LOCATION OHIANUI                 HI

Tentative Series
RTG/MRK/KP
02/2012

OHIANUI SERIES

The Ohianui series consists of moderately deep, well drained soils that formed in basic volcanic ash and cinders over lava. Slopes range from 2 to 20 percent. The mean annual rainfall is about 580 millimeters (23 inches), and the mean annual temperature is about 11 degrees C. (51 degrees F.)

TAXONOMIC CLASS: Ashy over pumiceous or cindery, mixed, isomesic Typic Ustivitrands

TYPICAL PEDON: Ohianui extremely gravelly ashy loamy sand, on a south facing, 13 percent slope, under shrubs at an elevation of 1917 meters (6290 feet). (Colors are for dry soil unless otherwise noted. All textures are "apparent field textures". When described on October 13, 1998 the soil was dry throughout.)

A1--0 to 8 millimeters (0 to 3 inches); very dark brown (10YR 2/2) very gravelly ashy loamy sand, black (10YR 2/1) moist; weak very fine granular structure; soft, very friable, nonsmeary, nonsticky and nonplastic; many very fine and fine roots; many very fine irregular pores; 50 percent gravel-size cinders; surface covered by 95 percent gravel-size cinders; hydrophobic when dry; neutral (pH 6.7); abrupt smooth boundary. (5 to 10 centimeters {2 to 4 inches} thick)

A2--8 to 20 centimeters (3 to 8 inches); dark yellowish brown (10YR 3/4) extremely gravelly ashy loamy sand; very dark brown (10YR 2/2) moist; single grain; loose when dry or moist, nonsmeary, nonsticky and nonplastic; many very fine, common fine, and few medium roots; many very fine interstitial pores; 70 percent gravel-size cinders; neutral (pH 6.8); abrupt wavy boundary. (10 to 15 centimeters {4 to 6 inches} thick)

2C1--20 to 46 centimeters (8 to 18 inches); black (N 2.5/) and dark gray (5YR 4/1) gravels; few very fine and fine roots; many fine and medium interstitial pores; 95 percent gravel from cinders; abrupt wavy boundary. (23 to 28 centimeters {9 to 11 inches} thick)

2C2--46 to 61 centimeters (18 to 24 inches); dark reddish brown (5YR 3/2) gravels; few very fine roots; many fine and medium interstitial pores; 60 percent gravel from cinders, 35 percent cobbles; abrupt wavy boundary. (13 to 18 centimeters {5 to 7 inches} thick)

3R--61 centimeters (24 inches); hard pahoehoe bedrock.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; from Puu o Mawae, drive north for 1.3 miles; pedon is located 15 meters (50 feet) east of 4WD road. Hualalai quadrangle; lat. 19 degrees 39 minutes 41.1 seconds and long. 155 degrees 49 minutes 41.8 seconds. (Old Hawaiian Datum)

RANGE IN CHARACTERISTICS:
Depth to bedrock: 50 to 102 centimeters (20 to 40 inches).
Mean annual soil temperature: 9 to 13 degrees C. (49 to 56 degrees F.)
Rock fragments: 40 to 95 percent gravel-size cinders on the surface.
Soil reaction: Neutral (pH 6.6 to 7.3).

A1 horizon
Hue: 7.5YR or 10YR.
Value: 2 or 3 moist or dry.
Chroma: 1 or 2 moist or dry.
Texture: Very or extremely gravelly ashy loamy sand or sandy loam.
Structure: Weak to strong granular or subangular blocky.

A2 horizon
Hue: 5YR to 10YR.
Value: 2 or 3 moist or dry.
Chroma: 1 or 2 moist or dry.
Texture: Extremely gravelly ashy loamy sand or sandy loam.

COMPETING SERIES: There are no competing series. Similar soils include Huikau and Nawahine series. Huikau soils have a mollic epipedon and have lithic contact at 102 to 152 centimeters (40 to 60 inches). Nawahine soils are medial over cindery and are deeper than 152 centimeters (60 inches).

GEOGRAPHIC SETTING: The Ohianui soils are on nearly level to moderately steep lava flows on high mountain slopes of Hualalai Volcano at elevations from 1615 to 2438 meters (5300 to 8000 feet). Slope gradients range from 2 to 20 percent. The soils formed in basic volcanic ash and cinders over lava. The mean annual rainfall is 380 to 760 millimeters (15 to 30 inches). The mean annual pan evaporation ranges from 1020 to 1780 millimeters (40 to 70 inches). The mean annual air temperature is 8 to 13 degrees C. (47 to 55 degrees F.)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kealoha and Nenenui soils and the similar Huikau and Nawahine soils. Kealoha soils are medial-skeletal. Nenenui soils are cindery over pahoehoe lava at 5 to 25 centimeters (2 to 10 inches).

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

USE AND VEGETATION: These soils are used for wildlife habitat. The natural vegetation is pukiawe (Styphelia tameiameiae), aalii (Dodonaea viscosa), and ohia lehua (Metrosideros polymorpha).

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

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

SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii 1998.

REMARKS: Soil moisture - usually moist, but dry for short intermittent periods totaling 90 or more days in most years. (Ustic moisture regime).

Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - from 0 to 8 centimeters (0 to 3 inches) (A1 horizon).
Lithic contact - at 61 centimeters (24 inches) (2R horizon).
Andic soil properties - from 0 to 61 centimeters (0 to 24 inches) (A1, A2, and 2C horizons).
Lithologic discontinuity identified at 20 and 61 centimeters.

ADDITIONAL DATA: NASIS User Pedon ID 01HI601023.

Edit log: 4/09 MRK. Andic textural modifiers added. 02/2012 KP Lithologic discontinuity added.

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National Cooperative Soil Survey
U.S.A.