Micromorphology of solonetzic horizons as related

Authors: M Lebedeva Verba M Gerasimova M Konyushkova

Publish Date: 2009/05/10

Volume: 6, Issue: 2, Pages: 132-138

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Abstract

Micromorphology of solonetz species with special attention to natric horizon was studied in microcatenas at the Dzhanybek Research Station northwestern Caspian Lowland The solonetzic natric horizon is easily identified and it occurs at varying depths which are the criteria for subdividing solonetzes into 4 species namely crusty shallow medium and deep In this sequence the depth of humusaccumulative horizons increases and the upper boundary of salinity manifestations goes downThe following micromorphological features are assumed as typical for natric horizons angular blocky microstructures with partially accommodated aggregates having sharp boundaries and narrow planelike packing voids bfabric speckled in the aggregates’ centers and monostriated at their peripheries merging into stress coatings very few interpedal voids organoclay coatings humusenriched infillings no calcite and gypsum pedofeatures A complete set of “natric” features was found only in the crusty solonetz the shallow solonetz lacks only illuviation coatings while the medium and deep species have several modifications of fabric elements blocky aggregates have a rounded shape and are penetrated by biogenic channels favoring their further biogenic reworking plant residues became more abundant and diverse and blackened tissues occur illuviation clay coatings evolved into papules stress coatings gave birth to striated bfabrics thus maintaining a high plasma orientationThe thin sections of natric horizons made 50 and 20 years ago were examined to study the influence of environmental changes increase in precipitation and rise of ground water table on micropedofeatures The following processes took place i in the topsoil humus accumulation and biogenic structurization ii in the natric horizon — rearrangement of clay coatings into micromass bfabrics and iii in the lower part of the natric horizon — development of pseudosand fabric calcite and gypsum formation The trends revealed are in good agreement with the environmental events

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