Papers by farhad khormali
One of the best indicators of the geological and environmental events in the Quaternary is the al... more One of the best indicators of the geological and environmental events in the Quaternary is the alternation of loess-paleosol. In this study, for paleoenvironmental identification of buried paleosols in loess sequences, 14 sections located between 36˚ 49′ 6˝ to 36˚ 49′ 20˝ northern latitude and 54˚ 26′ 45˝ to 54˚ 26′ 52˝ eastern longitude in the southern part of Gorgan (Kharazmi town) were studied. The disturbed soil samples for physico-chemical analysis and clay mineralogy and undisturbed samples for prepration of thin sections were collected. The physicochemical results (calcium carbonate content, particle size distribution, cationexchangable capacity and Feo/Fed) indicated that the soils had experienced several pedogenic periods. The result of mineralogy showed that a high amount of smectite, vermiculite and mixed layer mica-smectite in paleosols compared to loess deposits probably indicates moister regims through interglacial compared to glacial periods. The micromorphological observations revealed many evidences on the occurance of pedogenic processes. One of the most important index of pedogenesis, clay coating and hypocoating around void are presented only in buried paleosols, which is the evidence for moist climate conditions, enough for leaching and translocation of clay. Formation of the studied loess and paleosols, probably took place in glacial and interglacial cycles with different climate condition, respectively.
International Journal of Sciences: Basic and Applied Research (IJSBAR)
One of the best indicators of the geological and environmental events in the Quaternary is the al... more One of the best indicators of the geological and environmental events in the Quaternary is the alternation of loess-paleosol. In this study, for pale environmental identification of buried pale sols in loess sequences which located between 36˚ 49' 15˝ north latitude and 54˚ 26 52˝ east longitude in the southern part of Gorgan, the disturbed soil samples for physicochemical analysis and clay mineralogy and undisturbed samples for preparation of thin sections were collected. The physico-chemical results (calcium carbonate content, particle size distribution, cation exchangeable capacity and Fe o /Fe d) indicated that the soils had experienced several pedogenic periods. The result of mineralogy showed that a high amount of smectite, vermiculite and mixed layer mica-smectite in paleosols compared to loess deposits probably indicates moister regimes through interglacial compared to glacial periods. sign of climate oscillation has inherited in the shapes of pedogenic. The micro morphological observations revealed many evidences on the occurrence of pedogenic processes. One of the most important index of pedogenesis, clay coating and hypo coating around void are presented only in buried paleosols, which is the evidence for moist climate conditions, enough for leaching and translocation of clay. Formation of the studied loess and paleosols, have probably taken place in glacial and interglacial cycles with different climate condition, respectively.
The present study was carried out in Kharkeh Research Station, Kurdestan Province, western Iran t... more The present study was carried out in Kharkeh Research Station, Kurdestan Province, western Iran to investigate the effects of the change in land use on the degradation of Mollisols, their organic carbon content, clay mineralogy and K + status. The study area was partly under cultivation (for over 40 years) and partly preserved as rangelands. The results revealed that Mollisols are the dominant soils in non-cultivated natural rangelands. The adjacent cultivated soils, however, lack enough organic carbon to meet the requirements of Mollisols. Cultivation practices had exerted adverse effects on some such major soil properties as organic carbon, cation exchange capacity, as well as macro-and microstructure. Clay minerals and different forms of potassium did not show significant differences in the two land uses. Parent material rich in such potassium bearing minerals as feldspars and mica, as well as the dominance of illite in soils, were probably the main factors responsible for adjustment of the soil K + , rendering the changes relatively nonsignificant.
Monitoring the effect of land use on soil quality attributes within an ecosystem can provide a us... more Monitoring the effect of land use on soil quality attributes within an ecosystem can provide a useful way to control land degradation and achievement of sustainable management. In order to study the effects of different land uses on carbon stock and soil quality attributes, a loess hillslope was selected in eastern Golestan Province, Agh-Su area. Six pedons in four land uses including pasture; Oak natural forest; Cypress plantation forest and a cultivated land, were studied. Important physical, chemical and biological soil quality attributes such as bulk density (Bd), mean weight diameter (MWD), cation exchange capacity (CEC), available P, Biomass carbon (BioC) and Soil Microbial respiration (SMR) were studied. The results revealed that cultivation has led to the deterioration of soil quality attributes. Organic matter, CEC and MWD were significantly lower in the cultivated land. MWD varied between the highest 2.36 mm in the Oak natural forest and the lowest 0.54 mm in cultivated la...
Journal of Mountain Science, 2009
In order to study the effects of different land vegetative covers on soil quality attributes, a l... more In order to study the effects of different land vegetative covers on soil quality attributes, a loess hill slope was selected in eastern Golestan Province, Ghapan watershed, Iran. Four profiles in four land uses, including Quercus natural forest; Pinus artificial forest; Cupressus artificial forest and a cultivated land, were studied. Results showed that MWD was significantly different in the studied land uses, and it varied between 1.6 mm in Quercus natural forest and 0.31 mm in cultivated land use. The lowest CEC, microbial respiration rate and organic carbon were 28.4 cmol•kg -1 , 177 μgCO2•g -1 •day -1 and 1.32 % found in cultivated land use, respectively. The organic matter content in the forest areas was considerably higher than that of cultivated land use. The studies on soil profile development revealed that the natural forest soils were highly developed. The soils of the Quercus natural forest were classified as Calcic Haploxeralfs with a well developed argillic horizon unlike the cultivated soils which showed the minimum development and classified as Typic Xerorthents. The soils of the artificial forests had both mollic epipedons and were classified as Typic Calcixerolls with moderate profile development. Micromorphological studies revealed that argillic horizons had speckled and partly crystallitic b-fabric in the natural forest indicating the high landscape stability. In contrast, the crystallitic b-fabric of other land uses shows the absence of enough leaching of carbonate and the subsequent migration of clay particles indicating the unstable conditions and high soil erosion. Intense erosion of the surface horizons of cultivated land use has resulted in the outcropping of the subsurface carbonate rich horizons preventing soil development.
Clay Minerals, 2003
The clay mineralogy of soils and of the main calcareous sedimentary parent rocks of southern Iran... more The clay mineralogy of soils and of the main calcareous sedimentary parent rocks of southern Iran were investigated to determine their origin and factors controlling their distribution pattern in soils. The results revealed that the soil-available moisture plays the major role in the distribution pattern of palygorskite and smectite clay minerals in the arid and semi-arid areas studied. There is an inverse correlation between palygorskite and smectite with regard to the soil-available moisture as expressed by P/ETº (ratio of mean annual precipitation to mean annual reference crop evapotranspiration). At P/ETº values >0.4 palygorskite transforms to smectite. Smectite is thought to be mainly of ‘transformed’ origin. It is detected in trace amounts in soils of more arid areas and increases in soils having greater available moisture. The general decrease in illite content with depth is related mainly to its transformation to smectite under favourable moisture conditions of the deeper...
Geoderma, 2006
The micromorphology of calcitic pedofeatures in highly calcareous arid and semiarid soils of the ... more The micromorphology of calcitic pedofeatures in highly calcareous arid and semiarid soils of the Fars Province, Southern Iran has been studied in order to determine their genesis and distribution in different climatic regions. Available soil moisture, soil temperature, soil texture, vegetation and availability of calcium carbonate are amongst the main factors determining the type and morphology of calcitic features. Size and frequency of microcrystalline calcite nodules and coatings increase from aridic to xeric, but decrease again towards the areas with a ustic moisture regime. Cytomorphic and acicular calcite are observed mainly in areas with an ustic moisture regime and a denser vegetative growth, but rarely in xeric areas. Layered pendents of calcite are common beneath coarser fragments, but are considered as relicts of a more humid paleoclimate. Calcite depletion pedofeatures are observed in xeric-mesic areas with higher available soil moisture. Ultraviolet (UV) violet (VL) and blue light (BL) fluorescence and cathodoluminescence (CL) studies proved to be useful in differentiating in this region pedogenic from geogenic calcite. All types of pedogenic calcite were UV and BL-fluorescent but didn't show CL, whereas, limestone fragments showed CL, but no UV-BL-fluorescence. The absence of CL in the studied pedogenic calcite samples is suggested to be related to the oxidative environment, hindering mobilisation of Mn ++ .
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Papers by farhad khormali