Soil Genesis as Affected by Topography and Time in Highly Calcareous Parent Materials Under Semiarid Conditions in Iran1
- Ali Abtahi2
Soil formation as affected by topography and time was studied in highly calcareous parent materials under the semiarid conditions of southern Iran. Soils of the 95,000-ha Sarvestan basin were considered for this purpose.
Topographic features of the Sarvestan basin were related to variations in soil texture and salinity. Slightly saline, coarse-textured soils occurred at high elevations, whereas fine-textured soils of higher salinity occurred at low elevations. Based on salinity status, these two general soil types were classified as Inceptisols and Aridisols, respectively.
Soils comprising a chronosequence differed mainly in the redistribution and accumulation of carbonates. They ranged from those developed in Holocene alluvium (Typic Xerofluvents) and lacking any evidence of carbonate redistribution to those developed on Lower or Middle Pleistocene surfaces (provisionally classified as Petrocalcic Xerochrepts) and showing distinct petrocalcic horizons.
X-ray and electron optical analyses indicated a clear gradation in the relative contents of palygorskite and smectite clay minerals within this chronosequence. Palygorskite increased as smectite decreased in older soils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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