes 31.7 seconds W. (GPS/PLGR 30 feet. Old Hawaiian Datum)

RANGE IN CHARACTERISTICS:
Depth to bedrock: 50 to 102 centimeters (20 to 40 inches).
Mean annual soil temperature: 16 to 22 degrees C. (60 to 71 degrees F.)
Rock fragments: 5 to 30 percent by volume of the pedon and are paragravel, gravel and cobble size lava rocks.
Soil reaction: Very strongly acid to strongly acid.

Ap horizon
Hue: 7.5YR or 10YR.
Chroma: 1or 2 moist.
Texture: Hydrous silt loam, loam or silty clay loam. Some pedons have a cobbly surface.
Structure: Moderate to strong granular.
Smeariness: Weakly or moderately smeary.
Rupture resistance: Very friable or friable.
Stickiness: Slightly sticky or moderately sticky.
Plasticity: Non-plastic or slightly plastic.

Bw horizon
Hue: 2.5YR to 7.5YR.
Value: 2 to 3 moist.
Chroma: 4 to 6 moist.
Texture: Cobbly or very paragravelly hydrous silty clay loam or hydrous silty clay loam.
Structure: Moderate to strong subangular blocky.
Smeariness: Weakly or moderately smeary.
Rupture resistance: Very friable or friable.
Stickiness: Slightly sticky or moderately sticky.
Plasticity: Slightly plastic or moderately plastic.

COMPETING SERIES: These are the Alapai, Honaunau, Kailua, Kealakekua, Kukaiau, and Makaala series. Alapai soils have a perudic soil moisture regime and are greater than 102 centimeters (40 inches) deep. Honaunau and Kealakekua soils are moist in the control section from April to October. Kailua soils have strong subangular blocky structure and are silty clay in the control section. Kukaiau soils have a lithic contact at greater than 102 centimeters (40 inches). Makaala soils have a perudic soil moisture regime.

GEOGRAPHIC SETTING: Honuapo soils are on south and east mid elevation mountain slopes on the slightly dissected upland of Mauna Loa Volcano at elevations from 366 to 1,220 meters (1200 to 4000 feet). The soils are on all hillslope 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 3,810 millimeters (60 to 150 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 competing Alapai series, and the Akihi, Hilea and Moaula series. Akihi soils are hydrous-skeletal. Hilea soils have a lithic contact at less than 50 centimeters (20 inches). Moaula soils are greater than 102 centimeters (40 inches) deep.

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

USE AND VEGETATION: Used for agroforestry, forest land, wildlife habitat, and livestock grazing. The natural vegetation is kikuyugrass (Pennisetum clandestinum), broomsedge (Andropogon virgincus), sedges, Hilograss (Paspalum conjugatum), and hairy horseweed (Conyza bonariensis).

DISTRIBUTION AND EXTENT: Kau 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 County, Hawaii, 2012. Proposed 2000.

REMARKS: Soil moisture moist and not dry in any part for as long as 90 cumulative days in most years (Udic moisture regime).
Diagnostic horizons and features recognized in this pedon are:
Andic soil properties 0 to 99 centimeters (0 to 39 inches) (Ap and Bw horizons).
Lithic contact 99 centimeters (39 inches).
Umbric epipedon 0 to 48 centimeters (0 to 19 inches) (Ap horizon).
Cambic horizon 48 to 99 centimeters (19 to 39 inches) (Bw horizons).

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National Cooperative Soil Survey
U.S.A.