LOCATION TAKPOCHAO MP+PB
Established Series
RD: FJY/TLH/DWB/RTG
01/2023
TAKPOCHAO SERIES
The Takpochao series consists of very shallow and very shallow, well drained, moderately permeable soils on limestone plateaus, sideslopes and escarpments. They formed in sediments overlying coralline limestone. Slopes range from 3 to 99 percent. The mean annual precipitation is about 87 inches, and the mean annual temperature is about 77 degrees F.
TAXONOMIC CLASS: Clayey-skeletal, mixed, active, isohyperthermic Lithic Haplustolls
TYPICAL PEDON: Takpochao very cobbly clay, on a 28 percent northerly slope under native limestone forest. (Colors are for moist soil.)
Oi-- 0 to 0.5 inch; undecomposed leaf litter; abrupt smooth boundary; moderately acid (pH 5.6, 1:1 water); (0 to 0.5 inches thick)
A1-- 0.5 to 1 inch; black (N2/0) very cobbly loam; strong very fine granular structure; slightly hard, friable, nonsticky, nonplastic; many very fine, fine and common medium roots; many very fine interstitial pores; about 30 percent limestone cobbles and 20 percent gravel; neutral (pH 7.0); abrupt smooth boundary. (1 to 5 inches thick)
A2--1 to 7 inches; very dark grayish brown (10YR 3/2) very cobbly clay; strong very fine subangular blocky structure; slightly hard, friable, sticky, plastic; many very fine, fine and common medium roots; many very fine interstitial pores; about 20 percent cobbles and 20 percent gravel; slightly alkaline (pH 7.4); clear broken boundary. (3 to 10 inches thick)
Bw--7 to 12 inches; dark yellowish brown (10YR 4/4) very cobbly clay; moderate very fine subangular blocky structure; hard, friable, very sticky, very plastic; many very fine, common fine and medium roots; common very fine and fine tubular pores; about 20 percent cobbles and 20 percent gravel; slightly alkaline (pH 7.6); abrupt irregular boundary. (1 to 8 inches thick)
2R--12 inches; unweathered white limestone; strongly alkaline (pH 8.6, 1:1 water)
TYPE LOCATION: Saipan, Commonwealth of the Northern Mariana Islands; about 640 yards WNW of Bird Island, about 109 yards west of the road to the Bird Island overlook, along a small trail; lat. 15 degrees 15 minutes 30 seconds N. and long. 145 degrees 48 minutes 15 seconds E.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually dry for 90 to 120 cumulative days. Soil is usually moist from July through December.
Mean annual soil temperature - 77 degrees to 84 degrees F., with less than 4 degrees F. variation between summer and winter.
Mollic epipedon thickness - 4 to 10 inches. The epipedons that are 4 to 7 inches thick rest directly on the limestone bedrock.
Depth to bedrock - 4 to 16 inches.
A horizon
Color: 7.5YR 3/2, 3/3, 10YR 2/1, 2/2, 3/1, 3/2, N2/0.
Texture: Very cobbly loam, very cobbly clay loam.
Rock fragments: 35 to 60 percent, about one-half as cobbles and one-half as gravel. Surface gravel and cobbles are often much higher.
B horizon
Color: 5YR 3/4, 4/4, 4/6, 7.5YR 3/4, 4/6, 10YR 4/3, 4/4.
Texture: Very cobbly clay loam or very cobbly clay.
Rock fragments: 35 to 60 percent, about one-half as cobbles and one-half as gravel.
Other features: Intermittent buried horizons are present in some pedons.
COMPETING SERIES: These are the
Banaderu,
Chinen, and
Luta series. The Banaderu soils have gibbsitic mineralogy and an argillic horizon with hues of 10R and 2.5YR. Chinen soils have an argillic horizon. The Luta series lack a mollic epipedon and are not clayey-skeletal.
GEOGRAPHIC SETTING: Takpochao soils are on uplifted limestone plateaus, often adjacent to the coast, and are on side slopes and escarpments of limestone plateaus. The limestone is derived from a coral reef complex. They formed in residual and colluvial sediments, possibly with a component of volcanic ash. Slopes are 3 to 99 percent. Elevation is 16 to 1,529 feet. Mean annual temperature is 77 degrees F., with less than 4 degrees F. variation between summer and winter. Mean annual precipitation is 80 to 90 inches, most of which falls between June and November.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Banaderu,
Chinen,
Dandan,
Luta,
Kagman, and
Saipan soils. Banaderu, Chinen, and Luta soils have less than 35 percent coarse fragments. Dandan soils are moderately deep to limestone. Kagman and Saipan soils are deep to limestone.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to rapid. Permeability is moderate.
USE AND VEGETATION: Nearly all areas are in native vegetation. In most areas this is forest, but areas along windward coastlines are in low shrubs.
DISTRIBUTION AND EXTENT: Takpochao soils are on the Northern Marianas Islands. This series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Saipan, Commonwealth of the Northern Mariana Islands, 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the surface to a depth of 7 inches (Al, A2 horizons) or to the limestone contact.
Taxonomic Version: Keys to Soil Taxonomy, 10th edition 2006.
National Cooperative Soil Survey
U.S.A.