LOCATION PLATA PREstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, isohyperthermic Dystric Eutrudepts
TYPICAL PEDON: Plata clay-native pasture. (Colors are for moist soil)
Ap--0 to 6 inches; dark yellowish brown (10YR 3/4) clay; weak fine and medium subangular blocky breaking to moderate fine and medium granular structure; firm, slightly sticky, plastic; many fine roots; common fine and medium volcanic rock fragments; many fine quartz grains; strongly acid; clear smooth boundary. (4 to 8 inches thick.)
Bw--6 to 11 inches; dark yellowish brown (10YR 4/4) clay; weak fine and medium subangular blocky structure firm, slightly sticky; plastic; common fine roots; common fine and medium volcanic rock fragments; many fine quartz grains; strongly acid; clear smooth boundary. (4 to 8 inches thick.)
BC--11 to 17 inches; yellowish brown (10YR 5/8), pale brown (10YR 6/3), brown (10YR 5/3), and strong brown (7.5YR 5/8), crushed color, brownish yellow (10 6/6) gravelly clay loam; weak medium subangular blocky structure, friable; few fine roots; many medium and coarse volcanic rock fragments; few fine quartz grains; strongly acid; gradual wavy boundary. (4 to 8 inches thick.)
C1--17 to 27 inches; yellowish brown (10YR 5/8), pale brown (10YR 5/3), and strong brown (7.5YR 5/8), crushed color, pale brown (10YR 6/3), gravelly clay loam, massive; friable, slightly sticky, slightly plastic; strongly acid; diffuse wavy boundary.
C2--27 to 60 inches; brownish yellow (10YR 6/6) gravelly clay loam with few medium distinct light gray (10YR 6/1) mottles; massive; friable, slightly sticky, slightly plastic; very strongly acid.
TYPE LOCATION: Noroeste SCD, Puerto Rico; 4.5 miles southeast of the town of Aguada; 250 meters on dirt road from kilometer marker 5.6 of highway 417. 50 feet west of dirt road.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 12 to 30 inches. Depth to gravelly horizons vary from 8 to 16 inches. Reaction ranges from strongly to very strongly acid throughout. Base saturation of the epipedon and cambic horizon is 50 percent or more. Exchange capacity is more than 20 meg/100 grams of clay. Texture of the control section averages gravelly clay loam with less than 35 percent clay and more than 35 percent by volume of medium and coarse gravel. These soils have slightly sticky and plastic solum and slightly sticky and slightly plastic C horizons.
The A horizon has hue of 10YR, value of 3 and 4 and chroma of 4. Texture is clay loam or clay.
The Bw horizon has hue of 10YR, value of 4 and 5 and chroma of 4 and 6. Texture is clay loam or clay
The BC horizon has hue of 10YR, value of 4 to 6 and chroma of 3 to 8. Texture is loam, clay loam, or sandy clay loam.
The C horizon has texture and color similar to the BC horizon.
COMPETING SERIES: These are the Cuchillas, Quebrada, Morado, Maresua series in the same Subgroup and the Junquitos, Dique, Humacao, Mani, Caguabo, Malaya, Juncos and Montegrande series in the same Great Group. The Cuchillas soils have soil temperatures below 71.6 degrees F at depth of 20 inches and lack the coarse fragments in their profiles. The Quebrada and Morado soils are less acid and lack the gravelly horizons. The Maresua soils have finer textured profiles and are less acid. The Junquitos and Gurabo soils have finer textured profiles and have low chroma mottles within 20 inches of the surface. The Dique, Humacao and Mani soils lack the coarse fragments and have irregular distribution of organic matter with depth. The Caguabo and Malaya soils have semi-consolidated volcanic rock within 20 inches of the surface. The Juncos and Montegrande soils have horizons with COLE values exceeding 0.09.
GEOGRAPHIC SETTING: The Plata soils occur on moderately steep to steep sideslopes on slope gradients of 0 to 60 percent. The regolith consists of fine and moderately fine textured residuum derived from volcanic conglomerates. The climate is humid tropical. The average annual precipitation is 80 inches and the mean annual temperature 76 degrees F. The soil temperature at depth or 20 inches is over 71.6 degrees F and the difference between mean summer and winter temperatures is less than 9 degrees F. See Remarks.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Moca, Voladora, and Perchas series. The Moca and Voladora soils are redder and have argillic horizons. The Perchas soils are finer textured throughout and have low chroma mottles in the upper part of the sola.
DRAINAGE AND PERMEABILITY: Well drained, rapid runoff and moderate permeability.
USE AND VEGETATION: Native pasture and brush.
DISTRIBUTION AND EXTENT: Humid uplands of Northwestern Puerto Rico. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Raleigh, North Carolina
SERIES ESTABLISHED: Soil Survey of Puerto Rico, 1942.
REMARKS: In the Caribbean National Forest, a taxajunct of this series was correlated on nearly level terraces.
Diagnostic horizons and features recognized for this pedon:
Ochric epipedon - the zone from 0 to 6 inches (Ap horizon).
Cambic horizon - the zone from 6 to 17 inches (Bw and BC horizons).