LOCATION ATATE GU+PBEstablished Series
TAXONOMIC CLASS: Very-fine, parasesquic, isohyperthermic Vertic Haplustalfs
TYPICAL PEDON: Atate silty clay; on a nearly level upland bench, in a young forestry plantation with herbaceous cover. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)
Ap1--0 to 1 inch; dark reddish brown (5YR 3/3) silty clay; moderate very fine granular structure; hard, friable, sticky and plastic; many very fine roots, common fine roots, and few medium and coarse roots; many very fine and fine interstitial pores; strongly acid (pH 5.5); clear smooth boundary. (0 to 2 inches thick)
Ap2--1 to 5 inches; dark reddish brown (5YR 3/3) silty clay; moderate very fine subangular blocky structure; friable, sticky and plastic; many very fine roots, common fine roots, few medium and coarse roots; many very fine and fine tubular and interstitial pores; strongly acid (pH 5.5.); clear smooth boundary. (4 to 10 inches thick)
A--5 to 12 inches; dark reddish brown (5YR 3/4) clay; weak medium subangular blocky structure parting to moderate very fine subangular blocky; friable, sticky and plastic; common very fine roots and few fine roots; many very fine and few fine tubular pores; slightly acid (pH 6.2); gradual smooth boundary. (0 to 8 inches thick)
Bt1--12 to 22 inches; yellowish red (5YR 4/6) clay; moderate very fine subangular blocky structure; friable, sticky and plastic; common very fine roots and few fine roots; many very fine and few fine tubular pores; pressure faces on peds; few thin clay films on ped faces and lining pores; medium acid (pH 5.8); gradual smooth boundary. (8 to 24 inches thick)
Bt2--22 to 36 inches; dark red (2.5YR 3/6) clay; moderate very fine subangular blocky structure; friable, sticky and plastic; common very fine roots and few fine roots; many very fine and few fine tubular pores; pressure faces on peds; few thin clay films on ped faces and lining pores; medium acid (pH 5.9); diffuse boundary. (8 to 20 inches thick)
Bt3--36 to 43 inches; dark red (2.5YR 3/6) clay; moderate very fine subangular blocky structure; friable, sticky and plastic; common very fine roots; many very fine and few fine tubular pores; pressure faces on peds; few thin clay films on vertical ped faces and lining pores; less than l percent saprolitic flecks, irregularly distributed; medium acid (pH 6.0); diffuse boundary. (0 to 12 inches thick)
B/C--43 to 55 inches; dark red (2.5YR 3/6) clay; weak very fine subangular blocky structure; friable, sticky and plastic; few very fine roots; many very fine and few fine tubular pores; few thin clay films on vertical ped faces and lining pores; about 5 percent saprolitic sand-sized flecks; medium acid (pH 6.0); abrupt smooth boundary. (4 to 16 inches thick)
C--55 to 65 inches; dark red, weak red and red (10R 3/6, 4/4, 4/6) clay, about 30 percent each, remainder is yellowish red (5YR 4/6) and strong brown (7.5YR 4/6) colors in patches 1 to 2 inches in diameter; weak very fine subangular blocky and rock structure; very friable, sticky and plastic; few very fine roots; common very fine tubular pores; many sand-sized saprolitic flecks; few black irregular manganese stains; medium acid (pH 5.7).
TYPE LOCATION: Guam; Cotal Conservation Area, along road to Tarzan Falls trailhead, about 650 feet from highway on east side of road; lat. 13 degrees 23 minutes 25 seconds N. and long. 144 degrees 43 minutes 10 seconds E.
RANGE IN CHARACTERISTICS:
Soil moisture - Not continuously moist in all parts of the 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 - 40 to over 60 inches.
Percent clay - 60 to 80 percent in the argillic horizon.
A horizon - Color: 2.5YR 3/4, 4/4, 5YR 3/3, 3/4, 7.5YR 3/2. Texture: Clay loam, silty clay loam, silty clay, clay.
Structure: Granular or subangular blocky.
Reaction: Very strongly acid to slightly acid.
Pebbles: 0 to 2 percent.
B horizon - Color: Dominantly 2.5YR 3/6, 4/6, 5YR 3/6, 4/6, ranges to 10R 4/6, 4/8, 5YR 4/8, 5/8, 7.5YR 5/8.
Structure: Prismatic in some pedons, parting to angular or subangular blocky.
Reaction: Very strongly acid to medium acid.
C horizon - Color: Dominantly 10R and 2.5YR hues, subordinate hues of 5YR through 10YR.
Texture: Clay, silty clay.
Reaction: Very strongly acid to medium acid.
COMPETING SERIES: None.
GEOGRAPHIC SETTING: Nearly level to very steep upland plateaus and mountains. Slopes range from 0 to 60 percent. These soils formed in residuum and slope alluvium, tuff and tuff breccia. Elevation ranges from 100 to 1,000 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 Akina, Agfayan, Sasalaguan, Togcha, and Ylig soils. Akina soils are less than 40 inches to saprolite. Agfayan soils are very shallow. Sasalaguan soils have clayey B horizons with montmorillonite mineralogy. Togcha soils are stratified in the lower part. Ylig soils have low-chroma mottles.
DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderate permeability.
USE AND VEGETATION: Most areas are used as wildlife habitat or as watershed. Vegetation is mostly forest, but some areas are in savannah.
DISTRIBUTION AND EXTENT: Southern Guam; series is inextensive, with about 2,500 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 - From the surface to 12 inches.
Argillic horizon - From 12 to 55 inches.
ADDITIONAL DATA: This pedon was characterized by the National Soil Survey Laboratory (sample #S83-GU-066-011).