Multimedia Gallery - Packing pores and aggregation in an Oxisol

From the Soil Micromorphology Slide Collection

Description of slide: Welded crumbly aggregates and many densely packed pedotubules and few iron oxide nodules and concretions.Within pedotubules there are small mammilated vughs.

Data for the horizon Horizon sampled: Aps2 Depth sampled: 10-15 cm
Physical and chemical data available: pH = 5.8, OC = 1.7%, free Fe203 = 10% Particle size distribution (deferrated): sand = 5%, silt = 19%, clay = 76%
Clay mineralogy: Gibbsite dominant, goethite present
Macromorphological description of horizon: 5YR 4/6 clay; weak medium and fine subangular blocky parting to fine crumb structure
Micromorphological description of horizon: Dominantly inorganic plasma, reddish brown to yellowish red due to iron and organic pigments. Organic pigments are somewhat less prominent as compared with Aps1 material. The plasmic fabric is isotic to undulic, locally inundulic.
Skeleton grains are rare. There are few fresh root remains. Related distribution pattern is porphyroskelic (Stoop and Jongerius, 1975: c/f 2 µm open porphyric).

Soil Classification
U.S.: Clayey, gibbsitic, isohyperthermic Typic Acrudox
F.A.O.: Acri-Orthic Ferralsol

Elevation: 390 m above mean sea level
Physiographic position: Karst depression floored with bauxite deposits and surrounded by limestone hills
Topography and hill slope position: Nearly level to gently undulating
Parent material: Bauxite overlying limestone of the White Limestone Formation
Soil climatic data and/or soil water balance: Annual rainfall approximately 2000 mm
Vegetation:Citrus orchard with grass undergrowth in a tropical rainforest climate

Data for 35-mm slide
Light mode: Plane polarized
Scale: Bar on slide = 1 mm

Andriesse W. and J. J. Scholten. 1982. Acri-orthic Ferralsol (Haplic Acrorthox) Jamaica. ISM Soil Monolith Paper 6. International Soil Museum, Wageningen, The Netherlands.

Slide MS2. Soil Science Society of America, 1993. A Reference Slide Collection for Soil Micromorphology. SSSA, Madison, WI.