LOCATION KAHAUMANU               HI

Established Series
RTG-MRK
05/2012

KAHAUMANU SERIES

The Kahaumanu series consists of shallow, well drained soils that formed in basic volcanic ash over pahoehoe lava. Slopes range from 2 to 20 percent. The mean annual rainfall is about 560 millimeters (22 inches), and the mean annual temperature is about 20 degrees C. (68 degrees F.)

TAXONOMIC CLASS: Medial, amorphic, isothermic Lithic Haplustands

TYPICAL PEDON: Kahaumanu cobbly medial silt loam, on a northwest facing, linear, 12 percent slope under pasture at an elevation of 634 meters (2,080 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures". pH measured with organic dyes. When described on August 1, 1997, the soil was dry throughout.)

A--0 to 13 centimeters (0 to 5 inches); black (10YR 2/1) cobbly medial silt loam, very dark grayish brown (10YR 3/2) dry; moderate very fine and fine granular structure; soft, very friable, nonsticky and nonplastic; nonsmeary; hydrophobic when dry; many very fine and fine and common medium roots; many very fine and fine interstitial pores; 15 percent subangular cobbles and 2 percent subangular gravel; slightly acid (pH 6.5); clear smooth boundary. (10 to 15 centimeters {4 to 6 inches}) thick

Bw1--13 to 23 centimeters (5 to 9 inches); black (10YR 2/1) cobbly medial silt loam, dark brown (10YR 3/3) dry; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; nonsmeary; many very fine and fine roots; many very fine and fine interstitial pores; 20 percent subangular cobbles and 2 percent subangular gravel; neutral (pH 6.9); clear wavy boundary. (10 to 15 centimeters {4 to 6 inches} thick)

Bw2--23 to 38 centimeters (9 to 15 inches); black (7.5YR 2.5/1) cobbly medial silt loam, dark brown (7.5YR 3/3) dry; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; nonsmeary; many very fine and fine roots; many very fine and fine interstitial pores; 25 percent subangular cobbles and 2 percent subangular gravel; neutral (pH 7.0); abrupt wavy boundary. (0 to 15 centimeters {0 to 6 inches} thick)

2R--38 centimeters (15 inches); hard, massive pahoehoe lava.

TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; drive north on Highway 190 to Puu Anahulu area; at the power substation drive north 0.1 miles to ranch road on the makai (downslope) side of highway; turn left and drive makai through corral and 2 gates for 0.2 miles to telephone pole 8; pedon is 11 meters (35 feet) makai and 18 meters (60 feet) south of telephone pole. Puu Anahulu Quadrangle; lat. 19 degrees 49 minutes 39.3 seconds N. and long. 155 degrees 50 minutes 7.2 seconds W. (Old Hawaiian Datum measured by GPS/PLGR).

RANGE IN CHARACTERISTICS:
Depth to bedrock: 25 to 50 centimeters (10 to 20 inches).
Mean annual soil temperature: 18 to 22 degrees C. (65 to 72 degrees F.)
Rock fragments: 5 to 30 percent by volume of the pedon and range in size from gravel to cobbles.

A horizon
Hue: Neutral, 7.5YR, or 10YR.
Value: 2 to 3 moist or dry.
Chroma: 0, 1, or 2 moist or dry.
Texture: Medial silt loam or cobbly medial silt loam.
Soil reaction: Slightly acid to slightly alkaline (pH 6.1 to 7.8).

Bw horizon
Hue: 5YR to 10YR.
Value: 2 to 3 moist or dry.
Chroma: 1 to 3 moist or dry.
Texture: Medial silt loam or cobbly medial silt loam.
Soil reaction: Neutral to slightly alkaline (pH 6.6 to 7.8).

COMPETING SERIES: These are the Nakanui and Nanaia series. Nakanui soils formed in volcanic ash and gravels and do not contain cobbles. Nanaia soils have a lithic contact at 5 to 25 centimeters (2 to 10 inches) and are moist in the control section from October through May. Ahiu series is similar. Ahiu soils are ashy and have an ochric epipedon.

GEOGRAPHIC SETTING: Kahaumanu soils are on mid elevation, leeward slopes of Mauna Kea, Mauna Loa and Hualalai volcanoes at elevations from 305 to 1067 meters (1,000 to 3,500 feet). The soils are on depressions of constructional landscapes consisting of nearly level to moderately steep pahoehoe lava flows that are over 100,000 years old. Slope gradients range from 2 to 20 percent. The soils formed in basic volcanic ash over pahoehoe lava. The mean annual rainfall ranges from 380 to 760 millimeters (15 to 30 inches), with most of the rainfall occurring from January through July. The mean annual pan evaporation ranges from 1520 to 1780 millimeters (60 to 70 inches). The mean annual 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 the Akahipuu, Nanuku, Napuu, Puuikaaka, and Waawaa series. Akahipuu and Napuu soils are medial-skeletal over `a`a lava. Nanuku soils are sandy-skeletal over `a`a lava. Puuikaaka soils are medial-skeletal over pahoehoe lava (lithic contact) at 5 to 25 centimeters (2 to 10 inches). Waawaa soils are deeper than 152 centimeters (60 inches) to bedrock.

DRAINAGE AND PERMEABILITY: Well drained. Runoff is negligible in depressions on gentle slopes and high to very high on steeper slopes. Permeability is moderately rapid in the soil and very slow in the underlying bedrock.

USE AND VEGETATION: These soils are used for grazing. Vegetation is fountaingrass (Pennisetum setaceum), lantana (Lantana camara), and koa haole (Leucaena leucocephala).

DISTRIBUTION AND EXTENT: North Kona District, Island of Hawaii; MLRA 157. The series is of small extent.

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

SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii 2012. Proposed 1996.

REMARKS: Soil moisture - usually moist, but dry in some or all parts for short intermittent periods totaling 90 or more days during the months from July through January in most years (ustic moisture regime).
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from a depth of 0 to 38 centimeters (0 to 15 inches) (A and Bw horizons).
Andic soil properties - from a depth of 0 to 38 centimeters (0 to 15 inches) (A and Bw horizons).
Lithic contact - at a depth of 38 centimeters (15 inches) (2R horizon).

ADDITIONAL DATA: NASIS User Pedon ID 01HI601006. NSSL sample S94HI-001-008. (not the typical pedon)

Edit Log: 2/19/08 In Competing Series section, Nanaia series changed from Kahuku. Andic texture modifiers added. MRK

---

National Cooperative Soil Survey
U.S.A.