LOCATION NGATPANG PW+PBEstablished Series
TAXONOMIC CLASS: Very-fine, halloysitic, isohyperthermic Typic Haploperox
TYPICAL PEDON: Ngatpang silty clay loam - on a 3 percent slope in an anthropic savannah. When described (11/2/79), the soil was moist throughout. (Colors are for moist soil. All textures, except in the C horizon are apparent field textures.)
A11--0 to 2 inches; dark brown (10YR 3/3) silty clay loam; moderate fine granular structure; friable, slightly sticky and slightly plastic; many very fine, common fine, and few medium roots; common very fine and fine, and few medium tubular pores within interstices; approximately 10 percent spherical solid iron concretions .1 to .2 inch in diameter; very strongly acid (pH 4.9, 1:1 water); clear smooth boundary. (1 to 8 inches thick)
A12--2 to 6 inches; 85 percent dark yellowish brown (10YR 4/4) silty clay loam and 15 percent fine blotches of dark brown (10YR 3/3) silty clay loam; moderate fine subangular blocky structure; firm, slightly sticky and slightly plastic; common very fine and fine roots and few medium roots; common very fine and fine and few medium tubular pores within interstices; common fine specks of light yellowish brown (10YR 6/4) gibbsite; common thin and moderately thick dark brown (10YR 3/3) coatings in root and worm channels; approximately 10 percent spherical solid iron concretions .1 to .2 inch in diameter; very strongly acid (pH 4.6, 1:1 water); gradual smooth boundary. (2 to 6 inches thick).
B1--6 to 11 inches; strong brown (7.5YR 4/6) gravelly silty clay; moderate fine subangular blocky structure; firm, slightly sticky and slightly plastic; common very fine and fine roots and few medium roots; common very fine and fine and few medium tubular pores within interstices; common thin and moderately thick coatings on faces of peds and lining pores; approximately 20 percent spherical iron concretions .1 to .2 inch in diameter; very strongly acid (pH 4.9, 1:1 water); clear smooth boundary. (2 to 8 inches thick)
B21--11 to 19 inches; 70 percent strong brown (7.5YR 4/6) clay and 30 percent yellowish red (5YR 5/8) clay; weak medium prismatic structure parting to strong very fine and fine angular blocky; firm, sticky and plastic; few very fine and fine roots along vertical faces of peds; common very fine and fine tubular pores within interstices; continuous thin coatings on faces of peds and lining pores; approximately 2 percent spherical iron concretions .1 inch in diameter; very strongly acid (pH 4.6, 1:1 water); gradual wavy boundary. (6 to 20 inches thick)
B22--19 to 37 inches; strong brown (7.5YR 5/8) clay; common medium distinct yellowish red (5YR 5/8) mottles; weak medium prismatic structure parting to strong very fine and fine angular blocky; firm, sticky and plastic; few very fine and fine roots along vertical faces of peds; common very fine, fine, and medium tubular pores and few fine vesicular pores; continuous thin coatings on faces of peds and lining pores; approximately 2 percent spherical iron concretions .1 inch in diameter; very strongly acid (pH 4.7, 1:1 water); clear wavy boundary. (16 to 27 inches thick)
B3--37 to 45 inches;; yellowish brown (10YR 5/6) clay; common distinct yellowish red (5YR 4/6); strong brown (7.5YR 5/8 mottles; light yellowish brown (10YR 6/4) mottles; moderately medium and coarse subangular blocky structure parting to strong very fine and fine angular blocky; firm, sticky and plastic; few fine roots; common very fine and fine tubular pores; continuous pressure faces; few thin black (7.5YR 2/0) manganese coatings on faces of peds; very strongly acid (pH 4.9, 1:1 water); gradual wavy boundary. (4 to 12 inches thick)
C--45 to 60 inches; 50 percent light gray (10YR 7/2) clay, 50 percent yellowish brown (10YR 5/6) clay; common fine distinct yellowish red (5YR 4/6), strong brown (7.5YR 5/8), and light yellowish brown (10YR 6/4) mottles; moderate medium and coarse subangular blocky structure parting to strong fine angular blocky; firm, sticky and plastic; common very fine and fine tubular pores; continuous pressure faces; few thin black (7.5YR 2/0) manganese coatings on faces of peds; few fine and medium black (7.5YR 2/0) manganese concretions; very strongly acid (pH 4.9, 1:1 water).
TYPE LOCATION: Airai Municipality, Babelthuap Island, Palau, Western Caroline Islands; about 298 feet SW. of the prawn ponds in the eastern part of Airai Municipality; lat. 7 degrees 22 minutes 8 seconds N. and long. 134 degrees 35 minutes 17 seconds E.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 39 to 59 inches.
The A horizon has moist color of 10YR 3/3, 3/4, or 4/4 or of 7.5YR 3/4, 4/4, or 4/6. The apparent field texture is silt loam or silty clay loam. Eroded areas have an apparent field texture of silty clay loam, clay loam, or clay and are gravelly or very gravelly. Content of small, pebble size ferritic and gibbsitic concretions ranges from 0 to 15 percent. Reaction in 1:1 water is very strongly acid or strongly acid.
The B1 horizon has moist color of 7.5YR 4/4 or 4/6. It has an apparent field texture of clay loam, silty clay loam, or silty clay and is gravelly or very gravelly in some pedons. Content of small, spherical, solid pebble-size ferritic concretions ranges from 5 to 50 percent by volume.
The B2 horizon has moist color of 7.5YR 4/6 or 5/8, of 5YR 4/6, 5/6, or 5/8, or of 2.5YR 4/6, 5/6, or 5/8. It has an apparent field texture of silty clay or clay. Content of small, spherical, solid pebble-size ferritic concretions ranges from 0 to 6 percent. Reaction in 1:1 water is extremely acid or very strongly acid.
The C horizon has moist color of 10YR 8/2, 7/2, 8/3, 7/3, 7/4, 6/6, 5/4, or 5/6, or of 2.5Y 8/2, 8/4, 7/4, or 7/2. It is silty clay or clay. Reaction in 1:1 water is extremely acid or very strongly acid.
COMPETING SERIES: These are the Ngardok, Palau, and Gagil series. Gagil, Ngardok, and Palau soils are well drained, have moderately rapid permeability, and formed in highly weathered volcanic breccia. Gagil soils are degraded and less fertile.
GEOGRAPHIC SETTING: Ngatpang soils formed in bedded clays on marine terraces. Slopes are 2 to 50 percent. Elevation is 13 to 98 feet. The mean annual rainfall is 145 inches and varies from 130 to 183 inches from year to year, with the driest months of February, March, and April averaging 7 to 9 inches per month. The mean annual temperature is 81 degrees F. and does not vary by more than 34 degrees F from month to month. Mean annual maximum temperature is 88 degrees F., and mean annual minimum temperature is 75 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aimeliik, Babelthuap, Ngardmau, Tabecheding, and competing Palau soils. Aimeliik, Babelthuap, and Ngardmau soils formed in residuum derived from highly weathered volcanic breccia and tuff. Also, Aimeliik soils have greater than 12 kilogram organic carbon per surface meter to a depth of 1 meter; and Babelthuap and Ngardmau soils have 30 to 75 percent ferritic and gibbsitic concretions in the surface layer and have very low fertility. Tabecheding soils are somewhat poorly drained and lack an oxic horizon.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow through rapid runoff; moderately slow permeability to about 45 inches and very slow permeability to greater than 59 inches.
USE AND VEGETATION: These soils are in tropical rain forest and are used for watershed and a minor amount of timber harvesting; or they are in anthropic savannah and idle land.
DISTRIBUTION AND EXTENT: Island of Babelthuap. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Airai Municipality, Island of Babelthuap, Palau, Western Caroline Islands, 1981.
ADDITIONAL DATA: National Soil Survey Lab Data No. S79 TQ-632-6 and the Military Geology, Palau Islands, Western Caroline Islands, 1956, used to define the series.