S. Nazari; M. Rostaminia; shamsollah Ayoubi; A. Rahmani; S.R. Mousavi
Abstract
Abstract Background and objectives: High-accuracy of soil maps is a powerful tool for achieving land sustainability in agricultural and natural resources. The present study was conducted in Vargar lands of Abdanan city related to Ilam province for digital mapping of soil classes at two taxonomic level ...
Read More
Abstract Background and objectives: High-accuracy of soil maps is a powerful tool for achieving land sustainability in agricultural and natural resources. The present study was conducted in Vargar lands of Abdanan city related to Ilam province for digital mapping of soil classes at two taxonomic level from subgroup up to family by random forest (RF) and fuzzy logic models. Materials and methods: Study area with 1027 hectare have 628.6 mm and 22.6 C° mean annual precipitation and temperature respectively. Three major physiographic units included Hilland, Piedmont plain and Alluvial plain were observed. Soil moisture and temperature regimes are ustic and hyperthermic calculated based on Newhall model in JNSM 6.1 version software. A total of 44 soil profile observation with random sampling pattern was determined based on standardized soil surveys then digging, description and after sampling from all genetic horizons then soil samples were transferred to laboratory. Finally, all of soil profiles were classified based on soil taxonomy system (2014) up to family level. Geomorphometric covariates as a representative of soil forming factors were prepared from digital elevation model (ALOS PALSAR Satellite,2011) with 12.5 m resolution in SAGA GIS 7.4 version software. Three feature selection approaches included Boruta, Variance inflation factors (VIF) and Mean decrease accuracy (MDA) with two Random forest (RF) and Fuzzy logic data mining algorithms were applied for relating soil-landscape relationship by using “randomforest”, “caret” packages in R 3.5.1 and SoLIM solution version 2015 software. Sample based project used for predicting soil classes in Fuzzy logic modeling process. In totally observation profile split into two data set included 80 percent (n=36) for calibrating and 20 percent for validating (n=8) based on bootstraps sampling algorithm random forest. Internal validation of random forest algorithm was done based on out of bag error percentage (OOB%). The best model performance was determined based on overall accuracy (OA) and kappa index, also for each individual class user accuracy (UA) and producer accuracy (PA) were applied. Results: The results shown that from number of 40 geomorphometrics covariates, six covariates included Terrain classification index for lowlands, Annual insolation, Topographic position Index, Upslope curvature, Real surface area and Terrain surface convexity were selected by MDA as the best environmental covariates. Also, RF-MDA method with overall accuracy 84% and Kappa index 0.56 had the best performance compared to other methods (RF_VIF, RF-BO, Fuzzy-MDA) in subgroup level with 58, 55, 50 and 0.3, 0.67 and 0.18 respectively. Out of bag error results (%OOB) for RF-MDA, RF-VIF and RF-Boruta were obtained that 72.42%, 67.86% and 82.76% for subgroup level and 93.10%, 93.10% and 86.21% for family level respectively. while there was little difference between the accuracy of the method at the family taxonomic level and performed similar results in modeling of soil classes process. The results of the fuzzy approach showed that the kappa index values and overall accuracy of this method were similar to the other three scenarios and there was a slight difference between the accuracy of the results at the soil family level. In the fuzzy method, it was observed that the kappa and overall accuracy values at the subgroup level were lower than the other scenarios. Fuzzy approaches in contrasted to RF modeling prevented continues spatial variability by generating of fuzzy maps for each of soil class in the landscape. These results indicate that the random forest method is superior to the fuzzy method in family class mapping and soil subgroups. Based on MDA sensitivity analysis index, similarly, three geomorphometrics covariate included Terrain surface convexity (convexity), Terrain classification index for lowlands (TCI_Low) and Real surface area (Surface_Ar) had highest importance for predicting soil classes at two taxonomic level. With regarded to final soil predicted maps area, two classes (Fine-silty, carbonatic, hyperthermic Typic Haplustepts) and Typic Calciustolls with 32.70% and 48.90% and (Fine-silty, carbonatic, hyperthermic Typic Calciustolls) and Typic Haplustepts with 0.18% and 1.85% had the highest and lowest content at family and subgroup maps respectively. Conclusion: In general, using different variable selection approaches in situations where soil classes have a relatively imbalanced abundance can increase the accuracy of digital mapping in soil studies. Increasing the number of field observations and the use of other environmental variables affecting soil formation can also be used for gradating in prediction low-accuracy soil classes.
samaneh Tajik; shamsollah Ayoubi; jahangir khajehali; shaban shataee
Abstract
Introduction: Soil microorganisms are the essential part of forest ecosystems which play a key role on soil nutrient changes. The biological activity in soil is largely concentrated in topsoil. Despite the small volume of microorganisms in soil, they have a key role on nitrogen, sulphur and phosphorous ...
Read More
Introduction: Soil microorganisms are the essential part of forest ecosystems which play a key role on soil nutrient changes. The biological activity in soil is largely concentrated in topsoil. Despite the small volume of microorganisms in soil, they have a key role on nitrogen, sulphur and phosphorous cycles and the decomposition of organic residues. Soil microorganisms have been identified as the sensitive indicators for soil quality. The composition of microorganisms and their fractional activities in soils significantly affect biochemical cycles, carbon sequestration and soil fertility. As soil microbial communities respond differently respected to environmental conditions, it seems that variation in forest ecosystem could significantly affect microbial community. Plants are one of the important variables for assessing soil microbial communities which their effect is related to root secretions and litter decomposition. The phospholipid fatty acid (PLFA) analysis is one of the methods that can overcome the problem of selective growth of microorganisms on culture media which is a major defect in the identification of microbial diversity. The objective of this study was to investigate the effects of different tree compositions and soil properties on soil microbial community using PLFA analysis approach.
Materials and Methods: This study was conducted in ShastKalate forest, an experimental forest station of Gorgan University, located at eastern Caspian region, North of Iran (36° 43′ 27″ N ,54°24′ 57″ E). Eleven different tree compositions were selected and the surface soils collected from 0-10 cm depth of 33 plots. Soil samples were air dried and passed through a 2mm sieve. Then one portion of the sieved samples was used for physical and chemical analyses. The other portion was rewetted to 65% of field capacity and incubated at 37 °C for 3 days to analyses PLFA. Soil particle size distribution (clay, silt and sand) was determined using the hydrometer method. Soil pH in 1/ 2.5 soil to water suspension and electrical conductivity (EC) in the same extract were measured.. Calcium carbonate equivalent (CCE),soil organic carbon (OC) and total nitrogen (TN) was determined, too. Biological analyzes including soil microbial respiration determination and PLFA analysis were carried out. The PLFA detection and quantification were performed with a Hewlett-Packard 5890 Series II gas chromatograph (GC) equipped with an HP Ultra 2 capillary column and a flame ionization detector. The normalized data were employed for Pearson's correlation analysis and ANOVA to determine the effects of soil properties and different tree compositions on soil microbial community.
Results and Discussion: Gram+ and Gram- bacteria were the most microorganisms and protozoa were the least microorganisms in soil samples. The results of the correlation between soil properties and microorganisms showed that OC and TN had significant positive effects on microorganism’s communities. EC was significantly correlated with Arbuscular Mycorrhizal Fungi (AMF), actionbacterial, protozoa and total PLFA. In addition, soil microorganisms and total PLFA were significantly correlated with soil respiration. However, there was no significant correlation between TN and OC with protozoa. The correlations between pH, EC, CCE and sand with protozoa were significantly negative, but in the case of silt, this correlation was significantly positive. Different studies showed that soil organic matter is the main nutrient source for soil microorganisms and soil microorganisms are also the essential part of C and N cycles. The effects of tree compositions on 16:0 10-methyl, 18:2 w6c, 20:2 w6c, 20:3 w6c and 20:4 w6c were significant(p
vahid Moradinasab; mehran shirvani; shamsollah Ayoubi; mohammad reza babaei
Abstract
Introduction: Water shortage in arid and semiarid regions of the world is a cause of serious concerns. The severe water scarcity urges the reuse of treated wastewater effluent and marginal water as a resource for irrigation. Mobarake Steel Complex has been using treated industrial wastewater for drip-irrigation ...
Read More
Introduction: Water shortage in arid and semiarid regions of the world is a cause of serious concerns. The severe water scarcity urges the reuse of treated wastewater effluent and marginal water as a resource for irrigation. Mobarake Steel Complex has been using treated industrial wastewater for drip-irrigation of trees in about 1350 ha of its green space. However, wastewater may contain some amounts of toxic heavy metals, which create problems. Excessive accumulation of heavy metals in agricultural soils through wastewater irrigation may not only result in soil contamination, but also affect food quality and safety. Improper irrigation management, however, can lead to the loss of soil quality through such processes as contamination and salination. Soil quality implies its capacity to sustain biological productivity, maintain environmental quality, and enhance plants, human and animal health. Soil quality assessment is a tool that helps managers to evaluate short-term soil problems and appropriate management strategies for maintaining soil quality in the long time. Mobarakeh Steel Complex has been using treated wastewater for irrigation of green space to combat water shortage and prevent environmental pollution. This study was performed to assess the impact of short- middle, and long-term wastewater irrigation on soil heavy metal concentration in green space of Mobarake Steel complex.
Materials and Methods: The impacts of wastewater irrigation on bioavailable and total heavy metal concentrations in the soils irrigated with treated wastewater for 2, 6 and 18 years as compared to those in soils irrigated with groundwater and un-irrigated soils. Soils were sampled from the wet bulb produced by under-tree sprinklers in three depths (0-20, 20-40 and 40-60 cm). Soil samples were air-dried, and crushed to pass through a 2-mm sieve. Plant-available metal concentrations were extracted from the soil with diethylenetriaminepentaacetic acid-CaCl2-triethanolamine (DTPA-TEA). To determine the total concentration of heavy metals, the soil samples were digested in 6 M HNO3. Concentrations of heavy metals in the extracts were determined by Atomic Absorption Spectroscopy. Finally, available metal micronutrient levels in the soil were compared with the critical deficiency ranges suggested for calcareous soils. Also, total concentrations of the metals in the soils were compared with the standards of the Iranian Environmental Protection Agency to assess possible contamination of soils with heavy metals in the studied area.
Results and discussion: The results of this study showed significant increases of plant-available Fe in the soils irrigated with wastewater for 6 and 18 years as compared to the unplanted control. Regardless of the type of irrigation water used, available Mn and Ni were significantly increased in all forested areas as compared to the unplanted soils. Available Zn fraction was significantly higher in the soils with history of 6 and 18 years of wastewater irrigation. Increase in available Cu concentration was statistically significant only in the soils irrigated with wastewater for 18 years. As the metal concentration in the wastewater used for irrigation was very low, it seems that the major source of metal accumulation in the soils is particulate fallout or emissions directly from the dump sites and metal plating operation. Furthermore, irrigation and forestation practices might have improved bioavailability of micronutrient metals in the soils of green space of Mobarakeh Steel complex through increasing organic matter content of the soils which enhances metal chelation reactions.
Total concentrations of the metals in the forested soils also increased as compared to those of the control. Total Fe, Mn, and Zn concentrations were notably higher in all soils of the green space area as compared to those in the unplanted control sites. Wind-driven particle transport from dumping site to nearby soils may be the main reason for metal build-up in the green space soils. Total concentration of Cu showed no significant difference among the soils of the treatments and the control. Although metal accumulation has been occurring in the soils of the Mobarakeh Steel complex green space, total concentrations in the soils were still considerably lower than the allowable levels recommended by the Iranian Environmental Protection Agency.
Conclusions: The results of this study revealed that metal accumulation has been occurring in the green space soils of the Mobarakeh Steel complex. Considering the short distance of the dumping and metal smelting sites with the green space and very low concentrations of metals in wastewater, in may be concluded that fall out of metallic particles on the soil surfaces from the dumping and smelting sites is the main route for metals accumulation in the soils of the green space areas.
Ali Afshari; H. Khademi; shamsollah Ayoubi
Abstract
Introduction: Heavy metals are found to be one of the major environmental hazardous contaminants, for human health, animal life, air quality and other components of environment. They can affect geochemical cycles and accumulate in animal tissues since physical processes are not able to remove them, so ...
Read More
Introduction: Heavy metals are found to be one of the major environmental hazardous contaminants, for human health, animal life, air quality and other components of environment. They can affect geochemical cycles and accumulate in animal tissues since physical processes are not able to remove them, so they are consistent in long term. The analysis of the total concentration of heavy metals in soil may provide information about soils enrichment but in general, it is widely used to determine the potential mobility of heavy metals in environmental behavior under chemical forms of metals in soils. Heavy metals existat several phases including water-soluble, exchangeable, bounded to organic matter, bounded to carbonates, bounded to Fe-Mn oxides, secondary clay minerals and residual fraction within primary minerals network. There is a dynamic equilibrium between different fractions of elements in soil. The main objectives of the present study were a) The analysis of the total concentration of heavy metals such as Fe, Mn, Ni, Cr, Co, Pb, Zn, Cd and Cu and b) The fractionations of heavy metals and identification of controlling factors to distribution and behavior of heavy metals in soils at different land uses.
Materials and Methods: The study was performed at central area of Zanjan province (Iran). The study area was over 2000 km2 in coordinates 20´ 36° to 41´ 36° E and 19´ 48° to 53´ 48° N. The average altitudes were over 1500 meters above sea level. The major land uses of the study area included agriculture (AG), rangeland (RA) and urban (UR). Sample collection was done based on the random grid method in August 2011. Surface soil samples (0-10 cm depth) were taken from grid centers included 137, 77 and 27 samples from AG, RA and UR land uses, respectively. The samples were digested in Nitric acid 5 normal (Sposito et al., 1982) and total concentration of Pb, Zn, Ni, Mn, Cu, Cr, Fe and Co were measured by Perkin-Elmer: AA 200 atomic absorption instrument and cadmium was measured by atomic absorption equipped with Rayleigh: WF-1E graphite furnace. 75 soil samples were selected, DTPA-extraction and sequential extraction were performed and physiochemical characteristics of these samples analyzed. To extract the metals by DTPA, the method developed by Lindsay and Norvell, (1978) was used and sequential extraction was done by Tessier et al., (1979) method. All statistical parameters were calculated using SPSS 16.0 software, and mean comparison (mean separation) was carried out using Duncan test at probability level of 5%.
Results and Discussion: The results indicated that heavy metals concentrations and patterns were evidently affected by different land uses. Co concentration was between 17.0 – 35.7 mg/kg and had the lowest total coefficient of variation (14%). The maximum total Cr and Ni values were measured in AG land use (26.1 and 52.6 mg/kg, respectively) and lowest was in UR land use (17.0 and 37.2 mg/kg, respectively). The highest total average value of Mn was found in RA (698.9 mg/kg) and the lowest in UR (629.1mg/kg) land use. The highest Fe concentrations were measured in AG and RA land uses (17.2 and 17.0 g/kg, respectively) and the lowest in UR land use (14.0 g/kg). The maximum Concentration of total Cd was observed in UR land use (2.47 mg/kg) and its minimum values were found in RA and AG (0.83 and 0.75 mg/kg, respectively) in the study area. In UR land use, Cu and Zn were more significant than AG and RA land uses. Pb variation was the same as Zn so that its increased concentration was found in urban land use (90.2 to 1357.5 on average 220.1 mg/kg). The highest Pb values were measured in UR land use (220 mg/kg) while the lowest concentrations were found in RA and AG land uses (80.6 and 69.0 mg/kg, respectively).
Different elements showed various fractional distribution in different land uses. The highest Co percentage was related to residual fraction at all land uses, with values up to 48.4%, 54.0% and 48.1% in AG, RA and UR land uses, respectively. Ni fractionation had approximately the same pattern with Co in all factions and land uses, except exchangeable fraction of Ni that showed the lowest percentage in all land uses. The dominant fraction of Cu was residual fraction with the amounts of 73.3% 76.0% and 61.9% in AG, RA and UR land uses, respectively. The second dominant fraction in UR and AG land uses was related to that was bounded to OM, with 16.5% and 10.1%, respectively. Zn distribution in the AG and RA land uses had the same trend: Residual>bounded to Fe-Mn oxides>bounded to OM>bounded to carbonate>exchangeable fraction. Whereas, Zn distribution showed different trend in UR land use as bounded to Fe-Mn oxides>residual>bounded to carbonate>bounded to OM>exchangeable fraction. Pb distribution was different in each land use. Pb showed similar distribution to Zn in UR. In AG and RA land uses residual fraction of Pb was measured as highest value while other fractions of Pb had these distributions: Pb bounded to carbonate>bounded to Fe-Mn oxides>exchangeable >bounded to OM fraction in AG land use and Pb bounded to Fe-Mn oxides>bounded to OM>bounded to carbonate>exchangeable fraction in RA land use.
Conclusion: Based on the results of this study, Cr, Co, Ni, Mn and Fe magnitudes are uneven in soils. The total heavy metal concentrations fractionation can provide information on the contaminant metals sources. High levels of exchangeable fractions, acid soluble and easily reducible perhaps indicates anthropogenic activities. Naturally, Chemicals are associated to resistant soil fractions such as oxy hydroxides, organic matter and sulfides. In soil fractionation, the contribution of each fraction in soil was a function of metal type and land uses. Those metals were affected by anthropogenic activities such as lead, zinc, and partly copper, showed the highest percentage in the fraction that influenced by external input sources. Those were characterized by lithogenic origin (cobalt and nickel) was mainly found to be highest in residual fraction. However, in all metals, those fractions affected by anthropogenic activities (non-resistant fractions) were much more in urban land use than agriculture and rangeland ones.
rouhollaah vafaeezadeh; shamsollah Ayoubi; mohamamdreza mosaddeghi; maryam yousefifard
Abstract
Introduction: Land use changes are the most reasons which affect natural ecosystem protection. Forest soils have high organic matter and suitable structure, but their land use management change usually affects soil properties and decreases soil quality. There are several outcomes of such land use changes ...
Read More
Introduction: Land use changes are the most reasons which affect natural ecosystem protection. Forest soils have high organic matter and suitable structure, but their land use management change usually affects soil properties and decreases soil quality. There are several outcomes of such land use changes and intensification: accelerated soil erosion and decline of soil nutrient conditions, change of hydrological regimes and sedimentation and loss of primary forests and their biodiversity. Establishing effects of land use and land cover changes on soil properties have implications for devising management strategies for sustainable use. Forest land use change in Yasouj caused soil losses and decreased soil quality. The objectives of this study were to assess some soil physical and chemical properties and soil magnetic susceptibility changes in different land uses and slope position.
Materials and Methods: Soil samples were taken from natural forest, degraded forest and dryland farm from different slops (0-10, 10-20 and 20-30 percent) in sout east of Yasouj. They were from 0–10 cm depth in a completely randomized design with five replications. Soil moisture and temperature regimes in the study area are xeric and mesic, respectively. Particle size distribution was determined by the hydrometer method and soil organic matter, CaCO3 equivalent and bulk density was determined using standard procedures described in Methods of Soil Analysis book. Magnetic susceptibility was measured at low and high frequency of 0.46 kHz (χlf) and 4.6 kHz (χHf) respectively with a Bartington MS2D meter using approximately 20 g of soil held in a four-dram clear plastic vial. Frequency dependent susceptibility (χfd) is expressed as the difference between the high and the low frequency measurements as a percentage of χ at low frequency.
Results and Discussion: Soil texture was affected by land use change from silty clay loam in forest to silty loam in dry land farm. Declining of organic matter and aggregate stability caused soil surface loss by erosion. The bulk density increased from 1.12 to 1.54 gcm-3 when forest changed to dry land farms. Soil compaction by tillage and lower amount of organic matter in farm lands are some of the reasons for increasing bulk density. Another possible reason could be decreasing of biological activity and parent material with greater calcite mixed with soil surface layer during land use change. Thus, the maximum and minimum amount of calcite was observed in dry land farm in 20-30 % slopes (57.46 %) and forest in 0-10 % slopes (13.37 %), respectively. In addition during soil formation calcite was translocated to lower horizons in natural forest. The greatest organic matter was 7.45 % and related to natural forest in 0-10 % slopes. Overall, the organic matter content was greater in all forest slopes than all other land use. In mineral soil, total organic carbon is not a proper factor in soil physical behavior. Complex and noncomplex organic carbon influence the soil physical behavior. Organic carbon in degraded forest and dry land farming was in complex form but in forest land use it was observed in two complex and noncomplex forms. Noncomplex organic matter was 53% and complex organic matter was 47%. It means that forest soil have better quality than degraded forest and dry land farm, respectively. Sedimentary rocks have rather low concentration of magnetic minerals with magnetic susceptibility from 0.1 (10-8 m3 kg-1) in the limestone to approximately 20 (10-8 m3 kg-1) in the siltstone. Low magnetite susceptibility in natural forest was more than degraded forest and dry land farm. Mean magnetite susceptibility values were 61.8, 48.6 and 42.4 10-8 m-3 kg-1, respectively which probably related to magnetic minerals formation during pedogenesis. Frequency magnetite susceptibility (χfd) was more than 3% in the most soils, significantly in forest soil (from 4.63-5 percent). Greater frequency magnetite susceptibility (χfd) values are suggested to be indicative of the dominance of super-paramagnetic grains and fiug single domain particles. χfd in soils reflects significant pedogenic magnetic minerals which formed during soil formation from calcitic parent materials.
F. Ghiesari; S. Ayoubi
Abstract
Introduction: Arid and semiarid environment is the main climatic condition in central Iran, as well as 80 million km 2 of Iran (> 50%) is affected by wind erosion. During the last decades, the area affected by wind erosion and desertification processes has increased as a result of human activity, climate ...
Read More
Introduction: Arid and semiarid environment is the main climatic condition in central Iran, as well as 80 million km 2 of Iran (> 50%) is affected by wind erosion. During the last decades, the area affected by wind erosion and desertification processes has increased as a result of human activity, climate change and recent drought (Karimzadeh, 2001). Thus, it is crucial to control wind erosion in the arid regions of Iran as the most serious environmental problem. In this regard, the information on the rate of soil erosion is needed for developing management practices and making strategic decisions.. Soil erosion rate has increased as a result of improper gypsum and clay mining operations In the Segzi region of Isfahan,. coarsening of the soil texture (as a result of the loss of fine textured materials), depletion of soil organic matter and degeneration of vegetation are wind erosion damages occurred widely. The objective of this study was to estimate wind erosion rates with 137Cs technique, and also to determine changes in soil physical and chemical properties by wind erosion process, along the wind erosion transect across the Segzi district, east of Isfahan.
Materials and Methods: This study was conducted in arid region of east of Isfahan Province. sixteen sites were selected along a northeast- southwest transect with 42 km length. Eighty soil samples were taken from 0-30 cm in 5 cm layer depth sections. Some physical and chemical properties were measured and a reference site with lowest rate of soil erosion and sedimentation was also studied. 137-Cs technique was used for determination of erosional and depositional sites. Analysis of variance was used to compare physical and chemical properties sites to reference site.
Results and Discussion: The results showed that sites of 1 to 8, 10 and 12-16 were identified as erosional sites and two sites of 9 and 11 were recognized as depositional sites. Soil organic matter and total nitrogen contents were reduced significantly In eroded sites compared to reference site. Similarly, clay content was reduced in the eroded sites compared to depositional sites. But,the amount of gypsum and calcium carbonate equivalent increased in eroded sites. Bulk density significantly declined in eroded (23.95%) and depositional (33.33%) sites comparing to reference site. Silt and sand content significantly were increased and decreased in depositional sites respectively compared to reference site. High speed winds caused to translocate the fine and coarser particles to farther and closer distances from detachment locations. Therefore, soil texture was mainly affected by soil erosion and changed to coarser classes. Compare means between physical and chemical properties in the eroded and deposited sites and reference site showed that physical and chemical properties were affected by erosion and deposition processes significantly.
Conclusion: Overall results indicated that Cs-137 is powerful technique for differentiation between erosional and depositional sites in the regions under wind erosion. Moreover, the this study confirmed that eroded and depositional sites wrer significantly affected by wind erosion process and soil attributes were changed compared to reference site. and proper management, especially in gypsum mines of Segzi district should be considered .
A. Mehnatkesh; S. Ayoubi; A. Jalalian
Abstract
Introduction: Soil depth is defined as the depth from the surface to more-or-less consolidated material and can be considered as the most crucial soil indicator, affecting desertification and degradation in disturbed ecosystems. Soil depth varies as a function of many different factors, including slope, ...
Read More
Introduction: Soil depth is defined as the depth from the surface to more-or-less consolidated material and can be considered as the most crucial soil indicator, affecting desertification and degradation in disturbed ecosystems. Soil depth varies as a function of many different factors, including slope, land use, curvature, parent material, weathering rate, climate, vegetation cover, upslope contributing area, and lithology. Topography, one of the major soil forming factors, controls various soil properties. Thus, quantitative information on the topographic attributes has been applied in the form of digital terrain models (DTMs). The prediction of soil depth by topographic attributes depends mainly on: i) the spatial scale of topographic variation in the area, ii) the nature of the processes that are responsible for spatial variation in soil depth, and iii) the degree to which terrain-soil relationships have been disturbed by human activities. This study was conducted to explore the relationships of soil depth with topographic attributes in a hilly region of western Iran.
Materials and Methods: The study area is located at Koohrang district between 32°20′ to 32°30′ N latitudes and 50°14′ to 50°24′ E longitudes, in Charmahal and Bakhtiari province, western Iran. The field sites with an area of 30,000 ha are located on the hillslopes at about 20% transversal slope. The soils at the site are classified as Typic Calcixerepts, Typic Xerorthents and Calcic Haploxerepts for the representative excavated profiles in summit, shoulder and backslope, respectively. The soils located at footslope and toeslope were classified as Chromic Calcixererts. Measurements were made in twenty representative hillslopes of the studied area. At the selected site, one hundred points were selected using randomly stratified methodology, considering all geomorphic surfaces including summit, shoulder, backslope, footslope and toeslope during sampling. Overall, 100 profiles were dug and described; and the solum thickness was measured for each profile. DEM data were created by using a 1:2,5000 topographic map. Topographical indices were generated from the DEM using TAS software. Terrain attributes in two categories, primary and secondary (compound) attributes; primary attributes are included elevation, slope, aspect, catchment area, dispersal area, plan curvature, profile curvature, tangential curvature, shaded relief. Secondary or compound attributes such as soil water content or the potential for sheet erosion, stream power index, wetness index, and sediment transport index. Correlation coefficients to define relationships between soil depth and terrain attributes, and analysis of variance by Duncan test were done using the SPSS software. The statistical software SPSS was used for developing multiple linear regression models. Terrain attributes were selected as the independent variables and soil depth was employed as dependent variable in the model. Thirty sampling sites were used to validate the developed soil-landscape model. In testing soil-landscape model, we calculated two indices from the observed and predicted values included mean error (ME) and root mean square error (RMSE).
Results and Discussion: The soil depth in the studied profiles varied from 30 cm to 150 cm with an average of 108.6 cm. Relatively high variability (CV = 76%) was obtained for soil depth in the study area. The linear correlation analysis of the 12 topographic attributes and one soil property (soil depth), showed that there was a significant correlation among 36 of the 77 attribute pairs. Soil depth showed high positive significant correlations with catchment area, plan curvature, and wetness index, and showed high negative correlation with sediment transport index, sediment power index and slope. Low positive significant correlations of soil depth were identified with tangential curvature, and profile curvature. Moreover, soil depth was negatively correlated with elevation. The rest of the topographic attributes including aspect, shaded relief, and dispersal area were not significantly correlated with soil depth. Many of these relationships are similar to those found in other landscapes. The results of analysis of variance showed that there are significant differences for soil depth among the selected slope positions in the studied area. The highest values of soil depth were observed in the downslope positions including footslope and toeslope. The lowest soil depth was observed in shoulder position with the highest rate of soil erosion.
Conclusions: It seems that the high variability for soil depth depends on topography of the field, and the landscape position, causing differential accumulation of water at different positions on the landscape; and moreover the soil erosion and deposition processes, resulting in high variability in the soil depth. We found relatively high correlation coefficients of soil depth with two groups of topographic attributes (erosional processes and water accumulation). Empirical model (MLR) using selected terrain attributes explains 76% of the variation of soil depth in the studied area. The terrain attributes that best predicted soil depth variability in the selected site were mainly the attributes that had significant relationships with soil depth. The dominant attributes in the MLR model included slope, wetness index, catchment area and sediment transport index.
A. Afshari; H. Khademi; shamsollah Ayoubi
Abstract
Introduction: Heavy metals are types of elements naturally present in soil or enter into soil as a result of human activities. The most important route of exposure to heavy metals is daily intake of food. Crops grown in contaminated soil (due to mining activities, industrial operations and agriculture) ...
Read More
Introduction: Heavy metals are types of elements naturally present in soil or enter into soil as a result of human activities. The most important route of exposure to heavy metals is daily intake of food. Crops grown in contaminated soil (due to mining activities, industrial operations and agriculture) may contain high concentrations of heavy metals. Also closeness to cities and industrial centers can have a great influence on the accumulation of heavy metals to agricultural products grown in the region. The study aimed to determine the concentration of heavy metals in soil and agricultural products around urban and industrial areas of Zanjan province (North West of Iran) and consumption hazard probability.
Materials and Methods: Soil (75 samples of soil from a depth of 0 to 10 cm) and plant (101 samples) samples, in the summer 2011, were randomly taken from industrial areas as follow: tomatoes (Lycopersicum esculentum M), wheat seed (Triticum vulgare), barley seeds (Hordeum vulgare), alfalfa shoots (Medicago sativa L.), potato tubers (Solanumtuberosum L.), apple fruit, vegetables and fruits such as Dill (Aniethum graveolens L.), leek (Allium porrum L.), Gardencress (Barbara verna L.) and basil (Ocimum basilicum L.). Plant samples were then washed with distilled water, oven dried for48 hours at a temperature of 70 ´C until constant weight was attained and then they digested using 2 M hydrochloric acid (HCl) and nitric acid digestion in 5 M. Concentrations of heavy metals in the soil and crops were determined by atomic absorption spectrometry. DTPA extraction of metals by Lindsay and Norvell (1978) method and sequential extraction method by Tessier et al. (1979) were performed. Statistical analysis was accomplished using the software SPSS 16.0 and the comparison of mean values was done using the Duncan test at the 5% level of significance.
Results and Discussion: The magnitude of variations for total copper was from 11.5 to 352.5 (average 52.4), zinc was from 96.3 to 1353.8 (average 264.8), lead was between 40.0 and 470.0 (average 105.7), nickel ranged from 12.8 to 77.0 (average 46.7) and chromium varied from 10.0 to 49.5 (average 21.7) mg kg-1. DTPA extracted heavy metals for copper varied from 1.50 to 21.23, averaging 4.47, zinc from 0.57 to 76.50 averaging 23.15, lead from 2.43 to 63.38 averaging 16.81 and nickel from 0.28 to 2.32 averaging 1.20 mg kg-1. Chemical changes in the different fractions were as follows: Cu (residual > bounded to organic matter > bounded to Fe-Mn oxides > bounded to carbonate > exchangeable fraction), Zn and Ni (residual > bounded to Fe-Mn oxides > bounded to carbonate > bounded to organic matter > exchangeable fraction,) and Pb (residual > bounded to Fe-Mn oxides > bounded to organic matter > bounded to carbonate > exchangeable fraction). The concentration of heavy metals in plant parts were high with respect to studied location. The highest amounts of Zn (Gardencress), Pb (Dill), Cu (Leek), Ni (Basil) and Cr (Basil), respectively were found to be 150.25, 41.25, 23.13, 6.46 and 3.47 mg kg-1 and the minimum amounts of the metals studied were found in fruits, wheat and barley grains. The total amount of metals in plants were as follow (Zn >> Pb > Cu > Ni > Cr). Bioaccumulation factor (BAF) of metals in plants were as Zn=Cu > Pb >> Cr > Ni. Hazard probability (HQ) in cancerous diseases for each element (except Pb) in both children and adults was less than unit. HQ content of Pb was much higher than the unit and for children and adults 9.07 and 6.94, respectively showing high contribution of Pb contamination of crops that threatens the consumer health in that location. The total amount of risk (THQ) in children was higher than that in adults.
Conclusions: The results obtained in this study indicate that an urgent attention is required for consumer products related to public health, especially vegetables grown in the studied regions. Toxic effects of heavy metals have many deleterious effects which are more pronounced over time. With conventional monitoring of food quality produced in farms and presented in markets, excessive accumulation of heavy metals entering in to the human food chain can be prevented. Also, we can change the risk potential of heavy metals in the region by growing vegetables which accumulate heavy metals.
Keywords: Agriculture products, Biological risk, Heavy metals, Soil, Zanjan province
M. Valaee; Sh. Ayoubi; H. Khademi; F. Khormali
Abstract
Introduction: Soil moisture regime refers to the presence or absence either of ground water or of water held at a tension of less than 1500 kPa in the soil or in specific horizons during periods of the year. It is the most important factor in soil formation, soil evolution and fertility affecting on ...
Read More
Introduction: Soil moisture regime refers to the presence or absence either of ground water or of water held at a tension of less than 1500 kPa in the soil or in specific horizons during periods of the year. It is the most important factor in soil formation, soil evolution and fertility affecting on crop production and management. Also, it widely is practical in soil classification and soil mapping. The soil moisture regime depends on the soil properties, climatic and weather conditions, characteristics of natural plant formations and, in cultivated soils, is affected by the characteristics of crops grown, as well as the cultivation practices. Determination of soil moisture regime within a landscape scale requires high information and data about moisture balance of soil profile during some years according to Soil Survey Manual (2010). This approach is very expensive, labor, time and cost consuming. Therefore, achievement to an alternative approach is seems essential to overcome these problems. The main hypothesis of this study was to use capability of magnetic susceptibility as a cheap and rapid technique could determine the soil moisture regimes. Magnetic properties of soils reflect the impacts of soil mineral composition, particularly the quantity of ferrimagnetic minerals such as maghemite and magnetite. Magnetic susceptibility measurements can serve a variety of applications including the changes in soil forming processes and ecological services, understanding of lithological effects, insight of sedimentation processes and soil drainage.
Materials and Methods: This study was conducted in an area located between 36°46َ 10˝ and 37° 2’ 28˝ N latitudes, and 54° 29’ 31˝ and 55° 12’ 47˝ E longitudes in Golestan province, northern Iran. In the study region mean annual temperature varies from 12.4 to 19.4 °C. The average annual rainfall and evapotranspiration varies from 230 mm and 2335 mm in Inchebrun district (Aridic regime), to 732 mm and 846 mm in Touskstan uplands (Udic regime), respectively. this study was conducted in four soil moisture regimes (Aridic, Xeric, Udic and Aquic), for exploring the relationships between soil properties and magnetic measures. In each regimes, 25 soil profiles were drug, described and soil samples were collected from each of soil horizons. Soil samples were air-dried and sieved using a 2 mm sieve. The dithionite-citrate bicarbonate (DCB) method was used to measure Fed and acid ammonium oxalate for Feo. In this study, a set of environmental magnetic parameters including magnetic susceptibility at low frequency (χlf), saturation isothermal remnant magnetization (SIRM), isothermal remnant magnetization (IRM100 mT) were measured. Magnetic susceptibility (χ) was measured at low frequency (0.47 kHz; χlf) and high frequency (4.7 kHz; χhf) using a Bartington MS2 dual frequency sensor using approximately 20 g of soil held in a four-dram clear plastic vial (2.3 cm diameter). Frequency dependent susceptibility (χfd) was determined by the difference between the high and low frequency measurements as a percentage of χ at low frequency. IRM was measured at the field of 100 mT generated in a Molspin pulse magnetizer (IRM100mT) and at the back field of 100mT (IRM−100mT). The IRM acquired in the maximum field of 1000 mT was measured and defined as the saturation isothermal remnant magnetization (SIRM) of the soil sample.
Results and Discussion: The results showed that moisture regime induced significant differences for soil physical and chemical properties. Diversities in genetic soil horizons and soil development degree have been increased from Aridic to Udic soil moisture regime. The results also indicated that selected properties including magnetic measures and physical and chemical properties were significantly different in four soil moisture regimes. With increasing rainfall and reducing temperature from aridic to udic soil moisture regime, soil organic matter was increased. Otherwise, in arid environment Gypsic, Calcic and Salic horizons were observed in the near of soil surface. Fed and Fed-Feo were the highest in udic and the lowest in udic soil moisture regime, respectively. Moreover, higher soil development because of climate effect leaded to higher amount of pedogenic ferromagnetic minerals, as well as the highest were observed in the Udic regime. Otherwise, in Aquic moisture regime, the lowest value of magnetic susceptibility was obtained because of dissolution of ferromagnetic minerals (magnetite and maghemite) under supersaturating condition. In overall, close relationships were observed between soil physical and chemical properties and magnetic measures in various soil moisture regimes.
M.R. Rahimi Ashjerdi; shamsollah Ayoubi
Abstract
Conversion of forest and pasture lands into agricultural lands, which is triggered by the rapid population growth, causes serious soil degradation, especially in the hilly regions with undulating topography. The objective of this study was to explore the slope position and land use change effects on ...
Read More
Conversion of forest and pasture lands into agricultural lands, which is triggered by the rapid population growth, causes serious soil degradation, especially in the hilly regions with undulating topography. The objective of this study was to explore the slope position and land use change effects on some soil properties in hilly region of west of Isfahan province, Feryduhahr district. In the two mentioned dominant ecosystems, four slope positions including summit, shoulder, backs lope and foot slope were identified and in each land use and slope position, three cores were selected to collect 72 soil samples from three depths (0–10, 10–20, 20–30 cm). The results showed that soil organic matter (SOM) in pasture land (2.1%) was approximately 40% higher than cu1tivated land (1.2%). Overall, SOM, total nitrogen, available potassium, clay and sand content significantly in pasture land were higher than cu1tivated land. In consequence of land use change from pasture to cultivated land, some soil properties in surface soils including calcium carbonate, bulk density and soil acidity showed increasing tendency as compared to pasture soils. The pasture soil with lower soil erosion and higher fine materials (clay), indicated higher magnetic susceptibility as compared to cultivated land. Variability of most of measured soil properties showed significant differences in different slope positions. Improper management practices and consequently water soil erosion was identified as the most possible process which has affected soil properties in different slope positions. In overall, it is conc1uded that slope positions and land use significantly influenced soil physical, chemical and magnetic properties in steep slopes of the study area.
S. Falahatkar; S.M. Hosseini; shamsollah Ayoubi; A. Salman Mahiny
Abstract
Land cover/use changes and soil and forest degradation influence on emission of greenhouse gases effectively and lead to global warming. This research was done with objective of investigation of relationships between soil organic carbon density (SOCD) and primary terrain attribute in two depths 0-20 ...
Read More
Land cover/use changes and soil and forest degradation influence on emission of greenhouse gases effectively and lead to global warming. This research was done with objective of investigation of relationships between soil organic carbon density (SOCD) and primary terrain attribute in two depths 0-20 cm and 20-40 cm in Deylaman region, Giulan province. Stratified Random sampling method was used for determination of sampling plot location in uniform unit. A Walkely-Black method was used for content of soil organic carbon measurement. Finally, statistical and correlation analysis were used to understand the relationship between SOCD and primary terrain attributes. This research showed the primary terrain attributes had different roles on each land use/covers. Slope has significant impact on SOCD in forest land while has no significant role in cultivated land and rangeland. Aspect has not significant impact in different land covers/uses in 0-20 cm soil layer. Elevation has significant role on SOCD in cultivated land and rangeland while it has no significant impact in forest land. Exist of enough information about of impact of primary terrain attributes on increasing carbon sequestration process could be effective for land sustainable management in different land use especially in north of country.
shamsollah Ayoubi; Mohammad Reza Mosaddeghi
Abstract
Soil surface shear strength is an important parameter for prediction of soil erosion, but its direct measurement is difficult, time-consuming and costly in the watershed scale. This study was done to predict soil surface shear strength using artificial neural networks (ANNs) and multiple linear regression ...
Read More
Soil surface shear strength is an important parameter for prediction of soil erosion, but its direct measurement is difficult, time-consuming and costly in the watershed scale. This study was done to predict soil surface shear strength using artificial neural networks (ANNs) and multiple linear regression (MLR) and to rank the most important soil and environmental attributes affecting the shear strength. A direct shear box was designed and constructed to measure in situ soil surface shear strength. The device can determine two soil shear strength parameters i.e. cohesion (c) and angle of internal friction (φ). The study area (3500 km2) was located in Semirom region, Isfahan province. Soil surface shear strength was determined using the shear box at 100 locations. Soil samples were also collected from 0-5 cm layer of the same 100 locations at which the surface shear strength was measured using the shear box. Particle size distribution, fine clay content, organic matter content (OM), carbonate content, bulk density and gravel content were determined on the collected soil samples. Normalized difference vegetation index (NDVI), the type of land use and geology were also determined. The MLR and ANNs were used to model/predict soil surface shear strength (c and φ). In order to compare the modeling methods, coefficient of determination and root mean square errors were used as efficacy indices. The results showed that ANN models were more feasible in predicting soil shear strength parameters than MLR models due to capability of ANN models in deriving nonlinear and complex relations between the parameters. Results of sensitivity analysis for ANN models indicated that NDVI, bulk density and fine clay content are more effective parameters in predicting c in the studied region. Also it was found that sand content, bulk density and NDVI were more effective parameters and OM/clay ratio and organic matter content were less effective parameters in predicting φ in the region.
salman naimi marandi; shamsollah Ayoubi; B. Azimzadeh
Abstract
Soil pollution by heavy metals is an important environment issue throughout the world. Heavy metals’ origin, accumulation, and distribution in soil have been the focus of much attention by many researchers. The objective of this study was to recognize the sources of some heavy metals in surface soils ...
Read More
Soil pollution by heavy metals is an important environment issue throughout the world. Heavy metals’ origin, accumulation, and distribution in soil have been the focus of much attention by many researchers. The objective of this study was to recognize the sources of some heavy metals in surface soils in Zob-Ahan industrial district, Isfahan province, using multivariate geostatistical techniques. A total of 202 surface (0–30 cm) soil samples were collected. Total lead (Pb), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), nickel (Ni), cobalt (Co) and chromium (Cr) contents of the samples were determined. A multivariate geostatistical analysis was performed to identify the common source of heavy metals. The results of principal component analysis led to the identification of three components. So, these components were explained 31, 27, and 16 % of total variance of heavy metal concentration, respectively. The distribution of scores of each components were shown that the quantities of Fe, Mn, Pb and Zn were found to be associated with anthropogenic activities, corresponding to the first factor was termed the “anthropogenic component”. The quantities of Co were found to be associated with parent rocks, corresponding to the second factor was termed the “lithologic component”. Also, the third factor was mainly attributed to Cu, Ni and Cr which also comprised the first and third factors, indicating a mixed source both from lithologic and anthropogenic inputs.
maryam yousefifard; shamsollah Ayoubi; A. Jalalian
Abstract
This study was conducted to assess different chemical weathering indices and to evaluate the weathering rates of soils developed on volcanic (hornbelende andesite, pyroxene andesite and dacite) and plutonic (alkali granite, granodiorite, monzodiorite, syenite and pyroxene diorite) igneous rocks in the ...
Read More
This study was conducted to assess different chemical weathering indices and to evaluate the weathering rates of soils developed on volcanic (hornbelende andesite, pyroxene andesite and dacite) and plutonic (alkali granite, granodiorite, monzodiorite, syenite and pyroxene diorite) igneous rocks in the northwestern Iran. Representative soil profiles were described and soil samples were collected and analyzed for selected chemical and physical properties. Total concentrations of major elements and trace element (Zr, V, Ti and Y) were determined with ICP-OES and ICP-MS, respectively. Significant correlation coefficients were obtained between soil properties (clay percent, pedogenic iron and bulk density) and Ba, B/A, B/R, CIA, CIW, PIA, PWI and the WR chemical weathering indices. These indices are based on the ratio of a group of mobile oxides to one or more immobile oxides and are suitable for explaining the weathering rate of the soils developed on igneous rocks in this semiarid region. A-CN-K and MFW ternary plots showed that the soils developed on volcanic rocks (hornbelende andesite> pyroxene andesite> dacite) were more weathered than those on the plutonic parent rocks (alkali granite, granodiorite, monzodiorite, syenite, pyroxene diorite). Ba and CIA weathering indices predicted weathering trend such as MFW ternary plot, and it seems these two weathering indices are the most suitable weathering indices after W index (or MFW ternary plot) in this semiarid region. Ca, Na and K elements are presented in chemical weathering formulas of these two indices. These elements are in the feldspar minerals structures which are the most mineral in the earth crust.
salman naimi marandi; shamsollah Ayoubi; H. Khademi
Abstract
Soil pollution by heavy metals from the manufacturing process due to metal smelting plants closely related to human health is very important. Given the importance of the province to industrial and agricultural activities, this study was conducted to explore the vertical and horizontal variability of ...
Read More
Soil pollution by heavy metals from the manufacturing process due to metal smelting plants closely related to human health is very important. Given the importance of the province to industrial and agricultural activities, this study was conducted to explore the vertical and horizontal variability of lead and nickcl metals in contaminated soils around the Zobahan melting factory, in nearby of Isfahan city. For this purpose, 202 profiles were dug and described in the green landscapes of Zobahan industrial site by a manner of gird sampling method. Five hundred soil samples were taken from depths of 0–30, 60–90, and 120–150 cm. Conccntration of total lead (Pb) and nickel (Ni) were measured in the soil samples. To explore the vertical distribution of selected metals, the mean values of Ni and Pb were compared statistically. The horizontal variability of selected metals was evaluated by variography analysis and the spatial distributions of them were constructed by kriging method. The overall results of study showed that Pb content in surface horizons is controlled by industrial activity, otherwise the concentration of Ni mainly attributed to parent material.
S. Tajik; Sh. Ayoubi; F. Nourbakhash
Abstract
Enzymes are so crucial in the mineralization process of organic material. Information of the soil enzymes activity is used in determining of the soil microbial properties and they are also important in soil health and quality. Topographic attributes, soil properties and soil enzymes are associated together. ...
Read More
Enzymes are so crucial in the mineralization process of organic material. Information of the soil enzymes activity is used in determining of the soil microbial properties and they are also important in soil health and quality. Topographic attributes, soil properties and soil enzymes are associated together. Hence, it is essential to know how these parameters affect on the soil enzymes activity. This study has been implemented in hilly region of Semiroum district located at southern Isfahan province, to develop a regression model between soil enzymes activity and soil and topographic characteristics. Mean annual temperature and precipitation in the studied area is 10.6°C and 350 mm, respectively. Soil sampling was done in a systematic randomly manner from the 0-10 cm surface layer. Topographic attributes were calculated by the digital elevation model with 10×10 m spatial resolution. Soil properties were determined by laboratory analysis. Multiple regression models between these parameters and soil enzymes activity were established and then the predictive models were validated using 20% of data. Results indicated soil parameters explained 33-63% of total variability of soil enzymes activity in the studied site. Topographic attributes explained 14- 15 %, and a combination of soil and topographic characteristics could explain 33-67% of total variability of soil enzymes activity. Therefore, the use of a combined data set of soil properties and topographic attributes could provide the powerful models for predicting of soil enzymes activity. These results confirmed that soil enzyme activity in the studied area is influenced by soil and topographic attributes synchronously. The results of validation ascertained that the predictors were unbiased and sufficiently accurate.
M. Mohseni Sajadi; M. Afyuni; H. Khademi; Seyed Asadallah Mohseni Movahed; Sh. Ayoubi
Abstract
Abstract
Fluoride (F-) is an essential element for human and some animals. The fluoride concentration in irrigation water is an important index for water quality. The objective of the present study was to determine spatial variability of fluoride in groundwater and soils of some areas in Arak plain. ...
Read More
Abstract
Fluoride (F-) is an essential element for human and some animals. The fluoride concentration in irrigation water is an important index for water quality. The objective of the present study was to determine spatial variability of fluoride in groundwater and soils of some areas in Arak plain. Therefore, during two seasons, autumn (2007) and the end of spring (2008), 87 and 92 water samples were collected from the wells, in the study area, respectively. Furthermore thirty soil samples were taken from the same positions. Fluoride concentrations in groundwater and soil samples around Arak city was measured by Ion Selective Electrode (ISE) method. The results show that the average fluoride of water samples during two seasons ranged from 0.3 to 0.06 mg/L which is below the standard level (1.5). These values were suitable for irrigation. Generally, spatial distribution in groundwater and isopiezometry maps indicated that fluoride increased where groundwater flow lines were centralized. Besides, fluoride concentration has increased in the rural zones and discharge areas. Average concentration of fluoride in agricultural and industrial areas were 1.5 and 7.5 mg/Kg respectively. Maximum concentration of fluoride belonged to industrial areas with 26.5 mg/Kg showing significant difference in 1 % scale in comparison with agricultural zone. There was negative correlation between fluoride with lime values and positive correlation with pH.
Keywords: Fluoride, Spatial variability, Groundwater, Soil, Arak plain
A. Hadinezhad; H. Khademi; Sh. Ayoubi; H. Lotfi Parsa
Abstract
Abstract
Heated micaceous minerals under different commercial brand names (including vermiculite) are used as culture medium in greenhouses. Heating minerals affects the release of elements, such as potassium, by changing their structure. The present study, investigates the ability of alfalfa, as one ...
Read More
Abstract
Heated micaceous minerals under different commercial brand names (including vermiculite) are used as culture medium in greenhouses. Heating minerals affects the release of elements, such as potassium, by changing their structure. The present study, investigates the ability of alfalfa, as one of the most important fodder around the world, to take up the non-exchangeable and structural potassium from heated micaceous minerals. The simultaneous effects of heat treatments and rhizospheric conditions on potassium release from two heated micaceous minerals including muscovite, as a di-ochtahedral mica, and phlogipite, as a tri-ochtahedral one, were studied in a pot experiment. The experiment was carried out as a completely randomized design with factorial combinations and three replications. Minerals were heated at 100 to 900 0C for 5 hours and mixed with quartz sand to fill the pots as the culture medium. Pots were irrigated with two different nutrient solutions (+K or -K) and distilled water during a period of five months. At the end of experiment, dry matter of shoot and root samples was measured separately. The K uptake by plant was then measured by flame photometer following the dry ash extraction. Results revealed different responses of micaceous minerals to heat treatments. In K-free treatments, the plant K uptake was significantly influenced by culture media. The most plant K available was released at 100 and 200 0C for muscovite and phlogopite treated plants, respectively. The structural changes causing a considerable decrease in potassium release, also took place at 700 0C for phlogopite and 500 to 700 0C for muscovite.
Keywords: Heat treatments, Potassium release, Muscovite, Phlogopite, Alfalfa
A. Jafari; Sh. Ayoubi; H. Khademi
Abstract
چکیده
شناسایی رقومی خاک ها بهعنوان ابزاری برای ایجاد اطلاعات مکانی خاک، راه حل هایی برای نیاز رو به افزایش نقشه های خاک با تفکیک مکانی بالا را تأمین می کند. بنابراین، ...
Read More
چکیده
شناسایی رقومی خاک ها بهعنوان ابزاری برای ایجاد اطلاعات مکانی خاک، راه حل هایی برای نیاز رو به افزایش نقشه های خاک با تفکیک مکانی بالا را تأمین می کند. بنابراین، باید روش های جدید بهمنظور بهدست آوردن اطلاعات مکانی خاک با تفکیک مکانی بالا توسعه پیدا کند. به همین منظور مطالعه ای جهت پیش بینی کلاس های خاک با استفاده از مدل های رگرسیونی در منطقه زرند کرمان طراحی گردید. در این مطالعه، مدل های رگرسیونی شامل رگرسیون لاجیستیک چندجمله ای و رگرسیون درختی توسعه یافته چندکلاسه برای پیش بینی گروه بزرگ خاک به کمک داده های سنجش از دور، پارامترهای سرزمین و نقشه ژئومرفولوژی استفاده گردید. کیفیت پیش بینی مدل ها با شاخص های حاصل از آرایه خطا بررسی گردید. نتایج نشان داد در پیش بینی همه گروه های بزرگ خاک، سطوح ژئومرفیک بهعنوان یک پیش بینی کننده مؤثر محسوب می شود. بعد از سطوح ژئومرفیک، پارامترهای سرزمین و شاخص های سنجش از دور در پیش بینی وارد شدند. در هر دو مدل خلوص نقشه برای همه گروه های بزرگ خاک در موقعیت های اعتبارسنجی و واسنجی بیشتر از 6/0 بود. نتایج نشان داد عملکرد پیش بینی برای گروه های بزرگ هاپلوجیپسید و هاپلوسالید بهتر از گروه های بزرگ کلسی جیپسید و هاپلوکمبید بود. در بین گروه های بزرگ خاک، مقادیر بالای دقت کاربر و قابلیت اطمینان تولیدکننده برای گروه بزرگ هاپلوسالید بهدست آمد. خاک های با قابلیت اطمینان بهتر خاک هایی هستند که به شدت تحت تأثیر مشخصات توپوگرافی و ژئومرفولوژی قرار گرفتند (گروه های بزرگ هاپلوسالید، تری سامنت و هاپلوجیپسید) و خاک های با قابلیت اطمینان و دقت پیش بینی کمتر خاک هایی هستند که به سختی تحت تأثیر مشخصات توپوگرافی و ژئومرفولوژی (گروه های بزرگ هاپلوکمبید و کلسی جیپسید) قرار گرفتند.
واژه های کلیدی: نقشه برداری رقومی خاک، رگرسیون لاجیستیک چندجمله ای، رگرسیون درختی توسعه یافته
M. Taghipour; H. Khademi; Sh. Ayoubi
Abstract
Abstract
Accumulation of heavy metals in soils has become a serious environmental problem in many parts of the world. No information is currently available on the distribution pattern of heavy metals concentration in soils of Hamadan province. The objective of this research was to determine the spatial ...
Read More
Abstract
Accumulation of heavy metals in soils has become a serious environmental problem in many parts of the world. No information is currently available on the distribution pattern of heavy metals concentration in soils of Hamadan province. The objective of this research was to determine the spatial distribution of Pb and Zn and its relationship with land use and parent materials of a selected area surrounding the city of Hamadan. A total of 263 composite surface soil samples (0-10 Cm) were taken from an area of about 1600 km2. The location of each sampling site was recorded by using a GPS and its land use type (residential, uncultivated, agricultural land and dryland wheat) was also determined. In addition from six major types of bedrock in the Hamadan province were also sampled with 3 replicates. The total and plant available Zn and Pb in soil samples and the total concentration of these elements in parent rocks were measured by atomic absorption spectrophotometer after extraction. Selected soil properties including pH, electrical conductivity, organic matter, cation exchange capacity and soil texture were also determined. The spatial variability of variables was examined by variography and kriging analysis. The mean concentration of total and available Zn were 71.4 and 2.5 mg Kg-1 and those for Pb were 24 and 2.5 mg Kg-1, respectively. The results of geostatistical analysis showed that spherical model was the best model for describing the spatial variability of Pb and Zn. The range of influence was estimated 9750 m for Pb and 11550 m for Zn. It seems that the major factor controlling the high concentration of total Pb and Zn in the area is land use type. Analysis of parent rock samples indicated that shale as the major parent rock occurring in the southeast and west part of the study area contains a high quantity of Zn (96.2 mg Kg-1). Therefore, it appears that Zn has entered the soils in the study area through the weathering of parent materials. In other words, the content of Zn in the soils studied seems to be mainly controlled by soil parent material and land use. A significant correlation was found between organic matter and the concentration of Pb.(r2= 0.35) and Zn (r2= 0.33).
Keywords: Spatial variability, Heavy metals, Parent materials, Variogram, Kriging, Hamadan
A.R. Pilevar Shahri; Sh. Ayoubi; H. Khademi
Abstract
Abstract
Spatial prediction of soil organic carbon is a crucial proxy to manage and conserve natural resources, monitoring CO2 and preventing soil erosion strategies within the landscape, regional, and global scale. The objectives of this study was to evaluate capability of artificial neural network ...
Read More
Abstract
Spatial prediction of soil organic carbon is a crucial proxy to manage and conserve natural resources, monitoring CO2 and preventing soil erosion strategies within the landscape, regional, and global scale. The objectives of this study was to evaluate capability of artificial neural network and multivariate linear regression models in order to predict soil organic carbon using terrain attributes. A study area of 24 km2 in hilly regions of Zargham Ababd in south of Semirom under natural rangeland uses, was selected and then 125 soil samples (0-10 cm depth) were collected. Soil organic carbon was measured for the collected soil samples. Topographic attributes were calculated by a digital elevation model with 10 m spacing. Finally, multiple linear regression (MLR) analysis and ANN models were developed for soil organic carbon estimation in the study area and then the developed modeless were validated by additional samples (25 points). The results showed that the MLR and ANN models explained 60 and 89 % of the total variability of SOC, respectively, in the study area using terrain attributes. Sensitivity analysis based upon the ANN models, revealed that the profile curvature, stream power index, slope, sediment transport index, wetness index, plan curvature and aspect were identified as the important topographic attributes influencing the SOC distribution within the selected hillslope. The overall results indicated that topographic attributes and hydrological process control a significant variability of SOC. Prediction of the statistical studied models in the study area resulted in mean error and root mean square error values of 0.25, 0.3 in MLR equation and 0.006, 0.027 in ANN, respectively. Therefore, the ANN model could provide superior predictive performance when compared with developed MLR model.
Keywords: Soil organic carbon, Terrain attributes, Linear regression, Artificial neural network
F. Khayamim; H. Khademi; A. Khoshgoftar manesh; Sh. Ayoubi
Abstract
Abstract
Mineral weathering is a major source of most essential nutrients including potassium. It is well known that potassium plays an important role in improving the quality of agricultural products and micaceous minerals, as the major source of potassium, are abundant in Iranian soils. No information ...
Read More
Abstract
Mineral weathering is a major source of most essential nutrients including potassium. It is well known that potassium plays an important role in improving the quality of agricultural products and micaceous minerals, as the major source of potassium, are abundant in Iranian soils. No information is available on the role of micaceous minerals in supplying K to barley as the second major crop in Iran. The objective of this research was to demonstrate the ability of barley (Hordeum vulgare L.) to take up structural potassium from muscovite and phlogopite. The experiment was carried out in a completely randomized design with factorial combinations and three replicates. Culture medium was a mixture of quartz sand (as filling material) and K-bearing minerals including muscovite or phlogopite. Pots were irrigated with different nutrient solutions (+K and -K) during a period of four months. Barley Govhar cultivar was used which is widely cultivated in the Isfahan province. At the end of experiment, shoots and roots were separated and plant samples were prepared with dry ashing method and their K content was determined with flame photometer. In K-free treatments, total plant K uptake was significantly higher in phlogopite treated medium as compared to muscovite. No significant difference was found between control and muscovite amended treatment under K-free solution. In pots amended with phlogopite, K concentration was in sufficient limit, even under K-free nutrient solution. This indicates the importance of the type of micaceous minerals in plant K availability, particularly in soils where minerals structural K is the only source of K supply.
Key words: Muscovite, Phlogopite, Barley, Rhizospheric effections, Potassium release