LOCATION KAHUA HI

Established Series
Rev. HHS/RCH/MRK
02/2012

KAHUA SERIES

The Kahua series consists of deep, somewhat poorly drained soils that formed in basic volcanic ash over basaltic lava. Kahua soils are on uplands and have slopes of 6 to 70 percent. The mean annual rainfall is about 3,050 millimeters (120 inches) and the mean annual temperature is about 15 degrees C. (59 degrees F.)

TAXONOMIC CLASS: Medial, ferrihydritic, isothermic Aquic Placudands

TYPICAL PEDON: Kahua mucky medial silt loam, on a west facing, 6 percent slope, under graases, at an elevation of 1,140 meters (3,740 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures.")

A--0 to 5 centimeters (0 to 2 inches); very dark brown (7.5YR 2/2) mucky medial silt loam; weak fine granular structure; friable, slightly sticky and moderately plastic, weakly smeary; many very fine and fine roots; many very fine and fine interstitial and irregular pores; extremely acid (pH 4.4); abrupt smooth boundary. (5 to 10 centimeters {2 to 4 inches} thick)

Ag--5 to 20 centimeters (2 to 8 inches); grayish brown (10YR 5/2) medial silty clay loam; moderate very fine subangular blocky structure; friable, moderately sticky and moderately plastic, weakly smeary; many very fine and fine roots; common fine tubular and interstitial pores; many fine faint mottles of dark yellowish brown (10YR 3/4);very strongly acid (pH 4.9); abrupt wavy boundary. (8 to 18 centimeters {3 to 7 inches} thick)

Bsm--20 to 22 centimeters (8 to 8.5 inches); dark reddish brown (5YR 3/3) cemented material of ironstone; moderate thin to thick platy structure; very firm; many very fine and fine roots matted on top of pan; very strongly acid (pH 4.7); abrupt smooth boundary. (0.5 to 2.5 centimeters {0.2 to 1 inch} thick)

Bw1--22 to 38 centimeters (8.5 to 15 inches); very dark grayish brown (10YR 3/2) medial silty clay loam; moderate medium and fine subangular blocky structure; friable, moderately sticky and moderately plastic, strongly smeary; common very fine and fine roots; many very fine tubular pores; few fine faint dark yellowish brown (10YR 3/4) redox concentrations; very strongly acid (pH 4.8); abrupt smooth boundary. (15 to 23 centimeters {6 to 9} inches thick)

Bw2 --38 to 58 centimeters (15 to 23 inches); brown (10YR 4/3) medial silty clay loam; moderate medium and fine subangular blocky structure; friable, moderately sticky and moderately plastic, strongly smeary; common very fine roots; many very fine tubular pores; 2 percent paragravels; very strongly acid (pH 4.8); clear smooth boundary. (18 to 25 centimeters {7 to 10 inches} thick)

Bw3 -- 58 to 91 centimeters (23 to 36 inches); dark grayish brown (10YR 4/2) hydrous silty clay loam; moderate fine subangular blocky structure; friable, moderately sticky and moderately plastic, strongly smeary; few very fine roots; many very fine tubular pores; few fine faint dark brown (7.5YR 3/2) redox concentrations and few fine faint dark gray (10YR 4/1) redox depletions; strongly acid (pH 5.3); abrupt wavy boundary. (25 to 36 centimeters {10 to 14 inches} thick)

Bw4 -- 91 to 152 centimeters (36 to 60 inches); dark yellowish brown (10YR 4/4), brown (7.5YR 4/2), very dark gray (N 3/) and reddish brown (5YR 4/4) variegated paragravelly hydrous silty clay loam; massive; friable, moderately sticky and moderately plastic; strongly smeary; few very fine roots; many very fine irregular pores; 30 percent paragravels; very strongly acid (pH 5.0).

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; from Kahua Ranch headquarters travel upslope to end of jeep trail on the southern side of Puu Iki; pedon is located approximately 15 meters (50 feet) south of gate at an elevation of 1,140 meters (3,740 feet). Hawi Quadrangle; latitude 20 degrees 7 minutes 43.0 seconds N. and longitude 155 degrees 46 minutes 3.0 seconds W. (Old Hawaiian Datum.)

RANGE IN CHARACTERISTICS:
Depth to bedrock: 102 to greater than 152 centimeters (40 to greater than 60 inches). Depth to Placic horizon: from 20 to 51 centimeters (8 to 20 inches) Depth to Aquic conditions: 5 to 51 centimeters (2 to 20 inches) Mean annual soil temperature: 15 to 17 degrees C (59 to 63 degrees F.) Rock fragments: 0 to 30 percent of the pedon Pedons in the forest can have a histic epipedon from 5 to 20 centimeters (2 to 8 inches)

The A horizon Hue: 5YR to 10YR Value: 2 or 3 moist Chroma: 1 to 3 moist Texture: mucky, medial or hydrous, silt loam or silty clay loam Structure: weak to moderate granular or subangular blocky Smeariness: nonsmeary to weakly smeary Redoximorphic features: few to many, faint to prominent concentrations. Reaction: extremely acid to very strongly acid (pH 4.2 to 5.0)

The Bsm horizon Hue: 5YR or 7.5YR Boundary: smooth or broken. May not be present in some pedons.

The Bw horizon Hue: 7.5YR or 10YR. Value: 3 or 4 moist Chroma: 2 or 3 moist Texture: noncobbly to very cobbly, medial or hydrous, silt loam or silty clay loam
Structure: weak to moderate Smeariness: weakly smeary to strongly smeary Redoximorphic features: few to many, faint to prominent depletions and concentrations. Reaction: very strongly acid to strongly acid (pH 5.0 to 5.5)

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Kahua soils are on upper elevation, summit area of Kohala Mountain at elevations from 1,066 to 1,585 meters (3,500 to 5,200 feet). These soils are on all hillslope positions of gently sloping to steep lava flows, very steep cinder cones and gully slopes. Slope gradients range from 3 to 70 percent. The soils formed in basic volcanic ash over basaltic lava. The mean annual rainfall ranges from 2,032 to 3,810 millimeters (80 to 150 inches), with most of the rainfall occurring from October through April. The soils are wet throughout the year and are subject to frequent cloudiness and fog. The mean annual temperature ranges from 14 to 17 degrees C. (57 to 63 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 Amalu, Kehena and Palapalai soils. Amalu soils have a paralithic contact between 25 and 51 centimeters (10 to 20 inches). Kehena soils have lithic contact between 51 to 102 centimeters (20 to 40 inches). Palapalai soils are well drained and do not have a placic horizon.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; medium to high runoff; moderately slow permeability.

USE AND VEGETATION: Kahua soils are used for pasture, woodland and watershed. Natural vegetation is ohia lehua (Metrosideros polymorpha), hapuu treefern (Cibotium glauca or C. chamissoi), uluhe (Dicranopteris linearis), hilograss (Paspalum conjugatum), and kikuyu grass (Pennisetum clandestinum).

DISTRIBUTION AND EXTENT: North Kohala District, Island of Hawaii. The series is approximately 9,968 acres in extent.

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

SERIES ESTABLISHED: Hawaii County, Hawaii, 1971.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Aquic soil moisture regime
Umbric epipedon - from the surface to 20 centimeters (0 to 8 inches) (A horizons).
Placic horizon - from 20 to 22 centimeters (8 to 8.5 inches)
Andic soil properties - from 0 to 152 centimeters (0 to 60 inches) (All horizons).
Cambic Horizon - from 22 to 152 centimeters (8.5 to 60 inches) (Bw and Bw/C horizons).
Redox concentrations - from 3 to 38 centimters (1 to 15 inches).

ADDITIONAL DATA: NASIS User Pedon ID 08HI603002.

Edit Log: 8/19/09 Soil classification revised from Medial, ferrihydritic, isothermic, Acrudoxic Hydric Hapludands due to changes in series concept. Range in characteristics and competing series updated plus other minor edits. MRK.

National Cooperative Soil Survey
U.S.A.