LOCATION EL PAPAYO PREstablished Series
TAXONOMIC CLASS: Clayey, mixed, superactive, isohyperthermic, shallow Typic Haplocambids
TYPICAL PEDON: El Papayo gravelly clay loam--naturalized pastureland (Colors are for moist soil).
Ap--0 to 2 inches; dark brown (7.5YR 3/2) gravelly clay loam, dark brown (7.5YR 3/2) dry; moderate medium granular structure; soft, very friable; slightly sticky, slightly plastic; common very fine roots; many very fine irregular pores; about 25 percent, by volume, pebbles; neutral; clear smooth boundary. (2 to 5 inches thick)
Bw--2 to 14 inches; dark brown (7.5YR 3/2) clay, dark brown (7.5YR 3/2) dry; strong medium subangular blocky structure; hard, firm; sticky, plastic; common fine roots; common very fine irregular and tubular pores; about 5 percent, by volume, angular pebbles; neutral; abrupt smooth boundary. (5 to 15 inches thick)
Cr--14 to 16 inches; highly fractured unconsolidated andesite rock. (2 to 11 inches thick)
R--16+ inches; hard consolidated andesite bedrock.
TYPE LOCATION: Lajas, Puerto Rico. Approximately 1.7 miles southeast of the intersection of P.R. Hwy. 304 and P.R. Hwy. 324; about 0.2 mile south of P.R. Hwy. 324 from the intersection with the trail between El Papayo and Fortuna salt mines; 200 feet west of trail on naturalized pastureland. USGS Parguera topographic quadrangle (1966); lat. 17 degrees 58 minutes 34 seconds N.; long. 67 degrees 01 minute 09 seconds W.
RANGE IN CHARACTERISTICS: Depth to fractured unconsolidated andesite rock ranges from 7 to 17 inches. Depth to hard consolidated andesite bedrock ranges from 12 to 25 inches. Reaction ranges from slightly acid to neutral throughout. The combined total of rock fragments in the control section is less than 35 percent by volume.
The A or Ap horizon has hue of 7.5YR or 10YR, value of 3, and chroma of 2. Content of rock fragments range from 10 to 40 percent, by volume. Texture is clay loam or their gravelly or very gravelly analogs.
The Bw horizon has hue of 7.5YR or 10YR, value of 3, and chroma of 2. Content of rock fragments range from 0 to 10 percent, by volume. Texture is clay loam or clay.
The C horizon, where present, has hue 10YR, value of 3, and chroma of 3. Texture is loamy sand.
The Cr horizon is composed of unconsolidated andesite rock. It can be excavated with difficulty with hand tools, and is rippable by mechanical equipment.
The R layer is composed of hard consolidated basic andesite bedrock.
COMPETING SERIES: There are no known series in the same family.
GEOGRAPHIC SETTING: El Papayo soils are on ridge tops, summits and side slopes of the volcanic hills on the Semiarid Mountains and Valleys MLRA. Slopes range from 2 to 60 percent. They formed in residuum and colluvium that weathered from basic volcanic rocks. The climate is semiarid tropical. The average annual precipitation ranges from 28 to 36 inches and the average annual temperature ranges from 78 to 82 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Costa (T) and Pitahaya (T) series. Costa (T) and Pitahaya (T) soils are on similar positions but are shallow to limestone bedrock.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Most areas of El Papayo soils are on naturalized pastureland and wildlife habitat.
DISTRIBUTION AND EXTENT: Ridge tops, summits, and side slopes of volcanic hills of southern Puerto Rico. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina.
SERIES ESTABLISHED: Lajas Municipality, Puerto Rico; 2007. The name is from the nearby El Papayo community where it was originally recognized.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Ochric epipedon - the zone from 0 to 2 inches (Ap horizon).
Cambic horizon - the zone from 2 to 14 inches (Bw horizon).
Paralithic contact - the contact at 14 inches (Cr horizon).
Lithic contact - the contact at 16 inches (R horizon).
These soils were formerly included in the Descalabrado series. A soil moisture study performed in the San German Area Soil Survey Update recognize the Aridic Soil Moisture Regime in southern Puerto Rico.
El Papayo soils are in MLRA 271.