LOCATION KAHANUI HI

Established Series
Rev. SN/MRK/ET
09/2019

KAHANUI SERIES

The Kahanui series consists of moderately deep, well drained soils that formed in residuum from weathered from andesite. Kahanui soils are on mountain ridges and have slopes of 3 to 20 percent. Mean annual rainfall is about 1778 millimeters (70 inches), and mean annual temperature is about 18 degrees C. (65 degrees F.)

TAXONOMIC CLASS: Very-fine, parasesquic, isothermic Typic Placorthods

TYPICAL PEDON: Kahanui gravelly silty clay - woodland. (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures.")

Oi--1 to 0 centimeters (0.5 to 0 inch); undecomposed leaves and twigs.

A1--0 to 8 centimeters (0 to 3 inches); dark brown (10YR 3/3) gravelly silty clay, gray (10YR 5/1) dry; strong very fine, fine, medium and coarse granular structure; hard, firm, sticky and plastic; many roots; many very fine interstitial pores; many ironstone concretions up to 1/2 inch long; many glistening specks; common worm casts; moderately high bulk density; slight effervescence with hydrogen peroxide after a delay; very strongly acid (pH 4.8); abrupt smooth boundary. (8 to 13 centimeters thick)

A2--8 to 38 centimeters (3 to 15 inches); dark brown (7.5YR 3/2) gravelly silty clay, grayish brown (10YR 5/2) dry; dense slaglike layer breaking into weak fine and medium subangular blocky structure; hard, firm, very sticky and very plastic; few roots; many very fine tubular pores; many ironstone fragments up to 1/4 inch long; very high bulk density; slight effervescence with hydrogen peroxide; very strongly acid (pH 4.8); abrupt wavy boundary. (28 to 31 centimeters thick)

Bo--38 to 53 centimeters (15 to 21 inches); dark yellowish brown (10YR 4/4) moist and dry silty clay; moderate very fine subangular blocky structure; hard, friable, sticky and plastic; few roots; many very fine tubular pores; common elongated ironstone fragments up to 1 inch long embedded horizontally throughout the horizon; very strongly acid (pH 4.8); abrupt wavy boundary. (13 to 15 centimeters thick)

Bsm--53 to 64 centimeters (21 to 25 inches); dark brown (7.5YR 4/4) moist and dry clay; moderate very fine and fine subangular blocky structure; hard, friable, very sticky and very plastic; few roots; many very fine and common fine and medium tubular pores; the top of this horizon has a weakly developed ironstone sheet that is impermeable to roots and water except through cracks; very strongly acid (pH 4.8); clear wavy boundary. (10 to 18 centimeters thick)

C1--64 to 76 centimeters (25 to 30 inches); soft weathered andesite, dark brown (10YR 3/3), brown (7.5YR 5/2) and gray (N 6/) moist; dark brown (7.5YR 4/4) mottles; has some original rock structure that breaks down to clay; massive; hard, firm, sticky, slightly plastic and smeary; very strongly acid (pH 4.8). (5 to 13 centimeters thick)

C2--76 to 152 centimeters (30 to 60 inches); soft weathered andesite, yellowish red (5YR 4/6), reddish yellow (7.5YR 8/6), reddish brown (5YR 4/3) and dark gray (5YR 4/1) moist; massive; breaks down to a gritty silt loam; hard, firm, slightly sticky, slightly plastic and smeary; very strongly acid (pH 4.8).

TYPE LOCATION: Island of Molokai, Maui County, Hawaii; Kaunakakai Quadrangle - 21 degrees 08 minutes 31.29 seconds north latitude and 156 degrees 57 minutes 29.26 seconds west longitude (WGS84 datum); in the Forest Reserve, along Meyer Lake Road 0.4 mile northwest of intersection of the Forestry Camp Road and Meyer Lake Road. The site is approximately 50 feet south of the road.

RANGE IN CHARACTERISTICS: Ironstone concretions and fragments range from 5 to 30 percent in the A horizon. In some pedons the ironstone concretions form a slaglike mass to depths of up to 91 centimeters (3 feet). The discontinuous ironstone sheet is at a depth of 51 to 64 centimeters (20 to 25 inches) and ranges from slightly hard to very hard and is 0.3 to 2.50 centimeters (1/8 to 1 inch) or more in thickness. In depressions it is hard or very hard, continuous and impermeable to roots and water. Hard bedrock is at a depth of 1.5 to more than 2.5 meters (5 to more than 8 feet). The mean annual soil temperature is about 18 degrees C. (65 degrees F.)

The A horizon has hue of 7.5YR through 2.5Y, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 or 3 moist and 1 or 3 dry.

The B horizon has hue of 7.5YR or 10YR, value of 4 or 5 moist and chroma of 4 through 6 moist.

COMPETING SERIES: There are no competing series in this family.

The Hulua and Olokui series are similar. Hulua soils have continuous ironstone sheet at shallow depths and mottles in the A horizon. Olokui soils have continuous ironstone sheet at shallow depths, mottles in the A horizon and are isomesic.

GEOGRAPHIC SETTING: Kahanui soils are on mountain ridges at elevations ranging from 381 to 1,143 meters (1,250 to 3,750 feet). Slopes are 3 to 20 percent. These soils formed in residuum from weathered from andesite. The mean annual rainfall is 1,524 to 2,032 millimeters (60 to 80 inches). Rainfall is distributed fairly evenly throughout the year. Fog and cloud cover are common during the winter. On the island of Lanai annual rainfall is only 890 millimeters (35 inches), but the effective rainfall is 1,524 to 2,032 millimeters (60 to 80 inches) because of frequent fog and cloud cover. The mean annual temperature is about 18 degrees C. (65 degrees F.); average January temperature is about 17 degrees C. (63 degrees F.); and the average July temperature is about 19 degrees C. (67 degrees F.)

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Amalu and Olelo soils and the similar Olokui soils. Amalu soils have a histic epipedon and a continuous ironstone sheet at shallow depths. Olelo soils have an argillic horizon.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; slow to medium runoff; very low saturated hydraulic conductivity.

USE AND VEGETATION: Woodland and watershed are the major uses. Vegetation is hilograss (Paspalum conjugatum), sweet vernalgrass (Anthoxanthum odoratum), Boston fern (Nephrolepis exaltata), ohia lehua (Metrosideros polymorpha), and glenwoodgrass (Sacciolepis indica).

DISTRIBUTION AND EXTENT: Islands of Molokai and Lanai, Hawaii. Approximately 2,300 acres in extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Island of Molokai, Maui County, Hawaii, 1971.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Fibric material- 1 to 0 centimeters (Oi)
Umbric epipedon- the zone from the surface to 38 centimeters (A1, A2)
Placic horizon- 53 to 64 centimeters (Bsm)
Spodic materials- 8 to 64 centimeters (A2, Bo, Bsm)
Spodic horizon- 8 to 64 centimeters (A2, Bo, Bsm)

There are areas where depth to the ironstone sheet is as shallow as 12 inches, but these areas are considered out of the range for this series.

Last updated by state 8/2000

National Cooperative Soil Survey
U.S.A.