مقالات رزومه دکتر احمد حیدری

The wetting drying cycles, through the creation of Swelling Shrinkage sequences in soil aggregates, lead to changes in the soil's microstructure. In this study, attempts were made to investigate changes in the geometric properties of loamy sand and silty clay soils by applying moisture cycles in different treatment conditions, including amendmentsand degradations. The hypothesis of this research is based on the premise that the presence of different treatment intensities of the effects of wetting drying cycles affects the soil's microstructure from the perspective of soil aggregates. Using ImageJ software, image processing was performed on 2D and 3D images acquired from soil blocks. In addition to soil aggregate volume and surface area, properties such as sphericity and flatness coefficients were estimated and used for the classification of soil aggregates. For statistical analysis and chart plotting, Orange 3 and Excel 2016 software were used. The results indicated that treatments such as calcium carbonate, cations, and organic matter increased the coefficient of soil aggregates elongation, while degradation treatments led to an increase in the coefficient of soil aggregates flatness in both studied soil textures. Geometric classification of soil aggregates revealed that a small portion of loamy sand soil aggregates were categorized as elongated soil aggregates, while more than half of them fell into the category of flatted soil aggregates. In silty clay soil samples, a uniform distribution of elongated, bladed, and flatted soil aggregates was observed. However, none of the studied treatments resulted in soil aggregates falling into the category of compacted soil. Considering the direct impact of soil aggregate shape on the hydraulic conductivity of soils, the method employed in this research can effectively determine the microstructural status of soils from the perspective of soil aggregates.

This study aimed to investigate the spatial changes of soil salinity using RF model in a part of Eyvanekey Plain (Semnan Province 2018). Grid sampling with 100 m intervals (106 samples) was taken from 105 ha of soils developed on marl and gravely alluviums. The land uses were pistachio plantations with furrow irrigation and abandoned land. The maximum EC was (173.2 and 34 dS/m) in the abandoned and furrow irrigation pistachio plantations respectively. The main factors of salinization were saline marls, saline irrigation water, and high PET. The R2 for the salinity prediction map by RF model was 0.49, and the most important covariates were normalized difference salinity index (NDSI), topographic wetness index (TWI), Channel Network Base Level (CNBL), normalized difference vegetation index (NDVI), and modified soil vegetation index (SAVI). Spectral ratio indices derived from Landsat 8 contributed the most to the soil salinity prediction. Out of 5 main auxiliary variables, 3 variables are related to spectral ratio indices and the reason was the presence of salt on the soil in the studied area. Using NDVI with other salinity and moisture indices improved the salinity prediction model. Examining the results of covariates correlation and the implementation of recursive feature elimination showed that many covariates increase model complexity and prediction error. Recursive feature elimination helped to simplify the model by identifying the most important covariates. The salinity prediction map by random forest was consistent with the field observations and clearly defined the critical saline area.

The dissolution of carbon dioxide in water is one of the sources of soil carbonates, which have an inverse relationship with water temperature. The origin of soil-forming carbonates formed in glacial sediments, and the effect of glacial processes on their formation were investigated. This study was conducted in the year 2021 in Alborz province, and eight profiles located in Karaj and Hashtgerd regions with glacial-alluvial parent materials were described and sampled. Physical and chemical characteristics, including soil texture before and after the removal of carbonates by the hydrometer method, pH, and EC in saturated extract, organic carbon by the Walkley-Black method, Calcium Carbonate Equivalent (CCE) measured by the calcimetric method in 27 samples were determined. Cation Exchange Capacity (CEC) measured by the ammonium acetate method. Soil description and classification were performed based on the American classification system. A micromorphological study of undisturbed samples, before and after the removal of carbonates, was carried out following their impregnation with polyester resin, cutting, sawing, mounting on glass slides, and reducing the thickness to about 30 microns. Imaging was done with a polarizing microscope, and the analysis and interpretation of the results were carried out according to the guide for the analysis of thin sections. The results showed that the petrocalcic horizons formed on glacial tills and moraines are the result of the long-term infiltration of cold water rich in dissolved carbonates into the soil. This model of the formation of secondary carbonates in the soil is different from other models that mainly consider the origin of carbonates to be the dissolution and recrystallization of primary carbonates or the biological respiration of roots and living organisms.

Soil compaction and formation of plow pan in Iranian agricultural soils became a serious problem, which threatens regional productivity. The formation of plow pan due to the long-term use of tillage tools at a constant depth, is a common consequence of conventional tillage, which limits crop growth. In order to prove the existence of plow pan and its effect on physical and chemical soil characteristics, 32 soil profiles (eight soil profiles in each region) were analyzed in Qazvin, Golestan, Markazi and Khuzestan provinces. In all four regions and in 70% of the soils, plow pan with an average thickness of 24 cm was observed at 16 to 64 cm below the surface. Total porosity and the amount of bulk density showed respectively about 7-19% decrease and 5-14% increase in the plow pan compared to other horizons. The depth of the formation of this layer and its vertical expansion as well as the intensity of compaction in the soils of the studied areas have been different. The presence of the plow pan (except for Abyek region of Qazvin) had caused the accumulation of 14 to 40% of dissolved salts and the creation of a relatively saline layer under the surface horizon (Ap). The most important reason for the high compaction of the plow pan in the Gonbad agricultural area compared to the other three areas, was the high average percentage of silt (about 60%) in this area. In addition to the effect of soil texture, the predominance of submerged irrigation, despite the aridity of the climate, intensifies the compaction and resistance to root penetration especially in the agricultural areas of Golestan, Khuzestan and Markazi provinces, because annual plowing at constant depths along with heavy irrigation with a large volume of water leads to the eluviation of clay and silt particles from the surface and illuviation in depth.

Microscopic techniques provide invaluable information about soil genesis and also physicochemical and morphological properties of undisturbed natural soil structure. Determination of micromorphological indices is an advanced method of quantifying soil properties and increasing the accuracy of morphological and micromorphological studies. At present, there are no quantitative criteria in the American soil classification system to determine the classification of soils with an aquic moisture regime or with aquic conditions; so that there is no distinction between saturated soils and their reduction due to high groundwater and soils which saturation and reduction due to water infiltration from the soil surface is temporarily saturated only in the upper horizons. To prevent this problem, the general purpose of this research is to use micromorphology and image analysis in order to manage soil resources through the correct identification of soils with aquic conditions. In addition to the specific purpose, a new hydromorphic index (SHI) for soil evolution in aquic conditions based on micromorphological features was proposed.

To do this research and determine the micromorphological index of soil hydromorphic properties, after preparing intact samples from different horizons of the studied profiles (six control pedons with aquic conditions from northern Iran), their thin sections were prepared. In the following, thin sections were prepared and analyzed using a polarizing microscope. To determine the soil hydromorphic index (SHI) for aquic soils the following steps were then performed in the following order: 1-Preparation of thin sections, 2-Study of the micromorphological properties, 3-Preparation of necessary images, 4- Image analysis and quantification of micromorphological parameters, 5- Score attributes between 0 and 100 points and 6-Calculation of soil hydromorphic index (SHI).

The obtained hydromorphic index was correlated with microstructure, fine soil materials, birefringence fabric, organic materials, hydromorphic features and mineral alteration. This index can be useful for correlation of soils with aquic horizons formed on different landscape units. The results showed that the hydromorphic index varied from very high values in paddy soils under aquic moisture regime to very low values in non-paddy soils under kiwifruit cultivation. In paddy soils under aquic moisture regime, SHI values increased with soil depth and its maximum was seen in deeper horizons, whereas in non-paddy soils, the relationship between SHI and soil depth was unclear.

The defined hydromorphic index in soils under aquic moisture regime was more than 0.35 and in the soil taxonomy keys were in the aquic soils class. In contrast, soils with a hydromorphic index of less than 0.35 are found in soils that have only aquic conditions. Finally, many of the problems that exist in the American Soil Classification System in distinguishing soils with aquic moisture regime from soils with aquic conditions can be solved by determining the hydromorphic index.

Assessment and management of environmental impacts imposed by forest harvesting activities are one of the key factors that are increasing important. The purpose of this study was to investigate the effect of ground-based system on soil physical and chemical properties and the recovery process of these properties over the course of seven years. Hence, the compartments no. 316, 318, 310, and 309 of the Gorazbon District in the Kheyrud educational and research forest were selected. In this study, a completely randomized factorial design was applied and the treatments included duration (years) from timber extraction (one, two, five, and seven years), three traffic intensities (low, medium, and high) and soil depths (0-10 and 10-20 cm). The soil bulk density after seven years has not yet returned to the original state. There is still a significant difference between the control area and the skid trail. The amount of organic matter after seven years showed a recovery process compared with the first year after timber extraction, so that in the seventh year no significant difference was observed between the amount of organic matter in the control area and timber extraction track, while the amount of organic matter in the first year of timber extraction track is much lower than that of adjacent control areas. The recovery of some soil properties such as organic matter occurs faster than other ones like bulk density and porosity.

Accurate knowledge of soils and their classification plays a decisive role in the application of various management systems. The purpose of this study is to summarize some of the results of studies in the form of dissertations and articles extracted from them on the factors and processes of soil formation in different climates of Iran during the two last decades performed in different climates of the country in the Department of Soil Science and Engineering, University of Tehran. Variety of soil-forming factors including climate, parent materials, topography, vegetation, and time have led to the emergence of various characteristics and classes based on the Soil Taxonomy system. The predominant morphological traits in the studied soils in each study area, including the existing limitations and advantages, have been determined. In addition to soil classes, morphological, micromorphological, physical, chemical, clay mineralogy, organic and inorganic carbon storage, and geochemistry of formed soils are described in detail. Of the 12 soil categories in the American Classification System, at least 7 categories, and of the 32 reference groups of the WRB System, there are at least 16 reference groups in the study areas. The micromorphological results proved the effect of aeolian sediments on the soils formed on the basalt. Illite and chlorite in the clay mineralogy of many soils of the studied areas indicate that the studied soils are young. Smectite was found in slightly more developed soils (Vertisols and Aridisols). The formation of allophanes from pyroclastic materials is also a proof of the predominance of aluminum over silicon in the early stages of their aeration. Almost all soil-forming processes in this research were studied and discussed, and from an educational and research point of view, a clear view of the country's soils was shown.

Magnetic susceptibility (MS) is one of the indices used in soil development evaluation. The aim of this study was to investigate the efficiency of soil magnetic susceptibility in study of soil evolution in the Bandar mountainous landscape of Mazandaran province. In order to achieve the objectives of this study, soil taxonomic classes and morphological index were determined after field studies and physicochemical analysis of 56 soil profiles. Some chemical and geochemical indices were determined and magnetic susceptibility in low (χlf) and high (χhf) frequency were measured by Bartington MS2 dual-frequency sensor on topsoil samples. The correlations between soil magnetic susceptibility and soil taxonomic classes, physicochemical properties, and development indices indicated more efficiency of magnetic susceptibility and morphological index in the representation of soil development in this region. The slope of the study area, as well as the presence of a high amount of carbonates, has caused an inverse relationship between geochemical indices and soil taxonomic classes.

Changes of soil carbon is one of the most important indicators showing the climate impacts on the soil genesis. Soil organic carbon management requires knowledge of its amount and the effective factors. In the current study, the distribution of soil properties especially soil organic carbon were studied in 76 soil profiles consist of different climatic zones arid (Alborz province), semi-arid (Alborz and Qazvin province) and semi-humid (Guilan and Mazandaran province) and humid (Mazandaran province) with aridic, xeric and udic moisture regimes and thermic and mesic temperature regimes. Changes in climatic parameters cause changes in species diversity in the ecosystem and ultimately effect on various forms of carbon, especially soil organic carbon. One of the most important climatic factors in this study is the temperature that increasing the soil temperature in arid and semi-arid regions compared to the two wetter regions causes intensification of mineralization and as a result, soil organic carbon is reduced. The results showed that the amount of organic carbon in the studied soil decreases with increasing depth and the average amount of organic carbon in Mollisols was higher than Alfisols= Inceptisols > Entisols > Aridisols. The general results of this study showed that increasing the parameters of soil electrical conductivity (salinity), soil acidity and clay content have a negative effect, while increasing the parameters of cation exchange capacity and silt content have positive effects on soil organic carbon content.

Basalt is among igneous rocks that contains susceptible minerals to weathering minerals, and their weathering products are deposited as secondary minerals and different cations in the soil. Soils derived from basalt bedrock have many distinctive properties that are rarely found in other soils. Clay minerals constitute an important component of the soil system, and knowledge of their role in soil fertility is imperative for sustainable soil management and productivity. Therefore, the objective of the current study was to evaluate clay minerals formation of in situ soil derived from basalt in three different climate conditions. In the present study, physicochemical properties of 24 soil profiles, which formed on basalt rocks, were investigated in the arid, semi-arid, and semi-humid regions of middle Alborz and also mineralogical properties were studied in 6 profiles. X-ray diffraction analysis indicated that illite and smectite were the dominant minerals in the arid and semi-arid soils, respectively. Results revealed that the neosynthesis mechanism and deformation process of other minerals (especially illite) confirm the pedogenic formation of smectite soils in semi-arid regions. Evidence suggested that the illite in the studied soils had a pedogenic origin. Also, the vermiculite origin was to affected by the weathering of mica and chlorite within the three study areas.

Iran is one of the countries with the highest production of greenhouse gases in the world, which according to estimates is a significant part of these effects are related to agricultural activities. There are various methods for assessing the environmental impact of agricultural activities. Life cycle assessment is one of the methods for assessing the effects of sustainability that has been developed based on the product production process. Existing methods for assessing the effects of life cycle and determining the effects of agricultural activities are determined by classifying and modeling the evaluation and possible changes in soil quality indicators as a result of agricultural activities in the field. The main purpose of this study is to investigate the environmental effects of the forage maize production system using the Life Cycle Assessment (LCA) method in order to better manage and control these effects.

The study area is an educational farm of the University of Tehran with an area of 260 hectares. The required information was collected through interviews with field experts. The amount of inputs used and the emission of pollutants in several groups of effects including global warming, eutrophication, acidification, surface water poisoning and ozone depletion, classification per functional unit (one ton of forage corn) are determined and their effect on the exchange life cycle. Life cycle evaluation calculations were performed by Sima Pro software.

The results showed that (1): The most environmental degradation due to forage maize production is related to surface water pollution with a value of 1.94×10-13 kg, 1,4-DBeq that chemical fertilizers and irrigation have the most effect on this pollution 1.33×10-13 and 4.96×10-14, kg 1,4-DBeq, respectively: (2): The value of the environmental index is 2.19×10-13 points or 0.219 picopoint. It was calculated that the normalized values of the effect groups are due to the production of fodder corn, which is calculated by multiplying the total amount of contamination of each effect group by the normalization and weighting factors, specific to each effect group. The lower the value and the closer it is to zero, the less environmental impact of the product is less.

Using different methods of crop management such as the use of organic inputs, rotation, nitrogen-fixing plants, and tillage, at least based on the using of low input principles to reduce these environmental effects and also by selecting appropriate methods of irrigation yield and optimal crop yield management environmental degradation reduced these operations. The solution that can be proposed and implemented to reduce the effects of this operation is to use different methods of crop management such as the use of organic inputs, rotation, nitrogen-fixing plants, and tillage at least, based on the use of minimizing principles to reduce these environmental effects. By selecting appropriate methods for irrigation and optimal management of water consumption while increasing crop yield, the environmentally destructive effects of this operation were reduced.

Detailed soil maps are an essential tool for achieving sustainable management. Despite the advances in digital soil mapping and efforts to produce accurate maps, insufficient reliability on the soil maps remains on different scales. Recent studies have been focused primarily on remote sensing, which pays less attention to the subsurface diagnostic properties of the soil. This study used a new interpolation method between the subsurface soil diagnostic properties to increase the accuracy of the prepared maps. In this study, the production of soil maps with two approaches including the use of geomorphic surfaces, as well as the interpolation of subsurface characteristics of the soil in the Chalous region, was examined.

The study area with an extent of 100 hectares in Bandar village, was located in the suburb of Kelardasht, in Chalous County, Mazandaran province. The thickness, or depth of the upper/lower boundary of the diagnostic horizons, or soil characteristic properties used as criteria for distinguishing soil map units. According to the Comprehensive American Soil Classification System, there are six influential characteristics (Upper Cambic horizon boundary, argillic horizon upper boundary, calcic horizon upper boundary, Mollic horizon thickness, soil profile thickness, and calcareous or non-calcareous parent materials) in soils at the family level, that were used for numerical interpolation and generate thematic maps. The final soil map of the region was obtained by a combination of these six thematic maps. After mapping each of the soil properties separately, all the prepared maps intersected, and homogeneous map units were obtained. The highlands of this region, are of special importance due to their unique ecosystem and the effect of slope direction on microclimate formation, vegetation changes, and high soil diversity. Grid sampling was carried out from 56 profiles and 44 auger points (to assess variability among profiles) as a grid network with 100 m intervals. To study and describe the spatial structure of the variables, a semivariogram was used. The existence of data trends and heterogeneity were also examined. After preparing the variograms, the selection of the best approach was done using the cross-validation method and RMSS index.

To prepare the soil map using the geomorphic surface method, out of 20 soil units were identified, 12 soil units were of the consociation type, and 8 unit were of the association type. However, all 20 map units obtained by interpolation of subsurface diagnostic properties were of consociation type. This method had high accuracy in mapping the boundaries among soil units. The main differences between this method and traditional methods are in the production of detailed soil maps, the use of supervised automatic interpolation instead of manual interpolation, and the use of a set of quantitative indicators.

One of the major advantages of this method is the use of internal characteristics of the soil as an auxiliary variable along with other climatic factors, topography, living organisms, parent material and time. This study underscored the importance of the role of factors in the SCORPAN model and showed that the internal properties of the soil, which are directly involved in soil classification, can be effectively used to separate soil map units

As regards Iran is covered by many arid and semi-arid regions, the formation of soil-pedogenic features are very important and effective to have a better understanding of the topics of the soil sciences in these regions. Parent material is one of the main factors controlling soil properties in arid and semiarid regions. Basalt and volcanic glass are among igneous rocks that contain minerals susceptible to weathering minerals. Their weathering products are deposited as secondary minerals and different cations in the soil and the consumption of weathering products accelerate the weathering, soil formation and evolution during these processes. In this study, morphological and physicochemical properties of eight soil profiles formed on basalt rocks in semiarid region of middle Alborz were investigated and micromorphological properties were studied in six thin sections. Micromorphological observations showed different evidences of the occurrence of weathering processes. Formation of hypocoating and nodules of iron oxide and manganese, cubic microstructure and its evolution in different soils from semi-angular to angular cubic, layered clayey clusters indicating periodic deposition of this. Also, the layers were in favorable conditions, and the formation of a variety of pedogenic carbonate effects such as nodules, coating and hypocoating, cavities filled by micritic and sparite crystals were suggested alternating dry and wet periods, and the effect of these periods on progresses in weathering processes. One of the unanticipated consequences in the micromorphological study was the large volume of clay produced in some soil profiles due to the greater weathering intensity of volcanic glass.

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. 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. 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. 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.

Topography by affecting soil quality can significantly affect the production of agricultural products. This study was conducted in Toshan area of Golestan province to evaluate the spatial variation of wheat production and to create regression models between the crop, soil, and topography characteristics. Wheat and soil sampling from different slope positions were collected randomly from 100 points. Soil physical-chemical analyses and wheat yield parameter measurements were carried out. The digital elevation model was prepared, and topographic attributes were calculated. The results showed that the highest total yield (14.53 t/ha) and grain yield (4.41 t/ha) were observed in <10% slope class, which showed a significant difference compared to steeper slopes. The highest (15.82 t/ha) and the lowest (5.68 t/ha) total mean yields were corresponded to paw slope and shoulder slope, respectively. The highest grain yield was obtained from the foot slope and paw slope. The amounts of mean grain yield were 4.61 t/ha in foot slope and 4.66 t/ha in paw slope. Curvature and wetness index had a remarkable relationship with wheat yield. According to the regression analyses, topography indexes have been able to explain the spatial variability of yield, indicating the importance of these factors' impact on water distribution in yield production process in the studied area. Increasing yield productions in low slope positions in this study was probably due to increasing in soil depth and plant available water, as well as accumulation of organic matter and nutrient elements such as nitrogen and potassium due to deposition of eroded materials in these positions.

In the present study, mid-term variations in soil quality were studied on the farm scale. The studied area was a research-educational farm of the Agricultural and Natural Resources Campus of University of Tehran covers 260 hectares, with thermic soil temperature and aridic soil moisture regimes, respectively. In this study, the process of improving or destruction of the integrated soil quality index at two depths (0-20 and 20-40 cm) in years of 1379 and 1396 was compared. The minimum data set was determined using the method of two-phases PCA. Definition of standard scoring functions and non-linear fuzzy membership functions were performed through programming in the MATLAB software environment. Covariance-correlation method was used for weighing the selected variables in determining Soil Quality Integrated (SQI) index. The results of this study showed that in most of the adaptive areas of the soil, the incremental and decreasing pattern of the soil quality index in the first and second depths of the previous and present studies were consistent and in some places, this pattern was almost constant. In profiles No. 1, 5, 11 of the previous research which include 27.3% of the samples, and in profiles No. 1, 5, 7, 9 and 18 of the present study which include 20.83% of the samples, the soil quality index at the first depth was less than the one in the second depth. Classification of the soil quality classes for all samples in both years revealed a reduction in soil quality index. So that the soil quality reduced from grade III (45%) and IV (54%) to grade IV (73-75%).

Spatial variability of soil organic carbon in different land uses could be effective in interpreting and simulating the behavior of ecosystems in encountering the climate and environmental changes. The hilly lands of the study area are unique ecosystem with particular importance due to the effect of slope in creating microclimates with different vegetation. The spatial variability of soil organic and inorganic carbon contents and storages were studied at various depths. The effects of land use, parent material, topographical properties and some of soil characteristics on soil organic and inorganic carbon contents and storages were investigated in 56 soil pedons. In average, the highest (SOC=196.6 Mg/ha, SIC=88.2 Mg/ha) and lowest (SOC=59.9 Mg/ha, SIC=11.3 Mg/ha) storage contents of soil organic and inorganic carbon were found in Mollisols and Entisols, accordingly. The highest average total carbon storage also was found in Mollisols (284.9 Mg/ha) while the lowest was in Entisols (71.2 Mg/ha). Increasing soil inorganic carbon with increasing soil organic carbon indicates that inorganic carbon originates from soil organic carbon. In forestland, most amounts of soil organic carbon stocks are located in surface horizons, in fresh and semi-decomposed forms and in combination with silt fractions. Therefore, forest soils are more fragile in response to the changes in management rather than rangelands that contain most of their organic carbon stocks in subsurface horizons and in combination with clay fractions.

Soil porosity plays the major role in relation with soil genesis, soil processes control and its interactions with the environmental factors and translocation of water and solutes. The heterogeneity of soil porosity components is simplified by considering some assumptions such as taking into accounr all of the pores do actively and are spherical. Micromorphological approaches by direct observation and determination of soil pores geometry prepares detailed characterization of soil pores. The aim of this study was quantifying soil pores geometric properties using flouerecent dye method. 39 undisturbed soil samples impregnated with a mixture of resin-acetone containing flouerecent dye, dryed out and cut. Then 40 digital images were taken from each sample under ultraviolet light. The images were thresholded until the soil pores distinguished as white from the matrix. The results of pores based on area, perimeter, elongation, compaction, roundness, ferret diameter, long and short axis diameters were classified visually. The quantitative results of pores area showed that the pores smaller than 100 μm2 in the plough layer (depth 29% in the plough pan due to compaction. Pores with > 100 μm2 area in plough layer increases > 80% of total porosity. The dominant compaction class was the (0.3-0.5 unit less) that its maximum percent was (56.94%) in the depth of 35-30 cm. According to the elongation index the most elongated pores (the class

Erosion has been known as an important factor in soil resources degradation and non-point pollutions. A wide range of damaging effects involve social, economic and environmental problems occur when soil erosion rate go beyond the allowable value. There are several method to determine soil loss tolerance that each has specific advantage and limitations. In this paper, two widely used methods have been compared in determining tolerable erosion on a watershed scale. The first approach is based on assessment of the productivity index (PI) and the second approach is based on soil depth and soil quality index. A particular minimum data set of soil properties include infiltration, water holding capacity, organic carbon, aggregate stability, bulk density, and fertility status (nitrogen, phosphorus, potassium) was used to calculate criteria. The results showed the calculated tolerable erosion by two methods are closely related. The average tolerable soil loss for the study area was determined 9.2 and 10.2 ton/ha/year based on soil productivity method and soil depth-quality approach, respectively. The PI-based approach is preferred over the soil depth-quality approach for two reasons: First, the PI-based approach is a depth-wise and chemo-physical properties of topsoil are compared with subsoil layers. Second, the soil depth-quality based approach is a general guide that cannot take the differences between soils into account in details. As both model take into account just onsite effects of erosion, these values can be used for managers and decision-makers to soil conservation regardless off offsite impacts.

Phosphorus is an essential element for plant that appears in different chemical and biochemical forms in soil, therefore, it is susceptible to effects by pedogenic processes. In order to investigate effect of pedogenic processes on P forms and their distribution, 8 soil profiles were studied in forest land of Kelardasht. Available P (Pav), total P (TP), organic P (OP), mineral P (MP) and 8 mineral P forms were determined in the genetic horizons and the correlation of these forms with each other and also the physicochemical soil parameters were investigated. The results showed that pedogenic process significantly affected distribution of different P forms. Fe-P and Al-P showed significant positive correlation with Pox, which could indicate simultaneous extraction of poorly crystalline Fe-Al oxide (by dissolution) or adsorbed/absorbed P by Al-Fe oxides (anion and ligand exchange). These poorly crystalline forms, octa-calcium phosphate (Ca8-P) and occluded P (Oc-P) correlate positively and significantly with clay content that enhance possibility of these components linkage with clay particles during different chemical reaction and co-migration of P and clay by lessivage and eluviation-illuviation process. Labile mineral P (LPi) and moderately labile mineral P (MLPi) did not show significant correlation with Pav, whereas apatite significantly and positively correlated with Pav. Removal of P from surface horizons can explain this result. Nevertheless, the highest correlation was between Pav, OP, and organic carbon (OC). According to this result, littering and humification may be considered as the most important processes that can influence P availability.

Sulfur oxidizing bacteria are important in agriculture. The aim of this study was to identify the sulfur oxidizing bacteria in Sarcheshmeh (Kerman, Iran) agricultural soil.
Sampling was conducted from agricultural soil in Kerman province, Iran. After enrichment, samples were purified in the basic mineral culture containing sulfur as the only source of energy. Sulfur oxidation capability was evaluated based on the variation of pH and sulfate content and then strains of sulfur oxidizing were isolated and identified using morphological characteristics and phylogenic techniques. The best strains were selected and were evaluated for variation of pH and sulfate content by isolates in different pH and temperature.
Six sulfur-oxidizing strains were isolated and identified which had similarity to Thiobacillus and Starkeya genous. Isolates of 103, 129, 190 and 158 were mesophyll and neutrophil, but isolates of 192 and 156 were thermophile and alkalophill. Of these isolates, isolate 103 was 99.86% similar to Starkeya novella, identified as superior isolate, due to the most sulfur oxidation capability in the synthetic mineral medium containing sulfur.
Discussion and Isolate 103 was able to grow in neutral to slightly alkaline conditions with pH 7.5. Most of the growth of this isolate was at 30 ° C as aerobic. This isolate was facultative chemolithotroph and the results of this research showed capacity of the isolate for oxidizing sulfur, so that it could be used as a practical isolate in bio-fertilizers for neutral to alkaline and saline conditions in agriculture.

One ways to increase the operational efficiency of leaching metals from sulfide minerals is using efficient species of sulfur oxidizing bacteria in metal mining. Thus, the aim of this study was to isolate and identify sulfur oxidizing bacteria from soils of Sarcheshmeh copper mine (Kerman, south of Iran) and to survey their operation in sulfur oxidation. After enrichment, samples were purified and then isolates were identified based on their morphological characteristics and phylogenic techniques. Subsequently, three sulfur-oxidizing strains which belonged to Acidithiobacillus sp and Sulfobacillus sp were isolated and identified. Of these three, strain 184, with 95% similarity to Acidithiobacillus ferridurans was selected as the superior strain due to higher growth rate (change of 2 value pH and 385 mg S/L during 2 weeks) in the synthetic mineral medium containing sulfur which can now be used as an applicable strain in bioleaching of copper metal.

Soil carbon changes is one of the most important indicators impacts of climate change impacts on soil genesis. Study of soil carbon, including organic and inorganic carbon (carbonates) and its impact on other soil characteristics in different climates, is essential for the proper management of soil carbon on a global scale. It is too important the balance between different parts of carbon sources in the environment. In current study, organic and inorganic carbon complex with primary particles were studied in 9 profiles a climosequence including three climates arid, semi-arid and semi-humid with typic aridic, dry xeric and typic xeric moisture regimes and mesic and thermic temperature regimes. Results showed that the amount of organic carbon in all three components decreases with increasing depth and also clay component has more organic carbon content in all depths compared with other components of soil. Contrast to organic carbon, inorganic carbon content is lower in surface horizon compared with the subsurface in all three components of particle size and increases with increasing depth. The avearage of organic carbon components of particle size in three studied regions showed that the following trend clay (1.1%) > silt (0.68%) > sand (0.23%), while inorganic carbon in the soil with trend silt (14.41%) > sand (12.11%) > clay (8.14%).

Quantitative, continuous and three-dimensional soil data at appropriate scales are prerequisites for modeling of natural resources and environment. Despite the importance of soil texture, its legacy soil maps are often provided for the surface layers in which vertical and lateral variations of soil properties are not considered. The combination of digital soil mapping (DSM) and soil depth functions is an alternative tool to cope with these problems, especially in countries with limited data such as Iran. Therefore, equal-area spline depth function and DSM techniques were employed to assess the vertical and lateral distribution of soil texture in Silakhor Plain, located in Lorestan province, western Iran. By fitting the depth function to the measured clay, silt and sand percent in 103 sites to a depth of one meter, their estimated percents were obtained at five standard soil depths of Global Soil Map project (0-5, 5-15, 15-30, 30-60 and 60-100 cm). Also artificial neural network model was employed to predict lateral distribution of soil texture fractions using the auxiliary variable derived from satellite image and digital elevation model (DEM) in the standard depths. The results of the sensitivity analysis showed although the relative importance of auxiliary variables in predicting soil texture was different according to the depth and texture fractions, the performance of artificial neural network in upper layers was more than lower layers. R2 values for clay, silt and sand and from the top to the bottom were 0.73 to 0.49, 0.43 to 0.76 and 0.26 to 0.68, respectively. Results also showed, for estimating soil texture, auxiliary variables derived from satellite image were more important in surface layers and of DEM were more important in subsurface layers.