LOCATION GUANAJIBO PREstablished Series
TAXONOMIC CLASS: Very-fine, mixed, isohyperthermic Plinthic Kandiudults
TYPICAL PEDON: Guanajibo sandy clay loam--pastureland (Colors are for moist soil).
Ap--0 to 10 inches; very dark reddish brown (5YR 3/2) sandy clay loam; moderate fine granular structure; friable; nonsticky; nonplastic; common very fine and fine roots; common fine pores; about 12 percent, by volume, ironstone pebbles; strongly acid; abrupt wavy boundary. (6 to 12 inches thick)
Bt--10 to 21 inches; strong brown (7.5YR 5/8) clay; moderate fine and medium subangular blocky structure; firm; slightly sticky, slightly plastic; few faint clay films on ped faces and root channels; common very fine and fine roots; common fine pores; about 5 percent, by volume, ironstone pebbles; common medium distinct red (2.5YR 5/8) masses of iron accumulation; very strongly acid; clear wavy boundary. (5 to 9 inches thick)
Btv1--21 to 30 inches; strong brown (7.5YR 5/6) clay; weak fine and medium subangular blocky structure; firm; slightly sticky, slightly plastic; few faint clay films on ped faces and root channels; common fine roots; few fine pores; about 5 percent, by volume, ironstone pebbles; about 5 percent, by volume, plinthite; common medium distinct red (2.5YR 4/8) masses of iron accumulation; very strongly acid; clear wavy boundary.
Btv2--30 to 37 inches; strong brown (7.5YR 5/6) clay; weak fine and medium subangular blocky structure; firm; slightly sticky, slightly plastic; few faint clay films on ped faces and root channels; common very fine roots, few fine roots; few fine pores; about 10 percent, by volume, ironstone pebbles; about 10 percent, by volume, plinthite; many medium distinct red (2.5YR 4/6) masses of iron accumulation; very strongly acid; gradual irregular boundary.
Btv3--37 to 63 inches; 20 percent light olive brown (2.5Y 5/6), 20 percent pale yellow (2.5Y 8/3), 20 percent dark red (2.5YR 3/6), 20 percent strong brown (7.5YR 4/6), and 20 percent brown (10YR 4/3) clay; weak fine and medium subangular blocky structure; few faint clay films on ped faces; firm; slightly sticky, slightly plastic; few fine roots; common fine pores; about 25 percent, by volume, plinthite; the areas of olive brown, dark red, and brown are iron accumulations and the areas of pale yellow are iron depletions; very strongly acid.
TYPE LOCATION: Cabo Rojo, Puerto Rico. Approximately 0.9 miles northwest from the intersection of P.R. Hwy 100 and P.R. Hwy. 311, about 600 feet north from the road on naturalized pastureland. USGS Mayaguez topographic quadrangle (1964); latitude 18 degrees, 07 minutes 43 seconds N; longitude 67 degrees, 10 minutes 06 seconds west.
RANGE IN CHARACTERISTICS: Solum thickness is more than 60 inches. Depth to the horizons having more than 5 percent plinthite ranges from 30 to 54 inches. Reaction ranges from very strongly acid to strongly acid throughout, except where the surface has been limed.
The A or Ap horizon has hue of 5YR, value of 2 or 3, and chroma of 2 or 3. Content of ironstone pebbles range from 0 to 15 percent, by volume. Texture is loam, sandy clay loam, or their gravelly analogs.
The Bt horizon has hue of 5YR or 7.5YR, value of 4 to 6, and chroma of 6 or 8. Content of ironstone pebbles ranges from 0 to 10 percent, by volume. Texture is clay loam or clay.
The upper part of the Btv horizon has hue of 5YR or 7.5YR, value of 4 to 6, and chroma of 6 or 8. Iron accumulations in shades of red range from few to common. Content of ironstone pebbles range from 0 to 10 percent, by volume. Content of plinthite ranges from 5 to 15 percent, by volume. Texture is clay loam or clay.
The lower part of the Btv horizon has hue of 2.5YR to 7.5YR, value of 4 to 6, and chroma of 6 or 8; or there is no dominant color and it is multicolored in shades of red, yellow, and brown. Content of ironstone pebbles range from 0 to 10 percent, by volume. Content of plinthite ranges from 10 to 30 percent, by volume. Texture is clay loam or clay.
COMPETING SERIES: These are no known series in the same family.
GEOGRAPHIC SETTING: Guanajibo soils are on coastal terraces and alluvial fans on humid coastal plains. Slopes range from 2 to 12 percent. They formed in regolith consisting of fine-textured sediments of mixed origin. The climate is humid tropical. The average annual precipitation ranges from 65 to 70 inches and the average annual temperature ranges from 76 to 78 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cabo Rojo, Delicias, and Nipe series. All of these soils have less than 5 percent plinthite in the solum. The moderately well drained Cabo Rojo soils are on higher positions and have less clay in the control section. Nipe and Delicias soils are Oxisols and have darker red subsoils. In addition, Delicias soils are on similar to higher positions and have less clay in the control section. Nipe soils are on higher positions.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Most areas of Guanajibo soils are in naturalized pastureland. The vegetation consists of native and introduced grasses, shrubs, and trees.
DISTRIBUTION AND EXTENT: Humid coastal plains of Puerto Rico. The series is of minor extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Suroeste SCD, Puerto Rico; 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Umbric epipedon - the zone from 0 to 10 inches (Ap horizon).
Argillic horizon - the zone from 10 to 63 inches (Bt, Btv1, Btv2, and Btv3 horizons).
Plinthic horizon - the zone from 21 to 63 inches (Btv1, Btv2, and Btv3 horizons).
The type location was moved to its present location in 2002. The change from Plinthic Paleudults to Plinthic Kandihumults was based on soil lab data and observations in the field.
These soils were formerly included in the Sabana Seca series.
ADDITIONAL DATA: Characterization pedon - Cabo Rojo Municipality, Puerto Rico; S02PR-023-002. Sample by NSSL, Lincoln, NE. 08/2002.