LOCATION RUBIAS PREstablished Series
TAXONOMIC CLASS: Fine, mixed, active, isothermic Humic Eutrudepts
TYPICAL PEDON: Rubias clay loam--coffee plantation (Colors are for moist soil).
Ap--0 to 8 inches; very dark grayish brown (10YR 3/2) clay loam, dark gray (10YR 4/1) dry; strong very fine and fine granular structure; hard, firm; slightly sticky, moderately plastic; common very fine and fine roots; many very fine and fine interstitial pores; few faint pressure faces on faces of peds; about 5 percent, by volume, pebbles; neutral; clear wavy boundary. (3 to 8 inches thick)
Bw1--8 to 13 inches; very dark grayish brown (10YR 3/2) clay loam, dark gray (10YR 4/1) dry; strong very fine and fine subangular blocky structure; hard, firm; slightly sticky, moderately plastic; common very fine and fine roots; common very fine and fine irregular pores; common distinct pressure faces on faces of peds; about 5 percent, by volume, pebbles; neutral; clear wavy boundary.
Bw2--13 to 18 inches; very dark grayish brown (10YR 3/2) clay loam, dark gray (10YR 4/1) dry; moderate very fine and fine subangular blocky structure; hard, firm; slightly sticky, moderately plastic; common very fine and fine roots; common very fine and fine irregular pores; common distinct pressure faces on faces of peds; about 10 percent, by volume, pebbles; neutral; abrupt wavy boundary. (Combined thickness of the Bw horizons ranges from 4 to 12 inches.)
C--18 to 25 inches; brown (10YR 4/3) loam, dark yellowish brown (10YR 4/4) dry; massive; hard, firm; slightly sticky and moderately plastic; few very fine and fine roots; common very fine and fine irregular pores; neutral; abrupt wavy boundary. (0 to 7 inches thick)
Cr--25 to 50 inches; moderately weathered, unconsolidated mudstone.
R--50 to 80 inches; hard fractured consolidated mudstone.
TYPE LOCATION: Yauco, Puerto Rico. Approximately 4.0 miles southwest from the Castaner community from the intersection of P.R. Hwy. 135 and P.R. Hwy. 374; about 0.3 mile southwest of Hacienda Las Pinas homestead on coffee plantation; USGS Monte Guilarte topographic quadrangle (1960); lat. 18 degrees 08 minutes 01.2 seconds N. and long. 66 degrees 52 minutes 10.4 seconds W.
RANGE IN CHARACTERISTICS: Depth to fractured, unconsolidated, mudstone ranges from 10 to 25 inches. Depth to hard fractured consolidated mudstone ranges from 18 to 50 inches. Reaction ranges from slightly acid to neutral throughout, except where the surface has been limed. The combined total of rock fragments in the control section is less than 35 percent, by volume.
The A or Ap horizon has hue of 10YR or 2.5Y, value of 3 to 5, and chroma of 1 to 3. Content of rock fragments range from 5 to 12 percent, by volume. Texture is clay loam.
The Bw horizon has hue of 10YR or 2.5Y, value of 3 to 6, and chroma of 1 to 3. Content of rock fragments range from 5 to 40 percent, by volume. Texture is clay loam in the fine-earth fraction.
The C horizon, where present, has hue of 7.5YR or 10YR, value of 4 to 6, and chroma of 3 to 8. Content of rock fragments range from 5 to 10 percent, by volume. Texture is loam.
The Cr layer is composed of moderately weathered, unconsolidated mudstone. It can be excavated with difficulty with hand tools, and is rippable by mechanized equipment.
The R layer is composed of hard fractured consolidated mudstone.
COMPETING SERIES: These are no known series in the same family.
GEOGRAPHIC SETTING: Rubias soils are on side slopes and summits of mountains on the Humid Mountains and Valleys MLRA. Slopes range from 40 to 90 percent. They formed in residuum material weathered from mudstone. The climate is humid tropical. The average annual precipitation ranges from 68 to 134 inches and the average annual temperature ranges from 62 to 68 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Agueybana (T),
Chiquito (T),
Cuchillas and
Maricao series. Agueybana (T) and Maricao soils have an argillic horizon and have finer textured profiles. Chiquito soils are shallow to bedrock. Cuchillas soils have coarser texture profiles.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Most areas of Rubias soils are used for naturalized pastureland, bananas, citrus, coffee and plantains. The vegetation consists of native and introduced grasses, shrubs and trees.
DISTRIBUTION AND EXTENT: Side slopes and summits of mountains of southern Puerto Rico. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Yauco Municipality, Puerto Rico; 2007. The name is from the Rubias ward where it was originally recognized.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - the zone from 0 to 8 inches (Ap horizon).
Cambic horizon - the zone from 8 to 18 inches (Bw1 and Bw2 horizons).
Paralithic contact - the contact at 25 inches (Cr layer).
Lithic contact - the contact at 50 inches (R layer).
Rubias soil formed in the Yauco Mudstone Formation (Ky).
Rubias soils were formerly included in the Caguabo series. A soil moisture and soil temperature study performed in the San German Area Soil Survey Update recognized the Perudic Soil Moisture Regime in Puerto Rico, recognized the isothermic soil temperature regime at 750 meters above sea level (in Perudic Soil Moisture Regime) and 900 meters above sea level (in Udic Soil Moisture Regime) and adjusted the isothermic-isohyperthermic line.
Rubias soils are in MLRA 270.