نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شهید باهنر کرمان، کرمان، ایران
2 بخش علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objectives:
Geomorphology concerns the arrangement, differentiation, formation, and evolution of landforms, while pedology focuses on the processes of soil formation and development. Geomorphological studies provide insights into the genetic relationships between soils and landforms, enabling interpretation of landscapes both past and present. This research aimed to investigate the physical, chemical, and micromorphological properties of soils. Specifically, the objectives were to examine soil genesis and evolution in relation to geomorphic surfaces and to assess the influence of soil characteristics on classification using the latest editions of Soil Taxonomy (Thirteenth edition) and the World Reference Base for Soil Resources (Fourth edition).
Materials and Methods:
This study was conducted in a section of the Central Iranian Plateau (Jazmurian sub-watershed), encompassing parts of Jiroft and Faryab counties in southern and southwestern Kerman Province, Iran. The study area extended along a north–southwest transect from the Khatunabad area of Jiroft to the Faryab plain. The region features a semi-arid desert climate, with weak aridic moisture and hyperthermic temperature regimes. Landforms investigated include mountains, alluvial fans, and alluvial plains.
The Khatunabad alluvial fan was divided into four geomorphic surfaces: (1) mid-alluvial fan with recent alluvium (Pedon 1), (2) mid-alluvial fan with young alluvium (Pedon 2), (3) mid-alluvial fan with older sediments, and (4) base of the alluvial fan with recent alluvium (Pedon 4). The Jiroft alluvial plain was categorized into upland (Pedon 5) and lowland (Pedon 6) positions based on elevation. The Bulok mid-alluvial fan (Pedon 7) and Faryab alluvial plain (Pedon 8) were not subdivided due to geomorphic uniformity.
One pedon was excavated, described, and sampled on each geomorphic surface, resulting in a total of eight pedons. Physical and chemical analyses were conducted, and soils were classified according to both Soil Taxonomy (Thirteenth edition) and the WRB (Fourth edition). For micromorphological studies, undisturbed soil clods were used to prepare thin sections, which were subsequently analyzed and photographed.
Results:
Based on WRB classification, Fluvisols (alluvial soils), Calcisols (calcareous soils), Gypsisols (gypsiferous soils), and Solonchaks (saline soils) were identified. Corresponding Soil Taxonomy classifications included Aridisols (Salids, Gypsids, and Calcids suborders) and Entisols. Field observations revealed the presence of calcite soft masses, gypsum pendants, and anhydrite pendants in soil profiles. Evaporative calcium sulfate minerals—gypsum (CaSO₄·2H₂O) and anhydrite (CaSO₄)—were identified in field studies of the Jiroft alluvial plain uplands and micromorphological analysis of the Boluk mid-alluvial fan.
Micromorphological features observed included amorphous forms, lenticular and plate-like gypsum crystals, interlocked gypsum plates, and interlocked plates of amorphous anhydrite crystals. These pedofeatures were noted in both the soil matrix and pore infillings.
Conclusion:
A strong relationship between soils and geomorphic surfaces was evident. Pedons situated on river alluvium in the Khatunabad alluvial fan were younger, with recent deposits exhibiting calcareous properties and older deposits showing calcareous–gypsiferous characteristics. The origin and type of alluvial fan deposits influenced the rate of soil evolution, as observed in the contrast between the non-gravelly, saline, and sodic soils of Boluk and the gravelly, non-saline, non-sodic soils of Khatunabad. Saline and sodic soils were prevalent in the alluvial plain.
Both Soil Taxonomy (down to sub-group level) and WRB (reference soil groups with principal and supplementary qualifiers) systems successfully classified the soils of the area. Soil Taxonomy provided a more detailed reflection of field realities, including identification of anhydritic diagnostic horizon. A significant correlation was observed between soil classification (under both systems) and geomorphic surfaces.
Overall, soil–geomorphology studies are strongly recommended for informed decision-making in land use planning and soil management, particularly in the context of sustainable agricultural production.
کلیدواژهها [English]
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