LOCATION LAOLAO MP+PBEstablished Series
TAXONOMIC CLASS: Very-fine, ferruginous, isohyperthermic Kandiustalfic Eutrustox
TYPICAL PEDON: Laolao clay, on an 8 percent easterly slope under mixed grasses and trees. (Colors are for moist soil unless otherwise stated.)
A1--0 to 1 inch; dark reddish brown (5YR 3/3) clay, reddish brown (5YR 4/3) dry; strong medium granular structure; hard, friable, sticky and plastic; common very fine through medium roots; many fine interstitial pores; strongly acid (pH 5.3); abrupt smooth boundary. (1 to 3 inches thick)
A2--1 to 6 inches; dark reddish brown (5YR 3/4) clay, reddish brown (5YR 4/4) dry, with common fine and medium patches of red (2.5YR 4/6) from the Bt1 horizon; moderate medium subangular blocky structure; hard, friable, very sticky and very plastic; common very fine and fine and few medium and coarse roots; many fine and medium and few coarse tubular and few fine interstitial pores; weak pressure faces on peds; strongly acid (pH 5.5); clear wavy boundary. (2 to 6 inches thick)
Bt1--6 to 15 inches; red (2.5YR 4/6) clay, with common fine and medium patches of dark reddish brown (5YR 3/4) as wormcasts; moderate medium prismatic structure parting to moderate coarse subangular blocky; friable, very sticky, very plastic; common very fine and few fine exped roots; few very fine through medium tubular pores; root channels stained dark reddish brown; few thin clay films on ped faces and in pores; strong pressure faces on peds; medium acid (pH 5.7); diffuse boundary. (5 to 20 inches thick)
Bt2--16 to 32 inches; red (2.5YR 4/6) clay; moderate medium prismatic structure parting to weak coarse subangular blocky; friable, very sticky and very plastic; few very fine roots, mostly exped; few very fine through medium pores; root channels stained dark reddish brown; few thin clay films on ped faces and in pores; strong pressure faces on peds; medium acid (pH 5.7); clear wavy boundary. (12 to 24 inches thick)
Cr--32 to 60 inches; saprolitic tuff, crushes to mixed red (2.5YR 4/6) and strong brown (7.5YR 4/6) clay, with many sand-sized white (10YR 8/1) grains; tuffaceous rock structure; friable, sticky and plastic; few very fine roots; few very fine and fine pores; continuous thin clay films in pores; few sand-sized manganese modules and concretions, few manganese stains, medium acid (pH 5.6).
TYPE LOCATION: Saipan Island, Commonwealth of the Northern Mariana Islands; about 250 feet northwest of As Lito road and 10 feet north of a private driveway, about 700 feet west of the intersection of As Lito road and the road that passes through the southern part of Susupe Swamp; lat. 15 degrees 7 minutes 45 seconds N and long. 145 degrees 42 minutes 35 seconds E.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually dry in the moisture control section for 90 to 120 cumulative days. The moisture control section is usually moist from July through December.
Soil temperature - 77 to 86 degrees F., with less than 4 degrees F. variation between summer and winter.
Depth to paralithic contact - 20 to 40 inches
Clay content - 60 to 80 percent in the argillic horizon.
A horizon - Color: 2.5YR 2.5/2, 3/4, 5YR 2.5/2, 3/2, 3/3, 3/4, 7.5YR 3/1, 3/2, 10YR 3/3.
Texture: Silty clay or clay
Reaction: Strongly acid to neutral
Gravel: Ranges from 0 to 10 percent on the surface.
B horizon - Color: 2/5YR 4/4, 4/6, 5YR 4/4, 7.5YR 4/4, 4/6, 5/6, 6/8 Reaction: Medium acid to neutral.
Other features: Sand-and gravel-sized saprolitic flecks are in the lower B horizons of some pedons.
C horizon - Present in some pedons.
Cr horizon, saprolite - Color: mixed, with dominant matrix colors similar to B horizon. Subordinate colors commonly have high value and variable chroma. These subordinate colors are often present as discrete sand-sized saprolitic flecks and as thin bands.
Texture: Crushes and rubs easily to clay loam, silty clay, clay. Structure: Rock structure.
Consistence, moist: Friable to very firm.
Gravel: 0 to 10 percent.
Reaction: Medium acid to mildly alkaline; weakly effervescent in some pedons.
COMPETING SERIES: None.
GEOGRAPHIC SETTING: Nearly level to steep uplands. Slopes range from 0 to 60 percent. These soils formed in andesitic marine tuffs and tuffaceous sandstones. Mean annual precipitation ranges from 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 mean summer and mean winter temperatures. Elevation ranges from near sea level to 660 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Akina, Chacha, Chinen and Kagman soils. Akina soils have low base saturation in the B horizon. Chacha soils are somewhat poorly drained and have manganese concretions and modules in the B horizon. Chinen soils are shallow over limestone. Kagman soils are deep over limestone.
DRAINAGE AND PERMEABILITY: Well drained; moderate to rapid runoff; moderately permeability.
USE AND VEGETATION: These soils are used for wildlife habitat and watershed, for homesites and for subsistence farming. Vegetation in most areas is secondary forest, agroforest or mixed forest and grassland.
DISTRIBUTION AND EXTENT: Saipan, Tinian, and Rota islands. This series is inextensive, with about 1,000 acres mapped.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Saipan; August 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Argillic horizon - from 6 to 32 inches.
High base saturation - inferred from the sum of bases (around 20 meq. per l00 gallons soil in the B horizon).
ADDITIONAL DATA: Profile was sampled and analyzed for pH, organic matter and extractable bases by the Agricultural Experiment Station, University of Guam.