LOCATION GUANABANO PREstablished Series
TAXONOMIC CLASS: Fine, smectitic, isohyperthermic Calcidic Argiustolls
TYPICAL PEDON: Guanabano cobbly clay--pastureland (Colors are for moist soil).
Ap--0 to 6 inches; dark reddish brown (5YR 3/2) cobbly clay; moderate medium granular structure; firm; slightly sticky, slightly plastic; many fine roots; about 15 percent, by volume, cobbles; strongly effervescent; moderately alkaline; clear smooth boundary. (2 to 8 inches thick)
Bt--6 to 11 inches; dark reddish brown (5YR 3/2) clay; moderate medium subangular blocky structure; firm; slightly sticky, slightly plastic; few fine roots; few fine prominent clay films on face of peds; about 2 percent, by volume, pebbles; many very fine volcanic and limestone fragments; strongly effervescent; moderately alkaline; clear smooth boundary. (4 to 19 inches thick)
Bk--11 to 20 inches; reddish brown (5YR 4/3) silty clay loam; weak medium and coarse subangular blocky structure; firm; slightly sticky, slightly plastic; common fine roots; about 2 percent, by volume, pebbles; many very fine volcanic fragments; many fine soft masses and filaments of calcium carbonate; violently effervescent; moderately alkaline; clear wavy boundary. (7 to 12 inches)
C1--20 to 50 inches; reddish brown (5YR 5/3) silty clay loam; massive; firm; slightly sticky, slightly plastic; violently effervescent; moderately alkaline; clear wavy boundary.
C2--50 to 60 inches; reddish gray (5YR 5/2) very gravelly silty clay loam; massive; slightly sticky and plastic; about 50 percent, by volume, subrounded and angular volcanic and limestone pebbles; violently effervescent; moderately alkaline.
TYPE LOCATION: Juana Diaz, Puerto Rico. Approximately 1.0 mile southwest of Cuatro Calles community from the intersection of P.R. Hwy. 14 and P.R. Hwy. 540, about 300 feet south of the Ubarris farmstead on pastureland. USGS Rio Descalabrado topographic quadrangle (1982); lat. 18 degrees 02 minutes 33 seconds N.; long. 66 degrees 28 minutes 27 seconds W.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 16 to 28 inches. Reaction ranges strongly acid to neutral in the Ap and AB horizons and from slightly acid or neutral in the B and C horizons. 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 5YR to 10YR, value of 2 to 4, and chroma of 2 to 4. Texture is silty clay loam, clay loam, clay or their gravelly or cobbly analogs.
The AB horizon, where present, has hue of 5YR to 10YR, value of 2 to 4, and chroma of 2 to 4. Texture is silty clay or clay.
The Bt horizon has hue of 5YR to 10YR, value of 2 to 4, and chroma of 2 to 4. Texture is silty clay, clay or their gravelly analogs.
The Bk horizon, where present, has hue of 5YR, value of 2 to 4, and chroma of 2 to 4. Texture is silty clay loam.
The C horizon has hue of 5YR, value of 4 or 5, and chroma of 2 to 6; or is multicolored in shades of brown, yellow, and gray. Content of pebbles and cobbles range from none in the upper part to more than 75 percent, by volume, in the lower part. Texture is sandy clay loam, clay loam or clay.
COMPETING SERIES: There are no known series in the same family.
GEOGRAPHIC SETTING: Guanabano soils are on side slopes and summits of hills on the Semiarid Mountains and Valleys MLRA. Slopes range from 20 to 60 percent. They formed in lenticular deposits of sand and gravel, mudstone and sandstone, or deposits of shale, sandy limestone and sandy conglomerate. The climate is semiarid tropical. The average annual precipitation ranges from 21 to 52 inches and the average annual temperature ranges from 77 to 81 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Callabo, Descalabrado and Llanos series. Callabo and Descalabrado soils are on similar positions but do not have argillic horizon. In additions, Descalabrado soils are shallow to volcanic bedrock. Llanos soils are on adjacent lower foot slopes and terraces, are very deep, have clayey, smectitic control sections, and are Vertisols.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Most areas of Guanabano soils are used for pastureland. A few small areas are used for pigeon peas plantations. The vegetation consists primarily of Kleberg bluestemgrass, huricane grass, and guinea grass.
DISTRIBUTION AND EXTENT: Side slopes and summits of hills of the Semiarid Mountains and Valleys MLRA of southern Puerto Rico. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Juana Diaz, Puerto Rico; 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon - the zone from 0 to 6 inches (Ap horizon).
Argillic horizon - the zone from 6 to 11 inches (Bt horizon).
Calcic horizon - the zone from 11 to 20 inches (Bk horizon).
These soils were formerly included in the Descalabrado series.
ADDITIONAL DATA: Characterization pedon - Yauco Municipality, Puerto Rico; S01PR-153-005R. Sample by NSSL, Lincoln, NE., 03/2001.
Guanabano soils are in MLRA 271.