LOCATION POHAKULEHU HI
Established Series
CDJ
06/2012
POHAKULEHU SERIES
The Pohakulehu series consists of deep or very deep, well drained soils that formed in volcanic ash and `a`a lava. Slopes range from 6 to 50 percent. The mean annual rainfall is about 500 millimeters (20 inches) and the mean annual temperature is about 12 degrees C (53 degrees F).
TAXONOMIC CLASS: Ashy-skeletal over fragmental or cindery, amorphic over mixed, isomesic Humic Ustivitrands
TYPICAL PEDON: Pohakulehu very stony highly organic medial sandy loam, on a south facing, 18 percent slope, in chaparral, at an elevation of 8,220 feet (2,506 meters). When described the soil was dry throughout. (Colors are for moist soil unless otherwise noted).
A/2C1--0 to 10 centimeters (0 to 4 inches); very dark brown (10YR 2/2) very stony highly organic medial sandy loam, brown (7.5YR 4/2), dry; weak very fine subangular blocky structure; very friable, soft, nonsticky, slightly plastic; weakly smeary; moderate excavation difficulty; common fine roots throughout and common medium roots throughout; common very fine irregular pores; 10 percent very angular very strongly cemented 2- to 75-millimeter `a`a fragments and 15 percent very angular very strongly cemented 75- to 250-millimeter `a`a fragments and 15 percent very angular very strongly cemented 250- to 610-millimeter `a`a fragments; noneffervescent, by HCl, 1 normal; strongly acid, pH 5.4, pH meter 1:1 water; very strongly hydrophobic when dry; the 2C part of this horizon consists of unconsolidated `a`a lava fragments of variable size; abrupt smooth boundary. (thickness of the A horizon is 5 to 15 centimeters (2 to 6 inches))
Bw1--10 to 24 centimeters (4 to 9 inches); very dark brown (10YR 2/2) stony ashy loamy sand, dark yellowish brown (10YR 3/4), dry; weak medium subangular blocky structure; very friable, soft, nonsticky, nonplastic; nonsmeary; moderate excavation difficulty; few fine roots throughout and few medium roots throughout; 5 percent very angular very strongly cemented 2- to 75-millimeter `a`a fragments and 10 percent very angular very strongly cemented 250- to 610-millimeter `a`a fragments and 10 percent very angular very strongly cemented 75- to 250-millimeter `a`a fragments; noneffervescent, by HCl, 1 normal; neutral, pH 7.3, pH meter 1:1 water; abrupt smooth boundary.
Bw2/2C2--24 to 68 centimeters (9 to 27 inches); variable soil colors; stratified very stony ashy sandy loam ranging to very stony coarse sand; weak medium subangular blocky structure ranging to single grain; weakly smeary to nonsmeary; high excavation difficulty; common fine roots throughout and common medium roots throughout and common coarse roots throughout; 15 percent very angular very strongly cemented 250- to 610-millimeter `a`a fragments and 15 percent very angular very strongly cemented 75- to 250-millimeter `a`a fragments and 15 percent very angular very strongly cemented 2- to 75- millimeter `a`a fragments; noneffervescent, by HCl, 1 normal; slightly alkaline, pH 7.5, pH meter 1:1 water; the 2C part of this horizon consists of unconsolidated `a`a lava fragments of variable size; clear wavy boundary. (combined thickness of the Bw horizon is 30 to 150 centimeters (12 to 59 inches))
2C3--68 to 132 centimeters (27 to 52 inches); stones; very high excavation difficulty; common coarse interstitial pores; 45 percent very angular very strongly cemented 250- to 610-millimeter `a`a fragments and 25 percent very angular very strongly cemented 75- to 250-millimeter `a`a fragments and 25 percent very angular very strongly cemented 2- to 75-millimeter `a`a fragments; noneffervescent, by HCl, 1 normal.(thickness of the 2C horizon when present is 40 to 100 centimeters (16 to 40 inches))
TYPE LOCATION: Hawaii County, Hawaii, Travel up the Mauna Kea observatory road, turn right on 2 track road located just makai of the DHHL lands. Pit is located on north side of the road about 50 meters before the road terminates. 19 degrees North latitude, 44 minutes, 31 seconds and 155 degrees, 26 minutes, 55 seconds West longitude, Old Hawaiian Datum - U.S.G.S Quad: Puu Oo, Hawaii.
RANGE IN CHARACTERISTICS:
Depth to bedrock: 101 to 200 centimeters (40 to 80 inches)
Mean annual soil temperature: 8 to 15 degrees C (47 to 59 degrees F).
Coarse fragments: 35 to 75 percent of the pedon
A horizons
Hue: 7.5YR or 10YR
Value: 2 or 3 moist and 2 through 4 dry
Chroma: 1 through 3 moist and 2 through 4 dry
Texture: Extremely or very, stony or cobbly, medial very fine sandy loam, medial fine sandy loam, medial sandy loam or medial loam and may be highly organic
Structure: granular or subangular blocky
Consistence: nonsticky to slightly sticky and nonplastic to moderately plastic
Smeariness: nonsmeary to weakly smeary
Slightly to very strongly hydrophobic when dry.
Bw horizons
Hue: 7.5YR or 10YR
Value: 2 or 3 moist and 2 through 4 dry
Chroma: 1 through 3 moist and 2 through 4 dry
Texture: Extremely or very, stony or cobbly, ashy very fine sandy loam, ashy fine sandy loam, or ashy sandy loam
Structure: subangular blocky or single grain
Consistence: nonsticky to slightly sticky and nonplastic to moderately plastic
Smeariness: nonsmeary to weakly smeary
2C horizons when present consist of 90 to 100 percent `a`a rock fragments.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Pohakulehu soils are on high elevation slopes of Mauna Kea volcano at elevations from 2,134 to 3,048 meters (7,000 to 10,000 feet). These soils are on ash and cinder covered `a`a lava flows. Underlying lava flows are 14,000 to 250,000 years old. Slope gradients range from 6 to 50 percent. The mean annual rainfall ranges from 400 to 600 millimeters (16 to 24 inches), with most of the rainfall occurring from October through April. The mean annual pan evaporation ranges from 1,520 to 1,780 millimeters (60 to 70 inches). The mean annual air temperature ranges from 7 to 14 degrees C (45 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
Lanapohaku and
Lapa soils. Lanapohaku soils contain less than 35 percent rock fragments and Lapa soils are shallow to underlying bedrock.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is low. Permeability is rapid.
USE AND VEGETATION: Used for wildlife habitat. Natural vegetation is Mamane (Sophora chrysophylla), Pukiawe (Styphelia tameiameiae), Pilo (Coprosma spp.), common velvetgrass (Holcus lanatus), fireweed (Senecio madagascariensis), and orchardgrass (Dactylis glomerata L.).
DISTRIBUTION AND EXTENT: Hamakua district, Island of Hawaii; MLRA 160. The soils are of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Island of Hawaii, Hawaii County, Hawaii, 2012. Proposed 2007.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Andic Soil Properties from 0 to 60 centimeters (0 to 24 inches)
Mollic Epipedon from 0 to 25 centimeters (0 to 10 inches)
Cambic Horizon from 25 to 68 centimeters (10 to 27 inches)
Abrupt Textural Change at 68 centimeters (27 inches)
Strongly Contrasting Particle Size Class at 68 centimeters (27 inches)
National Cooperative Soil Survey
U.S.A.