LOCATION MAUNAIU HI

Tentative Series
Rev. KH, RTG
04/2011

MAUNAIU SERIES

The Maunaiu series consists of very shallow and shallow, well drained soils that formed in volcanic ash over pahoehoe lava. Slopes range from 2 to 10 percent. The mean annual rainfall is about 1,296 millimeters (51 inches), and the mean annual air temperature is about 13 degrees C. (55 degrees F.).

TAXONOMIC CLASS: Medial, amorphic, isomesic Eutric Lithic Fulvudands

TYPICAL PEDON: Maunaiu medial silt loam, 4 percent slope under koa trees and grasses at an elevation of 1,460 meters (4,800 feet). (Colors are for moist soil unless otherwise noted. When described on 6/30/98 the soil was dry throughout. The soil temperature was 16 degrees C. (61 degrees F.) at a depth of 50 centimeters (20 inches). All textures are "apparent field textures". pH was measured using organic dyes.)

A1--0 to 5 centimeters (0 to 2 inches); black (10YR 2/1) medial silt loam, very dark brown (10YR 2/2) dry; strong fine and medium granular structure; slightly hard, friable, nonsticky and nonplastic, weakly smeary; many very fine and fine roots; many very fine and fine interstitial and tubular pores; strongly acid (pH 5.4); abrupt wavy boundary.

A2--5 to 15 centimeters (2 to 6 inches); black (10YR 2/1) medial silt loam, very dark brown (10YR 2/2) dry; weak medium subangular blocky structure parting to moderate fine and medium granular; slightly hard, friable, nonsticky and nonplastic, weakly smeary; many very fine, fine and few coarse roots; many very fine and fine interstitial pores; moderately acid (pH 5.7); clear wavy boundary. (Combined thickness of A horizons 5 to 20 centimeters (2 to 8 inches))

Bw1--15 to 24 centimeters (6 to 10 inches); black (7.5YR 2.5/1) medial silt loam, dark brown (7.5YR 3/3) dry; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, and medium roots; many very fine and fine interstitial pores; slightly acid (pH 6.2); clear wavy boundary.

Bw2--24 to 36 centimeters (10 to 14 inches); black (7.5YR 2.5/1) medial silt loam, strong brown (7.5YR 4/6) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine, fine, and medium roots; many very fine and fine interstitial pores; slightly acid (pH 6.2); clear wavy boundary.

Bw3--36 to 48 centimeters (14 to 19 inches); very dark brown (7.5YR 2.5/2) medial silt loam, dark yellowish brown (10YR 4/6) dry; massive; soft, very friable, nonsticky and nonplastic; common very fine and fine and few medium roots; many very fine and fine interstitial pores; moderately acid (pH 6.0); abrupt wavy boundary. (Combined thickness of Bw horizons is 13 to 38 centimeters (5 to 15 inches)).

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

TYPE LOCATION: Hawaii Volcanoes National Park; from State Hwy 11 turn north onto Mauna Loa Strip Road; travel 5.6 miles and park on north (right) side of road; walk a heading of 32 degrees magnetic 13 meters (45 feet) to type location; Kilauea Crater Quadrangle; lat. 19 degrees 27 minutes 36.65 seconds N. and long. 155 degrees 20 minutes 28.95 seconds W. (Old Hawaiian Datum measured by GPS/PLGR, 350 feet).

RANGE IN CHARACTERISTICS:
Depth to Bedrock: 5 to 50 centimeters (2 to 20 inches).
Mean annual soil temperature: 12 to 15 degrees C. (54 to 59 degrees F.).
Rock fragments: 0 to 15 percent.
Soil reaction: Strongly acid or moderately acid.

A horizon
Hue: 7.5YR or 10YR.
Texture: Medial loam or medial silt loam.
Structure: Granular or subangular blocky.
Rock fragments: 0 to 5 percent.
Smeariness: Nonsmeary or weakly smeary.

B horizon
Hue: 5YR to 10YR.
Value: 2 or 3 moist.
Chroma: 1 to 4 moist.
Texture: Medial sandy loam, medial loam, or medial silt loam.
Structure: Subangular blocky or massive.
Accretionary lapili: Occur in few pedons at lower elevations.
Plate-like fragments: 0 to 40 percent in the upper 5 centimeters (2 inches) occur in few pedons at lower elevations.
Rock fragments: 0 to 15 percent.

C horizon (when present)
Occurs in few pedons.
Hue: 7.5YR, 10YR, or N.
Value: 2 or 3 moist.
Chroma: 2 or 3 moist.
Texture: Ashy coarse sand to medial loam.

COMPETING SERIES: There are no competing series. The Kaholimo and Menehune series are similar. Kaholimo soils have a buried A horizon, have alternating bands of black and very dark brown loam in the Bw horizon, and typically do not have 7.5YR hues. Menehune soils do not have Bw horizons.

GEOGRAPHIC SETTING: Maunaiu soils are on Mauna Loa pahoehoe flows 3,000 to 5,000 years old at elevations of 1,341 to 1,700 meters (4,400 to 5,600 feet). Slopes range from 2 to 10 percent. The mean annual rainfall is 1,270 to 1,524 millimeters (50 to 60 inches), with about 75 percent of the rainfall occurring between October and April. The mean annual pan evaporation is 1,270 to 1,524 millimeters (50 to 60 inches). The mean annual air temperature is 12 to 15 degrees C. (54 to 59 degrees F.).

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ha`a, Ke`amoku, Pu`iwa, and the similar Kaholimo soils. These soils are deeper than 50 centimeters (20 inches) to bedrock.

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

USE AND VEGETATION: These soils are used for National Park Service land and pasture. Vegetation is `a`ali`i (Dodonaea viscosa), brackenfern (Pteridium aquilinum var. decompositum), koa (Acacia koa), pukiawe (Styphelia tameiameiae), and various grasses.

DISTRIBUTION AND EXTENT: These soils occur within Hawaii Volcanoes National Park and neighboring ranches; MLRA 160. The series is of small extent.

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

SERIES PROPOSED: Island of Hawaii, Hawaii County, Hawaii, 1998. The name is from Kipuka Mauna`iu.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Andic soil properties - from the soil surface to 48 centimeters (19 inches).
Umbric epipedon - from the soil surface to 48 centimeters (19 inches).
Soil temperature - mean summer and mean winter soil temperatures differ by less than 6 degrees C. (iso temperature regime).
Soil moisture - not dry in some or all parts for 90 days or more in most years (udic moisture regime).

Edit Log: 12/03 KH. Added "medial" modifier to textures. Added "very shallow" in lead paragraph.

11/2009:Removed diacritical marks from name.

National Cooperative Soil Survey
U.S.A.