LOCATION HAWI HI

Established Series
Rev. CWS/SN/HI/MRK
05/2012

HAWI SERIES

The Hawi series consists of deep and very deep, well drained soils that formed from weathered basic volcanic ash and residuum from basalt. Hawi soils are on uplands and have slopes of 0 to 12 percent. The mean annual rainfall is 760 millimeters (30 inches) and the mean annual air temperature is 23 degrees C (73 degrees F).

TAXONOMIC CLASS: Very-fine, parasesquic, isohyperthermic Aridic Dystrustepts

TYPICAL PEDON: Hawi silty clay on a north facing, 3 percent slope, under grasses, at an elevation of 21 meters (70 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures".)

Ap--0 to 38 centimeters (0 to 15 inches); very dark grayish brown (10YR 3/2) silty clay, brown (10YR 4/3) dry; strong fine granular structure; friable, very hard, sticky and very plastic; many fine roots; many fine and very fine irregular pores; violently effervescent with hydrogen peroxide; slightly acid (pH 6.1); abrupt smooth boundary. (18 to 38 centimeters {7 to 15 inches} thick)

Bw1--38 to 76 centimeters (15 to 30 inches); very dark grayish brown (10YR 3/2) silty clay; moderate coarse subangular blocky structure; firm, very hard, sticky and very plastic; common very fine roots; many very fine tubular pores, many very fine black (10YR 2/1) manganese concretions; strongly effervescent with hydrogen peroxide; slightly acid (pH 6.1); abrupt smooth boundary. (25 to 38 centimeters {10 to 15 inches} thick)

2C/Bw2--76 to 122 centimeters (30 to 48 inches); dark yellowish brown (10YR 3/4) and dark brown (10YR 3/3) extremely stony silty clay; moderate fine subangular blocky structure; firm, very hard, sticky and very plastic; common very fine roots; many fine tubular pores; many very fine black (10YR 2/1)manganese concretions; strongly effervescent with hydrogen peroxide; 2C material consists of unconsolidated lava fragments; 70 percent basalt stones; neutral (pH 7.0); abrupt smooth boundary. (25 to 50 centimeters (10 to 20 inches) thick)

Bw3--122 to 172 centimeters (48 to 68 inches); dark brown (10YR 3/3) stony silty clay; weak medium subangular blocky structure; firm, very hard, sticky and plastic; few very fine roots; many very fine tubular pores; few black (10YR 2/1) manganese concretions; strongly effervescent with hydrogen peroxide; 20 percent basalt stones; neutral (pH 7.0).

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; In North Kohala, From the building at Upolu Airport drive west 0.9 miles on 4WD road. Pedon is located 152 meters (500 feet) south in pasture at an elevation of 21 meters (70 feet); Hawi Quadrangle; lat. 20 degrees 15 minutes 53 seconds N. and long. 155 degrees 52 minutes 28 seconds W. (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).

Ap horizon
Hue: 7.5YR or 10YR.
Value: 3 or 4 moist and dry.
Chroma: 2 or 3 moist and dry.
Structure: moderate or strong granular 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 6.5).

Bw horizon
Hue: 5YR or 2.5YR.
Chroma: 2 to 4 moist
Texture: silty clay loam or silty clay
Structure: weak or moderate, fine to coarse subangular blocky.
Reaction: slightly acid to neutral (pH 6.1 to 7.3).

COMPETING SERIES: There are no competing series. Similar soils include the Kohala and Mahukona series. Kohala soils have less than 50 percent base saturation and have strong subangular blocky structure in the B horizon. Mahukona soils have an aridic soil moisture regime and have a B horizon with hue of 2.5YR or 5YR.

GEOGRAPHIC SETTING: Hawi soils are on low elevation, windward slopes of Kohala Mountain at elevations from sea level to 610 meters (0 to 2000 feet). These soils are on all hillslope positions of nearly level to strongly sloping lava flows that are 250,000 to 750,000 years old. Slope gradients range from 0 to 12 percent. The soils formed from weathered basic volcanic ash and residuum from basalt. The mean annual rainfall ranges from 640 to 1020 millimeters (25 to 40 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 21 degrees (69 degrees F); average July temperature is 24 degrees (75 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 Kohala and Mahukona soils.

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

USE AND VEGETATION: These soils are used for pasture. Natural vegetation is lantana (Lantana camara), uhaloa (Waltheria americana), ilima (Sida fallax), Natal redtop (Rhynchelytrum repens) and bermudagrass (Cynodon dactylon).

DISTRIBUTION AND EXTENT: North Kohala District, Island of Hawaii, Hawaii. MLRA 158. This series is of small extent, with a total of approximately 8,500 acres.

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

SERIES ESTABLISHED: Island of Hawaii, County of Hawaii, Hawaii, 1967. Name is from Kohala District.

REMARKS: Ustic soil moisture regime- the moisture control section is dry in some or all parts for 90 or more cumulative days in normal years.
Diagnostic horizons and features found in this pedon include:
Umbric epipedon- 0 to 38 centimeters (0 to 15 inches)
Cambic horizon- 38 to 172 centimeters (15 to 68 inches)
FCC Classification: Cdki.
ADDITIONAL DATA: NASIS User Pedon ID 08HI603003.

Edit Log: 12/07 MRK. Classification changed from Fine, kaolinitic, isohyperthermic Pachic Haplustolls due to changes in Soil Taxonomy. Edits to type location; range in characteristics; geographic setting geographically associated soils; use and vegetation; and distribution and extent. 12/03 SN. Horizon designations updated.

National Cooperative Soil Survey
U.S.A.