LOCATION OANAPUKA HIEstablished Series
TAXONOMIC CLASS: Medial, amorphic, isohyperthermic Typic Vitritorrands
TYPICAL PEDON: Oanapuka very stony silt loam - pasture. (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures".)
A11--0 to 2 inches; very dark brown (10YR 2/2) very stony silt loam, dark brown (10YR 3/3) dry; weak fine and medium granular structure; soft, very friable, nonsticky and slightly plastic; many fine roots; common fine and very fine pores; 15 percent stones; slight effervescence with hydrogen peroxide; medium acid (pH 6.0); abrupt smooth boundary. (1 to 3 inches thick)
A12--2 to 6 inches; very dark grayish brown (10YR 3/2) silt loam, brown (10YR 4/3) dry; weak medium and coarse subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine roots; many fine and very fine pores; few fine red weathered cinders; slight effervescence with hydrogen peroxide; slightly acid (pH 6.5); clear smooth boundary. (3 to 6 inches thick)
B2--6 to 15 inches; very dark grayish brown (10YR 3/2) silt loam, dark brown (7.5YR 3/2) dry; moderate medium prismatic structure; slightly hard, friable, slightly sticky, slightly plastic and weakly smeary; many fine roots; many fine pores; thin patchy coatings on peds that look like clay films; few fine red weathered cinders; neutral (pH 6.8); clear wavy boundary. (8 to 14 inches thick)
C1--15 to 28 inches; dark yellowish brown (10YR 3/4) silt loam, yellowish brown (10YR 5/6) dry; massive; soft, very friable, slightly sticky and slightly plastic; common fine roots; many fine pores; common fine red cinders; neutral (pH 7.2); gradual wavy boundary. (10 to 16 inches thick)
C2--28 to 43 inches; dark yellowish brown (10YR 3/4) loam, yellowish brown (10YR 5/6) dry; massive; soft, very friable, slightly sticky and nonplastic; common fine roots; many fine and medium pores; common weathered cinders; few hard stones; mildly alkaline (pH 7.4); gradual wavy boundary. (10 to 20 inches thick)
C3--43 to 46 inches; dark yellowish brown (10YR 3/4) very cobbly loam, yellowish brown (10YR 5/4) dry; massive; soft, very friable, nonsticky and nonplastic; 50 percent gravel- and cobble-size Aa lava fragments; common hard cinders; mildly alkaline (pH 7.5); clear wavy boundary. (2 to 4 inches thick)
IIC4--46 to 55 inches; Aa lava with very little soil material in voids; the soil material is dark yellowish brown (10YR 3/4) loam, yellowish brown (10YR 5/4) dry; massive; soft, very friable, nonsticky and nonplastic; slight effervescence with hydrochloric acid; mildly alkaline (pH 7.6).
TYPE LOCATION: Island of Maui, Maui County, Hawaii; Makena Quadrangle - 20 degrees 39' 44" north latitude and 156 degrees 25' 10" west longitude; 100 feet northeast of Makena Road and about 2.3 miles east of Makena and Kihei Road intersections.
RANGE IN CHARACTERISTICS: Depth of soil ranges from 40 to more than 60 inches. Depth to free calcium carbonate ranges from 40 to 60 inches. Stoniness ranges from very stony to extremely stony. The mean annual soil temperature is 73 degrees F. The A horizon has hue of 7.5YR or 10YR, value of 2 or 3 moist, and 3 or 4 dry, and chroma of 3 or 4 dry. The B horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist or dry, and chroma of 2 through 4 moist or dry. The C horizon is loam or silt loam.
COMPETING SERIES: These are the Koko, Makena, Pakini and Waikaloa series. Koko soils have hue of 5YR in the A horizon and upper part of the B horizon and lack prismatic structure in the B horizon. Makena soils have an ochric epipedon. Pakini soils have an epipedon too thin for a mollic epipedon, have weak structure in the B horizon and are high in olivine sand. Waikaloa soils are silty clay loam in the IIB horizon and a mean annual soil temperature of 62 degrees F.
GEOGRAPHIC SETTING: The Oanapuka soils are on uplands. Slope is 7 to 25 inches. Outcrops of Aa lava are common on the landscape. The landscape is made up of narrow ridges of Aa lava and moderately wide valleys. Elevation ranges from 100 to 800 feet. The soils formed in volcanic ash and cinders over Aa lava. Annual rainfall is 15 to 25 inches. Mean annual temperature is about 73 degrees F.; average January temperature is 70 degrees F.; average July temperature is 76 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Io and Kula soils and the competing Makena soils. Io soils have an ashy over cindery control section. Kula soils have a mean annual soil temperature of 66 degrees F.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability.
USE AND VEGETATION: This soil is used for pasture. The natural vegetation is apple of Sodom (Solanum sodomeum), feather fingergrass (Chloris virgata), ilima (Sida fallax), kiawe (Prosopis chilensis), klu (Acacia farnesiana), koa haole (Leucaena glauca), lantana (Lantana camara), Natal redtop (Tricholaena repens), pitted beardgrass (Andropogon pertusus) and wiliwili (Erythrina sandwicensis).
DISTRIBUTION AND EXTENT: Island of Maui, Maui County, Hawaii. This series is approximately 6,400 acres in extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Maui County, Hawaii, 1971.
OSED scanned by SSQA. Last revised by state on 5/78.