LOCATION CHACHA GU+MP PB
Established Series
RD: FJY
01/2023
CHACHA SERIES
The Chacha series consists of deep, somewhat poorly drained soils with slow permeability. They are in concave, basin positions on limestone plateaus, and formed in alluvial sediments and volcanic saprolite overlying limestone. Slopes range from 0 to 7 percent. The mean annual precipitation is about 90 inches, and the mean annual temperature is about 79 degrees F.
TAXONOMIC CLASS: Very-fine, parasesquic, isohyperthermic Oxyaquic Vertic Paleustalfs
TYPICAL PEDON: Chacha clay, on a level area adjacent to a crop of yardlong beans. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)
Ap1--0 to 4 inches; dark brown (10YR 3/3) clay; moderate medium subangular blocky structure parting to strong fine subangular blocky; hard, friable, sticky and plastic; many very fine roots; common very fine and fine tubular pores and few fine interstitial pores; common fine rounded black manganese concretions; moderately acid (pH 6.0); clear wavy boundary. (2 to 5 inches thick)
Ap2--4 to 8 inches; dark brown (10YR 3/3) and dark yellowish brown (10YR 3/4) clay; faintly mixed in a very fine irregular pattern; moderate very fine subangular blocky structure; friable, sticky and plastic; many very fine roots; common very fine and fine tubular and few interstitial pores; common fine subrounded black manganese concretions; moderately acid (pH 6.0); clear wavy boundary. (4 to 10 inches thick)
Bt1--8 to 23 inches; strong brown (7.5YR 5/6) clay with few medium faint patches of yellowish red (5YR 5/6); moderate very fine and fine subangular blocky structure; firm, very sticky and very plastic; few very fine roots; common very fine and few fine and medium tubular and common very fine interstitial pores; common thin clay films on ped faces and lining pores; pressure faces on ped faces; common fine subrounded black manganese concretions and nodules; neutral (pH 6.8); gradual wavy boundary. (12 to 31 inches thick)
Bt2--23 to 33 inches; variegated matrix colors with about 50 percent strong brown (7.5YR 5/6), 30 percent yellowish red (5YR 4/6), and 20 percent red (2.5YR 4/8) clay, with about 20 percent one-eight to one-half inch thick irregularly shaped black manganese nodules; moderate medium subangular blocky structure; firm, very sticky and very plastic; few very fine roots; common very fine and few fine tubular and few very fine interstitial pores; common thin clay films on ped faces and lining pores; pressure faces on peds; some pores stained by dark brown decomposing roots; slightly alkaline (pH 7.5); diffuse boundary. (8 to 24 inches thick)
Bt3--33 to 43 inches; variegated matrix colors with about 50 percent strong brown (7.5YR 5/6) and 50 percent red (2.5YR 4/8) clay; with about 40 percent one-eight to one and one-half inch thick irregularly shaped black manganese nodules and few one-half inch thick prominent elongated seams of very pale brown (10YR 7/4) and red (2.5YR 4/5) soil material is slightly brittle and pale brown seams are more sticky and plastic than the matrix; moderate fine subangular blocky structure; friable, very sticky and very plastic; few very fine roots; common very fine and few fine tubular and few very fine interstitial pores; common thin pressure faces on ped faces; few thin clay films on ped faces and lining pores; some pores are stained with decomposing roots, particularly in pale brown seams; slightly alkaline (pH 7.8); diffuse boundary. (8 to 24 inches thick)
Cr--43 to 63 inches; 40 percent strong brown (7.5YR 5/6), 40 percent red (2.5YR 4/8), and 20 percent white (10YR 8/1) strongly weathered saprolite that crushes and rubs to clay; rock structure; friable, very sticky and very plastic; few very fine roots; common very fine and few fine tubular and few very fine interstitial pores; pressure faces on all ped faces; white material in long seams about 0.5 inch wide tilted at approximately 45 degrees; red soil material is slightly brittle and white seams are more sticky and plastic than the matrix; slickensides along the white seams; common dark brown (7.5YR 3/2) staining in pores in the white seams; slightly alkaline (pH 7.7).
TYPE LOCATION: Guam; about 330 feet west of Talofofo Village, along a farm road, about 16 feet north of the road; lat. 13 degrees 21 minutes 25 seconds N. and long. 144 degrees 45 minutes 0 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. A water table is present at between 20 to 36 inches during these months unless drained.
Soil temperature - 77 to 86 degrees F., with less than 4 degrees F. variation between summer and winter.
Depth to bedrock - 60 to over 80 inches.
Depth to paralithic contact - 40 to 50 inches.
Percent clay - 60 to 90 percent in the argillic horizon.
A horizon - Color: 7.5YR 3/2, 10YR 3/2, 3/3, 3/4.
Texture: Texture is silty clay or clay. In uncultivated pedons a thin clay loam or silty clay loam A1 horizon is present.
Reaction: Moderately acid to slightly alkaline.
Rock fragments: 0 to 5 percent pebbles.
Other features: In some pedons the A horizon material extends into the B horizon along pores, cracks, and wormholes.
B horizon - Color: Dominantly 7.5YR 4/4, 5/6, 5/8, with subordinate colors of 2.5YR 3/6, 4/3, 4/6, 5/6, 5/8, 5YR 4/4, 4/6, 4/8 in irregular patches, more abundant with depth.
Structure: Angular or subangular blocky.
Reaction: Strongly acid to slightly alkaline.
Other features: Manganese concretions, nodules and staining are present in all pedons, but range from 10 to about 40 percent by volume in individual horizons.
Cr horizon - Color: Matrix is roughly half 7.5YR hues and half 2.5YR and 5YR hues, with values and chroma as in the B horizons. Thin, less than one-half inch thick, seams or joints occupy 5 to 30 percent of the horizon, and are 10YR 5/6, 6/6, 7/2, 7/4, 7/6, 8/l, 2.5YR 7/2, 7/4. Manganese concretions, nodules, and stainings are common.
Reaction: Strongly acid to mildly alkaline.
COMPETING SERIES: None.
GEOGRAPHIC SETTING: Nearly level to rolling limestone plateaus, in concave or basin positions. Slopes range from 0 to 7 percent. These soils formed in sediments derived mostly from argillaceous coralline limestone that overlie volcanic saprolite. Elevation is 200 to 400 feet. 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 summer and winter.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Chinen,
Guam,
Kagman,
Pulantat, and
Saipan soils. Chinen, Guam, and Pulantat soils are very shallow and shallow to limestone. Kagman soils are moderately well drained, have little or no manganese concretions and do not have volcanic saprolite. Saipan soils have less than 60 percent clay in the B horizons and are well drained.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; ponded or very slow runoff; slow permeability.
USE AND VEGETATION: Mainly in row crops such as beans, cucumbers, or melons, or fallow in grasses and forbs. A few areas are in forest dominated by Leucaena leucocephala.
DISTRIBUTION AND EXTENT: Chacha soils are on Guam and Saipan. The series is not extensive, with about 1,500 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 - Surface to 8 inches.
Argillic horizon - 8 to 33 inches.
Aquic subgroup - Manganese concretions and nodules in the B horizon that becomes saturated with water during the monsoon period.
Soil would be an Aquic Oxic Haplustalf if such a subgroup were recognized.
ADDITIONAL DATA: This pedon was sampled and characterized by the National Soil Survey Laboratory (sample #S83-GU-066-008).
National Cooperative Soil Survey
U.S.A.