LOCATION KAU HI

Established Series
PGN-CDJ-AMS
05/2012

KAU SERIES

The Kau series consists of deep, well drained soils that formed in volcanic ash deposited over `a`a lava. Kau soils are located on the windward slopes of Mauna Loa volcano. Slopes range from 3 to 50 percent. The mean annual rainfall is about 2300 millimeters (91 inches), and the mean annual air temperature is about 13 degrees C (55 degrees F).

TAXONOMIC CLASS: Hydrous-skeletal, ferrihydritic, isomesic Typic Hydrudands

TYPICAL PEDON: Kau hydrous silt loam, grazed forest under ohia lehua, koa and shrubs on a 5 percent slope at an elevation of 1,509 meters (4,950 feet). (Colors are for moist soil unless otherwise noted. When described on 01/08/02 the soil was moist throughout. All textures are "apparent field textures". pH was measured using organic dyes.)

A--0 to 10 centimeters (0 to 4 inches); very dark brown (10YR 2/2) hydrous silt loam, dark grayish brown (10YR 4/2) dry; moderate fine and medium granular structure; moderately hard, friable, slightly sticky and slightly plastic; many very fine, fine, and medium roots; many fine interstitial pores; moderately smeary; very strongly acid (pH 4.5); abrupt smooth boundary. (5 to 18 centimeters (2 to 7 inches) thick)

Bw1--10 to 15 centimeters (4 to 6 inches); very dark brown (7.5YR 2.5/2) cobbly hydrous silt loam, very dark grayish brown (10YR 3/2) dry; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many very fine, fine and medium roots; many very fine and fine interstitial and tubular pores; 15 percent subangular `a`a cobbles and 5 percent subangular `a`a gravel, moderately smeary; very strongly acid (pH 5.0); abrupt smooth boundary. (5 to 20 centimeters (2 to 8 inches) thick)

Bw2--15 to 38 centimeters (6 to 15 inches); very dark brown (10YR 2/2) cobbly hydrous silt loam, very dark grayish brown (10YR 3/2) dry; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; many very fine, fine and common medium roots; common fine interstitial and tubular pores; 5 percent dark gray (5YR 4/1) rounded paragravel, soft to hard; 15 percent subangular `a`a cobbles and 5 percent subangular `a`a gravel, moderately smeary; very strongly acid (pH 5.0); clear smooth boundary. (5 to 25 centimeters (2 to 10 inches) thick)

Bw3/2C1--38 to 51 centimeters (15 to 20 inches), very dark brown (7.5YR 2.5/2) very cobbly hydrous silt loam, very dark grayish brown (10YR 3/2) dry; massive; soft, friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; common fine interstitial and tubular pores; 10 percent dark gray (5YR 4/1) rounded paragravel, soft to hard; 25 percent subangular `a`a cobbles, 10 percent subangular `a`a stones, and 10 percent subangular `a`a gravel, moderately smeary; very strongly acid (pH 4.5); the 2C part of this horizon consists of unconsolidated `a`a lava fragments of variable size; clear wavy boundary. (18 to 30 centimeters (5 to 12 inches) thick)

2C2/Bw4--51 to 102 centimeters (20 to 40 inches), dark brown (7.5YR 3/3) extremely cobbly hydrous silt loam, brownish yellow (10YR 6/6) dry; single grain; loose when dry or moist, slightly sticky and slightly plastic; common fine and medium roots; many very fine and fine interstitial pores; 45 percent subangular `a`a cobbles, 10 percent subangular `a`a stones, and 20 percent subangular `a`a gravel, moderately smeary; moderately acid (pH 6.0); the 2C part of this horizon consists of unconsolidated `a`a lava fragments of variable size; clear wavy boundary. (18 to 38 centimeters (10 to 20 inches) thick)

2R--102 centimeters (40 inches); hard, massive `a`a blue rock.

TYPE LOCATION: Island of Hawaii, Hawaii; from State Highway 11 in Kau travel north on Piimauna Road toward Volcano Golf Course for 1.0 mile; at Keauhou Ranch gate continue straight onto Puu Oo trail for approximately 3.65 miles to lat. 19 degrees 29 minutes 18 seconds N and long. 155 degrees 18 minutes 49 seconds W. (Old Hawaiian Datum). Turn to right (northeast) and follow 4WD trail for 0.3 miles to fork in trail. Turn right (northeast) and follow trail and fence 0.5 miles to road cut and type location on left (north) side of trail; Kilauea Crater Quadrangle. (lat. 19 degrees 29 minutes 55 seconds N and long. 155 degrees 18 minutes 38 seconds W. Old Hawaiian Datum, 18 ft; measured by GPS PLGR)

RANGE IN CHARACTERISTICS:
Depth to bedrock: 100 to 150 centimeters (40 to 60 inches).
Rock fragments: average 35 to 80 percent in the control section.
Soil Reaction: Very strongly acid to moderately acid.
Soil moisture: The soil is typically moist but may experience periodic drying of control section with summer being the most likely season for drying.

A horizon
Hue: 7.5YR to 10YR.
Chroma: 2 or 3 moist.
Texture: Hydrous loam, hydrous silt loam, or very cobbly highly organic medial loam.

Bw horizons
Hue: 7.5YR to 10YR.
Value: 2 to 3 moist.
Chroma: 2 or 3 moist.
Texture: Cobbly or very cobbly hydrous loam or hydrous silt loam.

Bw/2C and 2C/Bw horizons
Hue: 2.5YR to 10YR.
Value: 2 to 5 moist.
Chroma: 2 to 8 moist.
Texture: Very cobbly or extremely cobbly with fines being hydrous loam or hydrous silt loam or coarse sand.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Kau soils are on south and southeast windward slopes of Mauna Loa volcano and younger lava flows on windward Mauna Kea volcano at elevations of 1,372 to 1,829 meters (4,500 to 6,000 feet). The soils formed on all hillslope positions in basic volcanic ash on undulating to hilly `a`a flows 5,000 to 10,000 years old. Slopes range from 3 to 50 percent. Mean annual rainfall is 1,500 to 2,500 millimeters (60 to 100 inches), with about 75 percent of the rainfall occurring between October and April. Mean annual pan evaporation ranges from 1,772 to 1,397 millimeters (45 to 55 inches). The mean annual air temperature is 12 to 14 degrees C (54 to 57 degrees F).

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Kaholimo and Lalo. Kaholimo soils have lithic contact within 51 centimeters (20 inches). Lalo soils are not skeletal.

DRAINAGE AND PERMEABILITY: Well drained; moderate to high runoff; moderate or moderately rapid permeability.

USE AND VEGETATION: These soils are used for livestock grazing, forestland, and wildlife habitat. Vegetation is kikuyugrass (Pennisetum clandestinum), Koa (Acacia koa), ohia lehua (Metrosideros polymorpha), olapa (Cheirodendron trigynum), prickly Florida blackberry (Rubus argustus) and hapuu pulu or tree fern (Cibotium glaucum).

DISTRIBUTION AND EXTENT: These soils occur on Keauhou Ranch and the neighboring Kilauea Forest Reserve on Mauna Loa and on younger lava flows in the northern extent of the Hilo Forest Reserve on Mauna Kea; MLRA 160. The series is of small extent.

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

SERIES ESTABLISHED: Island of Hawaii, Hawaii, 2012. Proposed 2003. The soil is named for the island district in which type location occurs.

REMARKS: Diagnostic horizons and features (8th edition, Keys to Soil Taxonomy) recognized in this pedon are:
Andic soil properties - from the soil surface to 102 centimeters (40 inches).
Umbric epipedon - from the soil surface to 38 centimeters (15 inches).
Isomesic soil temperature regime.
Udic soil moisture regime.

National Cooperative Soil Survey
U.S.A.