LOCATION ALONSO PREstablished Series
TAXONOMIC CLASS: Very-fine, parasesquic, isohyperthermic Oxic Dystrudepts
TYPICAL PEDON: Alonso clay--coffee plantation. (Colors are for moist soil.)
Ap--0 to 6 inches; dark reddish brown (5YR 3/3) clay; weak medium subangular blocky structure parting to granular; firm; slightly sticky, plastic; many fine roots; very strongly acid; clear smooth boundary. (5 to 7 inches thick)
Bw1--6 to 16 inches; dusky red (2.5YR 3/2) clay; moderate medium subangular blocky structure; firm; slightly sticky, plastic; many fine roots; few faint clay films on ped faces; very strongly acid; clear wavy boundary.
Bw2--16 to 25 inches; dark reddish brown (2.5YR 3/4) clay; moderate fine and medium subangular blocky structure; firm; slightly sticky, plastic; common fine roots; many faint clay films on ped faces; very strongly acid; clear wavy boundary.
Bw3--25 to 32 inches; dark reddish brown (2.5YR 3/4) clay; moderate fine subangular blocky structure; firm; slightly sticky, plastic; few fine roots; few faint clay films on ped faces; very strongly acid; clear wavy boundary.
Bw4--32 to 47 inches; dark reddish brown (5YR 3/3) clay; weak fine and medium subangular blocky structure; firm; slightly sticky, plastic; few fine roots; few faint clay films on ped faces; common medium distinct dark red (2.5YR 3/6) masses of iron accumulations; very strongly acid; clear wavy boundary. (Combined thickness of the Bw horizons ranges from 30 to 45 inches)
BC--47 to 53 inches; 50 percent dark reddish brown (5YR 3/3) and 50 percent dark red (2.5YR 3/6) clay; weak fine subangular blocky structure; friable; slightly sticky, plastic; very strongly acid; about 15 percent, by volume, saprolite; gradual wavy boundary. (5 to 8 inches thick)
C--53 to 60 inches; 25 percent reddish brown (5YR 4/3), 25 percent red (2.5YR 4/6), 25 percent very dark gray (5YR 3/1) and 25 percent white (5YR 8/1) saprolite having clay texture; massive; friable; slightly sticky, plastic; the colors are derived from the parent material and not indicative of wetness; very strongly acid.
TYPE LOCATION: Sur SCD, Puerto Rico; approximately 50 feet east of kilometer marker 67.0 on P.R. Highway 135.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 40 to 64 inches. Reaction is very strongly acid or strongly acid throughout.
The A or Ap horizon has hue of 2.5YR or 5YR, value of 3 or 4, and chroma of 2 or 3. Texture is clay.
The Bw horizon has hue of 10R to 5YR, value of 3 or 4, and chroma of 2 to 4. Iron accumulations in shades of red range from none to common. Texture is clay.
The BC horizon has hue of 10R to 5YR, value of 3 or 4, and chroma of 2 to 4; or there is no dominant color and is mixed in shades of red and brown. Texture is silty clay or clay.
The C horizon is composed of saprolite in variegated colors of red, brown, yellow, gray, and white. Texture is silty clay loam, clay loam, or clay.
COMPETING SERIES: The Hihimanu series is the only known competing series in the same family. Hihimanu soils are in the Hawaiian Islands and have yellowier hues.
GEOGRAPHIC SETTING: Alonso soils are on side slopes and ridges of maturely dissected uplands. Slopes range from 12 to 60 percent. They formed in fine-textured residuum that weathered from basic volcanic rocks. The climate is humid tropical. The average annual air temperature ranges from 74 to 78 degrees F., and the average annual rainfall ranges from 80 to 90 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Consumo, Daguey, Humatas, and Morado soils. All of these soils are on similar positions. Consumo and Morado soils are moderately deep, have less clay in the control section, and have mixed mineralogy. Daguey soils have kaolinitic mineralogy and are Oxisols. Humatas soils have a thinner solum and parasesquic mineralogy.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Most areas of Alonso soils are used for coffee and pasture. Some small areas are in crops. The vegetation consists of native and introduced grasses, shrubs, and trees.
DISTRIBUTION AND EXTENT: Humid uplands of Puerto Rico. The series is of limited extent, with about 7,300 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Soil Survey of Puerto Rico; 1943.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Umbric epipedon - the zone from 0 to 16 inches (Ap horizon).
Cambic horizon - the zone from 6 to 47 inches (Bw1, Bw2, Bw2, and Bw4 horizons).