LOCATION HAO HI
Established Series
Rev. KH-RTG-MRK
05/2012
HAO SERIES
The Hao series consists of deep and very deep, moderately well drained soils that formed in volcanic ash. Slopes range from 2 to 20 percent. The mean annual rainfall is about 3,680 millimeters (145 inches), and the mean annual air temperature is about 15 degrees C (59 degrees F).
TAXONOMIC CLASS: Medial, ferrihydritic, isothermic Typic Placaquands
TYPICAL PEDON: Hao medial silt loam, 3 percent slope under rain forest at an elevation of 1,067 meters (3,500 feet). (Colors are for moist soil unless otherwise noted. When described on 4/4/97 the soil was moist throughout. All textures are "apparent field textures". pH was determined by adjusting field organic dye values via regression to approximate pH in 1:1 water.)
A1--0 to 4 centimeters (0 to 2 inches); black (10YR 2/1) medial silt loam; moderate medium platy structure parting to moderate medium subangular blocky; friable, slightly sticky and slightly plastic, weakly smeary; many very fine to medium roots; many very fine and fine interstitial and tubular and few medium and coarse interstitial pores; 2 percent gravel; strongly acid (pH 5.4); abrupt wavy boundary.
A2--4 to 8 centimeters (2 to 3 inches); black (7.5YR 2.5/1) medial silt loam; weak medium subangular blocky structure; friable, slightly sticky and slightly plastic, weakly smeary; few very fine to medium roots between peds and matted at bottom of horizon; many very fine and fine interstitial pores; moderately acid (pH 5.7); abrupt wavy boundary. (Combined thickness of A horizons 5 to 13 centimeters (2 to 5 inches))
Bs--8 to 15 centimeters (3 to 6 inches); very dark brown (7.5YR 2.5/2) medial sandy clay loam over medial silt loam; massive; firm, moderately sticky and moderately plastic, weakly smeary; few very fine and fine roots; many very fine and fine interstitial pores; 0.3 to 0.6 centimeter (1/8 to 1/4 inch) dark red (2.5YR 3/6) and black (N 2/0) ironstone sheet mainly at top of horizon; few fine irregular prominent black (N 2/0) shot-like nodules that do not effervesce with hydrogen peroxide; few fine and medium prominent black (N 2/0) redox concentrations throughout; moderately acid (pH 5.7); abrupt wavy boundary. (5 to 10 centimeters (2 to 4 inches) thick)
Bw--15 to 20 centimeters (6 to 8 inches); very dark brown (7.5YR 2.5/2) medial silty clay loam; weak medium subangular blocky structure; friable, slightly sticky and slightly plastic, weakly smeary; common very fine to medium roots; many very fine and fine interstitial pores; common fine and medium prominent black (N 2/0) redox concentrations throughout; moderately acid (pH 6.0); clear wavy boundary. (3 to 8 centimeters (1 to 3 inches) thick)
2A--20 to 23 centimeters (8 to 9 inches); black (10YR 2/1) medial silty clay loam; weak medium subangular blocky structure; friable, slightly sticky and slightly plastic, weakly smeary; common very fine and fine and few medium roots; many very fine and fine interstitial pores; 2 percent gravel; moderately acid (pH 6.0); clear wavy boundary. (0 to 5 centimeters (0 to 2 inches) thick)
2Bs--23 to 25 centimeters (9 to 10 inches); black (7.5YR 2.5/1) medial sandy clay loam; massive; firm, moderately sticky and moderately plastic, weakly smeary; common very fine and fine and few medium roots; many very fine to medium interstitial pores; common fine and medium irregular black (5YR 2.5/1) and dark reddish brown (5YR 3/3) masses of ironstone at top of horizon; common dark brown (7.5YR 3/3) gravel-size sand masses near top of horizon; slightly acid (pH 6.3); clear wavy boundary. (0 to 5 centimeters (0 to 2 inches) thick)
3A1--25 to 30 centimeters (10 to 12 inches); very dark brown (7.5YR 2.5/2) medial silty clay loam; massive; friable, slightly sticky and slightly plastic, weakly smeary; common very fine and fine and few very coarse roots; many very fine and fine interstitial pores; many common fine, medium, and coarse prominent black (N 2/0) redox concentrations throughout; slightly acid (pH 6.3); abrupt wavy boundary. (0 to 5 centimeters (0 to 2 inches) thick)
3A2--30 to 34 centimeters (12 to 13 inches); dark reddish brown (5YR 2.5/2) medial silty clay loam; weak medium subangular blocky structure; friable, slightly sticky and slightly plastic, weakly smeary; common very fine and fine and few medium roots; many very fine and fine interstitial pores; many common fine, medium, and coarse distinct black (10YR 2/1) redox concentrations throughout; slightly acid (pH 6.3); clear wavy boundary. (0 to 5 centimeters (0 to 2 inches) thick)
3Bs--34 to 38 centimeters (13 to 15 inches); dark reddish brown (5YR 2.5/2) medial sandy clay loam; massive; firm, moderately sticky and moderately plastic, weakly smeary; common very fine to medium roots; many very fine and fine interstitial pores; few fine irregular black (5YR 2.5/1) and dark reddish brown (5YR 3/3) masses of ironstone at top of horizon; many fine, medium, and coarse faint dark reddish brown (5YR 3/3) redox concentrations throughout; slightly acid (pH 6.3); abrupt wavy boundary. (0 to 5 centimeters (0 to 2 inches) thick)
3Bw1--38 to 46 centimeters (15 to 18 inches); very dark brown (7.5YR 2.5/2) medial silty clay loam; weak medium subangular blocky structure; friable, slightly sticky and slightly plastic, weakly smeary; common very fine and fine and few medium roots; few distinct patchy black (N 2/0), organic coats in root channels; many very fine and fine interstitial pores; many fine, medium, and coarse prominent black (N 2/0) redox concentrations at 16 inches and common fine prominent dark red (10R 3/6) redox concentrations under black redox concentrations; slightly acid (pH 6.3); clear wavy boundary. (3 to 10 centimeters (1 to 4 inches) thick)
3Bw2--46 to 53 centimeters (18 to 21 inches); very dark brown (7.5YR 2.5/2) medial silty clay loam; massive; friable, slightly sticky and slightly plastic, weakly smeary; few very fine and fine roots; many very fine and fine interstitial pores; 5 percent gravel; common medium prominent black (N 2/0) and common fine and medium prominent red (2.5YR 4/6) redox concentrations throughout; slightly acid (pH 6.3); abrupt wavy boundary. (3 to 10 centimeters (1 to 4 inches) thick)
3Bw3--53 to 58 centimeters (21 to 23 inches); very dark brown (7.5YR 2.5/3) medial sandy clay loam; massive; firm, moderately sticky and moderately plastic, weakly smeary; few very fine and fine roots; many very fine and fine interstitial pores; few fine irregular black (N 2/0) hard masses; many fine and medium distinct yellowish red (5YR 4/6) and few fine and medium prominent black (N 2/0) redox concentrations throughout; slightly acid (pH 6.3); abrupt wavy boundary. (3 to 8 centimeters (1 to 3 inches) thick)
3Bg--58 to 61 centimeters (23 to 24 inches); gray (N/6) medial fine sandy loam; massive; friable, nonsticky and nonplastic, nonsmeary; few very fine and fine roots; many very fine and fine interstitial pores; many fine, medium, and coarse prominent red (2.5YR 4/6) threads of redox concentrations throughout; slightly acid (pH 6.3); clear wavy boundary. (0 to 5 centimeters (0 to 2 inches) thick)
4A1--61 to 64 centimeters (24 to 25 inches); very dark brown (7.5YR 2.5/2) medial silty clay loam; massive; friable, moderately sticky and moderately plastic, moderately smeary; few very fine and fine roots; many very fine and fine interstitial pores; few fine irregular black (N 2/0) hard masses; neutral (pH 6.6); clear wavy boundary. (0 to 5 centimeters (0 to 2 inches) thick)
4A2--64 to 76 centimeters (25 to 30 inches); very dark brown (7.5YR 2.5/2) medial silty clay loam; massive; friable, slightly sticky and slightly plastic, moderately smeary; few very fine and fine roots; many very fine and fine interstitial pores; very few distinct thin continuous black (10YR 2/1), thin clay films in root channels and pores; 10 percent indurated ash; common fine and medium prominent black (N 2/0) and few medium prominent yellowish red (5YR 4/6) redox concentrations throughout; neutral (pH 6.6); clear wavy boundary. (8 to 15 centimeters (3 to 6 inches) thick)
4Bw/5Cm--76 to 104 centimeters (30 to 41 inches); very dark brown (7.5YR 2.5/2) medial silty clay loam; massive; friable, slightly sticky and slightly plastic, moderately smeary; few very fine and fine roots; many very fine and fine interstitial pores; few faint patchy very dark brown (7.5YR 2.5/2) clay films on horizontal faces of peds and few distinct continuous very dark brown (7.5YR 2.5/2) clay films in root channels and pores; 30 percent dark reddish brown (5YR 3/4) indurated ash; common fine and medium prominent black (N 2/0) and common prominent yellowish red (5YR 4/6) redox concentrations throughout; slightly acid (pH 6.2); diffuse wavy boundary.
5R--104 to 152 centimeters (41 to 60 inches); dark reddish brown (5YR 3/4) indurated ash. (Combined thickness of 5Cm horizon more than 50 centimeters (20 inches))
TYPE LOCATION: From State Hwy 11, drive 2.2 miles northwest on State Hwy 148 (Wright Road) to the Olaa tract of Hawaii Volcanoes National Park; walk east along Park boundary fence approximately 2 miles to where fence turns north; walk north along fence approximately 900 meters (3000 feet); type location is 4 meters (12 feet) northwest of the fence; Volcano Quadrangle; lat. 19 degrees 28 minutes 47.52 seconds N. and long. 155 degrees 13 minutes 32.85 seconds W. (Old Hawaiian Datum measured by GPS/PLGR.)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 15 to 18 degrees C (59 to 64 degrees F).
Depth to indurated ash: 104 to 137 centimeters (41 to 54 inches).
Soil reaction: Strongly acid to slightly acid.
A horizon
Hue: 5YR to 10YR.
Texture: Medial silt loam and medial loam.
Structure: Granular, subangular blocky.
Soil reaction: Very strongly acid to moderately acid.
B horizon
Hue: 10R, 2.5YR to 10YR.
Texture: Medial sandy loam, medial sandy clay loam, medial loam, medial silt loam, or medial silty clay loam.
Structure: Subangular blocky or massive.
Soil reaction: Strongly acid or moderately acid.
Nodules: Fine shot-like hard black masses that do not effervesce with hydrogen peroxide occur in most horizons.
COMPETING SERIES: There are no competing series in this family.
GEOGRAPHIC SETTING: Hao series formed in material weathered from two main basic volcanic ash packets: Uwekahuna ash 2,000 to 3,000 years old, and an unnamed ash about 10,000 years old over Mauna Loa landforms about 10,000 years old. Elevations range from 975 to 1,372 meters (3,200 to 4,500 feet). Slopes range from 2 to 20 percent. Mean annual rainfall is 2,921 to 4,064 millimeters (115 to 160 inches), with about 75 percent of the rainfall occurring between November and May. The mean annual pan evaporation is 1,016 to 1,270 millimeters (40 to 50 inches). The mean annual air temperature is 13 to 21 degrees C (55 to 70 degrees F).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Puaulu,
Eheuiki, and Lithic Endoaquands soils. Puaulu soils do not have placic horizons. Eheuiki soils do not have placic or densic horizons and have more than 35 percent coarse fragments in the lower part of the subsoil. Lithic Endoaquands soils have bedrock at less than 50 centimeters (20 inches).
DRAINAGE AND PERMEABILITY: Moderately well drained. Runoff is medium. Permeability is moderate.
USE AND VEGETATION: These soils are used for National Park Service land and State of Hawaii Forest Reserve land. Vegetation is banana poka (Passiflora mollissima), kawau or Hawaiian Holly (Ilex anomala), koa (Acacia koa), loulu (Pritchardia beccariana), ohia lehua (Metrosideros polymorpha), olapa (Cheirodendron trigynum), hapuu pulu or tree fern (Cibotium glaucum), and yellow Himalayan raspberry (Rubus ellipticus).
DISTRIBUTION AND EXTENT: These soils occur in the Olaa portion of Hawaii Volcanoes National Park and the adjoining State of Hawaii Olaa Forest Reserve; MLRA 159A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii; 1996. The name is coined from the Hawaiian word for iron.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
-- Soil temperature - mean summer and mean winter soil temperatures differ by less than 6 degrees C (iso temperature regime).
-- Soil moisture - precipitation exceeds evapotranspiration in all months in normal years (perudic moisture regime).
-- Andic soil properties - from 0 to 117 centimeters (0 to 46 inches).
Placic horizon - from 8 to 15 centimeters (3 to 6 inches) (Bs horizon), and 23 to 25 centimeters (9 to 10 inches) (2Bs horizon).
-- Densic material - from 8 to 15 centimeters (3 to 6 inches) (Bs horizon); 23 to 25 centimeters (9 to 10 inches) (2Bs horizon); and 34 to 38 centimeters (13 to 15 inches) (3Bs horizon).
-- Aquic condition - from 58 to 61 centimeters (23 to 24 inches) (3Bg horizon).
Edit Log: 12/03 KH. Added "medial" modifier to textures; changed horizon designation 5Cm from 5Bsm; and made minor changes in horizon depth and color. 02/2012 MRK. Updated temperature data.
2/01 KH. Permeability changed from slow to moderately slow.
ADDITIONAL DATA: Similar soil is Puaulu, NSSL S96HI-001-001.
National Cooperative Soil Survey
U.S.A.