LOCATION JUNCOS PREstablished Series
TAXONOMIC CLASS: Fine, smectitic, isohyperthermic Chromic Hapluderts
TYPICAL PEDON: Juncos clay - sugar cane (Colors are for moist soil.)
Ap--0 to 8 inches; black (10YR 2/1) clay; weak fine and medium subangular blocky structure; very hard, firm, slightly sticky, plastic; many fine roots; few fine black (10YR 2/1) concretions; common fine distinct yellow (10YR 7/6) masses of iron accumulation; slightly acid; clear smooth boundary. (4 to 12 inches thick)
Bss--8 to 18 inches; brown (7.5YR 4/4) clay; weak fine and medium subangular blocky structure; very hard, firm, slightly sticky, plastic; common fine roots; few pressure faces on ped surfaces; common intersecting slickensides having distinct polished and grooved surfaces; common fine black (10YR 2/1) masses, concretions, and coatings along root channels; few subrounded volcanic fragments 0.25 to 1.0 inch in diameter; slightly acid; gradual smooth boundary. (10 to 16 inches thick)
C1--18 to 31 inches; yellowish brown (10YR 5/6) clay; massive; firm, slightly sticky, plastic; common fine roots; few pressure faces on surfaces of peds; few intersecting slickensides having faint polished and grooved surfaces; many fine black (10YR 2/1) concretions and coatings on root channels; few subrounded volcanic fragments 0.25 to 1.0 inch in diameter; neutral; gradual smooth boundary.
C2--31 to 40 inches; yellowish brown (10YR 5/6) clay; massive; firm, slightly sticky, slightly plastic; few fine roots; about 15 percent, by volume, volcanic paragravel; neutral; gradual wavy boundary.
R--40 inches, semi-consolidated volcanic rock.
TYPE LOCATION: Turabo SCD, Puerto Rico. Approximately 0.3 kilometer west of the town of Gurabo at the Experiment Station Farm; about 800 feet north of the SW corner of the substation.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 12 to 24 inches. Depth to semi-consolidated volcanic rock ranges from 40 to 60 inches. Reaction ranges from moderately acid to neutral in the solum and upper part of the C horizon and from slightly acid or neutral in the lower part of the profile. The COLE has value of 0.09 to 0.13 in the solum.
The A or Ap horizon has hue of 10YR or 2.5Y, value of 2 or 3, and chroma of 1 or 2. Texture is clay.
The B horizon has hue of 7.5YR, value of 4 or 5, and chroma of 4 to 6. Texture is clay.
The C horizon has hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 4 to 6. Texture is clay.
COMPETING SERIES: There are no other known series in the same family.
GEOGRAPHIC SETTING: Juncos soils are on side slopes and foot slopes of strongly dissected uplands. They formed in fine textured residuum that weathered from extrusive basic volcanic rocks and to a small degree from sediments of similar materials. The climate is humid topical. Slopes range from 5 to 20 percent. The average annual precipitation is 66 inches and the average ranges from 72 to 78 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Caguabo, Junquitos, Mabi, Montegrande, and Mucara series. The well drained Caguabo soils are on higher positions, are shallow to bedrock, and have loamy mixed control sections. Junquitos soils are on lower positions, are very deep, and have very-fine mixed control sections. The somewhat poorly drained Mabi soils are on lower adjacent alluvial fans and terraces, and are very deep. Montegrande soils are on lower foot slope positions, are very deep, and have very-fine control sections. Mucara soils are on similar positions, are moderately deep, and have fine-loamy mixed control sections.
DRAINAGE AND PERMEABILITY: Moderately well drained; slow permeability.
USE AND VEGETATION: Sugar cane and pasture.
DISTRIBUTION AND EXTENT: Humid uplands of Puerto Rico. The series is of minor extent with about 2,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Soil Survey of Puerto Rico, l942.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - the zone from 0 to 8 inches (Ap horizon).
Vertic features - the zone from 8 to 31 inches (Bss and C1 horizons).
Lithic contact - 40 inches.