Showing 56 results for Alian
A. Karimi, H. Khademi, A. Jalalian,
Volume 12, Issue 44 (summer 2008)
Abstract
Despite the existence of highly silty soils in southern Mashhad, there is no information about the aeolian and /or in situ formation of these soils. The main objective of this study was to determine the source of silt generation in this area. Granitic hilly lands in southern Mashhad have been covered by silty deposits. Based on the soil origin, four profiles including a residual soil covered by a silty layer, a residual soil with low amount of silt, a highly silty soil and an alluvial soil as well as a deep profile containing a succession of silty and alluvial materials were studied. Cumulative particle size distribution curve (CPSDC), depth distribution curves of silt/sand ratio (Si/S), Folk inclusive graphic standard deviation, Folk inclusive graphic skewness (SKI) and sand grain morphology analyzed by scanning electron microscopy (SEM) were determined and used to identify the source of the silty materials. Based on the results obtained, silty (L), residual-silty (R-L), residual (R), alluvial (A) and alluvial-silty (A-L) horizons were identified. CPSDC of L horizons is sigmoidal in shape and is easily distinguishable from that of the other horizons. In contrast, the CPSDC of alluvial and residual horizons is spherical in shape. CPSDCs for R-L and A-L horizons are neither sigmoidal nor spherical, but something in between. The L horizons have the highest SKI (very skewed to fine particles) and the lowest Folk inclusive graphic standard deviation (very badly sorted). In this regard, alluvial and residual horizons are intermediate. Because of the silt addition to R-L and A-L horizons, these horizons have a nearly zero SKI (symmetrical) and the highest Folk inclusive graphic standard deviation (very badly sorted). Particle size distribution histograms of R-L and A-L horizons are bimodal, a mode for sand and a mode for silt, suggesting two different sources. Depth distribution of Si/S, SKI and Folk inclusive graphic standard deviation of highly silty and other horizonz show a drastic change between L horizons and the other horizons-an indication of lithologic discontinuity and difference in origin. In conclusion, despite the possible contribution of granitic parent rocks to silt generation in the area, loess deposits recognized appear to have mostly been transported by aeolian movement.
P. Heydarizadeh, M. Sabzalian, M.r. Khajehpour,
Volume 12, Issue 45 (fall 2008)
Abstract
During recent years, several genotypes have been selected from Isfahan land race Kouseh. The performance of safflower selected genotypes was studied in the field conditions, at Agriculture Research Station, Isfahan University of Technology during 2003. The experiment was carried out using a split plot arrangement according to a randomized complete block design with three replications. Planting dates (March 11, April 20, May 22 and June 23) were considered as the main plots and subplots consisted of 20 genotypes of safflower including 19 selections from Kouseh and Arak-2811 genotype. Days from planting to emergence and emergence to stem elongation were reduced as planting was delayed until the fourth planting date. Days from stem elongation to head visible was reduced with delay from the first to the third planting date, and then increased. Days from head visible to 50% flowering was reduced with delay from the first date to the third planting date, but increased in the fourth planting date. Days from 50 percent flowering to physiological maturity was increased with delay in planting. Days from planting to emergence, emergence to stem elongation, stem elongation to head visible and 50 percent flowering to physiological maturity were not influenced by genotypes. Genotype DP7 had the highest and genotype C111 and genotype DP25 had the lowest days from head visible to 50% flowering. The interaction between planting date and genotype in regard to days from stem elongation to head visible was also significant. Seed weight per plant was reduced with delay in planting date. Genotype ISF66 had the highest and genotype Arak-2811 had lowest seed weight per plant. The number of days from emergence to head visible in ISF66, DP5, C128 and Arak-2811 was affected by maximum temperature (Tmax), in genotype DP7 by Tmax2, in genotypes DP17, DP1 and C41100 by Tmin2 and in genotypes DP9, DP25, ISF28, ISF22, and C111 was affected by day length. It seems that development period from emergence to head visible was affected by temperature in the most genotypes. On March 11 planting date, genotypes had the maximum response to temperature and day length and the minimum response was observed in the fourth planting date. The genotype ISF66 had the highest seed yield on March 11 planting date. The result of this study showed that safflower should be planted in late March under condition similar to this experiment for maximum yield production.
B. Hatami, J. Khajehali, M. R. Sabzalian,
Volume 12, Issue 45 (fall 2008)
Abstract
Safflower having oil with high unsaturated fatty acids is a very valuable plant. However the sensitivity of safflower to some pests as safflower fly (Acanthiophilus helianthi), particularly in drought stress conditions has limited its production. In order to evaluate the effect of drought stress on population density and damage of important safflower pests, especially safflower fly, an experiment was conducted in the field using 5 irrigation treatments including 50, 70, 90, 110 and 130 mm evaporation from class A pan in a randomized complete block design with three replications. The local safflower variety used in this study was Isfahan land variety, Kooseh. In each irrigation regime, the half of one plot was locally sprayed by Chlorpyrifos in 2ml per liter of water to be compared with non-sprayed part. During 8 weeks of sampling, population of aphids, Uroleucon carthami, leafhopper, Empoasca decipiens and safflower fly, A. helianthi and also percentage of damaged heads by safflower fly were measured. The results showed that in non-sprayed conditions, the highest safflower fly (2.38 flies per net) and aphid population (165.57 aphids per plant) was observed at 130 mm evaporation regime. Drought stress also decreased (30.23 %) safflower seed yield. Severe drought stress together with non-spaying may increase safflower pests population particularly safflower fly and reduce seed yield. However low level of drought stress (70 mm evaporation from class A pan) may decrease relative number of insects and save irrigation water. Drought stress also decrease the population of leafhopper. In this study, 70 mm evaporation regime was the optimum irrigation treatment regarding lower aphid and fly damage (15.86% damaged heads in non-sprayed condition) and higher safflower seed yield (1687.5 kg/ha in sprayed condition).
M Lotfalian, B Majnonian, M Rezvanfar, A Parsakho,
Volume 12, Issue 46 (fall 2009)
Abstract
In this research, the logging and wood extraction damages caused by wood and paper companies was investigated. The average volume per hectare of compartments 17 and 28 of Waston watershed and Compartment 7 of Alandan watershed was more than 150 cubic meters. So, these compartments were selected as the suitable research sites. The systematic randomized sampling method with 1000 m2 circular plots was used to assess the damages to residual stands and 100 m2 circular plots was used to assess the damages to regeneration. Sampling in skid trail was done with one hundred percent inventory method with a width of 12 meter. Results of this study indicated that 3.2 percent of regeneration was damaged in felling and bucking operations and 4.8 percent of regeneration was also damaged after winching and skidding operations. Most of these damages occurred for thicket stage. The felling and bucking operations damaged 13.6 percent of the residual stand. The amount of damage to the stand after skidding including the whole logging damages equals 15.5 percent. Unnecessary damages to stand and regeneration could have been avoided by selecting the best harvesting method, skidding practices, adequate incentives/disincentives and appropriate supervision.
M Momeni, M Kalbasi, A Jalalian, H Khademi,
Volume 12, Issue 46 (1-2009)
Abstract
The forms and dynamics of soil phosphorus can be greatly affected by land use changes, which often involve changes in vegetation cover, biomass production and nutrient cycling in the ecosystem. Present research evaluates the impact of land use change on the amount of total organic and inorganic P, labile, moderately labile and nonlabile P pools in semiarid soils of central Zagros. Samples were collected from surface soils (0-10 cm) of i) of moderately degraded pasture (20-25% plant cover), ii) highly degraded pasture (5-10 % plant cover), and iii) cultivated field (10 years) in Soolegan sub watershed and i) moderately degraded pasture (25-30 % plant cover) and ii) highly degraded pasture (5-10 % plant cover) in Sadat Abad sub-watershed. Significantly (P<0.05) low amounts of total organic P were found following cultivation (23.9%) and overgrazing (18.2 and 40.8 %) in Soolegan and Sadat Abad, respectively. The largest depletion of labile organic P (NaHCO3-Po) (72.3%) and moderately labile organic P (H2SO4-Po plus NaOH-Pi) (24.3%) were observed in cultivated rainfed land in Soolegan. Overgrazing led to decrease in labile organic P (42.1 and 64.4%), moderately labile organic P (13.9 and 35.7%) and nonlabile organic P (NaOH-Po) including moderately resistant and resistant organic P (12.9 and 44.4%) in Soolegan and Sadat Abad, respectively. Our results showed that degradation of natural plant cover cause to depletion in the soil P pools. Decreasing the amounts of moderately resistant and resistant P pools led to a decline in soil productivity and fertility.
M Noruzi, A Jalalian, Sh Ayoubi, H Khademi,
Volume 12, Issue 46 (1-2009)
Abstract
Crop yield, soil properties and erosion are strongly affected by terrain parameters. Therefore, knowledge about the effects of terrain parameters on strategic crops such as wheat production will help us with sustainable management of landscape. This study was conducted in 900ha, of Ardal district, Charmahal and Bakhtiari Province to develop regression models on wheat yield components vs. terrain parameters. Wheat yield and its components were measured in 100 points. Points were distributed randomly in stratified geomorphic surfaces. Yield components were measured by harvesting of 1 m2 plots. Terrain parameters were calculated by a 3×3 m spacing from digital elevation model. The result of descriptive statistics showed that all variables followed a normal distribution. The highest and lowest coefficient of variance (CV) was related to grain yield (0.36) and thousand seeds weight (0.13), respectively. Multiple regression models were established between yield components and terrain parameters attributes. The predictive models were validated using validation data set (20% of all data). The regression analysis revealed that wetness index and curvature were the most important attributes which explained about 45-78% of total yield components variability within the study area. The overall results indicated that topographic attributes may control a significant variability of rain-fed wheat yield. The result of validation analysis confirmed the above-stated conclusion with low RMSE and ME measures.
A Parsakho, S.a Hosseini, M Lotfalian, H Jalilvand,
Volume 13, Issue 47 (4-2009)
Abstract
Forest roads must be constructed according to technical standards and guidelines which have been published by the scientific and operational organizations. Recently, hydraulic excavators have been used beside the bulldozer for excavating the forest roads. Thus, it is necessary that their ability in construct of standard cross sections be compared. This study was conducted in Lattalar forest which is located south of Sari city (Mazandaran Province). 60 cross section samples were randomly selected for each machine in slope classes of 30-40, 40-50, 50-60 and 60-70%. Then, cross sections were taken by niveau and clinometer. The results in different slope classes showed that the hydraulic excavator and bulldozer had no significant effect on cut and fill slopes length and gradient. Roadbed width in bulldozer construction area was more than the hydraulic excavator at probability level of 1%. Also, there was a significant difference between the hydraulic excavator and bulldozer earthworking width in slope classes of 30-40 and 40-50% at probability level of 5 and 1%, respectively, whereas this difference was not significant in other slope classes. Finally, the average standard cross sections for hydraulic excavator and bulldozer were 89.96 and 84.81%, respectively.
M Nael , A Jalalian1 , H Khademi, M Kalbasi, F Sotohian, R Schulin,
Volume 14, Issue 51 (spring 2010)
Abstract
Geologic and pedologic controls are the main factors determining the behavior of elements in natural soil environments. In order to assess the role of these factors on content and distribution of selected major and trace elements in soil, six parent materials including: phyllite, tonalite, periditite, dolerite, shale and limestone were selected in Fuman-Masule region. Soil genesis and development of representive residual pedons were studied for each parent material and the total content of Si, Al, Ca, Mg, Fe, Ti, Mn, Ni, Co, Cr, Cu, Pb, V and Zn were compared among them. Enrichment/depletion patters of trace elements were assessed using Ti as reference element. Generally, Cr, Ni, Co and V are highest in soils derived from peridotite (984, 285, 53 and 204 mg/kg, respectively) and dolerite (1023, 176, 39 and 185 mg/kg, respectively). In the same way, Si and Al exhibit the features of parent materials in the sense that the lowest content was observed in soils developed on peridotite, dolerite and limestone. Zinc and Pb are highest in soils derived from shale (106 and 27 mg/kg, respectively). In a given pedon, different elements exhibited different enrichment/depletion patterns moreover, a given element may behave differently not only in soils with different parent materials but also, in some cases, in soils developed on similar lithology. Lead, Zn, Cu and Mn have been generally enriched in most pedons, except in some acidic and strongly leached soils, whereas Co, Cr, Fe, Ni and V have been leached, especially from Dystrudepts and Eutrudepts. The latter elements, however, showed enrichment trend in Hapludalfs and Argiudolls parallel to the development of illuvial B horizons.
M. Nael , A. Jalalian , H. Khademi , M. Kalbasi , F. Sotohian , R. Schulin ,
Volume 14, Issue 54 (winter 2011)
Abstract
Geologic and pedologic controls are the main factors determining the distribution of elements in natural soil environments. In order to assess the role of these factors in the content and distribution of major elements of soil, six parent materials including phyllite (Ph), tonalite (To), periditite (Pe), dolerite (Do), shale (Sh) and limestone (Li) were selected in Fuman-Masule region. Soil genesis and development of representive residual pedons were studied for each parent material. Total content of Si, Al, Ca, Mg, Fe, Mn, K, Na, Ti and P of soil horizons were measured and compared to the geochemical and mineralogical composition of parent materials. Maximum concentrations of Fe2O3 and MgO were found in the soils derived from Pe and Do however, these soils had low content of SiO2 and Al2O3, which is in conformity with the geochemical composition of the parent rocks. On the contrary, FeCBD content of these soils was lowest, indicating the low degree of soil development and, by the same fact, the importance of inheritance factor in soil Fe concentration. However, comparison of total Fe and FeCBD in Li1, Sh2 and To2 revealed that relative development of these pedons is higher than the others. Silicon depletion in Ph1, To2 and Sh2 pedons, relative to parent rocks, is higher than in Pe and Do pedons. However, this element is enriched in Li pedons. MnO content of Pe and Do pedons is governed by geogenic factors, while in Sh pedons, pedogenic factors, especially redox conditions, play the major role. Exchangeable forms of Ca and Na are determined by soil properties rather than by parent material type. Notwithstanding the redistribution of all major elements throughout pedons due to soil forming processes, the importance of inheritance factor in soil Si, Al, Mg, Fe, K, and Ti is higher than pedogenic factors.
M. Hamidpour, A. Jalalian, M. Afyuni, B. Ghorbani,
Volume 16, Issue 62 (Winte - 2013 2013)
Abstract
Models are helpful tools to predict runoff, sediment and soil erosion in watershed conservation practices. The objectives of this research were to investigate sensitivity analysis, calibration and validation of EUROSEM model in estimation of runoff in Tangh-e-Ravagh sub-basin of Karoun watershed. The model was tested in a one hectare experimental test site. The area was divided into nine elements according to EUROSEM user's manual. A triangular weir was installed at the outlet of the area to collect runoff in specified time periods for six rainfall events. Sensitivity analysis of the model was performed by a ±10% change in the dynamic parameters of the model and examining the outputs for a rainstorm. Sensitivity analysis showed that total runoff was sensitive to saturated hydraulic conductivity and insensitive to soil cohesion. Sensitivity analysis indicated that the model sensitivity depends on evaluation conditions and it is site-specific in nature. Calibration and validation of the model was performed on input parameters. Calibration of hydrographs was performed by decreasing saturated hydraulic conductivity and capillary drive and increasing initial soil moisture. Validation results showed that EUROSEM model simulated well the total runoff and peak of runoff discharge, but it could not simulate well the time of runoff, time to peak discharge
B. Khalili Moghadam, M. Afyuni, A. Jalalian, K. C. Abbaspour, A. A. Dehghani,
Volume 19, Issue 71 (spring 2015)
Abstract
With the advent of advanced geographical informational systems (GIS) and remote sensing technologies in recent years, topographic (elevation, slope, and aspect) and vegetation attributes are routinely available from digital elevation models (DEMs) and normalized difference vegetation index (NDVI) at different spatial (watershed, regional) scales. This study explores the use of topographic and vegetation attributes in addition to soil attributes to develop pedotransfer functions (PTFs) for estimating soil saturated hydraulic conductivity in the rangeland of central Zagros. We investigated the use of artificial neural networks (ANNs) in estimating soil saturated hydraulic conductivity from measured particle size distribution, bulk density, topographic attributes, normalized difference vegetation index (NDVI), soil organic carbon (SOC), and CaCo3 in topsoil and subsoil horizon. Three neural networks structures were used and compared with conventional multiple linear regression analysis. The performances of the models were evaluated using spearman’s correlation coefficient (r) based on the observed and the estimated values and normalized mean square error (NMSE). Topographic and vegetation attributes were found to be the most sensitive variables to estimate soil saturated hydraulic conductivity in the rangeland of central Zagros. Improvements were achieved with neural network (r=0.87) models compared with the conventional multiple linear regression (MLR) model (r=0.69).
F. Hosseini, M. R. Mosaddeghi, M. A. Hajabbasi, M. R. Sabzalian, M. Soleimani, M. Sepehri,
Volume 21, Issue 2 (Summer 2017)
Abstract
Soil water repellency can affect several soil properties such as aggregate stability. Soil texture and organic matter are two main internal factors responsible for the variability of soil water repellency. Major sources of organic matter in soil include plant residues, and exudates of plant roots and soil microorganisms. Tall fescue (Festuca arundinacea Schreb.) as an important cool-season perennial forage grass is usually infected by a fungal endophyte (Epichloë coenophiala) which often enhances resistance to biotic and abiotic stresses as well as altering the litter decomposition rate and soil properties. In this study, the effects of endophyte-infected (E+) and endophyte-free (E−) tall fescue residues (in three different levels of 0, 1 and 2%) on soil organic carbon, basal microbial respiration, water-dispersible clay and water repellency index (determined by intrinsic sorptivity method) were investigated in four texturally-different soils in the laboratory. E+ and E− tall fescue residues were completely mixed with moist soil samples and then were incubated at 25 °C. During two months of incubation period, the amended soil samples were subjected to 10 wetting and drying cycles and then, the above-mentioned soil properties were measured. The results indicated that soil organic carbon and water-dispersible clay were greater, while basal soil respiration and repellency index were lower in fine-textured soils. Water repellency index was increased by production of hydrophobic substances (for the rate of 1%) and was reduced by induced greater soil porosity (for the rate of 2%). Presence of endophyte in plant residues had no significant effect on water sorptivity, ethanol sorptivity and water repellency index; nevertheless, E+ residues increased soil organic carbon and decreased water-dispersible clay significantly. Overall, it is concluded that tall fescue residues, especially those with E+, can improve soil physical quality due to improving soil organic carbon storage and water repellency index and decreasing water-dispersible clay (as an index for aggregate instability). These E+ species and the residues have great potential to be used in sustainable soil conservational managements.
N. Alian, M. M. Ahmadi, B. Bakhtiari,
Volume 23, Issue 4 (Special Issue of Flood and Soil Erosion, Winter 2019)
Abstract
One of the most important problems in flood manegment is the damages induced by this phenomenon. Expected annual damage (EAD) is an important index for basin vulnerability against flood. Prediction of flood damages requires the analysis of spatial and temporal risk and must be calculated by the combination of hydrologic, hydraulic and economic models. In this research, the uncertainty was considered in the flood risk analysis. The probability of flood occurrence was calculated by the parabolistic model. By using the river analysis systems software (HEC-RAS) and the geographic information system (GIS) and utilizing the Google-Earth software, the floodplains of Zayande Roud river in Esfahan province were investigated with the return period of 25, 50, 100, 200 and 500 years. The Monte Carlo method was also sed to perform the uncertainty analysis in the proposed method. The logarithmic persion type III was selected as the best distribution of flood. The damage-stage relationship was calculated as well. Based on the uncertinity analysis, the river discharge could be regarded as the major parameter in the uncertainty of EAD.
T. Yousefi Babadi, M. Lotfalianand, H. Akbari,
Volume 23, Issue 4 (Special Issue of Flood and Soil Erosion, Winter 2019)
Abstract
Soil erosion and its consequences are important factors in forest road network management. Cutslopes are the most important source of making sediment among different parts of the forest roads structure. For this research, a new and bare road in district No. 2, series No. 5 of NekaChoob forest, was selected; then the study data was measured. The study design was a completely randomized design in 10 plots with the size of 2 m2 along 500 meters of road with the 8 natural rainfall events. The results of the Pearson correlation showed that among soil properties, the contents of the liquid limit at the 5% confidence level and the plastic limit at the 1% confidence level had positive correlations with runoff and soil loss. Also, organic matter at the 1% confidence level and the contents of the sand at the 5% confidence level had negative correlations with runoff and soil loss. With increasing the soil moisture and bulk density, runoff and soil loss were enhanced. The results of the multivariate model showed that soil loss could be estimated using the Plastic Limit and sand percentage variables with a the correlation coefficient of 0.948.
N. Shahabinejad, M. Mahmoodabadi, A. Jalalian, E. Chavoshi,
Volume 24, Issue 3 (Fall 2020)
Abstract
Wind erosion is known as one of the most important land degradation aspects, particularly in arid and semi-arid regions. Soil properties, by affecting soil erodibility, can control the wind erosion rate. The aim of this study was to attribute the soil physical and chemical properties to the wind erosion rate for the purpose of determining the most important property. To this aim, wind erosion rates were measured in-situ at 60 points of Kerman province using a portable wind tunnel facility. The results indicated that wind erosion rates varied from 0.03 g m-2 min-1 to 3.41 g m-2 min-1. Threshold wind velocity decreased wind erosion rate following a power function (R2=0.81, P<0.001). Clay and silt particles, shear strength, mean weight diameter (MWD), surface gravel, dry stable aggregates (DSA<0.25mm), soil organic carbon (SOC), calcium carbonate equivalent (CCE) and the concentrations of the soluble Ca2+, K+ and Mg2+ were inversely proportional to the wind erosion rates following nonlinear functions. On the other hand, Wind erosion was significantly enhanced with increasing the sand fraction, soluble Na+, electrical conductivity (EC) and sodium adsorption ratio (SAR). According to the final results, among the studied soil properties, SAR and MWD were s the most effective properties controlling wind erosion in the soils of Kerman province. Therefore, it is recommended to consider suitable conservation practices in order to prevent the sodification and degradation of arid soils.
S. S. Ariapak, A. Jalalian, N. Honarjoo,
Volume 25, Issue 2 (Summer 2021)
Abstract
In this study, spatial-temporal variation of dust deposition rate in the western and eastern half of Tehran and its climatic parameters affecting were studied. At 34 points in the city, dust samples were collected by glass traps from the roof, for twelve months, and the climatic data were obtained and analyzed from relevant organizations. The highest deposition rate is in the western half of the city and its total amount has varied from 54.52 to 121.21 g/m2/y. In both halves of the city, summer has the highest dust deposition rate and its central areas have the highest amount. There were significant positive correlations between dust deposition rate with temperature and medium wind speed, and there were significant negative correlations between dust deposition rate with rainfall and relative humidity in all months, which justifies the high dust deposition rate in the dry seasons of the year. The results of stepwise regression showed that rainfall was the most important factor affecting the dust deposition rate in both halves of the city. The city of Tehran has a special geographical location the presence of mountains like a barrier has prevented dust from leaving the city and the air inlet corridor of Tehran has faced problems due to the expansion of building construction and high-rise building. Other factors affecting the rate of dust deposition in this city, in addition to the distance from the main source of dust production, atmospheric parameters can be mentioned the existence of barren lands around the city, vegetation cover, construction operations, and traffic.
H. Alipour, A. Jalalian, N. Honarjoo, N. Toomanian, F. Sarmadian,
Volume 25, Issue 4 (Winiter 2022)
Abstract
Dust is one of the environmental hazards in arid and semi-arid regions of the world. In some areas, under the influence of human activities, dust is contaminated by heavy metals. In this study, the dust of 10 stations in the Kuhdasht region of Lorestan province in four seasons of spring, summer, autumn, and winter, as well as adjacent surface soils (a total of 40 dust samples and 10 surface soil samples), were sampled and some heavy metals including Zn, Pb, Cd, Ni, Cu, and Mn were analyzed. The results revealed that the amount of Zn in the dust was much higher than the surface soils of the region (800 vs. 85 mg/kg). Contamination factor index calculation indicated that high contamination of Cd and Zn, significant contamination of Ni and Pb, and lack of contamination by Cu and Mn. The annual enrichment factor of Cd (33.9) and Zn (24.6) was very high, Ni (11.3) was significant, Pb (6.4) was moderate, Mn (1) and Cu (0.82) were low. Based on the enrichment factor values, Cd, Zn, and Ni seem to have a human origin, Pb has both human activities and natural origin, and Cu and Mn have an only natural origin.
A.r Modares Nia, M. Mirmohamad Sadeghi, A. Jalalian,
Volume 25, Issue 4 (Winiter 2022)
Abstract
Desertification has become one of the main problems of human societies living in the vicinity of desert areas in recent years. One of the methods that have been considered in recent years and are rapidly expanding in the field of soil mechanics is the Microbial Induced Carbonate Precipitation (MICP). In this method, urea-positive organisms that are naturally present in the soil can stabilize the soil and improve its engineering parameters by using urea and calcium chloride. Recently, attempts have been made to use this method to create a crustal layer on the soil to prevent wind erosion. In the present study, the effect of environmental conditions in deserts such as temperature and sand bombardment on microbial soil treatment has been investigated using this new method. The soil of the Segzi region as one of the main centers of dust in the Isfahan region was studied in this research. Therefore, the improved samples are subjected to regional temperatures which increased the surface layer resistance with increasing temperature. Also, the sandstorm conditions of the region were simulated using three different grain sizes of sand inside the wind tunnel. The results of these experiments showed that stabilized soil could withstand the conditions at wind speeds of 7 and 11 m/s. However, by increasing the wind speed to 14 m/s and the grain size, the crustal layer destroys and increases the wind erosion of the soil. Also, the resistance of the surface layer increased by increasing temperature in the tested samples. This increase in resistance continued up to 24 degrees with a high slope, but from 24 degrees onwards, this slope decreases. Based on the results of this research, it can be said that the microbial improvement method can be used as an alternative method in the future to stabilize desert soils.
E. Javiz, A. Jalalian, M.r. Mosaddeghi, E. Chavoshi, N. Honarjoo,
Volume 26, Issue 4 (Winiter 2023)
Abstract
One of the most significant environmental crises in arid, semi-arid, sub-humid, and even humid regions is the destructive phenomenon of desertification and in the arid and semi-arid regions is wind erosion. These problems exist in large areas of Iran and it is necessary to use an environmentally friendly and economic method to solve this problem. In this study, calcium bentonite clay was used for the first time in Iran and perhaps in the worlds in the critical region of Sajzi, which covers an area of 65 hectares. Experiments were performed on the crusts after one year of mulching with bentonite clay. The results showed that wind erosion has a negative and significant correlation with the mean weight diameter and geometric weight diameter of aggregate, aggregates with diameters greater than 0.25 mm, shear strength, and penetration resistance. On the other hand, the results of the permeability test using double-ring and by three models (Kostiakov, Horton, and Philip) showed that the lowest mean square error (SSE) and the highest coefficient of determination (R2) belonged to the Kostiakov model in the mulch-applied and control samples. This result indicated the superiority of the Kostiakov model compared to Horton and Philip's models. Wind erosion intensity was also measured in situ using a portable wind tunnel at 20 points in the Sajzi region. The findings showed that mulch application has controlled more than 95% of soil erosion.
A.r. Eftekhari, M. Mirmohammad Sadeghi, A. Jalalian,
Volume 27, Issue 2 (Summer 2023)
Abstract
The use of biotechnology-based methods in the field of geotechnical engineering has led to the birth of new knowledge of biogeotechnology and several studies have been conducted using this new knowledge in various geotechnical issues including reducing permeability and increasing shear strength, especially in sandy soils and the desired results have been obtained. Nevertheless, little research has been done using biogeotechnology in the field of improving the mechanical properties of clay soils, especially in reducing the swelling of expansive soils, which is considered one of the types of problematic soils. The main cause of swelling of expansive soils is the presence of montmorillonite clays in these types of soils. Using chemical additives to stabilize expansive soils such as lime and cement is a common practice. However, environmental concerns related to greenhouse gas production caused by the production of chemical substances and the destructive effects of these substances on the environment and soils have encouraged researchers to use other sustainable stabilization alternatives. Microbial Induced Carbonate Precipitation (MICP) is a technique that can be a promising solution to solve this problem. The objective of the present study was to investigate the effect of the MICP method on the swelling of expansive clay soils and its effect on the mechanical strength of this type of soil. One-dimensional swelling tests, uniaxial compressive strength tests, and Atterberg limits tests were performed on clay soil with a liquid limit of 53 using Sporosarcina pasteurii bacteria, calcium chloride, and urea as nutrients. Taguchi's method was used for the design of the experiments and the statistical analysis of the results. This method designs experiments through partial factorial and reduces their number without a significant effect on the results. Bacterial concentration, nutrient molarity ratio, treatment time, and soil moisture were selected as four factors with Four levels of variation. The results showed that the (MICP) method was effective in reducing the swelling potential of expansive soils and also caused a significant increase in the unconfined compressive strength of the soil and its undrained shear strength.
