LOCATION MAHUKONA HI

Established Series
Rev. CWS/SN/HI/MRK
06/2012

MAHUKONA SERIES

The Mahukona series consists of deep, well drained soils that formed in material weathered from basic volcanic ash and residuum from basaltic lava. Mahukona soils are on ash fields and have slopes of 3 to 12 percent. Mean annual rainfall is about 635 millimeters (25 inches) and mean annual temperature is about 23 degrees C. (74 degrees F.)

TAXONOMIC CLASS: Fine, parasesquic, isohyperthermic Ustic Haplocambids

TYPICAL PEDON: Mahukona silty clay loam, on a west facing, 3 percent slope, under pasture, at an elevation of 95 meters (310 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures.")

A -- 0 to 15 centimeters (0 to 6 inches); dark reddish brown (5YR 3/3) silty clay loam, dark reddish brown (5YR 3/4) dry; weak very fine granular structure; soft, friable, slightly sticky and plastic; many fine roots; many fine pores; 2 percent gravel and 5 percent cobbles; strongly effervescent with hydrogen peroxide; moderately acid (pH 5.8); clear smooth boundary. (13 to 18 centimeters {5 to 7 inches} thick)

Bw1 -- 15 to 31 centimeters (6 to 12 inches); dark reddish brown (5YR 3/3) silty clay loam, dark reddish brown (5YR 3/4) dry; weak medium and fine subangular blocky structure; hard, friable, slightly sticky and plastic; many fine roots; many very fine pores; strongly effervescent with hydrogen peroxide; many black specks; slightly acid (pH 6.1); clear smooth boundary. (13 to 18 centimeters {5 to 7 inches} thick)

Bw2 -- 31 to 48 centimeters (12 to 19 inches); dark reddish brown (5YR 3/3) silty clay loam, dark reddish brown (5YR 3/4) dry; moderate fine prismatic structure; slightly hard, friable, slightly sticky and plastic; compact in place; common fine roots; many very fine pores; strongly effervescent with hydrogen peroxide; many black specks; slightly acid (pH 6.1); abrupt smooth boundary. (15 to 23 centimeters {6 to 9 inches} thick)

Bw3 -- 48 to 91 centimeters (19 to 36 inches); dusky red (2.5YR 3/2) silty clay loam, reddish brown (5YR 4/4) dry; moderate very fine subangular blocky structure; hard, friable, sticky and plastic; few fine roots; many very fine and fine pores; strongly effervescent with hydrogen peroxide; common black specks; neutral (pH 6.8); abrupt wavy boundary. (38 to 48 centimeters {15 to 19 inches} thick)

2Cr -- 91 to 127 centimeters (36 to 50 inches); very dark grayish brown (10YR 3/2) silt loam saprolite; massive; firm, moderately cemented, slightly sticky, slightly plastic; neutral (pH 6.8); abrupt wavy boundary. (25 to 38 centimeters {10 to 15 inches} thick)

2R -- 127 centimeters (50 inches); hard pahoehoe bedrock.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; about 0.8 miles east of Kapaa Beach Park in North Kohala. Drive 0.4 miles south on Highway 270 from Kapaa Beach Park. Turn left onto 4WD road and head east 0.2 miles. Pedon is located 100 feet south of 4WD road at an elevation of 95 meters (310 feet). Mahukona Quadrangle; lat. 20 degrees 12 minutes 7.0 seconds N. and 155 degrees 53 minutes 34.0 seconds W. long. (Old Hawaiian Datum).

RANGE IN CHARACTERISTICS:
Depth to bedrock: 102 to greater than 152 centimeters (40 to greater than 60 inches).
Mean annual soil temperature: 22 to 24 degrees C. (72 to 75 degrees F.)

A horizon
Hue: 5YR or 7.5YR.
Value: 2 to 4 moist and dry.
Chroma: 2 to 4 moist and dry.
Structure: weak or moderate granular, subangular blocky, prismatic, or platy. In places the granular A horizon is capped by a 1/4 to 2 inch thick weak medium platy layer.
Some A horizons are slightly hydrophobic when dry.
Reaction: moderately acid to slightly acid (pH 5.6 to 6.2).

Bw horizon
Hue: 5YR or 2.5YR.
Value: 3 to 5 moist or dry.
Chroma: 2 to 4 moist or dry.
Structure: weak or moderate, prismatic parting to angular blocky or subangular blocky.
Reaction: slightly acid to neutral (pH 6.1 to 6.8).

2Cr horizon
Cementation: weakly to moderately

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Mahukona soils are on lower elevation, leeward slopes of Kohala Mountain at elevations from sea level to 610 meters (0 to 2,000 feet). These soils are on all hillslope positions of gently sloping to strongly sloping ash fields on pahoehoe flows that are 750,000 to 250,000 years old. Slope gradients range from 3 to 12 percent. The soils formed in basic volcanic ash over residuum from basaltic lava. The mean annual rainfall ranges from 510 to 760 millimeters (20 to 30 inches), with most of the rainfall occurring from October through April. The mean annual pan evaporation ranges from 2,286 to 2,540 meters (90 to 100 inches). The mean annual temperature ranges from 21 to 24 degrees C. (70 to 76 degrees F.) average January temperature is 71 degrees F.; average July temperature is 76 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 Hawi, Kawaihae, and Waimea soils. Hawi soils have strong granular structure in the A horizon and 7.5YR or 10YR hue in the B horizon. Kawaihae soils have a very cobbly very fine sandy loam, silt loam, or loam texture in the A horizon. Waimea soils have andic soil properties in the control section.

DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderate permeability.

USE AND VEGETATION: These soils are used principally for grazing. Natural
vegetation is mainly kiawe (Prosopis pallida), uhaloa (Waltheria indica),
ilima (Sida fallax), buffelgrass (Pennisetum ciliare), swollen fingergrass (Chloris inflata), and bermudagrass (Cynodon dactylon).

DISTRIBUTION AND EXTENT: North Kohala District, Island of Hawaii; MLRA 157. The series is of small extent, with a total of approximately 2,798 acres.

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

SERIES ESTABLISHED: Hawaii County, Hawaii, 1970.

REMARKS:
FCC Classification: Cd+i.

Edit Log: 11/07 MRK. Edits to type location, range in characteristics, geographic setting, geographically associated soils, and distribution and extent. 5/04 SN. Horizon designations updated, plus minor edits.
8/02 SN. Classification changed from Fine, kaolinitic, isohyperthermic Aridic Haplustolls due to changes in Taxonomy.

ADDITIONAL DATA: H.C. Gardiner, Genesis of the Climosequence of Soils in the Kohala Region, MS Thesis, UH 1967.

National Cooperative Soil Survey
U.S.A.