LOCATION SAIPAN MP+PB

Established Series
RD: FJY/TLH/RTG
01/2023

SAIPAN SERIES

The Saipan series consists of deep and very deep, moderately permeable, well drained soils. They are on uplifted limestone plateaus and formed in sediments overlying porous coralline limestone. Slopes range from 0 to 30 percent. The mean annual precipitation is about 85 inches, and the mean annual temperature is about 78 degrees F.

TAXONOMIC CLASS: Very-fine, mixed, isohyperthermic Kandiustalfic Eutrustox

TYPICAL PEDON: Saipan clay, on an 8 percent southeast slope under mixed native forest and agroforest. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)

A1--0 to 4 inches; dark brown (7.5YR 3/2) clay, dark brown (7.5YR 3/2) dry; strong very fine and fine subangular blocky structure; hard, firm, moderately sticky and slightly plastic; common very fine through coarse roots; common very fine and fine tubular and interstitial pores; about 2 percent coral gravel; soil is difficult to rub down; neutral (pH 7.0); abrupt smooth boundary. (1 to 4 inches thick)

A2--4 to 6 inches; dark reddish brown (5YR 3/3) clay, dark reddish brown (5YR 3/3) dry; strong very fine and fine subangular blocky structure; hard, firm, moderately sticky and slightly plastic, common very fine, fine and coarse roots and many medium roots; common very fine and fine interstitial and few fine tubular pores; few fine pieces of Btl material throughout horizon; neutral (pH 7.0); clear wavy boundary. (2 to 6 inches thick)

Bt1--6 to 19 inches; reddish brown (5YR 4/4) clay; moderate fine and medium subangular blocky structure; very friable, moderately sticky and moderately plastic; common very fine, fine and medium roots; common very fine, fine and medium tubular pores, some stained with organic material about half oriented along vertical ped faces; common thin and moderately thick clay films occurring on faces of peds and clay films line tubular pores; dark reddish brown (5YR 3/3) wormcasts; neutral (pH 7.0); gradual wavy boundary. (8 to 20 inches thick)

Bt2--19 to 29 inches; reddish brown (5YR 4/4) clay, with few fine patches of yellowish red (5YR 4/6); moderate fine and medium angular blocky structure; friable, moderately sticky and moderately plastic; few very fine and fine roots; few very fine and fine tubular pores; common moderately thick clay films occurring on ped faces and clay films line tubular or interstitial pores; very dark grayish brown (10YR 3/2) organic matter staining along most vertical root channels; fine manganese stains on about 3 percent of vertical ped faces; neutral (pH 7.0); gradual wavy boundary. (8 to 24 inches thick)

Bt3--29 to 42 inches; yellowish red (5YR 4/6) silty clay, moderate fine and medium angular blocky structure; friable, very sticky and moderately plastic; few very fine and fine roots; few very fine and fine tubular pores; many moderately thick clay films line interstitial pores; organic staining along most vertical root channels; fine manganese stains on about 3 percent of vertical ped faces; neutral (pH 7.2); gradual wavy boundary. (8 to 30 inches thick)

Bt4--42 to 47 inches; yellowish red (5YR 4/6) clay, strong brown (7.5YR 4/6); moderate medium and coarse subangular blocky structure; friable, very sticky and moderately plastic; few fine roots; few very fine and fine tubular pores; many moderately thick clay films on ped faces, and clay films line tubular pores; about 3 percent very fine manganese concretions; organic stainings along most vertical root channels; neutral (pH 7.2); abrupt smooth boundary.

2R--47 inches; white coralline limestone; strongly alkaline (pH 8.6, 1:1 water)

TYPE LOCATION: Saipan, Commonwealth of the Northern Mariana Islands; on the Francisco property, about 1 mile southeast of San Rogue Village, at the end of a jeep trail extending from the southern Kalabera area; lat. 15 degrees 14 minutes 15 seconds N. and long. 145 degrees 46 minutes 50 seconds E.

RANGE IN CHARACTERISTICS:

Soil moisture - Not continuously moist in all parts of the moisture control section for 90 to 120 cumulative days, primarily between February and May. The moisture control section is usually moist from July through December.

Mean annual soil temperature - 80 degrees to 86 degrees F., with less than 4 degrees F. variation between summer and winter.

Depth to bedrock - 40 to over 80 inches.

Control section - Percent clay: 35 to 60 percent in the argillic horizon.

A horizon - Color: 5YR 3/3, 3/4, 7.5YR 3/2, 3/4, 10YR 2/2, 3/2, 2.5YR 2/2, 3/2.
Texture: Clay, silty clay, silty clay loam.
Structure: Granular and subangular blocky.
Rock fragments: 0 to 10 percent, mostly gravel, a few cobbles.
Reaction: Slightly acid to slightly alkaline.

B horizon - Color: Dominantly 5YR 4/4, 4/6, 4/8, 7.5YR 4/6, 5/6 and 2.5YR 4/6, but ranges to 5YR 3/4, 5/6, 4/8, 7.5YR 4/4, 5/8 and 2.5YR 3/4, 3/6, 4/8.
Texture: Clay loam, silty clay, silty clay loam, and clay.
Structure: Angular or subangular blocky.
Reaction: Slightly acid to slightly alkaline.

COMPETING SERIES: None.

GEOGRAPHIC SETTING: Saipan soils are on uplifted limestone plateaus that are often tilted and dissected. Slopes range from 0 to 30 percent. Elevation ranges from 30 to 1,300 feet. These soils formed in sediments that are a mixture of alluvium, residuum, and volcanic ash which overlie porous coralline limestone. Mean annual precipitation ranges from 80 to 100 inches, most of which falls between June and November. Mean annual temperature is 78 degrees F., with less than 4 degrees F. difference between summer and winter.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chacha, Chinen, Guam, Kagman, Pulantat, and Takpochao soils. Chacha and Kagman soils have an argillic horizon with over 60 percent clay. Chinen, Guam, Pulantat, and Takpochao soils are shallow and very shallow to limestone.

DRAINAGE AND PERMEABILITY: Well drained; slow or medium runoff; moderate permeability.

USE AND VEGETATION: Many areas are farmed. Other areas are in agroforest or in forest dominated by Leucaena leucocephala.

DISTRIBUTION AND EXTENT: Guam and Commonwealth of the Northern Mariana Islands. The series is not extensive, with about 800 acres mapped.

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 thickness - 4 to 8 inches.
Argillic horizon: From the top of the Bt1 horizon in cultivated pedons to the limestone contact.
Hapl great group: Lithic contact at a depth of less than 59 inches.

ADDITIONAL DATA: The Saipan soil was characterized on Guam by the National Soil Survey Laboratory (sample #S83-GU-066-010). The type location in Saipan will be sampled in l985.

Taxonomic Version: Keys to Soil Taxonomy, 10th edition 2006.

National Cooperative Soil Survey
U.S.A.