LOCATION PALM PR

Established Series
BCD-HRM; Rev. GRB
10/2021

PALM SERIES

The Palm series consists of very deep, poorly drained, moderately slowly permeable soils on concave positions of benches along mountainsides. They formed in residuum and colluvium that weathered from andesitic to basaltic, marine deposited volcanic and volcanoclastic sandstone. Near the type location, the mean annual precipitation is about 180 inches and the mean annual temperature is about 68 degrees F. Slopes range from 35 to 85 percent.

TAXONOMIC CLASS: Clayey-skeletal, isotic, acid, isothermic Aquandic Humaquepts

TYPICAL PEDON: Palm mucky clay - forested. (Colors are for moist conditions.)

Oi--0 to 3 inches; many fine, medium, and coarse roots which form a surface root mat; abrupt smooth boundary. (0 to 6 inches)

A--3 to 10 inches; dark reddish brown (5YR 3/2) mucky clay; weak medium subangular blocky structure parting to weak fine subangular blocky and moderate fine granular; friable; nonsticky, slightly plastic; many very fine and fine roots; few very fine and fine interstitial and tubular pores; few fine distinct dark reddish brown (2.5YR 3/4) masses of iron accumulation and pore linings; strongly acid; clear smooth boundary. (4 to 18 inches)

BA--10 to 19 inches; black (5Y 2.5/2) clay; weak medium subangular blocky structure parting to weak fine subangular blocky; firm; slightly sticky, plastic; common very fine, fine and medium roots; common very fine and fine interstitial and tubular pores; few distinct brown (7.5YR 4/4) coatings on vertical and horizontal faces of peds; common large worm casts with dark yellowish brown(10YR 3/6) coatings and filled with black (N 2/) material; common distinct dark reddish brown (5YR 3/3) linings along root channels; very strongly acid; clear smooth boundary. (6 to 12 inches)

Bg--19 to 31 inches; olive gray (5Y 5/2) very cobbly clay; weak coarse angular blocky structure; firm; sticky, plastic; few very fine, fine, and medium roots; few fine interstitial and tubular pores; many distinct brown (7.5YR 4/4) stains on pressure faces and horizontal faces of peds; about 10 percent, by volume, pebbles, about 20 percent, by volume, cobbles, and about 30 percent, by volume, stones; common coarse distinct very dark grayish brown (10YR 3/2) areas of iron depletions; strongly acid; gradual wavy boundary. (10 to 25 inches)

Bw--31 to 63 inches; olive (5Y 5/3) very cobbly clay; weak fine subangular blocky structure; firm; sticky, plastic; few fine interstitial and tubular pores; about 10 percent, by volume, pebbles, about 20 percent, by volume, cobbles, and about 30 percent, by volume, stones; common coarse distinct yellowish red (5YR 4/6) masses of iron accumulation; few medium distinct greenish gray (5GY 5/1) areas of iron depletions; strongly acid. (25 to more than 35 inches)

TYPE LOCATION: Rio Grande Municipio; Noreste SWCD, Caribbean National Forest, Puerto Rico. Approximately 30 west of FDR number 10 about 4,300 feet from its junction with RD number 191. El Yunque topographic quadrangle; lat. 18 degrees 18 minutes 21 seconds N.; long. 65 degrees 47 minutes 45 seconds W.; PRD 1940.

RANGE IN CHARACTERISTICS: Solum thickness and depth to bedrock is more than 60 inches. Reaction ranges from extremely acid to strongly acid throughout the profile. Rock fragments range from 0 to 10 percent in the A and BA horizons and from 35 to 70 percent in the Bg and Bw horizons.

The A horizon has hue of 5YR to 10YR, value of 2 to 4 and chroma of 3 or less; or it is neutral with value of 2 to 4. Texture is mucky silty clay or clay.

The BA horizon, where present, has hue of 7.5YR to 5Y, value of 2 or 3, and chroma of 3 or less; or it is neutral with value of 2 or 3. Redoximorphic features in shades of brown and gray range from none to common. Texture is silty clay loam, silty clay, clay loam, or clay.

The Bg horizon has hue of 10YR to 5GY, value of 3 to 6 and chroma of 2 or less; or it is neutral with value of 3 to 6. Redoximorphic features in shades of brown and gray range from few to common. Texture is the gravelly, cobbly, or stony analogs of silty clay or clay.

The Bw horizon has hue of 10YR to 5Y, value of 3 to 6, and chroma of 3 to 6. Redoximorphic features in shades of yellow, red, brown, and gray range from few to many. Texture ranges from gravelly, cobbly, or stony to extremely gravelly, cobbly, or stony analogs of silty clay or clay.

COMPETING SERIES: There are no competing series in this family.

GEOGRAPHIC SETTING: Palm soils are on concave benches of mountain sides in uplands. They formed in residuum and colluvium in mountainous uplands. Slopes range from 35 to 85 percent. The climate is humid tropical. The average annual rainfall ranges from 170 to 230 inches and the average annual temperature from 60 to 70 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Dwarf, Guayabota, Moteado, Yunque, and Zarzal soils. All of these soils have less rock fragments in the control section and are non-skeletal. In addition, Dwarf soils are on higher positions, have a histic epipedon, and are isomesic. Guayabota soils are shallow to bedrock. Moteado soils are deep to bedrock and have more clay in the control section. The moderately well drained Yunque soils have less clay in the control section. The well drained Zarzal soils have more clay in the control section.

DRAINAGE AND PERMEABILITY: Poorly drained; moderately slow permeability.

USE AND VEGETATION: Palm soils are used for watershed protection, recreation, research, and wildlife habitat. Forested with native and introduced species.

DISTRIBUTION AND EXTENT: High mountains of Puerto Rico. The series is of small extent.

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

SERIES ESTABLISHED: Caribbean National Forest, Puerto Rico, 1992.

REMARKS: Diagnostic horizons and features recognized in this pedon:

Umbric epipedon - zone from 0 to 19 inches (O, A and BA horizons).

Cambic horizon - zone from 19 to 63 inches (BA, Bg, and Bw horizons).

The soil horizon depths were revised on 10/2021 to ensure the description began at the soil surface.

Acid feature - Reaction less than 5.5 throughout the zone of 10 to 40 inches (BA, Bg, and Bw horizons).

The field textures range from clay loam to silty clay loam throughout but the lab textures using 2.5 times 15 bar water come out clay throughout.

ADDITIONAL DATA: Characterization data - Pedon No. 87P305 and soil survey sample No. S87PR-3-4. Sample by NSSL, Lincoln, NE.

National Cooperative Soil Survey
U.S.A.