LOCATION LUQUILLO           PR
Established Series
GRB
12/2001

LUQUILLO SERIES


The Luquillo series consists of very deep, well drained, moderately slowly permeable soils on flood plains and low terraces of large streams and rivers. They formed in unconsolidated Quaternary terrace and bouldery alluvial deposits that weathered from material of sandstone origin. Near the type location, the mean annual precipitation is about 80 inches and the mean annual temperature 76 degrees F. Slopes range from 0 to 5 percent.

TAXONOMIC CLASS: Fine, mixed, semiactive, isohyperthermic Typic Eutrudepts

TYPICAL PEDON: Luquillo stony clay-forested. (Colors are for moist conditions.)

A--0 to 5 inches dark yellowish brown (10YR 4/6) stony clay loam; moderate fine granular structure; friable; many very fine, fine, and medium roots; about 5 percent, by volume, pebbles, about 5 percent, by volume, cobbles, and about 15 percent, by volume, stones; very strongly acid; abrupt smooth boundary.

Bw1--5 to 17 inches; yellowish brown (10YR 5/8) clay; moderate medium subangular blocky structure; firm; few fine and medium roots; strongly acid; common distinct black (10YR 2/1) concretions; clear smooth boundary.

Bw2--17 to 35 inches; strong brown (7.5YR 5/8) clay; moderate medium subangular blocky structure; firm; few fine and medium roots; common distinct black (10YR 2/1) concretions; strongly acid; clear smooth boundary. (Combined thickness of the Bw horizons ranges from 30 to 50 inches.)

2C--35 to 60 inches; brownish yellow (10YR 6/6) very stony clay; massive; firm; few fine and medium roots; about 60 percent, by volume, stones; common medium distinct yellowish red (5YR 5/6) masses of iron accumulation; extremely acid.

TYPE LOCATION: Municipio De Rio Grande, Caribbean National Forest, Puerto Rico. At the junction of the Rio Jimenez and the Forest boundary on the north cutback just before the river leaves the Forest. El Yunque topographic quadrangle; lat. 18 degrees 21 minutes 03 seconds N.; long. 65 degrees 48 minutes 09 seconds W.; PRD 1940.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 30 to 50 inches. Reaction ranges from extremely acid to strongly acid throughout the profile. Rock fragments ranges from 10 to 60 percent, by volume, in the A horizon, 0 to 30 percent, by volume, in the Bw horizons, and from 10 to 65 percent, by volume in the C horizon. Pebbles, cobbles, stones, and boulders cover 0.01 to more than 50 percent of the surface.

The A horizon has hue of 10YR, value of 4 or 5, and chroma from 3 to 6. Texture is loam, silt loam, clay loam, clay, their cobbly, stony, or bouldery analogs.

The Bw horizon has hue of 7.5YR to 2.5Y, value of 4 to 6, and chroma of 4 to 8. Soft masses of black concretions range from none to common. Texture is silty clay loam, clay loam, silty clay, sandy clay, clay, their pebbly or cobbly analogs.

The C or 2C horizon has hue of 10YR or 2.5Y, value of 4 to 6, and chroma of 3 to 8. Soft masses of iron accumulation range from none to common. Texture ranges from loam to clay or their cobbly and stony analogs.

COMPETING SERIES: There are no other known series in the same family.

GEOGRAPHIC SETTING: Luquillo soils are on flood plains and low terraces of large streams and rivers of northern Puerto Rico. They formed in unconsolidated Quaternary terrace and bouldery alluvial deposits that weathered from material of sandstone origin. Slopes range from 0 to 5 percent. The climate is humid tropical. The average annual precipitation ranges from 75 to 85 inches and the average annual temperature ranges from 75 to 77 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Coloso, Cristal, and Zarzal soils. The somewhat poorly drained Coloso soils are on similar to slightly lower positions, have kaolinitic mineralogy, and less stones and boulders on the surface. Cristal and Zarzal soils are on adjacent higher side slopes and do not flood. In addition, the somewhat poorly drained Cristal soils have more clay in the control section. Zarzal soils have more clay in the control section and are Oxisols.

DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.

USE AND VEGETATION: Cropland, pasture, woodland, and recreation. Vegetation consists of native and introduced species.

DISTRIBUTION AND EXTENT: Flood plains and lower river and steam terraces of northern Puerto Rico. The series is of minor extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.

SERIES PROPOSED: Caribbean National Forest, 1999.

REMARKS: Diagnostic horizons and features recognized for this pedon:

Ochric epipedon - the zone from 0 to 5 inches (A horizon).

Cambic horizon - the zone from 5 to 35 inches (Bw1 and Bw2 horizons).

MLRA: 270.


National Cooperative Soil Survey
U.S.A.