LOCATION HOKUKANO HIEstablished Series
TAXONOMIC CLASS: Medial, amorphic, isomesic Lithic Fulvudands
TYPICAL PEDON: Hokukano medial silt loam, on a west facing, slightly concave, 5 percent slope in pasture at an elevation of 1839 meters (6035 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 July 30, 1997, the soil was slightly moist throughout.)
A--0 to 15 centimeters (0 to 6 inches); very dark brown (7.5YR 2.5/2) medial silt loam, brown (7.5YR 4/2) dry; strong fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; slightly smeary; many very fine and few fine, and very few medium roots; many very fine interstitial pores; 5 percent subangular cobbles; slightly acid (pH 6.2); abrupt smooth boundary. (13 to 18 centimeters {5 to 7 inches} thick)
Bw1--15 to 25 centimeters (6 to 10 inches); dark reddish brown (2.5YR 3/4) cobbly medial silt loam, red (2.5YR 4/6) dry; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine interstitial pores; 10 percent subangular cobbles and 5 percent subangular gravel; slightly acid (pH 6.2); clear wavy boundary.
Bw2--25 to 50 centimeters (10 to 20 inches); dark reddish brown (5YR 3/3) cobbly medial silt loam, brown (7.5YR 4/4) dry; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; slightly smeary; many very fine and fine roots; many very fine interstitial pores; 15 percent subangular cobbles and 5 percent subangular gravel; moderately acid (pH 5.6); abrupt wavy boundary. (Combined thickness of the Bw horizon is 15 to 41 centimeters {6 to 16 inches} thick.)
2R--50 centimeters (20 inches); hard, massive pahoehoe lava.
TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; on Kealia Ranch, drive 1.0 mile north of Komakawai waterholes; pedon is located 21 meters (70 feet) west of ranch road and 49 meters (160 feet) south of the next `a`a flow. Kaunene Quadrangle; lat. 19 degrees 24 minutes 53.3 seconds N. and long. 155 degrees 46 minutes 31.9 seconds W. (GPS/PLGR; Old Hawaiian Datum).
RANGE IN CHARACTERISTICS:
Depth to bedrock: 25 to 50 centimeters (10 to 20 inches).
Mean annual soil temperature: 13 to 15 degrees C. (55 to 59 degrees F.)
Rock fragments: 0 to 15 percent by volume of the pedon and range in size from gravel to cobbles.
A horizon
Hue: 2.5YR to 10YR.
Value: 2 or 3 moist or 3 or 4 dry.
Chroma: 1 or 2 moist or 2 or 3 dry.
Wet consistence: Nonsticky or slightly sticky, and nonplastic or slightly plastic throughout.
Soil reaction: Strongly acid to slightly acid (pH 5.6 to 6.5).
Bw horizon
Chroma: 2 to 4 moist or 4 to 6 dry.
Soil reaction: Moderately acid to slightly acid (pH 5.6 to 6.5).
This horizon is discontinuous in some pedons.
COMPETING SERIES: There are no competing series. Similar soils include the Manahaa series. Manahaa soils are hydrous in the control section and have a lithic contact at 50 to 102 centimeters (20 to 40 inches).
GEOGRAPHIC SETTING: Hokukano soils are on upper elevation, leeward slopes on the uplands of Hualalai and Mauna Loa volcanoes at elevations from 1067 to 2133 meters (3500 to 7000 feet). These soils are on all hillslope positions of constructional landscapes consisting of nearly level to moderately steep pahoehoe lava flows that are 3,000 to 5,000 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 510 to 1270 millimeters (20 to 50 inches), with most of the rainfall occurring from April through October. The mean annual air temperature ranges from 12 to 14 degrees C. (53 to 57 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 Hapu`u, Kealoha, Kekake, Mawae, and Pu`ukala series, and the similar Manaha`a series. Hapu`u soils are sandy-skeletal. Kealoha and Pu`ukala soils are medial-skeletal. Kekake and Mawae soils are organic soils.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is negligible in depressions on gentle slopes and medium to high on steeper slopes. Permeability is moderately rapid in the soil and very slow in the underlying pahoehoe bedrock.
USE AND VEGETATION: Used primarily for grazing. The natural vegetation is kikuyugrass (Pennisetum clandestinum).
DISTRIBUTION AND EXTENT: North and South Kona districts, Island of Hawaii; MLRA 159 and 161. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii
1997.
REMARKS: Soil moisture - moist and are not dry in any part for 90 or more days (Udic moisture regime).
Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - from 0 to 15 centimeters (0 to 6 inches) (A horizon).
Cambic horizon - from 15 to 50 centimeters (6 to 20 inches) (Bw horizons).
Lithic contact - at 50 centimeters (20 inches) (2R horizon).
Andic soil properties - from 0 to 50 centimeters (0 to 20 inches) (A and Bw horizons).
Editlog: 2/5/08 Andic texture modifiers added to horizon textures. MRK
ADDITIONAL DATA: Hokukano NSSL sample S97HI-001-013.