Showing 53 results for Abbasi
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.
A. Farjad, Dr N. Abbasi,
Volume 21, Issue 2 (Summer 2017)
Abstract
To deal with the destructive effects of swelling soils, different methods have been proposed by researchers. Chemical stabilization of expansive soils is one of the effective methods that are low-cost and efficient economically and technically. Recently, with the improvements of nano science in nanomaterials production and application, using this type of materials has been considered in different sciences especially geotechnical engineering. In this research, the effect of adding different amounts of nanoclay on swelling behavior modification of two types of clayey soils with low plasticity and high plasticity has been studied. For this purpose, first, identification tests were implemented on two types of clayey soils and nanoclay. Then, swelling potential tests were conducted on samples of soils with different amounts of nanoclay including (0, 0.25, 0.5, 1 and 2 weight percent) considering curing ages of 3 and 10 days. The results showed that the effect of adding nanoclay to the high plastic soils swelling potential is more than adding it to that of low plastic soils. So, adding 0.25 to 0.5 weight percent of nanoclay reduces the swelling potential of high plastic soils about 67 percent, and that of low plastic solis about 3 percent. Furtheremore, the maximum reduction in swelling potential increases by adding up to 0.5 percent nanoclay; and decreases for adding amounts more than 0.5 percent.
N. Abbasi, A. A. Afsharian,
Volume 22, Issue 1 (Spring 2018)
Abstract
Gypsiferous soils are one of the problematic soils which, due to solubility and contact with water, are a threat to various civil structures, especially water structures. Various factors affect the rate and amount of gypsum particles solubility. Gypsum types, the soil texture, the amount of gypsum in soil, the hydraulic gradient, and temperature and flowing water from gypsum soil are the major factors affecting the quality and quantity of the gypsum solution. In this research, the effects of some peripheral conditions including water temperature and hydraulic gradient on the solubility of gypsum soils were studied. To this aim, samples of gypsum soils were provided artificially by adding various rates of the natural gypsum rock including 0, 5, 10, 20 and 30 percent by weight of clay soil. Then, all gypsum soils were leached under five hydraulic gradients levels including 0.5, 1, 2, 5 and 10. The results indicated that the rate of Gypsum in the soil had a direct effect on the rate of solution in a way that by increasing the percent of Gypsum, the rate of solubility was increased. Also, the rate of leaching (the rate of the derived Gypsum from soil to the primary rate of Gypsum) was decreased by increasing the rate of Gypsum. In addition, by increasing hydraulic gradient, the speed of water and its amount in soil environment within a specified time were raised; further the rate of gypsum was increased too. Also, it was found that the rate of the solubility was increased directly by the temperature. The solubility rate of the gypsum soil at 50 C0 was found to be 2.5 and 1.6 times greater than that of the soil at 5 and 20 C0, respectively.
E. Chavoshi, M. Afyuni, M. A. Hajabbasi,
Volume 22, Issue 2 (Summer 2018)
Abstract
This study covers a large agricultural and industrial area of Isfahan province, including three types of land use, i.e., agricultural, uncultivated, industrial and urban types. A total of 275 samples from surface soil (0-20 cm) were collected and water soluble fluoride concentrations of them were measured. The spatial structure of water soluble fluoride in the soils was determined by omnidirectional variogram in the GS+ software. The spatial distribution of water soluble fluoride in the soil was mapped by employing the point kriging method in the SURFER software. The results showed that the mean of the water soluble fluoride concentration in Isfahan soils (0.85 mg L-1) was higher than the mean world soils (0.53 mg L-1). The water soluble fluoride showed moderate spatial dependence, indicating that the spatial variability of water soluble fluoride was mainly controlled by intrinsic and extrinsic factors. The mean water soluble fluoride concentration was significantly higher in agricultural and urban areas, as compared with the uncultivated land. This could be due to application of phosphate fertilizer in agricultural areas and the atmospheric fallout of fluoride from the industrial sources such as steel factories. According to the generated kriging map, the higher concentration of fluoride was mainly recorded around the Zayande Rood River and in the central and western parts of the study area.
Z. Abbasi, H. Azimzadeh, A. Talebi, A. Sotoudeh,
Volume 22, Issue 4 (Winter 2019)
Abstract
Groundwater quality evaluation is very necessary to provide drinking water. Groundwater excessive consumption can cause subsidence and penetration of saline groundwater into freshwater aquifers in Ajabshir Plain, on the Urmia lake margin. The main goal of the current project was to evaluate the groundwater quality by employing the qualitative indices of groundwater and GIS. Ten parameters of 15 wells including EC, TDS, total hardness as well as the concentration of Ca++, Na+, Mg++, K+, SO4--, HCO3- and Cl- were analyzed. At first, the maps of parameters concentration were prepared by the kiriging method. Then based on WHO drinking water standards, the maps were standardized and ranked for drawing the maps of quality indices. The results showed that quality index changes were in the range of moderate (61) to acceptable (81). Removing the single map method of sensitivity analysis detected the quality index was more sensitive to the K+ parameter. Finally, the quality index from the eastern north to the western south of Ajabshir Plain and the other areas was ranked in the acceptable and moderate classes, respectively.
F. Soroush, B. Mostafazadeh-Fard, S. F. Mousavi, F. Abbasi,
Volume 23, Issue 1 (Spring 2019)
Abstract
Infiltration is the most important characteristic in the design and management of any surface irrigation system. Since the hydraulic of flow in meandering furrows is different from the standard furrows, the accuracy of infiltration function parameter estimation methods should be examined for the optimal design and management of meandering furrow irrigation. The main objective of this study was to compare Elliot and Walker’s two-point and two-time methods for estimating the empirical infiltration function parameters of meandering furrow irrigation using four sets of field data. The estimated infiltration functions, as obtained by the two methods, were validated by performing the unsteady flow simulations and using the Slow-change/slow-flow (SC/SF) model. The results showed that Elliot and Walker prediction of the advance trajectories (with a mean RMSE of 0.68 minutes) was comparable to the two-time method (with an average RMSE of 0.66 min). The Nash–Sutcliffe efficiency coefficient for the simulated outflow hydrograph by the two-time and two-point methods was 0.89 and 0.50, respectively, indicating the excellent predictive power of the two-times method. In addition, the two-time method predicted the total volume of infiltration with the less relative error (-1.5%), in comparison to the two-point method (-47.2%). Therefore, the use of post-advance data (such as a two-time method) for infiltration function parameters estimation improves the flow simulation in the meandering furrows.
A. Foyouji Shahrezaei, M. A. Hajabbasi,
Volume 23, Issue 3 (Fall 2019)
Abstract
A well healthy environment can quietly affect the life quality and human community. In recent decades the need for and utilizing fossil had increased and thus the environmental pollutions including for soil has also increased. Petroleum contaminated soils are not suitable for agricultural, residential and social usage and cause economical, ecological and agricultural damage. To cope with this challenge, the use of additives such as carbon nanotubes has expanded to soil, but the use of these elements has raised concerns about their risk to biological processes and systems, such as effects on physiology and plant growth, and there have not been much studies on this issue. In order to investigate the interaction of soil petroleum pollution and carbon nanotubes on some plant characteristics such as wet mass, dry matter and plant length, seed and maize seedling were separately treated with 0, 10, 20 and 40 mg/l carbon nanotubes at the beginning. In pots containing soil with three levels of petroleum pollution, 2.43, 2.76 and 4.16% were cultivated with 3 replications. A completely randomized design was used in the form of factorial experiments. Wet mass, dry matter and length of shoot and root of plants were determined. The results showed that petroleum pollution had a negative effect on the growth characteristics. It was also observed that application of carbon nanotubes to maize (whether seed or seedling) depending on the concentration of these materials, could have different effects on plant growth parameters.
F. Ansari Samani, S. H. Tabatabaei, F. Abbasi, E. Alaei,
Volume 23, Issue 3 (Fall 2019)
Abstract
Simulation of water and salt transfer in soil is very effective in managing optimal water and fertilizer use in the field. In this study, the HYDRUS-1D model was used to simulate the transfer of water and bromide in a laboratory column of soil with clay loam texture. Soil hydraulic parameters (including air entry point) α, (saturated hydraulic conductivity) ks, (residual moisture content) θr (saturation moisture content) θs, (pore and particle joint parameter) l (parameter of moisture curve shape) n through measurement and using Retc software was obtained Solubility transfer parameters including difiusion coefficient and actual velocity were estimated using soil hydraulic parameters and bromide concentration data by reverse modeling method. According to the target coefficients, the sensitivity analysis of the physical model was performed .The results showed that the correlation coefficient of observation and simulation bromide concentration in optimal mode was 0.84%. accordingly, the diffusion coefficient was estimated to be 4.9 cm. based on the results of the sensitivity analysis, the saturation hydraulic conductivity had the greatest effect on the variation of this parameter, so that the amount sensitivity coefficient of this parameter was 2.64 The RMSE coefficient with a value of 0.04 was the lowest and ME coefficient with the value of -0.0001 had the most parameter variations.
Sh. Ahmadi-Qolidaraq, A. Abbasi-Kalo, A. Esmali-0uri,
Volume 23, Issue 4 (Special Issue of Flood and Soil Erosion, Winter 2019)
Abstract
Soil is one of the most important natural resources of countries in which erosion occurs. In this research, the effect of soil characteristics on the amount of erosion at the suborder level was studied. For this purpose, 77 soil samples (0-30 cm) were prepared and the parameters were determined in the laboratory. The semi-variograms of soil parameters and their spatial distribution maps were prepared with GS+ and GIS, respectively. The study area was divided into work units by combining land use and geology maps and water erosion was estimated at each unit by the EPM method. By drilling profiles in different parts of study area, soil suborders were determined by Soil Taxonomy and the average values of parameters in each suborder was estimated. The principle components analysis (PCA) was then used for data analysis. The results showed that three parameters of silt, organic carbon and electrical conductivity could account for 30.384% as the first main component; clay, sand and vegetation could explain 11.189% as the second main component; and slope and height covered 15.330% as the third main component; in total, 63.805% percent of erosion variation could be justified by three main components. The lowest and highest amounts of erosion (69.12 and 343.57 m3/km2, respectively) were estimated in Xeralfs and Fluvents suborders. The erosion class of suborders at the study area was determined to be “few” and “medium”.
N. Abbasi, A. Heydari Pakroo, R. Bahramloo,
Volume 24, Issue 2 (Summer 2020)
Abstract
The use of additives to modify the physical, chemical and mechanical properties of soil and soil stabilization is one of the most common methods that have a history. By adding one or more additives to the soil and carrying out the required measures, the engineering properties of soils could be improved due to chemical reactions. Selecting the type and amount of additive depends on several factors such as: soil type, stabilization purpose, additives inherent characteristics, etc.; these are determined based on the technical and economic aspects of the projects. In this study, the effects of the simultaneous use of three types of additives including lime, stone powder and polypropylene fibers on the unconfined compressive strength of a clayey soil were investigated. To do this, four different levels of lime (0, 2, 3 and 5 percent by weight of soil) and four different levels of stone powder waste (0, 2, 5 and 10 percent by weight of soil) and Polypropylene fibers with different percentages in five levels of 0, 0.25, 0.5 and 1 percent by weight of soil were added into a high plastic clay soil classified as CH. Then, some physical and mechanical characteristics of different mixtures including plasticity, compaction and unconfined compressive strength were determined. The results showed that the samples were stabilized with lime and stone powder waste and reinforcement them with polypropylene fibers modified Atterberg Limits, optimum moisture and maximum dry density of the mixtures. Also, it was found that a combination of waste stone powder, lime and polypropylene fibers containing 5, 5 and 1 percent by weight of soil increased the unconfined compressive strength 8-fold, as compared to the natural soil. The curing time also had a significant impact on the compressive strength of the treated samples in which the 28-day compressive strength of was found to be about 2 times of the 7-day samples.
M. Seifollahi, S. Abbasi, M.a. Lotfollahi-Yaghin, R. Daneshfaraz, F. Kalateh, M. Fahimi-Farzam,
Volume 26, Issue 2 (ُSummer 2022)
Abstract
Unpredictable settlement of earth dams has led researchers to develop new methods such as artificial neural networks, wavelet theory, fuzzy logic, and a combination of them. These methods do not require time-consuming analyses for estimation. In this research, the amount of settlement in rockfill dams with a central core has been estimated using artificial intelligence methods. The data of 35 rockfill dams with a central core were used to train and validate the models. The artificial neural network, wavelet transform model, and fuzzy-neural adaptive inference system are the proposed models which were used in the present study. According to the results, the best model for an artificial neural network had two hidden layers, the first layer of 18 neurons and the second layer of 7 neurons, with the Tansig-Tansig activation function, with a coefficient of determination R2=0.4969. The best model for the fuzzy-neural inference system had the ring function (Dsigmoid) as a membership function, with three membership functions and 142 repetitions with a coefficient of determination R2=0.2860. Also, combining wavelet-neural network conversion with the coif2 wavelet function due to the more adaptation this function has to the input variables, the better the performance, and this function, with a coefficient of determination R2=0.9447, had the highest accuracy compared to other models.
I. Hasanpour, M. Shirvani, M.a. Hajabbasi, M.m. Majidi,
Volume 26, Issue 2 (ُSummer 2022)
Abstract
Low organic matter content and alkaline pH of calcareous soils in arid and semi-arid regions are the main reasons for the low nutrient availabilities for plants in these soils. One way to improve the chemical properties and fertility of calcareous soils is the application of organic substances such as biochar produced from pyrolysis of organic wastes. However, biochars have an almost predominant alkaline pH, which exacerbates plant nutrient deficiencies in calcareous soils when used for a long time. Pyrolysis of some organic wastes under controlled temperature conditions can lead to the production of acidic biochar. The effect of acidic biochars on several chemical properties of two calcareous soils in Isfahan province was investigated in the present study. Treatments included two types of biochar (pine cone and rice husk), three levels of biochar addition (one, three, and six percent), two types of soil (a sandy loam (Tiran) and a clay loam (Lavark)), and two incubation periods (one and six months). The results showed that applying biochar could slightly decrease soil pH but raised soil electrical conductivity. In addition, the amount of organic carbon, total nitrogen, and available concentration of manganese in all treatments and the concentrations of available phosphorus, potassium, iron, zinc, and copper in the most of treatments showed a significant increase compared to the control. Amending soil with biochar at a 6% rate caused the most significant changes in the measured parameters in both soil types. In general, the results of this study indicated that acidic biochar produced from pine cones and rice husk can be used as a suitable conditioner to improve the chemical properties and fertility of calcareous soils.
N. Salamati, M. Moayeri, F. Abbasi,
Volume 27, Issue 2 (Summer 2023)
Abstract
The objective of the present study was to conduct field studies for direct measurement of canola under farmers' management in one crop season (2019-2020) in 27 farms in Behbahan, Khuzestan province. Water requirement was calculated based on the FAO Penman-Monteith model using the daily statistics of the Behbahan synoptic meteorological station. A T-test was used to statistically compare the results such as the depth of irrigation and applied water productivity in the field in different irrigation systems. Linear multivariate regression analysis was used to investigate the effects of the independent variable on the dependent parameter of water productivity. The volume of applied water in the fields ranged from 4085.5 to 7865.3 m3/ha. The results of comparing the average yield of two irrigation systems in the t-test showed that the two sprinkler and surface irrigation systems with yields of 2614 and 2330 kg/ha, respectively, were not significantly different. Applied water productivity in traditional and modern irrigation systems was calculated to be 0.386 and 0.486 kg/m3, respectively, which had significant differences. The results of the analysis of variance in the regression model showed that among the independent variables, yield with t-statistic (23.997) and equivalent beta coefficient (0.880) had the most significant positive effect at a 1% level on applied water productivity. After that, the volume of applied water (irrigation water + effective rainfall) with a t-statistic of (-11.702) and a beta coefficient of equivalent (-0.793) had the most negative and significant effect at the level of 1% on the applied water productivity. The results of the Pearson correlation coefficient showed that irrigation events had a positive and significant correlation at a 5% level with applied water and yield. These correlations were 0.455 and 0.380, respectively. By increasing irrigation events, the volume of applied water has practically decreased and has become as close as the plant needs, and has increased water productivity.
