LOCATION KAPAA HIEstablished Series
TAXONOMIC CLASS: Very-fine, sesquic, isohyperthermic Anionic
Acrudox
TYPICAL PEDON: Kapaa silty clay - sugarcane. (Colors are for moist soil unless otherwise noted. All textures are "apparent field textures.")
Ap--0 to 14 inches; dark brown (10YR 4/4) silty clay, dark yellowish brown (10YR 4/4) dry; weak fine granular structure; slightly hard, friable, sticky and plastic; many roots, matted at bottom of horizon; many pores; about 10 percent of volume made up of yellowish red (5YR 4/6) material turned up by plowing; sand size soil aggregates resistant to crushing that break down with prolonged rubbing; slight reaction to hydrogen peroxide; a few angular gibbsite aggregates up to one inch across on surface and mixed in soil; strongly acid (pH 4.8); abrupt smooth boundary. (12 to 14 inches thick)
B21--14 to 22 inches; yellowish red (5YR 4/6) silty clay, reddish brown (5YR 4/4) dry; weak medium subangular blocky structure; hard, friable, sticky and plastic; few roots; many fine and medium pores; thin coatings in pores, patchy coatings on faces of peds, coatings that look like clay films; about 5 percent weathered pebbles impregnated with gibbsite; medium acid (pH 5.6); clear smooth boundary. (4 to 8 inches thick)
B22--22 to 31 inches; yellowish red (5YR 4/6) light clay loam, strong brown (7.5YR 4/6) dry; weak, medium and fine subangular blocky structure; hard, friable, sticky, plastic and weakly smeary; few roots; many medium, fine and very fine pores; gelatin-like coatings in pores; patchy on peds; about 25 percent soft weathered pebbles impregnated with gibbsite; medium acid (pH 5.8); clear smooth boundary. (8 to 10 inches thick)
B23--31 to 38 inches; reddish brown (5YR 4/4) silty clay, strong brown (7.5YR 5/6) dry; weak medium and fine subangular blocky structure; slightly hard, friable; sticky and plastic; few roots; many medium, fine and very fine pores; gelatin-like coatings in pores, patchy on peds; about 10 percent soft weathered pebbles impregnated with gibbsite; discontinuous bands and lenses of yellowish material that is presumed to be gibbsite are present in this horizon; medium acid (pH 5.8); clear smooth boundary. (6 to 12 inches thick)
B24--38 to 45 inches; yellowish red (5YR 4/6) silty clay, yellowish red (5YR 5/6) dry; weak medium and fine subangular blocky structure; hard, friable, slightly sticky and plastic; few roots; many medium, fine and very fine pores, about 30 percent soft weathered pebbles impregnated with gibbsite and lesser amounts of other whitish material that looks like halloysite; some soft and hard reddish yellow (7.5YR 6/8) material; medium acid (pH 5.8); clear wavy boundary. (6 to 15 inches thick)
B25--45 to 60 inches; yellowish red (5YR 4/8) light clay loam, strong brown (7.5YR 5/6) dry; massive; hard, friable, sticky, plastic and weakly smeary; many medium, fine and very fine pores; 25 to 40 percent soft weathered pebbles impregnated with gibbsite and lesser amounts of whitish material that looks like halloysite; vertical bands of red (2.5YR 4/6) with 1/16" edge of dark reddish brown (2.5YR 3/4), very strongly acid (pH 5.4).
TYPE LOCATION: Kauai County, Hawaii; latitude 22 degrees 2' 42" north, longitude 159 degrees 23' 31" west; 6,600' N. 7.3 degrees W. of road corner of Hawaiian Sugar Planters Association Variety Test Station.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is about 72 degrees F. The A horizon has hue of 7.5YR through 2.5Y, chroma of 2 through 4, and value of 2 through 4. The B horizon has hue of 5YR or 7.5YR, value of 3 or 4, and chroma of 3 through 8. In some pedons the B horizon is light clay loam and silty clay loam. In some pedons hard, angular, weathered rock fragments and concretions occur in any horizon and range from few to many.
COMPETING SERIES: These are the Pooku series in the same family and the Halii, Kahanui, and Puhi series. Halii soils have ironstone-gibbsite pebbles in the A horizon and ferritic mineralogy and clay loam texture in the control section. Kahanui soils have ironstone-gibbsite pebbles in the A horizon, ferritic mineralogy, and a discontinuous ironstone sheet in the B horizon. Pooku soils contain many smooth, hardened ironstone-gibbsite pebbles in the A horizon, and have moderate structure and hue of 2.5YR or redder in the B horizon. Puhi soils have a silty clay loam control section and lack nodules or sheets that contain more than 30 percent gibbsite.
GEOGRAPHIC SETTING: The Kapaa soils occur on uplands and have slopes of 3 to 100 percent. Elevation ranges from 200 to 800 feet. The soils formed in residuum from basalt. Annual rainfall is 80 to 120 inches. Average January temperature is about 67 degrees F.; average July temperature is 73 degrees F. Mean annual temperature is 71 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Halii and Puhi soils.
DRAINAGE AND PERMEABILITY: Well drained; slow to very rapid runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used mainly for nonirrigated sugarcane on Kauai; most of it is brush pasture and woodland on Oahu. Vegetation on cultivated areas consists of ricegrass (Paspalum orbiculare), hilograss (Paspalum conjugatum), yellow foxtail (Setaria geniculata), Christmasberry (Schinus terebinthifolius), false staghorn fern (Dicranopteria linearis), kikuyugrass (Pennisetum clandestinum), rhodomyrtus tomentosa), melastoma (Melastoma malabathricum), guava (Psidium guajava), ohia (Metrosideros collina).
DISTRIBUTION AND EXTENT: Islands of Kauai and Oahu, Hawaii. This series is moderately extensive with approximately 22,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Kauai County, Island of Kauai, Hawaii, 1971.
OSED scanned by SSQA. Last revised by state on 10/77.