LOCATION NEKKEN PW+PBEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, active, isohyperthermic Typic Haplohumults
TYPICAL PEDON: Nekken very gravelly silt loam - on a 27 percent slope in a broadleaf evergreen forest. When described (1/10/80), the soil was moist throughout. (Colors are for moist soil.)
O1--1 inch to 0; undecomposed and partially decomposed forest litter.
A1--0 to 8 inches; very dark brown (10YR 2/2) very gravelly silt loam; strong fine granular structure; friable, slightly sticky and slightly plastic; many very fine, fine, and medium roots and common coarse roots; many very fine interstitial pores; approximately 50 percent by volume platy fragments of hard coarse roots; many very fine interstitial pores; approximately 50 percent by volume platy fragments of hard tuff .8 to 4 inches by .4 to 2 inches in size; slightly acid (pH 6.1, 1:1 water); clear wavy boundary. (4 to 8 inches thick)
B2t--8 to 18 inches; dark yellowish brown (10YR 4/4) very gravelly silty clay loam; moderate very fine and fine subangular blocky structure; firm, sticky and plastic; many very fine, fine, and medium roots and common coarse roots; many very fine interstitial pores; common thin dark brown (10YR 3/3) coatings on faces of peds and lining pores; approximately 45 percent by volume platy fragments of hard tuff .8 to 4 inches by .4 to 2 inches in size; medium acid (pH 6.0, 1:1 water); clear wavy boundary. (8 to 21 inches thick)
C--18 to 22 inches; lithochromic very dark brown (10YR 2/2) very gravelly silt loam; massive; firm, slightly sticky and slightly plastic; common very fine and fine roots and few medium and coarse roots; many very fine tubular and interstitial pores; approximately 85 percent by volume platy, moderately hard, bedded tuff than can be dug with difficulty with a spade; soil material fills cracks and joints between tuff fragments; strongly acid (pH 5.4, 1:1 water); abruptly wavy boundary. (0 to 13 inches thick)
R--22 inches; black and olive (10YR 2/1 and 5Y 4/3) bedded tuff that has very fine phenocrysts of hornblend; very hard.
TYPE LOCATION: Ngatpang Municipality, Babelthuap Island, Palau, Western Caroline Islands; from land fall at back of channel through the mangroves, head south up slope along trail about 607 feet past stand of Betelnut trees. Site is on a north by northwest aspect; lat. 7 degrees 28 minutes 31.5 seconds N. and long. 134 degrees 29 minutes 30.5 seconds E.
RANGE IN CHARACTERISTICS: From 20 to 60 percent of the surface is covered with very hard cobbles and pebbles. Depth to bedrock ranges from 20 to 30 inches. Thickness of the solum ranges from 17 to 25 inches.
The A horizon has moist color of 10YR 2/2 or 3/3. By volume, it is 20 to 35 percent pebbles and 15 to 25 percent cobbles. Reaction in 1:1 water is medium acid or slightly acid.
The B horizon has moist color of 7.5YR 3/4, 4/4, or 4/6 or of 10YR 3/4, 4/4, or 4/6. It has an apparent field of texture of very gravelly clay loam or very gravelly silty clay loam. By volume, the B horizon is 15 to 25 percent pebbles and 20 to 25 percent cobbles. Reaction in 1:1 water is strongly acid or medium acid. Clay content, as measured by the product of 2.5 times the 15 bar water percentage, is more than 60 percent.
The C horizon has lithochromic moist color of 10YR 2/2, 3/2, 3/3, 3/4, 3/6, or 4/4. Pebble content ranges from 40 to 85 percent by volume. Reaction in 1:1 water is strongly acid or medium acid.
COMPETING SERIES: This is the Tolonier series in another family. Tolonier soils do not have an argillic horizon.
GEOGRAPHIC SETTING: Nekken soils are on hills and ridgetops. The soils formed in residuum from andesitic and basaltic breccia and tuff. Slopes are 12 to 75 percent. Elevation ranges from .1 to 9 inches. The mean annual rainfall is about 145 inches and the mean annual temperature is about 81 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aimeliik, Ngardok, Ollei, and Palau soils. Aimeliik, Ngardok, and Palau soils lack an argillic horizon, are non-skeletal, have a high aluminum saturation and are very deep. Also, Ngardok and Palau soils have an oxic horizon. Ollei soils have a cambic horizon and are shallow to a lithic contact.
DRAINAGE AND PERMEABILITY: Well drained; medium through very rapid runoff; moderate permeability.
USE AND VEGETATION: Nekken soils are in broadleaf, evergreen forest and are used for watershed and a minor amount of timber harvesting for village use.
DISTRIBUTION AND EXTENT: Nekken soils are of small extent in Palau on the island of Babelthuap.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Babelthuap Island, Palau, Western Caroline Islands, 1981.