LOCATION IWALANI HIEstablished Series
TAXONOMIC CLASS: Medial, amorphic, isomesic Lithic Haplustands
TYPICAL PEDON: Iwalani medial loam, on a southwest facing, slightly concave slope, under dry land forest, at an elevation of 1295 meters (4250 feet). (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures". pH measured with organic dyes. When described on September 10, 1997 the soil was dry to 5 centimeters {2 inches} and slightly moist below.)
A--0 to 5 centimeters (0 to 2 inches); black (10YR 2/1) medial loam, very dark grayish brown (10YR 3/2) dry; strong medium platy parting to weak fine and medium granular structure; hard, very firm, nonsticky and nonplastic; nonsmeary; many very fine and fine roots; many very fine and fine interstitial pores; very strongly acid (pH 4.8); hydrophobic when dry; abrupt smooth boundary. (3 to 5 centimeters {1 to 2 inches} thick)
Bw--5 to 8 centimeters (2 to 3 inches); very dark brown (7.5YR 2/2) medial very fine sandy loam, dark brown (7.5YR 3/3) dry; strong coarse platy parting to weak fine and medium subangular blocky structure; hard, very firm, nonsticky and nonplastic; nonsmeary; few very fine and fine roots; many very fine and fine interstitial and common fine tubular pores; slightly acid (pH 6.4); abrupt smooth boundary. (3 to 5 centimeters {1 to 2 inches} thick)
A'--8 to 13 centimeters (3 to 5 inches); black (5YR 2/1) medial loamy sand, very dark brown (7.5YR 2/2) dry; single grain; loose when dry or moist, nonsticky and nonplastic; nonsmeary; common very fine and fine roots; many very fine and fine interstitial pores; 10 percent gravel; slightly acid (pH 6.2); abrupt broken boundary. (0 to 8 centimeters {0 to 3 inches} thick)
B'w--13 to 25 centimeters (5 to 10 inches); very dark brown (10YR 2/2) medial very fine sandy loam, dark brown (7.5YR 3/3) dry; moderate very fine and fine subangular blocky structure; soft, very friable; nonsticky and nonplastic; nonsmeary; common very fine and fine, and few coarse roots; many very fine and fine interstitial pores; 2 percent gravel and 5 percent cobbles; neutral (pH 6.6); abrupt broken boundary. (0 to 15 centimeters {0 to 6 inches} thick)
2R--25 centimeters (10 inches); hard pahoehoe lava.
TYPE LOCATION: Island of Hawaii, Hawaii County, Hawaii; in Hawaii Ocean View Estates, at the intersection of Mahimahi Dr. and Plumeria Ln., drive 0.2 miles northeast on Mahimahi Dr.; pedon is located 24 meters (80 feet) makai (downslope) of road between Plumeria Ln. and Pineapple Pkwy. Papa Quadrangle; lat. 19 degrees 8 minutes 28.4 seconds N. and long. 155 degrees 45 minutes 2.4 seconds W. (Old Hawaiian Datum)
RANGE IN CHARACTERISTICS:
Depth to bedrock: 5 to 25 centimeters (2 to 10 inches).
Mean annual soil temperature: 13 to 15 degrees C. (55 to 59 degrees F.)
Rock fragments: 0 to 35 percent by volume of the pedon and range in size from gravel to cobbles.
10 to 20 percent of these soils have a hard crust on the surface.
A horizon
Hue: 7.5YR or 10YR.
Texture: Medial loam or silt loam.
Structure: Strong platy or weak granular.
Dry consistence: Soft, but hard if surface crust is present.
Soil reaction: Very strongly acid or strongly acid (pH 4.5 to 5.4).
Bw horizon
Hue: 7.5YR or 10YR.
Value: 2 or 3 moist or dry.
Chroma: 1 to 3 moist or dry.
Texture: Medial loam, very fine sandy loam, or loamy sand.
Structure: Strong platy or moderate subangular blocky.
Soil reaction: Slightly acid or neutral (pH 6.1 to 7.3).
COMPETING SERIES: There are no competing series. Similar soils include the Hokukano, Kekake, and Pu`ukala series. Hokukano soils have a udic soil moisture regime. Kekake soils are organic soils over pahoehoe lava. Pu`ukala soils are medial-skeletal.
GEOGRAPHIC SETTING: Iwalani soils are on south and east slopes on the upland and the southwest rift zone of Mauna Loa Volcano at elevations from 1067 to 1646 meters (3500 to 5400 feet). These soils are on all hillslope positions of nearly level to moderately steep pahoehoe flows that are 1,500 to 3,000 years old. Slope gradients range from 2 to 50 percent. The soils formed in basic volcanic ash and cinders over pahoehoe lava. The mean annual rainfall ranges from 1020 to 1270 millimeters (40 to 50 inches), which is generally evenly distributed throughout the year. The mean annual pan evaporation ranges from 1270 to 1780 millimeters (50 to 70 inches). The mean annual temperature ranges from 12 to 14 degrees C. (53 to 57 degrees F.) The mean summer and mean winter soil temperatures differ by less than 6 degrees C. (11 degrees F.)
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Ihuanu series. Ihuanu soils are medial-skeletal and have a lithic contact at 25 to 50 centimeters (10 to 20 inches).
DRAINAGE AND PERMEABILITY: Well drained. Runoff is high or very high. Permeability is rapid in the soil and very slow in the underlying bedrock.
USE AND VEGETATION: These soils are used for wildlife habitat and homesites. The natural vegetation is ohia lehua (Metrosideros polymorpha) and pukiawe (Styphelia tameiameiae).
DISTRIBUTION AND EXTENT: Kau District, Island of Hawaii; MLRA 157 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, 2008 Proposed in 1997.
REMARKS: Soil moisture - usually moist, but dry in some or all parts for short intermittent periods totaling 90 or more days (Ustic moisture regime).
Diagnostic horizons and features recognized in this pedon include:
--Mollic epipedon - from 0 to 25 centimeters (0 to 10 inches) (A and Bw horizons).
--Andic soil properties - from 0 to 25 centimeters (0 to 10 inches) (A and Bw horizons).
--Lithic contact - at 25 centimeters (10 inches) (2R horizon).
Editlog: 2/5/08 Andic modifiers added to horizon texture and minor edits.MRK