LOCATION PULANTAT GU PBEstablished Series
TAXONOMIC CLASS: Clayey, smectitic, isohyperthermic, shallow Udic Argiustolls
TYPICAL PEDON: Pulantat clay--on a 50 percent westerly slope under a low forest of Leucaena leucocephala (tangantangan). (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)
Oi--1 inch to 0; undecomposed leaves, twigs and tangantangan seed pods cover about 20 percent of surface.
A1--0 to 1 inch; very dark grayish brown (10YR 3/2) silty clay, dark grayish brown (10YR 4/2) dry; strong fine and medium granular structure; slightly hard, firm, sticky and plastic; few fine roots; many interstitial pores;. slightly acid (pH 6.5); abrupt smooth boundary. (0.5 to 2 inches thick)
A2--1 to 3 inches; black (10YR 2/1) and dark brown (10YR 3/3) clay; moderate
medium prismatic structure parting to strong fine and medium subangular blocky;
very hard, firm, very sticky and very plastic; common fine and medium roots;
common very fine and fine tubular and interstitial pores; cracks about 0.5 inch
wide; pressure cutans on faces of peds; slightly acid (pH 6.5); abrupt smooth
boundary. (2 to 6 inches thick)
A/B--3 to 7 inches; very dark grayish brown (10YR 3/2) and dark brown (10YR 3/3)
clay in a very fine pattern, with about 30 percent brown (7.5YR 4/4) clay as
fine and medium irregular pieces; moderate medium subangular blocky structure;
very hard, firm, very sticky and very plastic; common fine and medium roots;
common fine and very fine tubular and interstitial pores; pressure cutans on
faces of peds; wormcasts common; few very fine black manganese concretions;
neutral (pH 6.6); clear wavy boundary. (0 to 6 inches thick)
Bt--7 to 12 inches; brown (7.5YR 4/4) clay; weak medium prismatic parting to
strong fine and medium subangular blocky structure; hard, friable, very sticky
and very plastic; common fine and medium roots; few fine and very fine tubular
and interstitial pores; common thin and few moderately thick clay films on ped
faces and many moderately thick clay films line pores; pressure cutans on faces
of peds; few pebbles, some as wormcasts; mildly alkaline (pH 7.5); gradual
irregular boundary. (4 to 12 inches thick)
Cr--12 to 25 inches; brown (7.5YR 4/4) weathered argillaceous limestone, crushes
to extremely gravelly clay; many clay-filled cracks and fissures, with few thin
clay films; no roots; few interstitial pores; moderately alkaline (pH 8.2).
TYPE LOCATION: Guam; about 0.3 miles NE of Agfayan Bay, on the west slope of
Boaga Hill; lat. 13 degrees 15 minutes 10 seconds N. and long. 144 degrees 43
minutes 20 seconds E.
RANGE IN CHARACTERISTICS:
Soil moisture - Not continuously moist in all part of the moisture control
section for 90 to 120 cumulative days, primarily between February and May. Soil
is usually moist from July through December.
Soil temperature - 80 to 86 degrees F., with less than 4 degrees F. variation
between summer and winter.
Depth to paralithic contact - 10 to 20 inches.
Percent clay - Over 60 percent above the paralithic contact.
A horizon - Color: 5YR 3/3, 7.5YR 3/2, N 2/, 10YR 2/1, 2/2, 3/2. Texture: Silty
clay, clay.
Structure: Granular or subangular blocky.
Rock fragments: 0 to 5 percent cobbles, 0 to 10 percent pebbles. Reaction:
Slightly acid or neutral.
B horizon - Color: 7.5YR 4/4, 5/6, 5/8, 10YR 4/4.
Texture: Clay, gravelly clay.
Structure: Prismatic parting to subangular blocky.
Rock fragments: 0 to 5 percent cobbles, 2 to 15 percent pebbles. Reaction:
Neutral to moderately alkaline.
COMPETING SERIES: None.
GEOGRAPHIC SETTING: Sloping to very steep upland plateaus and hills. Slopes
range from 3 to 60 percent. Pulantat soils formed in residuum and slope alluvium
from argillaceous coralline limestone. Elevation is 16 to 330 feet. Mean annual
precipitation is 80 to 100 inches, most of which falls between June and
November. Mean annual temperature is 79 degrees F., with less than 4 degrees F.
difference between summer and winter.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Agfayan, Chacha, and Kagman
soils. Agfayan soils are very shallow. Chacha and Kagman soils are deep.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow
permeability.
USE AND VEGETATION: Most areas are in forest and are used as wildlife habitat
and as watershed. A few areas are farmed, and some areas are urbanized.
DISTRIBUTION AND EXTENT: Central and southern Guam; the series is moderately
extensive, with about 12,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Guam; July 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - Mixed color of the top 7 inches is 7.5YR 3/4. Argillic horizon
- 3 to 12 inches.
ADDITIONAL DATA: This pedon was characterized by the National Soil Survey
Laboratory (sample #S83-GU-066-005).