LOCATION KAPUA                   HI

Established Series
MRK-RTG
05/2012

KAPUA SERIES

The Kapua series consists of deep, somewhat excessively drained soils that formed in organic material mixed with minor amounts of basic volcanic ash in `a`a lava. Slopes range from 2 to 20 percent. The mean annual rainfall is about 889 millimeters (35 inches) and the mean annual air temperature is about 19 degrees C (67 degrees F).

TAXONOMIC CLASS: Euic, isothermic Typic Ustifolists

TYPICAL PEDON: Kapua very cobbly highly decomposed plant material, on a west facing, slightly concave, 9 percent slope in forest at an elevation of 427 meters (1400 feet). (Colors are for moist soils unless otherwise noted. All textures are "apparent field textures". pH measured with electrode in 1:1 water. When described on December 9, 1992, the soil was slightly moist.) The 2C part of these horizons consist of unconsolidated `a`a lava fragments of variable size.

Oa1/2C1--0 to 15 centimeters (0 to 6 inches); black (10YR 2/1) very cobbly highly decomposed plant material, very dark brown (10YR 2/2) dry; strong very fine and fine granular structure; slightly hard, very friable, slightly sticky and nonplastic; common very fine and fine, and few medium roots; common very fine irregular pores; hydrophobic when dry; 30 percent angular `a`a gravel and 20 percent angular `a`a cobbles; slightly acid (pH 6.1); clear wavy boundary. (10 to 20 centimeters {4 to 8 inches} thick)

2C2/Oa2--15 to 46 centimeters (6 to 18 inches); very dark brown (10YR 2/2) extremely gravelly highly decomposed plant material, very dark grayish brown (10YR 3/2) dry; moderate very fine and fine granular structure; slightly hard, very friable, slightly sticky and nonplastic; few very fine and fine roots; common very fine irregular pores; slightly hydrophobic when dry; 50 percent angular `a`a gravel and 20 percent angular `a`a cobbles; neutral (pH 6.6); gradual wavy boundary. (20 to 31 centimeters {8 to 12 inches} thick)

2C3--46 to 152 centimeters (18 to 60 inches); fragmental `a`a lava with very little soil material in voids.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; about 2.5 miles north of Mac Farms of Hawaii headquarters and 31 meters (100 feet) west of Highway 11. Papa Quadrangle; lat. 19 degrees 10 minutes 50 seconds N. and long. 155 degrees 51 minutes 59 seconds W. (Old Hawaiian Datum)

RANGE IN CHARACTERISTICS:
Depth to bedrock: 102 to 152 centimeters (40 to 60 inches).
Mean annual soil temperature: 18 to 22 degrees C (65 to 72 degrees F).
Rock fragments: 35 to 85 percent by volume and range in size from gravel to stones, but are primarily gravel and cobble size lava rocks.
Organic carbon (by weight): 25 to 30 percent of the less than 2.0 mm soil material.

Oa1/2C1 and 2C2/Oa2 horizons
Hue: 5YR to 10YR.
Value: 2 or 3 moist or dry.
Chroma: 1 or 2 moist or dry.
Texture: Very cobbly or extremely cobbly highly decomposed plant material or moderately decomposed plant material.
Soil reaction: Slightly acid or neutral (pH 6.1 to 7.3).

COMPETING SERIES: There are no competing series. Similar soils include Kaimu, Mawae, and Puna. Kaimu soils are isohyperthermic. Mawae soils are isomesic. Puna soils have an udic moisture regime.

GEOGRAPHIC SETTING: Kapua soils are on mid elevation, leeward slopes on the upland of Mauna Loa Volcano at elevations of 305 to 1067 meters (1,000 to 3,500 feet). These soils are on all hillslope components of constructional landscapes consisting of undulating to hilly `a`a flows that are 750 to 3,000 years old. Slope gradients range from 2 to 20 percent. The soils formed mainly in organic material consisting of decomposed leaves, twigs, and wood; and to a lesser degree basic volcanic ash, cinders, and weathered lava. The mean annual rainfall ranges from 508 to 1270 millimeters (20 to 50 inches), with most of the rainfall occurring from April through October. The mean annual pan evaporation ranges from 1270 to 1524 millimeters (50 to 60 inches). The mean annual air temperature ranges from 17 to 21 degrees C (63 to 70 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 Kahuku and Kali series. Kahuku soils are medial over pahoehoe lava. Kali soils are organic soils over pahoehoe lava.

DRAINAGE AND PERMEABILITY: Somewhat excessively drained. Runoff is negligible in depressions on gentle slopes and low on steeper slopes. Permeability is rapid.

USE AND VEGETATION: Used primarily for wildlife habitat; some areas are used for grazing and irrigated orchard. The natural vegetation is koa haole (Leucaena leucocephala), christmasberry (Schinus terebinthifolius), kukui nut (Aleurites moluccana), ohia lehua (Metrosideros polymorpha), guineagrass (Urochloa maxima), and morning glory (Ipomea spp.).

DISTRIBUTION AND EXTENT: Kau and South Kona districts, Island of Hawaii; MLRA 161B. The series is of small extent.

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

SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii 2008 Proposed in 1992.

REMARKS: Soil moisture - usually moist, but dry in some or all parts for short intermittent periods totaling 90 or more days during the months of October through April in most years (Ustic moisture regime).

Diagnostic horizons and features recognized in this pedon are:
--Sapric soil materials - from a depth of 0 to 46 centimeters (0 to 18 inches) (Oa1/2C1 and 2C2/Oa2 horizons).

Edit log: 2/5/08 Minor edits and organic textures updated. MRK

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National Cooperative Soil Survey
U.S.A.