LOCATION ONOMEA HI
Established Series
PGN/MRK/AMS
06/2012
ONOMEA SERIES
The Onomea series consists of deep and very deep, very poorly drained soils that formed in organic matter and volcanic ash over basaltic lava. Onomea soils are in bogs on mid elevation, northeast, windward slopes of Mauna Kea Volcano. Slopes range from 0 to 6 percent. The mean annual precipitation is about 5840 millimeters (230 inches) and the mean annual temperature is about 16 degrees C (61 degrees F).
TAXONOMIC CLASS: Hydrous, amorphic, nonacid, isothermic Histic Endoaquands
TYPICAL PEDON: Onomea muck, on an east facing 1 percent slope under a cover of sparse ohia lehua, sedges, and grasses at an elevation of 530 meters (1740 feet). When described the soil was saturated from 0 to 125 centimeters (0 to 49 inches). (Colors are for moist, crushed, soil unless otherwise noted).
Oa--0 to 15 centimeters (0 to 6 inches); very dark brown (10YR 2/2) rubbed, muck, very dark grayish brown (10YR 3/2) rubbed, dry; massive; soft, very friable, nonsticky, nonplastic; weakly smeary; many very fine and fine, and few medium roots throughout; common fine tubular pores; moderately acid, pH 5.9 by pH meter 1:1 water; clear smooth boundary.
Ag--15 to 35 centimeters (6 to 14 inches); very dark brown (10YR 2/2) crushed, mucky hydrous silt loam, very dark grayish brown (10YR 3/2) crushed, dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; weakly smeary; common very fine, fine, and medium roots throughout; common very fine and fine tubular pores; few fine distinct dark yellowish brown (10YR 4/6), moist, masses of oxidized iron, irregular, sharp boundaries in the matrix; moderately acid, pH 5.9 by pH meter 1:1 water; abrupt smooth boundary. (15 to 25 centimeters {6 to 10 inches} thick)
O'a--35 to 55 centimeters (14 to 22 inches); dark gray (10YR 4/1) rubbed, muck, brown (10YR 4/3) rubbed, dry; massive; slightly hard, very friable, slightly sticky, slightly plastic; strongly smeary; few fine roots throughout; common very fine tubular pores; few fine prominent reddish black (2.5YR 2/1), moist, nodules of iron-manganese, spherical, weakly cemented, sharp boundaries in matrix; moderately acid, pH 5.9 by pH meter 1:1 water; abrupt smooth boundary. (Combined thickness of Oa horizons is 35 to 60 centimeters {14 to 24 inches})
Bg--55 to 60 centimeters (22 to 24 inches); very dark brown (10YR 2/2) mucky hydrous loam, very dark grayish brown (10YR 3/2) crushed, dry; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; strongly smeary; few fine roots throughout; few very fine tubular pores; common fine distinct dark yellowish brown (10YR 4/6), moist, masses of oxidized iron, irregular, sharp boundaries in matrix; slightly acid, pH 6.2 by pH meter 1:1 water; abrupt smooth boundary. (5 to 25 centimeters {2 to 10 inches} thick)
Bhs--60 to 68 centimeters (24 to 27 inches); reddish black (2.5YR 2.5/1) mucky hydrous loam, dark reddish gray (2.5YR 3/1) crushed, dry; massive; slightly hard, friable, slightly sticky, slightly plastic; strongly smeary; few very fine tubular pores; slightly acid, pH 6.2 by pH meter 1:1 water; abrupt smooth boundary. (8 to 38 centimeters {3 to 15 inches} thick)
Bw--68 to 125 centimeters (27 to 49 inches); brown (10YR 4/3) mucky hydrous silty clay loam, grayish brown (10YR 5/2) crushed, dry; massive; slightly hard, very friable, slightly sticky, slightly plastic; strongly smeary; few very fine tubular pores; slightly acid, pH 6.2 by pH meter 1:1 water; abrupt smooth boundary. (34 centimeters {13 inches} thick or greater)
2R--125 centimeters (49 inches); hard basalt bedrock.
TYPE LOCATION: Island of Hawaii; just past mile marker 8 on Hwy 19 (Mamalahoa Hwy) turn due west (mauka) on Indian Tree Road. Follow road 0.7 miles through locked gate and then proceed on pasture road 3.7 miles to 19 degrees 47 minutes 30.1 seconds N., 155 degrees 8 minutes 54.2 seconds W. Park and walk 0.1 miles due west on forest trail. Turn due North and follow trail downhill to Kaieie stream. Cross stream to open bog area; Akaka Falls Quandrangle 19 degrees 47 minutes 48.1 seconds North latitude and 155 degrees 9 minutes 18.3 seconds West longitude, (Old Hawaiian Datum, +/- 6 ft., measured by GPSmap 76CSx).
RANGE IN CHARACTERISTICS:
Depth to bedrock: 105 to over 150 centimeters (41 to over 60 inches).
Soil moisture: The soil is typically satiated to the surface but may be wet from 0 to 30 centimeters (0 to 12 inches) during the driest months of the year, usually June thru August.
Soil temperature: 17 to 21 degrees C (62 to 70 degrees F).
Rock fragments: 0 to 30 percent `a`a rock fragments in the control section.
Oa horizons
Hue: 7.5YR to 10YR.
Value: 2 to 4 moist.
Chroma: 1 to 3 moist.
Texture: Muck or peaty muck.
Redoximorphic features: 0 to 2 percent 10YR 4/6 masses of oxidized iron and/or 2.5YR 2.5/1 nodules of iron-manganese.
Ag horizon (not present in all pedons)
Hue: 10YR.
Value: 2 or 3 moist.
Chroma: 1 or 2 moist.
Texture: Mucky hydrous silty clay loam or hydrous silt loam.
Bg horizons
Hue: 7.5 YR or 10YR.
Value: 2 to 4 moist.
Chroma: 1 to 2 moist.
Redoximorphic features: 2 to 20 percent masses of oxidized iron and/or 2 to 5 percent 2.5YR 2.5/1, 10YR2/2, or 5N masses of manganese in root channels or between peds.
Rock fragments: 0 to 30 percent cobble-sized `a`a rock fragments.
Bhs horizons
Hue: 2.5YR or 10YR.
Value: 2 to 3 moist.
Chroma: 1 to 3 moist.
Moist consistency: friable to extremely firm.
Bw horizons (not present in all pedons)
Hue: 10YR.
Value: 2 or 3 moist.
Chroma: 1 to 3 moist.
Redoximorphic features: 2 to 10 percent 10YR 4/6 masses of oxidized iron or 10YR 2/2 masses of manganese in root channels or between peds.
Rock fragments: 0 to 30 percent cobble-sized `a`a rock fragments.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Onomea soils are on mid-elevation windward slopes of Mauna Kea Volcano at elevations of 335 to 1615 meters (1100 to 5300 feet). These soils are found in bogs underlain by 100 to 300 thousand year old pahoehoe and `a`a lava flows at foot slopes and in micro depressions. Slopes are 0 to 6 percent. Mean annual precipitation is 5000 to over 6100 millimeters (200 to over 240 inches). The mean annual temperature is 15 to 21 degrees C (59 to 69 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
Kaiwiki and
Akaka soils. The Kaiwiki soils are well drained. Akaka soils are moderately well drained.
DRAINAGE AND PERMEABILITY: Very poorly drained. Runoff is very low. Permeability is moderately slow in the Oa and Bg horizons and slow to very slow in the Bhs horizon and underlying bedrock.
USE AND VEGETATION: These soils are used for forestland, livestock grazing, and wildlife habitat. Natural vegetation is sphagnum (Sphagnum spp.), uluhe fern or false staghorn fern (Dicranopteris linearis), or strawberry guava (Psidium catleianum), sedges (Carex spp.) and grasses (Poaceae). These consist mainly of Juncus, Carex, and Andropogon virginicus.
DISTRIBUTION AND EXTENT: These soils are not extensive with a total of about 8,500 acres. MLRA 159A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Island of Hawaii, 2012. Proposed 2011.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Aquic Moisture Regime.
Isothermic Temperature Regime.
Histic epipedon from 0 to 15 and 35 to 55 centimeters (0 to 6 and 14 to 22 inches)(Oa horizons).
Umbric epipedon from 15 to 35 centimeters (6 to 14 inches) (Ag horizon).
Cambic horizon from 68 to 125 centimeters (27 to 49 inches) (Bw horizon).
Sapric soil materials 0 to 15 and 35 to 55 centimeters (0 to 6 and 14 to 22 inches)(Oa horizons).
Andic soil properties 15 to 35 and 55 to 125 centimeters (6 to 14 and 22 to 50 inches) (Ag, Bg, Bhs, and Bw horizons).
Lithic contact 125 centimeters (49 inches) (R horizon).
ADDITIONAL DATA: NSSL pedons sampled as Onomea: S09HI001002 and S09HI001004
USER SITE ID: 08HI801315
National Cooperative Soil Survey
U.S.A.