Publication Date:
1999-08-01
Description:
Soil properties, mineral composition, available microelements for plant uptake and ultramicromorphological gravel characteristics in skeletal soils from amphibolite and serpentinite rocks with additions of silicon-rich colluvial materials were studied in the Mediterranean region (Sierra Nevada, southern Spain). The soils (Entic Cryumbrept, Typic Xerochrept, Pachic Cryoboroll and Typic Cryorthent) showed mineralogical discontinuities, exchangeable Ca:Mg ratios greater than 1 and a pH and base saturation profile that decreases in the central and lower parts of the solum. The different soil particle-size fractions had similar mineral compositions (X-ray diffraction [XRD] and infrared [IR] techniques) retaining unstable phases (amphibole, feldspar, serpentine). Inherited or slightly transformed phyllosilicates (serpentine, mica, chlorite, talc and interstratified phases) were shown to be dominant in the clay fraction. The scant pedogenic evolution contrasted with a high free iron content. The concentrations in fine earth of DTPA-Zn, -Cu, -Mn, -Co, -Cr, -Ni and -Fe were not toxic, showed interdependence and were related to the silt, clay and free forms content. The gravel fraction revealed significant amounts of free iron and available microelements (DTPA-extractable), which could be bound to deposits of precipitated secondary forms and to finer pedogenic material present in the fragments. Scanning electron microscope (SEM) observations confirmed these morphological characteristics in serpentinite and amphibolite pebbles. Key words: Mafic-ultramafic soils; mineralogy; DTPA-microelements; rock fragments
Print ISSN:
0008-4271
Electronic ISSN:
1918-1841
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Permalink