LOCATION AIMELIIK PW+ PBEstablished Series
TAXONOMIC CLASS: Very-fine, halloysitic, isohyperthermic Typic Kandiperox
TYPICAL PEDON: Aimeliik silt loam on an east-by-northeast-facing, convex linear, 65 percent slope under a mixed-upland forest plant community at an elevation of 146 meters (479 feet.) (Colors are for moist soil unless otherwise noted. All textures are apparent field textures. When described on June 19, 2006, the soil was moist throughout.)
Oi--0 to 4 centimeters (0 to 1 inch); very dark gray (7.5YR 3/1) slightly decomposed plant material intermixed with living root-mat; 80 percent fiber, 50 percent rubbed; structureless massive; nonsticky and nonplastic; many very fine, fine and medium and few coarse, very coarse roots; many very fine, fine, and medium tubular and interstitial pores; very strongly acid (pH 5.3, 1:1 in water); abrupt smooth boundary. (0 to 15 centimeters thick)
A--4 to 8 centimeters (1 to 3 inches); brown (7.5YR 4/3) silt loam; moderate medium granular structure; very firm, nonsticky and moderately plastic; common very fine, fine, medium, and coarse roots; common very fine, fine, and medium tubular and interstitial pores; common dark brown (10YR 3/3) worm casts filling; many fine and medium tubular pores; common thin clay coatings on faces of peds and lining pores; very strongly acid (pH 4.9, 1.1 water); abrupt smooth boundary. (8 to 23 centimeters thick) Lab sample # 07N00515
Bto1--8 to 33 centimeters (3 to 13 inches); brown (7.5YR 4/4) silty clay loam; strong medium subangular blocky structure parting to moderate very fine and fine angular blocky; firm, nonsticky and very plastic; few very fine, fine, and medium roots; common very fine, fine, and medium tubular and interstitial pores; common dark brown (10YR 3/3) worm casts filling; many fine and medium tubular pores; continuous thin clay coatings on faces of peds and lining pores; few thin black (7.5YR 2/1) manganese coatings on faces of peds; very strongly acid (pH 4.7, 1:1 water); 35 percent continuous prominent pressure faces on all faces of peds abrupt smooth boundary. (10 to 71 centimeters thick) Lab sample # 07N00516
Bto2--33 to 45 centimeters (13 to 18 inches); strong brown (7.5YR 4/6) silty clay; strong coarse subangular blocky structure; very firm, nonsticky and very plastic; few very fine, fine, and medium roots; common very fine and fine tubular and interstitial pores; common dark brown (10YR 3/3) worm casts filling many fine and medium tubular pores; continuous thin clay coatings on faces of peds and lining pores; very few thin black (7.5YR 2/1) manganese coatings on faces of peds; very strongly acid (pH 4.8, 1:1 water); 35 percent continuous prominent pressure faces on all faces of peds gradual wavy boundary. (10 to 20 centimeters thick) Lab sample # 07N00517
Bto3--45 to 86 centimeters (18 to 34 inches); strong brown (7.5YR 4/6) clay; strong coarse subangular blocky structure parting to moderate very fine and fine angular blocky; extremely firm, nonsticky and very plastic; few very fine, fine, and medium roots; common very fine and fine tubular and interstitial pores; common dark brown (10YR 3/3) worm casts filling; many fine and medium tubular pores; continuous thin clay coatings on faces of peds and lining pores; very few thin black (7.5YR 2/1) manganese coatings on faces of peds; very strongly acid (pH 4.8, 1:1 water); 60 percent continuous prominent pressure faces on all faces of peds; clear wavy boundary. (10 to 20 centimeters thick) Lab sample # 07N00518
CBt--86 to 200 centimeters (34 to 79 inches); variegated 60 percent yellowish red (5YR 4/6) and 25 percent strong brown (7.5YR 4/6) silty clay loam; about 15 percent by volume mixed yellowish red (5YR 4/6) and dusky red (10R 3/3) saprolite with a crushed texture of silty clay loam; also contains brown (7.5YR 4/4), weak red (10R 5/2), and pale yellow (5Y 8/2) saprolite material as specks or in a platy or variegated color pattern; massive; extremely firm, slightly sticky and very plastic; few very fine, fine, and medium roots in cracks; many very fine and fine, and common medium vesicular pores; common thin clay coatings on faces of peds and lining of pores; few thin very dark brown (7.5YR 2/2) manganese coatings on faces of peds; very strongly acid (pH 4.9, 1:1 water.) (0 to 150 centimeters thick) Lab sample # 07N00519
TYPE LOCATION: Ngardmau State, Babeldaob Island, Republic of Palau; from the entrance to Ngardmau Falls go to the end of the road past the gazebo on the left-hand side. Follow the trail about 18 meters (59 feet) SE past the outhouse. Then follow the trail into the woods about 10 meters (33 feet) heading NE for 10 meters (33 feet.) Next, go east about 43 meters (141 feet) down an old Japanese WWII road. The soil pit is located on the right hand side up along a hill; WGS 84 UTM 454431 meters E, 838598 meters N, zone 53; Lat 7 35 11.08" N and Long 134 28 13" E
RANGE IN CHARACTERISTICS:
Control section: 25 to 100 centimeters (10 to 39 inches)
Thickness of the solum: 50 to 150 centimeters (20 to 59 inches)
Depth to bottom of diagnostic features:
Ochric epipedon 7 to 29 centimeters (3 to 11 inches)
Fibric soil materials 2 to 8 centimeters (1 to 3 inches)
Depth to diagnostic features:
Kandic horizon: 8 to 40 centimeters (3 to 16 inches)
Abrupt textural change: 8 to 40 centimeters (3 to 16 inches)
Thickness of diagnostic features:
Ochric epipedon: 8 to 40 centimeters (3 to 16 inches)
Kandic horizon: 26 to 125 centimeters (10 to 49 inches)
Fibric soil materials: 1 to 10 centimeters (0 to 4 inches)
Linear extensibility: 4 to 11 percent, weighted average RV is 6 percent
Surface Fragments: Rock fragments are vesicular petroferric fragments, tuff, ironstone and gibbsite concretions; 0 to 15 percent total rock fragments; 0 to 15 percent gravel; 0 to 15 percent cobbles
Saturated hydraulic conductivity: High in the subsoil and moderately high in the underlying
material.
Oi and Oe horizon(s):
Hue: 7.5YR or 10YR
Value: 2 or 3 moist
Chroma: 1 or 2 moist
In lieu of texture: slightly or moderately decomposed plant material
Fragment size and content: Rock fragments are petroferric fragments, tuff, ironstone and gibbsite concretions; 0 to 15 percent total rock fragments; 0 to 15 percent gravel; 0 to 15 percent
cobbles.
Reaction: pH 5.6 to 6.5
Cation exchange capacity: 80 to 115 meq/100grams
Effective cation exchange capacity: 30 to 50 meq/100grams
Organic matter content: 60 to 70 percent
A and AB horizon(s):
Hue: 7.5YR or 10YR
Value: 3 or 4 moist
Chroma: 3 or 4 moist
Texture: silty clay, silty clay loam, silt loam, clay
Fragment size and content: Rock fragments are petroferric fragments, tuff, ironstone and gibbsite concretions; 0 to 15 percent total rock fragments; 0 to 15 percent gravel; 0 to 15 percent cobbles.
Sand content: 5 to 30 percent
Silt content: 10 to 80 percent
Clay content: 10 to 80 percent
Reaction: pH 4.7 to 5.4
New Zealand P Retention: 55 to 65 percent
Aluminum Saturation: 2 to 22 percent
Cation exchange capacity: 20 to 35 meq/100grams
Effective cation exchange capacity: 10 to 15 meq/100grams
Organic matter content: 9.0 to 17.0 percent
Bto horizon(s):
Hue: 2.5YR, 5YR, or 7.5YR
Value: 4 moist
Chroma: 4 to 6 moist
Texture: silty clay loam, silty clay, clay
Fragment size and content: Rock fragments are petroferric fragments, tuff, ironstone and gibbsite concretions; 0 to 15 percent total rock fragments; 0 to 15 percent gravel; 0 to 15 percent cobbles.
Sand content: 0 to 30 percent
Silt content: 10 to 70 percent
Clay content: 25 to 80 percent
Reaction: pH 4.9 to 5.5
New Zealand P Retention: 60 to 80 percent
Aluminum Saturation: 75 to 90 percent
Cation exchange capacity: 9 to 18 meq/100grams
Effective cation exchange capacity: 3.5 to 8 meq/100grams
Organic matter content: 1 to 3 percent
C, BCt, CBt, and BCt horizon(s):
Hue: 10R, 2.5YR, 5YR, 7.5YR, or 10YR
Hue of clay coatings: 7.5YR or 10YR
Hue pseudomorphs: 2.5Y, 5GY, or 5Y
Value: 3 to 5 moist
Chroma: 3 to 8 moist
Value of pseudomorphs: 6 to 8 moist
Chroma of pseudomorphs: 1 to 3 moist
Texture: silty clay, clay, silty clay loam, loam
Fragment size and content: Rock fragments are petroferric fragments, tuff, ironstone and gibbsite concretions; 0 to 15 percent total rock fragments; 0 to 15 percent gravel; 0 to 15 percent cobbles.
Sand content: 0 to 45 percent
Silt content: 15 to 80 percent
Clay content: 15 to 80 percent
Reaction: pH 5.1 to 5.5
New Zealand P Retention: 50 to 65 percent
Aluminum Saturation: 85 to 90 percent
Cation exchange capacity: 10 to 15 meq/100grams
Effective cation exchange capacity: 3.5 to 8 meq/100grams
Organic matter content: 0.5 to 0.6 percent
COMPETING SERIES: There are no competing series at this time.
GEOGRAPHIC SETTING: Aimeliik soils are on all hillslope positions of hills on volcanic islands. Slope is 2 to 75 percent. The soils formed in saprolite derived from andesite and basaltic volcanic breccia, tuff, or bedded tuff. They are dominant under Mixed Upland Forest plant communities, but also are under patches of forest in anthropic savannahs vegetation in depositional areas such as toeslopes and lower sideslopes of drainageways where fertility and organic matter contents are relatively high. Slopes are 2 to 75 percent. Elevation is 1 to 231 meters (3.3 to 758 feet.) The climate is tropical and moist. Because of the strong marine influence, the diurnal and annual range of temperature is limited. Rainfall averages about 3685 millimeters (145 inches) per year and ranges from approximately 2900 to 4400 mm (114 to 173 in.) The seasonal wet (May to November) and dry seasons (December to April) with the driest months (February, March, and April) averaging 178 to 229 milliliters (7 to 9 inches) per month. Rainfall is derived from convective uplift, which results in short duration rainstorms of high intensity. Rainfall is irregularly distributed geographically. These soils lie within the latitudinal zone that receives more solar radiation than it re-radiates back to space. This imbalance maintains the atmospheric temperatures in a quasi-steady state. The mean daily temperature throughout the year averages 27 C (81 F) with a mean diurnal range of about 4 C (7 F.) Relative humidity averages about 90 percent at night and 75 to 80 percent during the day.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Babelthuap, Ngardmau, and Palau soils. Babelthuap and Ngardmau soils occur on ridges, highly degraded, and support "degraded" savanna vegetation dominated by picture plants and false staghorn ferns, which tolerate high aluminum soils. Babelthuap soils are 50 to 100 centimeters (20 to 39 inches) deep to solum (saprolite C-horizon.) Ngardmau soils are 25 to 50 centimeters (10 to 20 inches) deep to solum (saprolite C-horizon.) and have subsoil that is too thin to meet the requirements of a kandic horizon. Palau series are under grassland savannas dominated by pandanus and grasses. They have 9 to 12 percent and occur on ancient anthropogenic hillslope terraces.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Runoff is low on the gentle slopes and high on the steeper slopes, moderately low to moderately high-saturated hydraulic conductivity.
USE AND VEGETATION: These soils are in mixed-upland forests plant communities and are used for native vegetation, watershed, and slash and burn or agroforestry cultivation of subsistence crops. A few areas are used for urban development. Agroforestry ground crops include; beans, cassava, kang kong, melon, peppers, noni, okra, pineapple, piper betle, pumpkin, taro squash, sugar cane, taro, and yams. Agroforestry tree crops include; avocados, bananas, betel nut, breadfruit, football fruit, guava, Inocarpus fagifer, keam, lemons, mango, medicinal plants, mountain apple, ngel, star fruit, titimel, and tropical almond. Most areas are in native tropical rainforest or, to a lesser extent, patches of forest in perennial grassland that is burned by humans almost annually. Native vegetation includes; (canopy) Pinanga insignis, Cyathea sp, Alphitonia carolinensis, Pouteria obovata, Fagraea ksid, Callophyllum inophyllum var. wakamatsui, Rhus taitensis, (understory) Atuna corymbosa, Garcinia matudai, Pleome multiflora, Finschia chloraxantha, Manilkara udoid, Symplocos racemosa, Campnosperma brevipetiolata, Cerbera floribunda.
DISTRIBUTION AND EXTENT: MLRA 193 Volcanic Islands of Western Micronesia, Republic of Palau. These soils of these series are of large extent; about 50,000 acres in size. They are mapped on the islands of island of Babeldaob and to a lesser extent on Koror and Arakabesan.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Airai Municipality, Babeldaob Island, Republic of Palau, 1981. Local pronunciation of the word Aimeliik is "Aim-e-leek."
REMARKS: The A horizon does not become dry for longer than 4 consecutive days and 24 cumulative days per year during the dry season (February, March, and April). Drying only occurs under bare soil conditions. The soil does not meet the definition of an oxic horizon because the clay content increases by more than 8 percent within 15 centimeters (6 inches.) The Ngardok forested series was correlated with Aimeliik, bedded tuff. The Aimeliik, bedded tuff substratum has a platy structure and seems to be more erosive when vegetation is removed. In addition, when Aimeliik occurs near Ollei and Nekken series the rock fragments are likely to be hard basalt and indurated tuff.
Particle-size distribution measurements are usually not reliable for tropical soils; therefore, apparent field textures and the corresponding mid-point values of texture classes were used rather than laboratory analysis for particle sizes. Particle size distribution is difficult to determine in tropical soils because of the tendency to form water-stable aggregates. The poor soil dispersion in laboratory analyses reflects the water-stable aggregates of clay in silt and sand-sized "particles." Therefore, the soils may have large clay content but physically they behave as coarser textures.
Diagnostic horizons and features recognized in this pedon are:
Fibric soil material - 0 to 4 cm (0 to 2 inches) (Oi horizon)
Ochric epipedon - 0 to 8 cm (0 to 3 inches) (A horizon)
Kandic horizon - 8 to 86 cm (3 to 34 inches) (Bo horizon)
Particle-size control section - 25 to 100 cm (10 to 39 inches)
Abrupt textural change - 8 cm (0 to 3 inches)
Soil moisture regime subclass: typic
Soil moisture regime class: perudic
Mean annual soil temperature: 27 C (81 F)
ADDITIONAL DATA: National Soil Survey Laboratory Data # 06PW002001 and Military Geology of Palau Islands, 1956, are used to define the series. Additional data are National Soil Survey Laboratory # S03PW002002, S03PW002007, S05PW212001, S05PW222001, S05PW227001, and 79TQ632003. University of Hawaii at Manoa - College of Tropical Agriculture and Human Resources # 06-4569 to 06-4573
Taxonomic Version: Keys to Soil Taxonomy, 10th edition 2006.