Soil science
S. Sanjari; M.H. Farpoor; M. Mahmoodabadi; S. Barkhori
Abstract
Introduction: Playa, as an important geomorphic position in arid areas, covers about 1% of the continents and has attracted attention of soil scientists and geomorphologists. Soil genetic processes related to landforms and geomorphic processes are of great importance. Micromorphology is among necessary ...
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Introduction: Playa, as an important geomorphic position in arid areas, covers about 1% of the continents and has attracted attention of soil scientists and geomorphologists. Soil genetic processes related to landforms and geomorphic processes are of great importance. Micromorphology is among necessary techniques in soil studies which has been used by several researchers. Micromorphological features together with other soil characteristics provide invaluable data for reconstructing soil genetic processes. Moreover, classification and identifying characteristics of soils are pre-requisites for the optimum use and management of soil resources. Soil Taxonomy and World Reference Base (WRB) is among the most extensively used classification systems worldwide. Since no data about soils of the Jazmoorian Playa is available, the present research was performed with the following objectives: 1) studying physical, chemical, and micromorphological properties of soils in the Jazmoorian Playa related to different geomorphic surfaces, and 2) classifying soils of the region by Soil Taxonomy (2014) and WRB (2015) systems. Materials and Methods: The Jazmoorian playa is located in Kerman and Sistan Baloochestan provinces. The Jazmoorian Playa is a continental depression of late Pliocene. The playa is about 360 m above sea level with about 65 km length and 45 km width located between 58 ˚ to 60 ˚ longitudes and 27 ˚ to 28 ˚ latitudes. The area extends to the igneous Bazman Mountains to the northeast, the igneous Jebalbarez Mountains (granodiorite, andesite, granite) to the north and northwest, the Beshagard Ophiolite Mountains of Cretaceous and Paleocene to the south, and the colored Mélanges to the Oman Sea. Soil moisture and temperature regimes of the area were aridic (and aquic in limited areas) and hyper thermic, respectively. Wet zone, fan delta, clay flat, puffy ground clay flat, sodic clay flat, and salt crust were among the geomorphic surfaces investigated in the playa. In order to study the maximum soil variations in the area, eight representative pedons were described and sampled. Collected soil samples were air dried, grounded, and passed through a 2 mm sieve, and routine physical and chemical soil properties were then analyzed. Undisturbed soil samples were used for micromorphological observations. The soils were classified according to Soil Taxonomy (33) and WRB (11) systems. Results and Discussion: Results showed that EC contents of the saturated extracts ranged from 0.5 (fan delta) to 222.2 (salt crust) dS/m. The soils of the playa in Kerman Province affected by the Halilrood River had less salinity compared to the soils on playa surfaces in Sistan Baloochestan Province under influence of the Bampoor River. In addition, salt crust was only formed in parts of the playa located in Sistan Baloochestan Province. Clay coating and lenticular gypsum crystals were among the micromorphological features observed in the Jazmoorian Playa’s soils. The clay coating was formed due to high Na content. However, lenticular gypsum was formed due to small volume pore spaces as well as high salinity of the area. High soluble salts (Table 3) caused a salt coating around pore spaces to be formed due to evaporation of saline water table. WRB system could better classify soils into Solonchak and Solonetz RSGs compared to Soil Taxonomy system which classifies all soils as the Salids sub order. Natric Aquisalids, Typic Natrisalids, Natric Haplosalids, and Puffic Haplosalids sub groups and Natrisalids great group are recommended to be added to Soil Taxonomy system for more harmonization between the two classification systems. Furthermore, the definition of salic horizon in WRB system (EC of at least 15 dS/m and the EC multiplied by thickness of at least 450) is recommended to be included in Soil Taxonomy, because of limitations induced by salts and for a better correlation of the two systems. Conclusion: Results of physicochemical properties clearly showed that electrical conductivity of soil saturated extracts was in the range of 0.5 to 222.2 dS/m. The part of the playa located in Sistan Baloochestan Province is more saline than the part in Kerman Province. More salinity of playa in Sistan Baloochestan Province was attributed to the Bampoor River which passes through evaporative formations located in east and southeast of the area. Micromorphological observations showed clay coatings and lenticular gypsum crystals as pedogenic features. The soils of the area were classified as Aridisols and Entisols (according to Soil Taxonomy system) and Solonetz, Solonchaks, Fluvisols, and Regosols Reference Soil Groups based on WRB classification system. Moreover, WRB system was capable of separating saline from saline-sodic soils, however, Soil Taxonomy classifies both soils as Salids suborder. Therefore, WRB system is better suited for classification of the soils of our study area as compared with Soil Taxonomy.
H.R. Rafiei; A. Jafari; A. Heidari; Mohammad Hady Farpoor; A. Abbasnejad
Abstract
Introduction: Soil carbon (C) sequestration is recognized as a potentially significant option to off-set the elevation of global atmospheric carbon dioxide (CO2) concentrations. Soils are the main sink/source of carbon and also, an important component of the global C cycle. Total soil carbon (C) comprises ...
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Introduction: Soil carbon (C) sequestration is recognized as a potentially significant option to off-set the elevation of global atmospheric carbon dioxide (CO2) concentrations. Soils are the main sink/source of carbon and also, an important component of the global C cycle. Total soil carbon (C) comprises of the soil organic C (SOC) and the soil inorganic C (SIC) components. The soil inorganic C (SIC) stock mainly consists of carbonates and bicarbonates. Processes governing the dynamics of the soil carbon stock differ among ecoregions and strongly interact with soil properties. Understanding the distribution of organic and inorganic carbon stocks in soil profiles is essential for assessing carbon storage at the regional and global scale. Although global estimates provide a general view of carbon stock levels, accurate local estimates and factors affecting soil carbon dynamics are very important. As a result, there is an essential requirement for accurately estimating the distribution of carbon reserves and their differences with regard to soil properties. Materials and Methods: The study area is located in the Sardooeyeh region, South of Kerman, under semiarid conditions. A total of 5 soil profiles were excavated. Percentage of coarse fragments (> 2 mm) using a 2 mm sieve, total organic C by the K2Cr2O7-H2SO4 oxidation method of Walkley-Black, soil inorganic carbon using the Gravimetric carbonate meter method were determined. Bulk density was measured by drying core samples in an oven overnight and dividing the weight of dry soil by the volume of the core occupied by the soil after correction for coarse fragments. Results and Discussion: Organic carbon in the surface horizons of all profiles is maximum due to vegetation and decreases with increasing soil depth. As the altitude increased, the amount of organic carbon increased in the surface horizons. Lower temperature and higher humidity at higher altitudes lead to the lower organic matter decomposition and consequently higher organic carbon content of the soil. Although the upper soil layers had the maximum soil organic C content, the maximum soil inorganic C content was observed in the sub-surface layers. The soil organic carbon storage was between 5.52 to 9.48 kg m-2 and the storage of soil inorganic carbon in profiles was between 14.41 and 91.34 kg m-2. The total soil carbon storage in the profiles varied between 19.92 to 100.83 kg m-2 and the average was 42.66 kg m-2. The average of soil organic carbon storage in 0-25, 25-60, 60-120 cm depths were 2.6, 1.97 and 1.26 kg m-2, respectively. The amount of soil inorganic carbon storage in 0 -25, 25-60 and 60-120 cm depths were equal to 2.7, 10.40 and 8.26 kg m-2, respectively. Therefore, it seems that more than 50% of the total soil inorganic carbon storage is stored at a depth of 25-60 cm from the soil surface. The portion of inorganic carbon storage of total soil carbon was 77.5%, and about 89% of it was stored in sub-surface horizons (below 25 cm). The portion of organic carbon storage of total soil carbon was 22.4%. It seems that an increase in the partial pressure of CO2 in soils leads to some dissolution of the pedogenic carbonate in the top soil. Dissolved pedogenic carbonate transfers to the deep soil and then re-crystallizes under relatively dry conditions and low CO2. Conclusion: The results showed that soil organic carbon storage was mostly higher in surface horizons, and soil inorganic carbon storage was higher in sub-surface horizons. On average, the ratio of soil inorganic carbon storage to soil organic carbon storage was 4.27. The high percentage of soil inorganic carbon storage in total soil carbon, shows that inorganic carbon plays a very important role in semi-arid regions. Almost 89% of the soil inorganic carbon content and about 80% of the total soil carbon were accumulated in the sub-surface horizon of soil (below 25 cm), indicating the importance of sub-surface soil for storing carbon in semi-arid regions.
S. Sanjari; M.H. Farpoor; M. Mahmoodabadi; S. Barkhori
Abstract
Introduction Increasing demand for an international classification system as a unique communication tool in soil science has caused development of different systems. Like many other countries, Soil Taxonomy and WRB are the most popular soil classification systems in Iran. Genetic and morphologic ...
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Introduction Increasing demand for an international classification system as a unique communication tool in soil science has caused development of different systems. Like many other countries, Soil Taxonomy and WRB are the most popular soil classification systems in Iran. Genetic and morphologic soil properties are used for soil classification in both systems. However, correlation of the two systems and efforts to harmonize them have been a major concern among soil scientists. Comparing Soil Taxonomy and WRB in gypsiferous and calcareous soils of central Iran, Sarmast et al. (13) reported that WRB using various qualifiers is more effective than Soil Taxonomy. Since no study on soils of Iranshahr and Dalghan Regions located in Sistan and Baloochestan Province has performed and/or no reported data is available, the present research was performed to: 1) study morphological, physical, and chemical soil properties in the area, 2) classify soils based on Soil Taxonomy (2014) and WRB (2015) systems, 3) compare the two systems for soil description in Iranshahr and Dalghan regions as a part of Sistan and Baloochestan Province, central Iran. Material and Methods: The study area starts from Iranshahr (590 m asl) in the center of the province and extends to Dalghan (390 m asl) in west. Alluvial fan, pediment, playa, and hill were among different landforms identified using field studies, topography maps (1:50000), and Google Earth image observations. To cover the maximum soil variations in the area, 10 representative pedons were selected, described, and sampled. Results and Discussions: Calcic, gypsic, anhydritic, argillic, natric, and salic horizons identified after field work and laboratory analysis. Results of the study showed that addition of Yermic Torrifluvent, Yermic Torriorthent, Calcic Gypsiargid, Gypsic Natrsalid, Natric Gypsisalid, Anhydritic Gypsisalid, Anhydritic Calcisalid subgroups to Soil Taxonomy system from one hand, and addition of anhydrite and aquic (for Solonchak reference soil group) qualifiers to WRB system from the other hand, causes a higher correlation and more harmonization between the two classification systems. Meanwhile, the minimum percentage of calcium carbonate equivalent necessary for calcic horizon identification in coarse textured soils including gravel in Soil Taxonomy is also suggested to be added to WRB system. Besides, requirements of salic horizon in WRB system is recommended to be added to Soil Taxonomy. At the same time, soil names in WRB system provide more information and data about soil properties and characteristics in young soils (such as yermic qualifier showing desert pavement) compared to Soil Taxonomy. Soil Taxonomy is not able to properly classify saline soils of arid regions down to subgroup level which is a weak point for this system. That is why newly added Gypsic Natrsalids is suggested for soils with natric, gypsic, and salic horizons in the upper 100 cm of the soil. On the other hand, the requirements of salic horizon in WRB system (the minimum EC content of 15 dS/m and the EC multiplied by the horizon thickness of more and/or equal to 450) are also suggested for Soil Taxonomy. Conclusion: Results of the study for both saline and sodic soils show more capability of WRB system compared to Soil Taxonomy to classify soils. From soil management point of view, natric horizon causes more negative effects compared to salic horizon because Na disperses the soil particles and destroys soil structure and sodic soils need more practices to be improved compared to saline soils. Results for gypsiferous soils also show more capability of WRB system compared to Soil Taxonomy because gypsum content which is important for gypsiferous soils management is properly concerned in WRB system. However, lack of anhydritic horizon in WRB seems to be a weak point for this classification system. That is why it is suggested to be added to WRB (13). Since Soil Taxonomy does not use independent abbreviations for anhydritic horizon compared to gypsic horizon, the Ba and Baa abbreviations are also suggested for Soil Taxonomy to be added.
H. Hosseini; M. Fekri; Mohammad Hady Farpoor; M. Mahmoodabadi
Abstract
Introduction: The availability of the applied phosphorus (P) is controlled by sorption-desorption reactions in soil. Since the sorption-desorption reactions are affected by physical and chemical properties of the soil, the presence of organic matter (OM) and carbonates can also effect on the ...
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Introduction: The availability of the applied phosphorus (P) is controlled by sorption-desorption reactions in soil. Since the sorption-desorption reactions are affected by physical and chemical properties of the soil, the presence of organic matter (OM) and carbonates can also effect on the P sorption capacity in soil. The purpose of this study was to investigate the effects of OM and carbonates on phosphorus sorption isotherms in some calcareous soils of Kerman province.
Materials and Methods: Six surface soil composite samples (0-30) were collected from Kerman Province located in southeast of Iran. The soils with a wide range of OM and calcium carbonate were selected for sampling. Samples were air dried and passed through a sieve of 2 mm. Physicochemical properties of the soil samples were determined according to the Soil Survey Laboratory Manual. Thereafter, the soil samples were divided into three parts. One portion was used for treatment with sodium hypochlorite to remove organic matter. The second part was treated with sodium acetate buffer (pH = 5) to remove carbonates. The third was used as a control without any treatment. Batch experiments were carried out to determinthe P-sorption isotherms in soil. The sorption behavior of P was studied by Langmuir and Freundlich isotherm models. All experiments were conducted in three replications.
Results and Discussion: The results showed that organic matter and equivalent calcium carbonate, removed from the studied soils with an average efficiency of 86.7% and 84.9%, respectively. Although the isotherms data showed that both Langmuir and Freundlich equations fits to data,Langmuir equation with higher mean of correlation coefficient (R2=0.982) and lower standard error (0.022) showed the best fit to P-sorption data for all soil samples (with and without treatment). Removal of organic matter by sodium hypochlorite increased the phosphorus adsorption capacity in the studied soils. After removal of soil organic matter, an increase in phosphorus adsorption capacity in the studied soils. With respect to control, removing the organic matter increased the adsorption capacity parameters (qmax and kf) about 37 to 104 mg.kg-1 and 11 to 23 L.kg-1, respectively. These results indicate that Fe- and Al-oxides and other available adsorption sites on the mineral surfaces are coated by organic matter and are activated after removal of OM. Removal of carbonates from the soil significantly reduced the P-sorption capacity. qmax and kf were decreased by 17% and 32%, respectively, compared to untreated soils. It is, therefore suggested that available P adsorbing surfaces decreases by removing carbonates from the soil.Constants related with bonding energy increased by 17.03% and decreased by 28.78% by removal of OM and calcium carbonate, respectively. The P maximum buffering capacity is an important indicator for assessing phosphorus stabilization capacity in soil. The greater P buffering capacity, the fewer ability of phosphorus replacement to soil solution. After removal of carbonates, this parameter decreased by an average of 42.5%. The results suggested that carbonates is an important factor in availability of phosphorus in soil. The required phosphorus standard increased by 14.43% by removing OM in the studied soils. However, the removal of carbonates reduced the need of soil for phosphorus by 40.5%.
Conclusion: In this study was investigated the effect of removing organic matter and carbonates on phosphorus sorption isotherms in some calcareous soils of Kerman province. The results of this study showed that P sorption capacity is affected by the amount of carbonates and organic matter. Removal of organic matter from the soil increased the sorption capacity of phosphorus due to Fe- and Al-oxides. Other available adsorption sites on the mineral surface which are coated by the organic matter are active. Carbonates is known as an active site for maintaining phosphorus in the soil and its removal from soils reduces the phosphorus adsorption capacity. Applying/Preserving organic matters to/in soil can increases the efficiency of phosphate fertilizer application and improves plant nutrition. The removal of carbonates from the studied soils reduced their need for phosphorus. Therefore, as well as the addition of organic matter to soil, the removal or reduction of carbonates from agricultural soils is important for improving phosphorus utilization efficiency and plant nutrition management.
E. Soleimani Sardoo; M.H. Farpoor
Abstract
Introduction: Several archaeologists believe that there is a relationship between cultural residuals, human beings, and soil. Soil related factors such as age index, climate change, and paleoclimate are important in archaeology. Soils could be accounted as records of invaluable information. Appropriate ...
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Introduction: Several archaeologists believe that there is a relationship between cultural residuals, human beings, and soil. Soil related factors such as age index, climate change, and paleoclimate are important in archaeology. Soils could be accounted as records of invaluable information. Appropriate compiling of these data cause better understanding of soil and landscape genesis, and human activities in the past. There are two distinguished archeological sites of Daqyanous (Islamic Era) and Konarsandal (before Islamic Era) in Jiroft area. Besides, Konarsandal site is surrounded by old and new Halilrood channels. Since no data about the comparison of soil evolution in the mentioned archeological sites were available, the present research was conducted to compare soil evolution of archaeological sites using soil classification, clay mineralogy, and micromorphology in Jiroft area.
Materials and Methods: soil samples were collected from three different archaeological sites including new channel of Halilrood (pedon 1), old channel of Halilrood (pedon 2) and, Daqyanous (pedon 3). The samples were air-dried and sieved (2 mm). Routine soil physical and chemical analyses including pH, EC, soil textural class, soluble sodium, calcium, and magnesium, and gypsum and calcite contents were performed. The studied pedons were classified using Soil Taxonomy system according to morphology, laboratorial results, and field observations. The clay minerals were determined by X-ray diffraction (XRD) method after carbonates, organic matter, and Fe were removed using Jakson (1965) and Kittrik and Hope (1963) procedures. Ten undisturbed samples were selected for micromorphology studies and thin section preparation.
Results and Discussion: Pedon 1 is affected by Halilrood River sediments, that is why an old soil together with a young soil was formed. Salinity and SAR in the old soil were higher than the upper young soil. A textural discontinuity was found between the old and the young soils. Natric, calcic, and gypsic horizons were found in pedon 1 and caused a Typic Natrargid to be formed in new Halilrood channel. Natric horizon due to high Na cation was formed in pedons 1 and 2. On the other hand, salic, natric, and cambic horizons formed a Typic Haplosalid in pedon 2 (old Halilrood channel). High salinity and SAR in the upper layers caused salic and natric horizons to be formed. Pedon 3 with argillic horizon is an old polygenetic soil. Available humidity in the past caused removal of carbonates from upper layers that followed by clay illuviation and argillic horizon formation. Salinity and SAR in this soil were low and a heavy texture was found in pedon 3. Since pedon 3 showed cambic, argillic, and calcic horizons, it was classified as Arenic Haplargids. Calcium carbonate, gypsum, Fe oxides, and clay coatings were among dominant micromorphological features observed in the studied pedons. Konarsandal archeological site is located in the lowlands of Jiroft plain downward Rabor and Baft elevations. Lenticular gypsum crystals could be attributed to the solution of upward Neogene formations and groundwater close to the surface which evaporates due to capillary. Powdery calcite, Fe-oxides, and clay coating and infilling of gypsum in pore spaces of pedon 1 were observed by micromorphological investigations. Diffused clay coating around pore spaces is explainable by high sodium content and Natric horizon formation. Lenticular, interlocked plates, and infillings of gypsum were observed in pedon 1. However, gypsum with irregular shapes and low content was investigated in pedon 2. This is due to location of this pedon in Halilrood old channel. That is why pedon 2 affected by Halilrood during long periods of time is unstable and shows less evolution compared to pedon 1. Irregular and lenticular forms of gypsum show weak soil development due to low rainfall, high evaporation, and excess salt. High NaCl is reported as a requirement for lenticular gypsum formation. This form of gypsum is supported by high salinity in pedons 1 and 2. High Na and natric horizon formation in pedons 1 and 2 caused dispersion of clay and ceased formation of clay films around pore spaces. Gypsum was not found in pedon 3 during filed and laboratory studies. Besides, gypsum was not observed by micromorphological observations. Clay and calcite coatings and calcite infillings were among the micromorphological features observed in pedon 3. Calcite coating on clay coating in this pedon could be attributed to the climate with more available humidity in the past followed by an arid climate. Carophyte algae fossil was only observed in pedon 3. Kaolinite, illite, chlorite, smectite, and palygorskite clay minerals were determined by X-ray diffraction. Palygorskite is highly related to the parent material and climate. Pedogenic palygorskite formation from transformation of 2:1 clay minerals and/or neoformation is reported by several studies.
Due to the impact of paleoclimate with more available humidity, palygorskite was not found in Daqyanous archeological site. It seems that higher humidity in the past did not allow palygorskite formation or transformed it into smectite. Chlorite and illite are originated from parent material. Evidences of pedogenic mica minerals in arid and semi-arid environments were also found which is due to K fixation among smectite layers. Smectite with pedogenic origin is also reported by Sanjari et al. (29) in the study area. Chlorite, illite, and kaolinite clay minerals seem to be originated from parent material in the present study.
Conclusion: Laboratories analyses and micromorphology observations clearly showed weak development in Konarsandal pedons compared to high evolution of soils in Daqyanous archaeological site. The same results were also found for unstable surfaces of pedons 1 and 2 compared to stable surface of pedon 3. The stable surface provided the accumulation of clay and calcite coatings around the cavities and the formation of argillic and calcic horizons indicating high soil development. Results of the study showed polygenetic formation in soils. Soils in old Halilrood channel show high salinity and Na adsorption ratio compared to other two pedons under study.
Saleh Sanjari; M.H. Farpoor
Abstract
Introduction: Soil studies have been used as complementary data in archaeological investigations. Review and acceptance of papers focusing on the use of micromorphology in archaeology were discussed and agreed in the 12th International Micromorphology Meeting in Turkey (8). Morphology, physicochemical, ...
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Introduction: Soil studies have been used as complementary data in archaeological investigations. Review and acceptance of papers focusing on the use of micromorphology in archaeology were discussed and agreed in the 12th International Micromorphology Meeting in Turkey (8). Morphology, physicochemical, clay mineralogy, and micromorphology investigations may provide invaluable data about the way ancient people used to live, the source of soil that was used for pottery and architecture, the reason of degradation or existence of monuments, and the suitable soil for the restoration of monuments. On the other hand, the restoration of our ancestor's monuments could be better performed if soil data and micromorphology techniques are used.
Materials and Methods: The present research was conducted to study the ancient and restored sections of Konar Sandal historical (5000 YBP) citadel, South Jiroft, Iran. The area under study located 30 km south of Jiroft in the Halilrud cultural area. Samples were collected from both ancient (3 samples) and restores (1 sample) sections of the citadel. Representative samples (3 from the ancient and the other from the restored sections) were also collected for clay mineralogy and micromorphology (undisturbed samples) investigations after physicochemical analysis performed on all samples. Routine physicochemical analysis performed on the air-dried samples that were passed through a 2 mm sieve.
Results and Discussion: Results of the study showed that the clay percentage of the ancient section was rough twice the restored section. On the other hand, soluble salts were about 3 times higher in the restored section than the ancient section. High salinity and solubility of salts caused restored sections to have lower resistance to environmental variations of the recent years. It seems that saline and gypsiferous soils close to the citadel were used for the restoration of Konar Sandal citadel. However, no gypsum was found in the thin section of the ancient section. Besides, Na monovalent cation plays an important role in the dispersion of soil particles compared to divalent Ca cation. Results of this study showed that soil with low clay content and high salinity was used for restoration recently. On the other hand, soils for construction of ancient sections with higher clay and lower salinity (compared to restored sections) were probably transferred from another area by our ancestors. Besides, pottery pieces to provide more stickiness and charcoal for more resistance to environmental variations were also used to construct the raw bricks in the old (5000 YBP) monument.
Illite, chlorite, smectite, and kaolinite clay minerals were found in the samples from the ancient section (Fig. 3). Palygorskite, quartz and trace amounts of sepiolite were only found in the restored sections together with the previously mentioned clay minerals (Fig. 4). The absence of palygorskite in the ancient samples may prove the presence of paleoclimate with more available humidity in the area because palygorskite is unstable in humid environments and transforms to smectite. It seems that palygorskite has a pedogenic origin in the area.
Micromorphological observations showed that the organic matter in the groundmass of the ancient samples (Fig. 6 a, b) is the reason for stability in this section. The same conclusion was also reported for samples of Bam citadel by Farpoor (4). Lenticular and interlocked plates of gypsum were found in the restored section (Figs. 6 c, and 7 a, b). Gypsum crystals were not observed in the thin sections of ancient samples. Calcium carbonate nodules were also observed in the ancient section (Fig. 7c). It seems that additives such as pottery pieces together with calcium carbonate have probably increased the stability of raw bricks through time.
Conclusion: Physicochemical properties showed more salinity in the restored compared to ancient sections and micromorphology showed gypsum crystals only in the restored samples. Besides, clay content and organic matter in the ancient section are about twice the restored section. Meanwhile, pottery pieces and charcoal were also found in the ancient section. These seem to be a reason for higher stability of ancient sections against environmental variations compared to restores sections with low clay content and high gypsum and more soluble salts that were degraded in 5 years. Illite, chlorite, kaolinite, and smectite clay minerals were investigated in both sections, but palygorskite and quarts were only found in the restored section. Results of the study clearly showed that soil data might be used as a helpful technique in archaeology studies and projects.
Samira Zamani; Majid Mahmoodabadi; Najme Yazdanpanah; Mohammad Hady Farpoor
Abstract
Introduction: Wind erosion is one of the most important destructive phenomena leading to land degradation and desertification, which occurs due to blowing of erosive winds over a susceptible soil surface or a smooth land. Iran is mostly located in arid and semiarid climates; consequently, wind erosion ...
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Introduction: Wind erosion is one of the most important destructive phenomena leading to land degradation and desertification, which occurs due to blowing of erosive winds over a susceptible soil surface or a smooth land. Iran is mostly located in arid and semiarid climates; consequently, wind erosion dominates large parts of the country due to the climate and land mismanagement. In this regard, Kerman as the largest province in Iran has been under influence of erosive winds with high damaging potential. Wind erosion is a function of two agents including erosivity and erodibility. As wind velocity increases, the rate of wind erosion increases as well, while an increase in threshold friction velocity results in sand drift potential reduction. On the other hand, soil properties can control wind erosion rate through affecting both soil erodibility and threshold velocity. In addition, wind erosion is directly influenced by the direction and velocity of wind. Therefore, for better understanding of this phenomenon, analysis of wind erosivity based on meteorological data is of importance. The aim of this study was to analysis wind erosivity in Kerman province and the wind erosion potential in different parts of the province.
Materials and Methods: This study was conducted to investigate the potential of wind erosion in different parts of Kerman province based on seasonal wind data obtained for the period from 2006 to 2010. For this purpose, eight synoptic stations were selected and wind rose and sand rose were plotted for each station using WR Plot View.8 and Sand Rose Graph 3. For each season and for the whole period, erosive wind speed classes, prevailing wind direction, and the sand rose components including drift potential, sediment load and uni-directional index were obtained for each station.
Results and Discussion: This study results indicated that the intermediate wind speed class i.e. 7.7 to 9.8 m s-1 with the west and southwest directions had the highest frequency at most stations. The most erosive winds occurred during winter and summer, while the lowest ones were found in autumn. In winter, the highest wind speed class i.e. >13 m s-1 was the most frequent class. However, precipitations mostly occurring during winter can moderate the sand transport potential, since the higher precipitation causes a higher soil moisture level and enhanced threshold velocity. In addition, Jiroft station had the most frequent calm winds, whereas Lalehzar station exhibited the least frequency of these winds as this site is located in a mountainous region. Among the stations, the highest potential of sand transport (1637 vector unit) and the greatest sediment discharge (102.62 kg m-1 s-1) were observed at Rafsanjan station. However, the lowest sediment discharge was found at Jiroft station with 22.40 kg m-1 s-1. In all stations, the values of DPt were more than 400 indicating high wind erosion potentials in most areas of the province. The assessment of the uni-directional index illustrated that the investigated wind properties varied for different seasons and regions. Analysis of this index showed that Zarand and Jiroft had multi-directional winds, while other stations with a uni-directional index ranging from 0.3 to 0.8 experienced bi-directional winds with moderate variations. Furthermore, the analysis of resultant drift direction implied that the sand transport direction in Kerman, Jiroft, Sirjan, Rafsanjan and Shahrbabak sites was from west to east, at Lalehzar station was from southwest to northeast, at Bam station was from north to south, and at Zarand station was from northwest to southeast. The highest values of total drift potential in Bam, Jiroft and Zarand were obtained in summer season, while the maximum total drift potential was recorded in wintertime for Kerman, Rafsanjan, Shahrbabak, Sirjan and Lalehzar locations. The findings of this study revealed the significance of wind erosivity analysis in order to make a better understanding of wind erosion processes and achieve a more suitable strategy to combat this environmental threat.
Conclusions: It was concluded that due to climate conditions, Kerman province as the largest province of Iran has experienced high potentials of wind erosion and sand transport. In addition, the prevailing direction and most frequent velocity classes of winds differ among different parts of the province demonstrating the possibility of the formation of different features of wind erosion. Finally, the high values of DPt (> 400) were obtained for most stations, showed a high wind erosion potential in the province.
Sahar Taghdis; Mohammad Hady Farpoor
Abstract
Introduction: Soil magnetic properties reflect the complex chemical, geological and biological interactions occur in the soil. Thus, knowledge about the factors affecting soil magnetic properties helps better understanding and interpreting the results.. The lithogenic magnetic minerals are often found ...
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Introduction: Soil magnetic properties reflect the complex chemical, geological and biological interactions occur in the soil. Thus, knowledge about the factors affecting soil magnetic properties helps better understanding and interpreting the results.. The lithogenic magnetic minerals are often found in the coarse soil fractions (sand and silt) and they have inherited from parent rocks. Weathering and soil formation factors may lead increasing or decreasing of magnetic susceptibility. Climate and vegetation type are among the other factors affecting magnetic susceptibility too. Amount and distribution of magnetic susceptibility may also be affected by land use. The main objective of this research was to study the effect of different land uses and vegetation types on the magnetic susceptibility of topsoil related to soil properties.
Materials and methods: The study area was located in MahoonakeZiba around the Bardsir region, Kerman Province. The moisture and temperature regimes of the study area were sub aridic and mesic, respectively. The study area is located in the alluvial plain with igneous parent material originated from andesite, volcanic tuff, anddacite. Four land uses including farmland, well-covered pasture, disturbed pasture and degraded dryland farm with similar climate, topography, and parent material were selected. Overall, 60 complex surface samples were collected from the depth of 0-15 cm. The physicochemical analyses were done on the samples after that the soils were air dried, crushed, and passed through a 2 mm sieve. The soils magnetic susceptibility (ᵡ) in low (0.46 kHz) and high (4.6 kHz) frequencies were measured using the Bartington MS2 dual frequency sensor in two replications. The frequency depended magnetic susceptibility (ᵡfd %) was calculated as a development index of soil forming factors reflecting ferrimagnetic particle sizes.
Results and discussion: The pH of studied soils were in the range of neutral to alkaline and had the lowest coefficient of variance between measured parameters. The average of soil EC was 1.76 dS/m with a high coefficient of variance. The lowest amount of organic matter was in land use ofdegraded drylandfarm (0.26 %) and the highest was in farmland (2.15 %). The lowest amount of calcium carbonate with the coefficient of variance 12.37 % measured in the degraded pasture and its maximum was in the farmland. The loamy sand and sandy loam textural classes were found in the area under study. The minimum and maximum amounts ofᵡlf were determined in farmland (134.8× 10-8 m3 kg-1)and well-coveredpasture (1778.9 ×10-8 m3 kg-1 ), respectively and the relatively high mean value was 695.83 × 10-8 m3 kg-1. The topsoil of the study area was formed on alluvial deposits with a parent material originated from igneous andesite, tuff and dacite rocks. The high values of magnetic susceptibility of all soils under study could be attributed to the existence of initial magnetic minerals inherited from the parent material. The statistical analysis revealed a significant difference among ᵡlf values (p
Leili Neghadzamani; Mohammad Hady Farpoor; Azam Jafari
Abstract
Introduction: Genesis and development of soils are highly affected by soil forming factors and processes. Climate and topography (landform) are among the factors affecting weathering of parent material and genesis and development of soils in an area. Besides, various morphological, physical, and chemical ...
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Introduction: Genesis and development of soils are highly affected by soil forming factors and processes. Climate and topography (landform) are among the factors affecting weathering of parent material and genesis and development of soils in an area. Besides, various morphological, physical, and chemical properties, micromorphology, and clay mineralogy of soils at different geomorphic positions are usually affected by different soil forming factors including parent material and climate. The objectives of the present research were to study the effect of climate and geomorphology on physicochemical properties, micromorphology, and clay mineralogy of the soils in Rayen area, Kerman Province.
Materials and Methods: The study area starts from Hezar mountain elevations close to Rayen city (south east of Kerman Province) and extends to plateaus surfaces around Bam city. Quaternary and Neogene formations were found from geology point of view. Mean annual precipitation is in the range of 200-300 mm. Five landforms including rock pediment, mantled pediment, piedmont plain, plateaus, and valley were investigated during field work followed by topography, geology, and Google map studies in the area. According to 1:2500000 map provided by Soil and Water Research Institute, xeric and aridic soil moisture regimes together with mesic soil temperature regime were found in the area. Nine representative pedons were studied based on climatic regimes and different geomorphic surfaces. Pedons 1 and 2 were located on rock pediment with an aridic soil moisture regime. On the other hand, pedon 3 was located on the same surface, but with xeric moisture regime. Pedons 4 and 5 were also located on mantled pediment with aridic and xeric moisture regimes, respectively. Pedon 6 was located on piedmont plain and in the aridic moisture zone. Pedons 7, 8 (Plateaus), and 9 (Valley) were all in the aridic moisture zone. Physical and chemical properties, micromorphology, and clay mineralogy of soils were investigated and the soils were classified using USDA Soil Taxonomy (12th edition) and latest edition of World Reference Base for Soil Resources (WRB) systems.
Results and Discussion: Cambic, gypsic, argillic (or argic), calcic, and petrocalcic horizons were investigated during field and laboratory studies. Typic Haplocambids (pedons 1 and 2), Typic Calcixerepts (pedon 3), Typic Torriorthents (pedon 8), Calcic Petrocalcids (pedon 7), Typic Calcigypsids (pedon 6), Typic Xerorthents (pedon 5), Typic Haplocalcids (pedon 4), and Typic Calciargids (pedon 9) were classified using Soil Taxonomy (2014) and Gypsisols (pedon 6), Calcisols (pedons 3, 4, 7, and 9), Cambisols (pedons 1 and 2), and Regosols (pedons 5 and 8) Reference Soil Groups were determined using WRB (2015) system. Electrical conductivity increased from rock pediment toward valley and decreased from aridic toward xeric soil moisture regimes. Formation of argillic horizon in pedon 5 (Xeric moisture regime) was attributed to the climate of present time, but pedons 8 and 9 with aridic moisture regime could probably have experienced a climate with more available humidity for argillic horizon to be formed. Besides, petrocalcic horizon formation in pedon 7 was also attributed to a climate with more available humidity in the past. A buried soil (Btkb horizon) was determined in pedons 5 and 8 under the modern soil. Soil moisture regime change from aridic to xeric in rock pediment surface caused change of Aridisol to Inceptisol, but classification of soils in WRB system, was not affected. Secondary forms of calcium carbonate including powdery pocket, soft masses, and mycelium and secondary gypsum such as fine and coarse pendants were found during field studies. Calcite, gypsum, and clay coatings and infillings together with isolated gypsum crystals and gypsum interlocked plates were among dominant micromorphological pedofeatures investigated. Calcite coatings on aggregates and soil particles associated with clay coating prove the role of paleoclimate in soil formation. On the other hand, presence of manganaze nodules is an evidence of oxidation/reduction condition taken place in the xeric moisture conditions of pedon 5 (rock pediment). Illite, chlorite, kaolinite, and smectite were investigated in both rock and mantled pediments, but palygorskite was only found in mantled pediments. Climate also played a significant role in determining the source (pedogenic or geogenic) of clay minerals.
Conclusions: Results of this study clearly showed the close relationship among soil formation, topography (geomorphic surface) and climate. Soil physicochemical properties, micromorphology, clay mineralogy, and soil classification were highly affected by climate and geomorphology.
A. Bayat; M. H. Farpoor; A. Jafari
Abstract
Introduction: Soil genesis and development in arid and semi-arid areas are strongly affected by geological formations and geomorphic surfaces. Various morphological, physical, and geochemical soil properties at different geomorphic positions are usually attributed to different soil forming factors including ...
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Introduction: Soil genesis and development in arid and semi-arid areas are strongly affected by geological formations and geomorphic surfaces. Various morphological, physical, and geochemical soil properties at different geomorphic positions are usually attributed to different soil forming factors including parent material and climate. Due to variations in climate, geological formations (Quaternary, Neogene and Cretaceous) and geomorphology, the aim of the present research was the study of genesis, development, clay mineralogy, and micromorphology of soils affected by climate, geology and geomorphology in Bardsir area, Kerman Province.
Materials and Methods: The study area, 25000 ha, starts from Bardsir and extends to Khanesorkh elevations close to Sirjan city. The climate of the area is warm and semi-arid with mean annual temperature and precipitation of 14.9 °C and 199 mm, respectively. Soil moisture and temperature regimes of the area are aridic and mesic due to 1:2500000 map, provided by Soil and Water Research Institute. Moving to west and southwest, soil moisture regime of the area changes to xeric with increasing elevation. Using topography and geology maps (1:100000) together with Google Earth images, geomorphic surfaces and geologic formations of the area were investigated. Mantled pediment (pedons 1, 3, 7, and 8), rock pediment (pedon 2), semi-stable alluvial plain (pedon 6), unstable alluvial plain (pedon 5), piedmont plain (pedons 9 and 11), intermediate surface of alluvial plain and pediment (pedon 4), and old river terrace (pedon 10) are among geomorphic surfaces investigated in the area. Mantled pediment is composed of young Quaternary sediments and Cretaceous marls. Rock pediments are mainly formed by Cretaceous marls. Quaternary formations are dominant in alluvial plains. Alluvial terraces and intermediate surface of alluvial plain and pediment are dominated by Neogene conglomerates. Siltstone, sandstone, and Neogene marls together with Neogene conglomerates are among dominant geological formations of piedmont plain. Eleven pedons affected by young Quaternary sediments, Neogene and Cretaceous marls in aridic, aridic border to xeric, and xeric moisture regimes on above-mentioned geomorphic surfaces were described and sampled using Natural Resources Conservation Service (2012) guideline. Physicochemical properties, clay mineralogy, and micromorphology of soil samples investigated and soils were classified by Soil Taxonomy (2014) and WRB (2015) systems.
Results and Discussion: Calcic, gypsic, argillic, and cambic diagnostic horizons investigated after field and laboratory studies. Typic Calcigypsids, Lithic Torriorthents, Typic Haplogypsids, Typic Haplocalcids, Typic Torrifluvents, Sodic Haplocambids, Typic Calciargids, and Xeric Haplocalcids subgroups were found using Soil Taxonomy (2014) system. Gypsisols, Calcisols, Luvisols, Cambisols, and Regosols reference soil groups identified by WRB (2015) classification system. Developed Alfisols, formed on piedmont plain geomorphic surface in xeric moisture regime. On the other hand, Entisols formed on rock pediments with aridic moisture regime. Soils in aridic moisture regimes were little developed with gypsic horizon, and where calcic horizon was formed, it was near the surface. Moving to the west with increasing humidity, gypsum was leached from the pedon and clay illuviation caused argillic horizon to be formed. Formation of Btk horizon in pedon 9 was attributed to a more paleoclimate. The maximum gypsum content of 44.7 % (gypsiferous soils) was found in soils affected by Quaternary formations and Cretaceous marls, but the maximum calcium carbonate (44 %, calcareous soils) was investigated in soils formed on Neogene conglomerate formations. Moreover, the maximum sodium adsorption ratio (SAR) content (29.2 (mmol(±) L-1)0.5) was determined for soils on unstable surface of alluvial plain. Smectite, vermiculite, illite, kaolinite, and chlorite clay minerals were investigated and smectite to illite ratio increased moving from aridic to xeric moisture regimes that prove the pedogenic source of smectite from weathering of illite. Coating and infilling of calcium carbonate, lenticular and interlocked plates and infillings of gypsum, and clay coatings were observed during micromorphological investigations. Micromorphological observations also showed that gypsum crystals decreased and calcite crystals and thickness of clay coatings increased from aridic to xeric moisture regimes. The minimum amount of gypsum crystals was found in Neogene formations. The results also showed that gypsum pedofeatures are dominant in Cretaceous formations, but calcium carbonate pedofeatures are the main features of Neogene formations. Due to presence of animal voids (channel, regular and star-shaped vughs, chamber, and vesicles), spongy microstructure was formed in agricultural lands.
Conclusion: Results of the research showed the important role of parent material, climate, and geomorphic surface on genesis and development of soils in Bardsir area.
Mohammad Akbar Bahoorzahi; Mohammad Hady Farpoor; Azam Jafari
Abstract
Introduction: The optimum and sustainable use of soil is only possible with correct and complete understanding of its properties. The objectives of the present research were to study 1) genesis and development of soils related to different geomorphic surfaces in Kouh Birk Area (Mehrestan City), 2) Soil ...
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Introduction: The optimum and sustainable use of soil is only possible with correct and complete understanding of its properties. The objectives of the present research were to study 1) genesis and development of soils related to different geomorphic surfaces in Kouh Birk Area (Mehrestan City), 2) Soil classification according to Soil Taxonomy (2014) and WRB (2014) systems, and 3) physicochemical properties, clay mineralogy and micromorphology of soils.
Materials and Methods: Mean annual rainfall and soil temperature in the selected location are 153.46 mm and 19.6 oC, respectively. From geological point of view, the studied area is a part of west and south west zones and Flysch zone of east Iran. Soil temperature and moisture regimes of this part are thermic and aridic, respectively. Eight representative pedons on different surfaces including rock pediment, mantled pediment, Alluvial fan and Upper terraces were selected, sampled, and described. Routine physicochemical analyses, clay mineralogy, and micromorphological observations performed on soil samples. Soil reaction, texture, electrical conductivity, calcium carbonate, and gypsum were identified. Four samples including Bt horizon of pedon 1, Bk1 horizon of pedon 4, By2 horizon of pedon 5 and Bk1 horizon of pedon 7 were selected for clay mineralogy investigations. Four slides including Mg saturated, Mg saturated treated with ethylene glycol, K saturated, and K saturated heated up to 550 oC were analyzed. A Brucker X-Ray diffractometer at 40 kV and 30 mA was used for XRD analyses. Undisturbed soil samples from Bt horizon of pedon 1, Bk2 horizon of pedon 2, Btn horizon of pedon 3, By2 horizon of pedon 5, Bk1 horizon of pedon 7, and By1 horizon of pedon 8 were selected for micromorphological observations. A vestapol resin with stearic acid and cobalt as hardener was used for soil impregnation. Bk-Pol petrographic microscope was used for micromorphology investigations.
Results and Discussion: Due to the presence of argillic and petrocalcic horizons in rock pediment, soils of this surface were more developed compared to other landforms. High amount of CaCO3 (39.5%) was observed in pedon 4 on rock pediment geomorphic surface which is attributed to calcareous parent material. The presence of argillic horizon in this geomorphic position is due to the more available water of the past climate. The maximum salinity was observed in the mantled pediments. Calcic over gypsic horizons formed in pedon 7 on alluvial fan surface due to higher solubility of gypsum than calcium carbonate. Kaolinite, illite, chlorite, and palygorskite clay minerals were found in pedons 1 and 4 on rock pediment. Palygorskite in this position seems to be pedogenic, but kaolinite, illite, and chlorite are inherited from parent material. Mantled pediment and alluvial fan showed smectite, kaolinite, illite, chlorite, and palygorskite clay minerals. Pedogenic smectite in this position is probably formed from weathering of illite and chlorite. On the other hand, palygorskite stability decreased in mantled pediment surface. This is the reason why smectite was the dominant clay mineral in this landform. Clay and calcite coatings were investigated in Bt horizon of pedon 1 (rock pediment). Coatings and infillings of calcite in Bk2 horizon of the same geomorphic position caused a calcic crystallitic b fabric. A diffused clay coating due to the presence of Na in Btn horizon of pedon 3 in rock pediment was observed. Micromorphological observations of By2 horizon in pedon 5 (mantled pediment) showed gypsum interlocked plates and gypsum infillings. Interlocked plates formed due to re-solubility of gypsum crystals. Micro spars and infillings of calcite are among dominant pedofeatures found in Bk1 horizon of pedon 7 (alluvial fan geomorphic surface). A calcic crystallitic b fabric and Primary calcite mineral were also observed in this pedon. Release of Ca from calcareous parent material caused Ca+2 to SO4-2 ratio to be increased which could be a probable source of gypsum formation. Results of the study showed that more and less developed soils formed on rock pediment and upper terrace geomorphic surfaces, respectively. Illuviation of clay, gypsum, and CaCO3 together with formation of cambic, calcic, petrocalcic, gypsic, argillic, and natric horizons were among the dominant pedogenic processes in studied soils. Paleosols containing Bt horizons were only observed on rock pediment geomorphic surface. Kaolinite, illite, chlorite, and palygorskite clay minerals were observed in almost all surfaces. Smectite was not discovered in rock pediment, but was only investigated in mantled pediment and alluvial fan which could be attributed to higher available moisture of formation time in these surfaces. Secondary calcite and gypsum caused stability of pedogenic palygorskite in soils under study. Micromorphological observations proved the presence of clay and calcite coatings, calcite and gypsum infillings, and gypsum interlocked plates. Gypsum pedofeatures were not observed in rock pediment, but clay and calcite pedofeatures were only found. On the other hand, clay and calcite pedofeatures were not observed in upper terraces and gypsum pedofeatures were the only features determinded in this position.
Conclusion Results of the present research showed that difference in soil characteristics is highly affected by geomorphology.
F. Nourmandipour; Mohammad Hady Farpoor; M. Sarcheshmehpour
Abstract
Crop management and irrigation water quality play an important role on soil properties. The present research aimed to study physicochemical properties and micromorphology of soils under pistachio orchards compared to non-cultivated adjacent soils. Four water samples with different Mg/ca ratios were selected ...
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Crop management and irrigation water quality play an important role on soil properties. The present research aimed to study physicochemical properties and micromorphology of soils under pistachio orchards compared to non-cultivated adjacent soils. Four water samples with different Mg/ca ratios were selected according to analyses of 500 irrigation water samples. Five pedons in pistachio orchards and 4 pedons in non-cultivated adjacent soils were studied. Routine physicochemical analyses and micromorphology observations performed on soil samples. Results of the study showed that electrical conductivity in non-cultivated soils (256 dS/m) was remarkably higher than cultivated soils (8.9 dS/m). Mg/Ca ratio in cultivated soils compared to adjacent non-cultivated soils increased with increasing Mg/Ca ratio of irrigation water. On the other hand, using high quality irrigation water decreased this ratio in cultivated soils compared to blank samples. Lenticular and interlocked plates of gypsum observed in non-cultivated soils. Isolated and small size lenticular gypsum crystals were dominant in pistachio orchard soils.
I. Esfandiarpour Borujeni; M.H. Farpoor; A. Kamali
Abstract
Abstract
Soil classification is a simple tool which is useful to improve human knowledge and to transfer the experience and technology obtained from landscape. The objective of the present research is to compare the efficiency of Soil Taxonomy and WRB in saline soils of different areas in Kerman province. ...
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Abstract
Soil classification is a simple tool which is useful to improve human knowledge and to transfer the experience and technology obtained from landscape. The objective of the present research is to compare the efficiency of Soil Taxonomy and WRB in saline soils of different areas in Kerman province. Soil climatic units of the province were separated and based on the area covered by each climatic unit, several pedons were studied. Finally, 12 saline pedons were selected. Results showed that WRB can better express field conditions from both horizontal and vertical dimensions for classification of saline soils of arid areas due to various qualifiers used and more flexibility of this system in reflecting effective properties in soil nomenclature. Besides, adding new "Calcic Natrisalids" and "Calcic Petrosalids" subgroups to Soil Taxonomy from one hand, and "Petrogypsic", "Hypergypsic", "Episalic", "Endosalic", and "Aquic" qualifiers to prefix qualifiers of Solonchaks reference group of WRB from the other hand, can better correlate subgroups of Soil Taxonomy with second level classes of WRB.
Keywords: Soil Taxonomy, WRB, Saline soils, Soil correlation, Kerman province
S. Sanjari; M.H. Farpoor; M. Karimiam Eghbal; I. Esfandiarpour Borujeni
Abstract
Abstract
Geomorphology and soil genesis and its development are closely related. Besides, soil-landscape studies provide a better understanding of soil forming processes. The objectives of the present research include soil genesis studies, micromorphology and clay mineralogy of soils related to geomorphic ...
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Abstract
Geomorphology and soil genesis and its development are closely related. Besides, soil-landscape studies provide a better understanding of soil forming processes. The objectives of the present research include soil genesis studies, micromorphology and clay mineralogy of soils related to geomorphic surfaces in Jiroft area. Soil temperature and moisture regimes of the area are hyperthermic and aridic respectively. Alluvial fan, mantled pediment, intermediate surfaces, alluvial plain, and lowland landforms were identified. Each landform was divided into different surfaces due to geomorphic stability. One representative pedon was studied and sampled on each geomorphic surface. Routine physicochemical, clay mineralogy, and micromorphology analysis were performed on soil samples. The results showed that electrical conductivity, pH, and SAR contents increased from mantled pediments toward lowland positions. Besides, fine soil textures were found in downward positions. Chlorite, illite, palygorskite, smectite, and kaolinite clay minerals were found. Moving down toward alluvial plain, palygorskite stability decreased due to high water table, that is why smectite is the dominant clay mineral in alluvial plain. Source of palygorskite in mantled pediment, intermediate surfaces, and alluvial plain is inherited, pedogenic, and detrital respectively. Clay coating and infillings in Btn and Btk horizons of stable and unstable surfaces were investigated during thin section observations. Besides, calcite coating and infilling were found in Btk horizon at stable geomorphic surfaces. Results of the present research show that difference in soil characteristics is highly affected by geomorphology.
Keywords: Geomorphology, Palygorskite, Clay and calcite coating, Jiroft
