LOCATION PICACHO PR

Established Series
Rev. GRB
10/2021

PICACHO SERIES

The Picacho series consists of very deep, somewhat poorly drained, moderately permeable soils on strongly dissected plutonic uplands. They formed in residuum and colluvium that weathered from granodiorite of the Rio Blanco stock. Near the type location, the mean annual precipitation is about 185 inches and the mean annual temperature is about 72 degrees F. Slopes range from 10 to 80 percent.

TAXONOMIC CLASS: Fine-loamy, mixed, subactive, isothermic Aquic Dystrudepts

TYPICAL PEDON: Picacho silty clay loam - forest. (Colors are for moist conditions.)

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

A--3 to 4 inch; reddish brown (5YR 4/3) sandy loam; moderate fine subangular blocky structure; very friable, slightly sticky, nonplastic; many fine and medium roots; few fine pores; common fine quartz grains; few faint dark yellowish brown (10YR 4/4) pore linings and stains in root channels; many fine distinct brown (10YR 4/3) and common coarse distinct brown (7.5YR 4/4) masses of iron accumulation; very strongly acid; clear smooth boundary. (6 to 12 inches thick)

Bw1--4 to 10 inches; brown (7.5YR 4/3) sandy clay loam; moderate medium subangular blocky structure; friable, slightly sticky, slightly plastic; common very fine, fine, and medium roots; common fine interstitial and tubular pores; few faint dark yellowish brown (10YR 4/4) pore linings and stains in root channels; few large wormcasts filled with very dark grayish brown (10YR 3/2) material; few fine quartz grains; common medium distinct yellowish brown (10YR 5/6) masses of iron accumulation; many medium distinct gray (10YR 5/1) areas of iron depletions; very strongly acid; clear smooth boundary. (8 to 12 inches thick)

Bw2--10 to 15 inches; reddish yellow (7.5YR 6/6) sandy clay loam; weak medium subangular blocky structure; friable, slightly sticky, slightly plastic, common very fine roots; common fine interstitial and tubular pores; few large wormcasts filled with brown (7.5YR 4/2) material; about 3 percent, by volume, pebbles; few faint clay films on ped surfaces and in root channels; common fine quartz grains; common fine distinct yellowish brown (10YR 5/6) masses of iron accumulation; common medium distinct grayish brown (10YR 5/2) areas of iron depletions; very strongly acid; clear smooth boundary. (6 to 12 inches thick)

Bw3--15 to 27 inches; yellowish brown (10YR 5/6) sandy clay loam; weak fine and medium subangular blocky structure; friable; slightly sticky, slightly plastic; few very fine roots; common very fine and fine interstitial and tubular pores; few faint clay films on ped surfaces and in root channels; many very fine mica flakes; few fine distinct grayish brown (10YR 5/2) areas of iron depletions; very strongly acid; clear smooth boundary. (6 to 10 inches thick)

C--27 to 63 inches; about 45 percent yellowish red (5YR 5/6), about 35 percent brown (7.5YR 5/4), and about 20 percent brown (10YR 4/3) cobbly sandy loam; massive; friable, nonsticky, plastic; few very fine roots; few very fine pores coated with dark brown (10YR 3/3) material; common distinct pockets of brownish yellow (10YR 6/6) loam; about 5 percent, by volume, pebbles and about 10 percent, by volume, cobbles; many distinct mica flakes; strongly acid.

TYPE LOCATION: Naguabo Municipio, Noreste SCD, Caribbean National Forest, Puerto Rico. Near kilometer marker 13.9 of Road 191. El Yunque topographic quadrangle; lat. 18 degrees 17 minutes 44 seconds N.; long. 65 degrees 47 minutes 38 seconds W.; PRD 1940.

RANGE IN CHARACTERISTICS: Solum thickness ranges from 24 to 47 inches. Reaction ranges from extremely acid to strongly acid throughout the profile. Content of pebbles and cobbles range from 0 to 10 percent, by volume in the A and Bw horizons and from 0 to 15 percent, by volume, in the C horizon.

The A horizon has hue of 5YR to 10YR, value of 3 or 4, and chroma of 2 to 4. Texture is sandy loam, loam, sandy clay loam, or silty clay loam.

The Bw horizon has hue of 5YR to 10YR, value of 4 to 6, and chroma of 3 to 8. Redoximorphic features in shades of gray, yellow, and brown range from few to many. Redox depletions are common to many in the upper Bw horizon and decrease with depth. Texture is sandy clay loam, loam, or clay loam.

The C horizon has colors in hue of 2.5YR to 7.5YR, value of 4 to 6, and chroma of 4 to 8; or there is no dominant color and is multicolored in shades of red, brown, and yellow. Texture is sandy loam, loam, sandy clay loam, clay loam, or their gravelly or cobbly analogs.

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

GEOGRAPHIC SETTING: Picacho soils are on strongly dissected plutonic uplands. They formed in residuum and colluvium that weathered from igneous rocks. Slopes range from 10 to 80 percent. The climate is humid tropical. The average annual precipitation ranges from 150 to 200 inches and the average annual air temperature ranges from 71 to 73 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These include the Ciales, Guayabota, Icacos, Los Guineos, Utuado, and Yunque soils. The poorly drained Ciales soils have an histic epipedon. The poorly drained Guayabota soils are shallow to bedrock. Icacos soils are on lower adjacent river flood plains. The well drained Los Guineos soils have more clay in the control section and are Oxisols. The well drained Utuado soils have coarse-loamy control sections. The well drained Yunque soils have mixed mineralogy.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; moderate permeability.

USE AND VEGETATION: Watershed protection, recreation, research, and wildlife habitat. Vegetation consists of woody native and introduced species.

DISTRIBUTION AND EXTENT: Tropical rain forests of Puerto Rico. The series is of minor extent.

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

SERIES ESTABLISHED: Puerto Rico; 1942.

REMARKS: Diagnostic horizons and features recognized in this pedon:

Ochric epipedon - zone from 0 to 4 inches (O and A horizon).

Cambic horizon - zone from 4 to 27 inches (Bw1, Bw2, and Bw3 horizons).

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

ADDITIONAL DATA: Characterization Pedon - Caribbean National Forest, Puerto Rico; S87-PR-003-005 or NSSL Pedon Number: 87P0306. Sample by NSSL, Lincoln, NE. April, 1987.

MLRA: 270.

National Cooperative Soil Survey
U.S.A.