LOCATION MOCA PREstablished Series
TAXONOMIC CLASS: Very-fine, mixed, semiactive, isohyperthermic Vertic Paleudults
TYPICAL PEDON: Moca clay - sugarcane. (Colors are for moist soil.)
Ap--0 to 6 inches; brown (7.5YR 4/2) clay; weak medium subangular blocky structure; very hard, firm, slightly sticky, plastic; small amount of Bt mixed with this horizon; many fine roots; fine and medium volcanic rock fragments; extremely acid; clear smooth boundary. (4 to 8 inches thick)
Bt1--6 to 10 inches; red (7.5R 4/8) clay with common fine distinct brown (10YR 5/3) mottles; weak medium subangular blocky structure; very hard, firm, slightly sticky, plastic; common fine roots; few faint clay films; common krotovinas 2 mm in diameter; very strongly acid; clear smooth boundary. (4 to 7 inches thick)
Bt2--10 to 18 inches; red (7.5R 4/8) and brown (10YR 5/3) clay; moderate medium subangular blocky structure; firm, slightly sticky, plastic; few fine roots; common distinct clay films; cracks to 20 inches; organic staining along root channels; few pressure faces and slickensides; very strongly acid; gradual smooth boundary. (7 to 12 inches thick)
Bt3--18 to 32 inches; grayish brown (10YR 5/2) with approximately 30 percent red (7.5R 4/8) clay; weak medium and coarse subangular blocky structure; firm, slightly sticky, plastic; few fine roots; few faint clay films; organic staining along root channels; few pressure faces and slickensides; very strongly acid, abrupt smooth boundary. (12 to 16 inches thick)
C1--32 to 48 inches; light gray (2.5Y 7/2) clay with many medium distinct red (7.5R 4/8) mottles; massive; firm, slightly sticky, slightly plastic; very strongly acid; abrupt smooth boundary. (12 to 18 inches thick)
C2--48 to 64 inches; red (7.5R 4/8), light gray (2.5Y 7/2) and reddish yellow (7.5YR 6/8) clay; massive; firm slightly sticky and slightly plastic; very strongly acid; gradual smooth boundary. (12 to 18 inches thick)
C3--64 inches plus; stratified mottled red and gray clays with varying amount of gravel. Fracture plains in gray clay lenses appear as pressure faces or slickensides and are light gray (5Y 7/1).
TYPE LOCATION: Culebrinas SCD, Puerto Rico; 2.5 miles southeast of the town of Moca; 0.6 kilometer north and 50 feet east of junction of Highways 111 and 110.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 27 to 43 inches. Thickness of the argillic horizon varies from 23 to 35 inches. Texture is clay throughout the profile. Consistence in the solum is slightly sticky or sticky and plastic. Reaction ranges from strongly to extremely acid in the whole profile. Cracks occur throughout the B horizon. The mean annual soil temperature ranges from 75 to 80 degrees F.
The A horizon has hues of 5YR or 7.5YR, values of 3 or 4, and chroma of 2 to 4. Structure is weak, fine or medium subangular blocky. Rock fragments range from 0 to 10 percent.
The Bt horizons have red, brown, and grayish brown colors in varying proportions. Structure is weak or moderate, medium or coarse subangular blocky. Clay films range from few faint to many prominent. Pressure faces may occur in any portion of the argillic horizon. Slickensides may or may not be present.
The C horizons have gray colors with varing proportions of red and reddish yellow. Varying amounts of gravel may be present in this horizon.
COMPETING SERIES: There are no other known series in the same family. The Consejo, Consumo, Corozal, Corozo, Ingenio, Jagueyes, Lirios, Maricao, Patillas and Rio Piedras series are similar soils in related families. The Consejo, Liros and Rio Piedras all lack horizons with COLE value of 0.09 or more. The Consumo and Maricao soils have thinner argillic horizons. The Corozal soils have low chroma mottles in the upper part of the argillic horizon. The Corozo soils have sandy surface layers. The Ingenio and Jagueyes soils have lower CEC values, less than 24 meq/100 grams of clay. The Patillas soils are coarser textured.
GEOGRAPHIC SETTING: The Moca soils are sloping to steep soils on foot slopes and side slopes of low hills on slope gradients of 5 to 40 percent. They formed in fine textured materials over clays, gravels, and cobbles geologically referred to as the San Sebastian Formation, a basal conglomerate. The climate is humid tropical. The average annual precipitation ranges from 70 to 90 inches and the mean annual temperature is 77 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Voladora, Plata, and Perchas series. The Voladora soils are redder, have thinner B horizons, and friable, coarser textured C horizons. The Plata soils are browner, and lack argillic horizons. The Perchas soils have cambic horizons, are browner, and have low chroma mottles.
DRAINAGE AND PERMEABILITY: Moderately well drained, medium to rapid runoff and moderately slow permeability.
USE AND VEGETATION: Gentler slopes in sugarcane. Steeper slopes in native pasture.
DISTRIBUTION AND EXTENT: Humid uplands of northwestern Puerto Rico. The series is of minor extent with about 8,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: Soil Survey of Puerto Rico; 1942.
REMARKS: The classification was updated with the 4/91 draft from Clayey, mixed, isohyperthermic Vertic Tropudults to Clayey, mixed, isohyperthermic Aquic Paleudults. Although this soil contains vertic features such as slickensides, there is no evidence of cracking to the surface or the base of the Ap horizon in the description. This needs to be tested. The previous OSED date was 11/75.
Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - zone from 0 to 6 inches
Argillic horizon - zone from 6 to 32 inches
Pale clay curve - Less than 20 percent clay cutback in Bt and C horizons.
Aquic feature - 2 chroma mottles in Bt3 horizon