LOCATION ALAPAI HI
Established Series
Rev. SN/CWS/MRK
05/2012
ALAPAI SERIES
The Alapai series consists of very deep well drained soils that formed in material weathered from basic volcanic ash. Alapai soils are on uplands and have slopes of 2 to 40 percent. The mean annual rainfall is about 3048 millimeters (120 inches) and the mean annual temperature is about 18 degrees C (65 degrees F).
TAXONOMIC CLASS: Hydrous, ferrihydritic, isothermic Typic Hydrudands
TYPICAL PEDON: Alapai hydrous silty clay loam on a southeast facing, convex, 6 percent slope, under abandoned sugarcane, at an elevation of 666 meters (2,185 feet). (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
Ap1--0 to 18 centimeters (0 to 7 inches); very dark brown (10YR 2/2) hydrous silty clay loam; moderate fine and very fine subangular blocky structure; friable, slightly sticky and slightly plastic; weakly smeary; common fine roots; common very fine irregular and tubular pores; 2 percent olivine crystals less than 1 millimeter in diameter; 2 percent firm and very firm, dark red (2.5YR 3/6) 1 to 4 millimeter cinders; very strongly acid (pH 4.7); abrupt wavy boundary. (13 to 23 centimeters {5 to 9 inches} thick)
Ap2--18 to 38 centimeters (7 to 15 inches); dark reddish brown (5YR 3/3) hydrous silty clay loam; moderate fine and very fine subangular blocky structure; friable, slightly sticky and moderately plastic; weakly smeary; common fine roots; common very fine and fine interstitial and tubular pores; common patches of gelatin-like coatings on surfaces of peds; moderately acid (pH 5.9); clear wavy boundary. (15 to 28 centimeters (6 to 11 inches) thick)
B/A--38 to 69 centimeters (15 to 27 inches); 50 percent dark brown (7.5YR 3/2) and 50 percent dark reddish brown (5YR 3/3) hydrous silty clay loam; moderate medium subangular blocky structure parting to moderate fine and very fine subangular blocky; friable, slight sticky moderately plastic; weakly smeary; common very fine roots; many very fine and fine interstitial and tubular pores; 2 percent firm to very firm, dark red (2.5YR 3/6) 1 to 4 millimeters cinders; neutral (pH 6.6); abrupt wavy boundary . (9 to 14 inches thick)
Bw1--69 to 91 centimeters (27 to 36 inches); dark reddish brown (5YR 3/4) hydrous silty clay loam; moderate medium subangular blocky structure parting to moderate fine and very fine subangular blocky; friable, slightly sticky moderately plastic; moderately smeary; few very fine roots; many very fine and fine tubular, common medium and few coarse interstitial pores; 2 percent firm to very firm, dark reddish brown (2.5YR 3/4) 1 to 4 millimeter cinders; slightly acid (pH 6.3); abrupt smooth boundary. (15 to 23 centimeters (6 to 9 inches) thick)
Bw2--91 to 109 centimeters (36 to 43 inches); 50 percent dark brown (7.5YR 3/4) and 50 percent dark reddish brown (5YR 3/4) hydrous silty clay loam; moderate fine and very fine subangular blocky structure; friable, slightly sticky moderately plastic; moderately smeary; few very fine roots; many very fine and fine tubular, common medium and few coarse interstitial pores; few, thin gelatin-like coatings on surfaces of peds; 2 percent firm to very firm, dark reddish brown (2.5YR 3/4) 1 to 4 millimeters cinders; slightly acid (pH 6.5); abrupt smooth boundary. (15 to 20 centimeters {6 to 8 inches} thick)
Bw3--109 to 127 centimeters (43 to 50 inches); 80 percent dark reddish brown (5YR 3/4) hydrous silty clay loam; moderate medium subangular blocky structure parting to moderate fine and very fine subangular blocky; friable, slightly sticky moderately plastic; moderately smeary; few very fine roots; many very fine and fine tubular, common medium and few coarse interstitial pores; few, thin gelatin-like coatings on surfaces of peds; 10 percent firm to very firm, dark reddish brown (2.5YR 3/4) 1 to 4 millimeter cinders; neutral (pH 6.7); abrupt smooth boundary. (13 to18 centimeters {5 to 6 inches} thick)
Bw4--127 to145 centimeters (50 to 57 inches); 50 percent dark reddish brown (5YR 3/4) and 50 percent dark brown (7.5YR 3/4) hydrous silty clay loam; moderate medium subangular blocky structure parting to moderate fine and very fine subangular blocky structure; friable, slightly sticky and moderately plastic; moderately smeary; few very fine roots; many very fine and fine tubular, common medium and few coarse interstitial pores; common, thin gelatin-like coatings on surfaces of peds; common, gray (7.5YR 5/1) and black (10YR 2/1) specks; 10 percent firm to very firm, dark reddish brown (2.5YR 3/4) 1 to 4 millimeters cinders; neutral (pH 6.8); abrupt smooth boundary. (15 to 18 centimeters {6 to 7 inches} thick)
Bw5--145 to 168 centimeters (57 to 66 inches); stratified bands of dark brown (7.5YR 3/3), reddish brown (5YR 4/4) and dark brown (10YR 3/3) hydrous silty clay loam; moderate coarse and medium subangular blocky structure parting to moderate fine and very fine subangular blocky structure; friable, slightly sticky moderately plastic; strongly smeary; few very fine roots; many very fine and fine tubular, common medium and coarse interstitial pores; common, thick gelatin-like coatings on surfaces of peds; 10 percent, fine, dark reddish brown (2.5YR 3/3) mottles; neutral (6.8); abrupt smooth boundary. (20 to 25 centimeters {8 to 10 inches} thick)
Bw6--168 to 178 centimeters (66 to 70 inches); dark reddish brown (2.5YR 2/4) hydrous silty clay loam. massive parting to weak medium and fine subangular blocky structure; very firm, slightly sticky moderately plastic; strongly smeary; few very fine roots; many very fine and fine tubular, common medium interstitial pores; common, thick gelatin-like coatings on surfaces of peds; neutral (pH 6.7); abrupt, smooth boundary. (8 to 13 centimeters {3 to 5 inches} thick)
Bw7--178 to 188 centimeters (70 to 74 inches); 25 percent dark reddish brown (2.5YR 3/4), 25 percent brown (7.5YR 4/4), 25 percent strong brown (7.5YR 4/6), and 25 percent yellowish brown (10YR 5/6) hydrous silty clay loam; moderate medium, fine, and very fine subangular blocky structure; friable, slightly sticky, moderately plastic; strongly smeary; few very fine roots; many very fine and fine tubular, common medium interstitial pores; common, thick gelatin-like coatings on surfaces of peds; slightly acid (pH 6.3).
TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; from Naalehu town, drive 1.9 miles north on Kaalaiki Road, turn west and drive 2.1 miles to elevation 640 meters (2,100 feet), turn southwest at road junction and drive 0.4 miles. Pedon is located 48 meters (158 feet) upslope of road at elevation of 666 meters (2,185 feet). Naalehu Quadrangle; lat. 19 degrees 5 minutes 22 seconds N. and long. 155 degrees 36 minutes 32 seconds W. (Old Hawaiian Datum)
RANGE IN CHARACTERISTICS:
Depth to bedrock: more than 152 centimeters (60 inches).
Mean annual soil temperature: 16 to 20 degrees C (61 to 68 degrees F).
Rock fragments: 0 to 10 percent by volume of the pedon and range from gravel to cobble size lava rocks.
A horizon
Hue: 5YR to 10YR
Value: 2 or 3 moist.
Chroma: 2 or 3 moist.
Texture: Medial or hydrous silt loam or silty clay loam.
Stickiness: Slightly sticky or moderately sticky.
Plasticity: Slightly plastic or moderately plastic.
Bw horizons
Hue: 5YR to 10YR.
Chroma: 2 to 4 moist.
Stickiness: Slightly sticky to moderately sticky.
Smeariness: Moderately smeary to strongly smeary.
Mottles: 1 to 10 percent in the lower Bw horizons.
Weathered cinders: 2 to 10 percent, firm or very firm dark reddish brown (2.5YR 3/4) to dark red (2.5YR 3/6).
Reaction: Slightly acid to neutral (pH 6.1 to 6.8)
COMPETING SERIES: These are the
Honaunau,
Honuapo,
Kailua,
Kealakekua,
Kukaiau, and
Makaala series. Honaunau, Honuapo and Makaala soils have a lithic contact at 50 to 102 centimeters (20 to 40 inches). Kailua soils are silty clay in the control section. Kealakekua soils are 30 to 48 inches deep over bedrock. Kukaiau soils are at elevations of 500 to 1,500 feet and have corresponding mean annual soil temperature about 68 degrees F. and the B horizon irreversibly dehydrates into sand and silt sized aggregates.
GEOGRAPHIC SETTING: Alapai soils are on mid elevation windward mountain slopes on the undissected upland of Mauna Loa Volcano at elevations from 487 to 1,220 meters (1,600 to 4,000 feet). The soils are on all hillslope positions of nearly level to steep lava flows. Slope gradients range from 2 to 40 percent. The soils formed in basic volcanic ash. The mean annual rainfall ranges from 1,524 to 3,810 millimeters (60 to 150 inches), with most of the rainfall occurring from October through April. The mean annual pan evaporation ranges from 640 to 1,270 meters (25 to 50 inches). The mean annual temperature ranges from 16 to 21 degrees C (61 to 70 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
Akihi,
Hilea, and the competing
Honuapo series. Akihi soils have a lithic contact at 50 to 102 centimeters (20 to 40 inches) and are in `a`a lava. Hilea soils have a lithic contact at 5 to 50 centimeters (2 to 20 inches) and are over pahoehoe lava.
DRAINAGE AND PERMEABILITY: Well drained; very low to high runoff; rapid permeability.
USE AND VEGETATION: Used for orchard crops, agroforestry, and grazing. The natural vegetation is ohia lehua (Metrosideros polymorpha), guava (Psidium guajava), hilograss (Paspalum conjugatum) and Californiagrass (Brachiaria mutica).
DISTRIBUTION AND EXTENT: Kau District, Island of Hawaii; MLRA 159B. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: County of Hawaii, Hawaii, 1971.
REMARKS:
FCC Classification: Chkx.
Edit Log: Soil moisture moist in all months (Perudic moisture regime).
Diagnostic horizons and features recognized in this pedon are:
Andic soil properties 0 to 188 centimeters (0 to 74 inches) (Ap, B/A and Bw horizons).
Umbric epipedon 0 to 69 centimeters (0 to 27 inches) (Ap and B/A horizons).
Cambic horizon 69 to 188 centimeters (27 to 74 inches) (Bw horizons).
Edit log: 12/8/00 Classification revised due to changes in Soil Taxonomy. Old classification: Thixotropic, isothermic Typic Hydrandepts. Competing series updated. MRK. 12/03 SN. Horizon designations updated; added FCC.
5/01 SN. Classification changed from Thixotropic, isothermic Typic Hydrandepts due to changes in Taxonomy.
ADDITIONAL DATA: Alapai NSSL sample S93HI-001-002.
National Cooperative Soil Survey
U.S.A.