Soil science
Fatemeh Rakhsh; Ahmad Golchin; Ali Beheshti Ale Agha
Abstract
Introduction
Soil texture is one of the most influential characteristics of soils that affect the decomposition and retention of soil organic matter because it directly or indirectly affects soil's physical, chemical, and biological properties. Soil clays play an important role in soil organic matter ...
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Introduction
Soil texture is one of the most influential characteristics of soils that affect the decomposition and retention of soil organic matter because it directly or indirectly affects soil's physical, chemical, and biological properties. Soil clays play an important role in soil organic matter stability. Organic matter adsorbed on phyllosilicate clays is more resistant to microbial decomposition than organic matter that has not interacted with any mineral. Exchangeable cations with the influence of physical and chemical characteristics of the soil probably cause changes in the absorption and retention of organic matter. In previous studies, the effect of soil texture on organic matter retention has been investigated, but the impact of clay type and exchange cation has not been investigated. This study aimed to examine the effect of different contents of vermiculite and zeolite clays and exchange cations on the mineralization of organic nitrogen.
Materials and Methods
A factorial experiment was conducted in a completely randomized design with three replications to study the effect of the type and content of clay and the type of exchange cations on organic nitrogen dynamics. Experimental treatments include two types of clay (vermiculite and zeolite), four different levels of clay (0, 15, 30, and 45%), and three types of exchangeable cations (Na+, Ca2+, and Al3+). The experiment included 24 treatments and three replications. There were total of 72 experimental units. Artificial soil of 50 grams was prepared separately according to the amount and type of clay and the type of exchange cation. Then, alfalfa plant residues were added to all the samples at 5% w/w. After adding the inoculum and air drying the samples, the humidity of the samples reached 60% of the field capacity (FC) using distilled water (We first air-dried the samples to prevent the excess water from causing an error in the final moisture, and then we added enough distilled water to each sample to reach 60% of FC). They were kept in the dark for 60 days at a temperature of 23 °C. Distilled water was added and sealed to the bottom of the incubation jars to keep the moisture content of the soil samples constant during incubation. The percentage of mineralized nitrogen, microbial biomass nitrogen, and the activity of acid and alkaline phosphatase and cellulase enzymes were determined in the prepared samples. The data were analyzed using ANOVA, and the means were compared using Duncan's Multiple Range Test (DMRT). Before applying ANOVA, the data's normality and variance homogeneity were checked using Kolmogorov- Smirnov and Levene tests, respectively. The SPSS software (Windows version 25.0, SPSS Inc., Chicago, USA) and SAS software (version 9.4, SAS Institute Inc., Cary, NC) were employed for data analysis.
Results and Discussion
The results of variance analysis of the data showed that the effect of the type and content of clay and the type of exchangeable cation on the percentage of mineralized nitrogen, microbial biomass nitrogen, and the activity of acid and alkaline phosphatase and cellulase enzymes were significant (p< 0.01). The results revealed that, regardless of the duration of the samples, with the increase in the amount of clay, the percentage of inorganic nitrogen and the activity of enzymes decreased, but the nitrogen of microbial biomass increased. The highest percentage of inorganic nitrogen was obtained 60 days after incubation of the samples and in clays saturated with calcium, and the lowest amount of these attributes was obtained 15 days after incubation of the samples and in clays saturated with aluminum. The results showed that nitrogen mineralization increased with the samples' incubation time. Also, the highest percentage of mineralized nitrogen, microbial biomass nitrogen, and enzyme activity were observed in soils with vermiculite clay.
Conclusion
The increase in the incubation duration increased the percentage of inorganic nitrogen. The percentage of mineralized nitrogen and microbial biomass nitrogen was higher in soils with vermiculite clay than in soils with zeolite clay. Moreover, regardless of the incubation duration of samples, with increasing clay content, the percentage of mineralized nitrogen and enzyme activity decreased, but with increasing clay nitrogen content, microbial biomass increased. The highest and lowest amounts of mineralized nitrogen and nitrogen of microbial biomass were measured in soils with calcium and aluminum, respectively. The results showed the effect of the clay type and content and the exchangeable cation type on organic nitrogen dynamics.
Soil science
A. Barikloo; P. Alamdari; A. Golchin
Abstract
IntroductionHeavy metals such as lead, aluminum, mercury, copper, cadmium, nickel, and arsenic are now commonly found worldwide. Among these, cadmium and lead are the most hazardous, posing significant risks to both the environment and human health. Cleaning soils contaminated with organic and inorganic ...
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IntroductionHeavy metals such as lead, aluminum, mercury, copper, cadmium, nickel, and arsenic are now commonly found worldwide. Among these, cadmium and lead are the most hazardous, posing significant risks to both the environment and human health. Cleaning soils contaminated with organic and inorganic contaminants is one of the most significant and fundamental challenges facing society today. One effective method for soil purification is to extract or immobilize the contaminant within the soil. Materials and MethodsIt is unclear how water-soluble polymers contribute to the immobilization of heavy metals. The purpose of this study is to examine how various polymers affect the immobilization of lead, zinc, and cadmium in the soil near a lead and zinc mine in the province of Zanjan. A factorial experiment with three replications was conducted using a randomized complete block design. The experimental treatments included one type of soil and three different kinds of acrylic polymers (cationic, nonionic, and anionic) applied at four different levels (0, 0.05, 0.1, and 0.2). The absorbable amounts of lead, zinc, and cadmium were tested at various intervals after the polymers were applied to the soil samples. After that, SAS statistical software was used to examine the data. To do this, the Duncan multiple range test was used to compare the means. The necessary tables and graphs were then created using Excel. Results and DiscussionThe findings demonstrated that, at 1% probability level, the kind of polymer had a considerable impact on the amount of lead, zinc, and cadmium that may be absorbed in the soil. The average concentration of soil-absorbable lead for the different types of polymers employed was 239.8, 260.15, and 267.65 mg/kg; anionic polymer had the lowest concentration. Stated differently, anionic polymer decreases the capacity to absorb lead and stabilizes more lead in the soil than the other two forms of polymer. Anionic polymers most likely have a stronger impact on soil granulation. Additionally, at 1% probability level, the impact of acrylic polymer intake on the amount of lead, zinc, and cadmium absorbable in the soil was considerable. With an increase in the amount of polymer utilized in the soil, the greatest absorbable lead concentration (301.58 mg/kg) in the control treatment dropped to the lowest absorbable lead concentration (0.2). It was possible to determine the polymer percentage and the lead concentration, which came out to be 205.9 mg/kg of soil. Zinc concentration dropped as acrylic polymer consumption increased; in the control treatment, absorbable zinc concentrations ranged from 0.2 to 83.5 mg/kg of soil, with 0.2 being the highest concentration. At 1% probability level, the impact of the polymer's contact time with the soil on the amount of lead, zinc, and cadmium that the soil may absorb was significant. As a result, the tested soil had 414.52 mg of these elements at the initial stage of polymer treatment. The quantity of absorbable lead in the soil became 66% immobilized after a month, and after 720 hours, the amount of absorbable lead dropped to 141.83 mg/kg. As the polymer's contact time with the soil increased, so did the concentration of absorbable zinc in the soil. At 1% probability level, there was a strong correlation between the kind and amount of acrylic polymers and the amount of lead, zinc, and cadmium that may be absorbed in the soil. The ingestion of 0.2% anionic polymer resulted in the largest amount of lead immobilization, lowering the soil's absorbable lead concentration from 300 to 192 mg/kg of soil. A higher amount of anionic polymer immobilized the lead, and both cationic and non-ionic polymers were positioned after it. Additionally, anionic polymer was more prevalent than cationic polymer. It caused the non-ionic polymer's absorbable zinc to become immobile. Following 720 hours of polymer treatment, the soil's absorbable zinc element was immobilized to a greater extent by the anionic polymer (20%) than by the cationic and non-ionic polymers (26%), respectively. In comparison to the original concentration, the largest amount of immobilization by anionic polymer after one month was 78%, and the lowest amount of immobilization by nonionic polymer was 61%. Anionic polymer was 27% more effective than non-ionic polymer, 18% more effective than cationic polymer, and stabilized more cadmium. Conclusion The results of this study showed that with increasing the duration of contact of polymers used with the soil, the amount of mobility of heavy metals in the soil decreased and also with increasing the amount of polymer consumption, the rate of metal stabilization in the soil increased. Anionic polymers immobilize more lead, zinc and cadmium in soil. To reduce the mobility of lead, zinc and cadmium and improve the stability and increase aggregation in soil, the use of acrylic polymer in contaminated soil is recommended.
L. Qasemi far; A. Golchin; F. Rakhsh
Abstract
Introduction: The accumulation of heavy metals in water, sediments, and soils has led to serious environmental problems. In recent years, several processes have been developed with the aim of reducing or recovering heavy metals from contaminated environments. Physical and chemical approaches are capable ...
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Introduction: The accumulation of heavy metals in water, sediments, and soils has led to serious environmental problems. In recent years, several processes have been developed with the aim of reducing or recovering heavy metals from contaminated environments. Physical and chemical approaches are capable of removing a broad spectrum of contaminants, but the main disadvantages of these methods lie in the increased energy consumption and the need for additional chemicals. In recent years, the processes such as bioleaching, biosorption, bioremediation, phytoremediation, and bio precipitation are all based on the use of microorganisms that have the ability to solubilize, adsorb, or precipitate heavy metals. Therefore, it is necessary to find some solutions to reduce the negative effects of heavy metals in soil. Materials and Methods: A factorial experiment was conducted in the greenhouse of the Faculty of Agriculture, the University of Zanjan, using a completely randomized design with three replications. In this experiment, the effects of different levels of soil cadmium (0, 5, 10, 25, and 50 mg/Kg) and soil inoculation (without inoculation and inoculation with Glomus mosseae, Glomus intraradices, Glomus mosseae + Rhizobium trifolii, Glomus intraradices + Rhizobium trifolii bacterium, Rhizobium trifolii, Glomus mosseae + Glomus intraradices and Glomus mosseae + Glomus intraradices + Rhizobium trifolii) on growth of berseem clover were assessed. Results and Discussion: The results of this study showed that the soil cadmium levels has a significant effect (p < 0.05 and p < 0.01) on fresh weights of aerial parts and roots, height, number of the plant in the pot, Fe, Zn and Cd concentrations in aerial parts and roots of berseem clover. The fresh weights of aerial parts and roots, height, number of the plant in the pot, Fe and Zn concentrations in aerial parts and roots of berseem clover decreased as the levels of soil cadmium increased. The lowest concentrations of iron and zinc were measured in treatment with 100 mg Cd/Kg. Also, Cd concentration in aerial parts and roots increased as the level of soil cadmium increased. The results of this experiment showed that soil inoculation with mycorrhizal fungi and Rihzobium trifolii had a significant effect (p < 0.05 and p < 0.01) on fresh weights of aerial parts and roots, height, number of plant per pot, Fe, Zn and Cd concentrations in aerial parts and roots of berseem clover. The inoculation of soil with mycorrhizal fungi and Rhizobium trifolii increased the fresh weights of aerial parts and roots, height and No. of plant per pot. The highest fresh weights of aerial parts and roots of berseem clover, height, and number of plant per pot were obtained in treatments co-inoculated with Glomus mosseae and Rhizobium trifolii. The highest and lowest concentrations of iron and zinc in aerial parts and roots of berseem clover were measured, respectively, for the treatment co-inoculated by Glomus mosseae and Rhizobium trifolii and control treatment (without inoculation). However, the opposite trends were found in Cd concentrations in the plant. The highest and lowest Cd concentrations in aerial parts and roots were measured in control treatment (without inoculation) and treatment co-inoculated by Glomus mosseae and Rhizobium trifolii (MT), respectively. Conclusion: Bioremediation and phytoremediation are considered as two very safe and necessary technologies which naturally occur in the soil by microbes and plants and pose no hazard to the environment and the people life. The procedure of bioremediation and phytoremediation can be simply carried out on site without initiating a major disruption of normal actions and threating the human life and the environment during transportation. Bioremediation and phytoremediation are used less than other technologies for cleaning-up the wastes and contaminated soils. Microorganisms and plants possess inherent biological mechanisms that enable them to survive under heavy metal stress and remove the metals from the environment. These microbes use various processes such as precipitation, biosorption, enzymatic transformation of metals, complexation and phytoremediation techniques of which phytoextraction and phytostabilization have been very effective. However, environmental conditions need to be adequate for effective bioremediation. The use of hyperaccumulator plants to remediate contaminated sites depends on the quantity of metal at that site and the type of soil. The results of this experiment showed that the Rhizobium trifolii and Glomus mosseae could be used to reduce the soil cadmium contamination. Also, the berseem clover is a hyperaccumulator plant for phytoremediation of cadmium in soils. According to the results of this study, co-inoculation of mycorrhizal fungus Glomus mosseae and Rhizobium trifolii can be recommended to improve the yield and uptake of micronutrients such as iron and zinc in cadmium contaminated soils.
S. Abdollahi; A. Golchin; F. Shahryari
Abstract
Introduction: Contamination of soils with heavy metals is one of the most serious environmental problems increasing the risk of the entry of heavy metals into food chains. Rhizosphere soil is distinct from the bulk soil and is defined as the volume of soil around living roots which is influenced by root ...
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Introduction: Contamination of soils with heavy metals is one of the most serious environmental problems increasing the risk of the entry of heavy metals into food chains. Rhizosphere soil is distinct from the bulk soil and is defined as the volume of soil around living roots which is influenced by root activities. Enzymes are produced by both roots and soil microorganisms to alter nutrient availability in rhizosphere soil. Soil enzymes promote the transformation of matter and energy in the soil, and their activity has a close relationship with soil nutrient availability. Detection of microbial enzymes in a natural environment is important to understand biochemical activities and to verify the biotechnological potential of microorganisms. However, there are few reports to indicate the biotechnological potential of plant growth promoting rhizobacteria (PGPR) and their effects on the activity of bacterial enzymes in rhizosphere soils under the stress of heavy metals. Thus, in the present study lead and cadmium contaminated rhizosphere soils were inoculated with PGPR species to investigate the influence of these bacteria on the activity of some enzymes. Materials and Methods: A factorial pot experiment with completely randomized design base and three replications was performed in the greenhouse conditions. The factors examined were (a) rhizosphere soils of three varieties of cabbage [Brassica oleracea var. acephala L. (Ornamental cabbage), Brassica oleracea var. italica L. (Broccoli cabbage) and Brassica oleracea var. capitata L. (Cabbage)] and (b) five species of PGPR, consisting Pseudomonas putida PTCC 1694, Bacillus megaterium PTCC 1656, Proteus vulgaris PTCC 1079, Bacillus subtilis PTCC 1715 and Azotobacter chroococcum, used to inoculate the rhizosphere soils. There was also a control treatment (without rhizobacteria). The experiment had 18 treatments and there were 54 experimental units. To study rhizosphere soils, several rhizoboxes were used and three seedlings of cabbage were planted in the central part of each rhizobox (rhizosphere area). In treatments inoculated with rhizobacterial species, 2 ml of a bacterial suspension with 107-108 (cfu ml-1) was used to inoculate the soil of rootzone. After three months, cabbage varieties were harvested and the activity of alkaline phosphatase, acid phosphatase, urease, and dihydrogenase were measured in rhizosphere soils. The data obtained from this study were statistically analyzed by SPSS statistical software package (Version 9.4) and the variance of the data was analyzed by one-way ANOVAs (Duncan’s test) range test at 1 and 5 percent probability levels. Results and Discussion: The analysis of variance of the data (ANOVA) showed that the cabbage varieties, inoculation with PGPR species and their interactions had significant effects (p < 0.01) on the activity of alkaline phosphatase, acid phosphatase, urease, and dihydrogenase in rhizosphere soils. The results showed that inoculation of the rhizosphere soils with PGPR species increased the activity of soil enzymes. The highest activity of alkaline phosphatase (1529.28 µg pNP.g-1 dm.h-1) was measured in rhizosphere soils of the broccoli inoculated with Pseudomonas putida PTCC 1694. But, the highest activity of acid phosphatase (497.92 µg pNP.g-1dm.h-1) was obtained in rhizosphere soils of cabbage inoculated with Pseudomonas putida PTCC 1694. Also, the highest activity of urease (208.36 µg N-NH4+.g-1dm.2h-1) was observed in rhizosphere soils of the cabbage inoculated with Azotobacter chroococcum and the highest activity of dihydrogenase (8.71 µg TPF.g-1dm.16h-1) was observed when rhizosphere soils of the cabbage were inoculated with Bacillus subtilis PTCC1715. Conclusion: From the results of this study, it may be concluded that inoculation of Pb and Cd contaminated soils with PGPR species could modulate the toxic effects of heavy metals on plant and increase the activity of some key enzymes for plant growth in rhizosphere soils.
S. Abdollahi; A. Golchin; F. Shahryari
Abstract
Introduction: Contamination of soils by heavy metals is one of the most serious environmental problems that increases the risk of toxic metal entry into the food chains. When heavy metals enter the soil, they are progressively converted to the insoluble form by reactions with soil components. A variety ...
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Introduction: Contamination of soils by heavy metals is one of the most serious environmental problems that increases the risk of toxic metal entry into the food chains. When heavy metals enter the soil, they are progressively converted to the insoluble form by reactions with soil components. A variety of mechanisms such as absorption, ion exchange, co-precipitation and complexation incorporates heavy metals into soil minerals or bounds them to various soil phases. Organic acids are natural compounds that are secreted from the root of the plant and can affect the solubility and uptake of heavy metals.
Materials and Methods: To evaluate the effects of plant growth promoting rhizobacteria (PGPR) on organic acids production and heavy metal uptake by different cabbage varieties, a factorial pot experiment with completely randomized design and three replications was performed under the greenhouse conditions. The factors included (a) rhizosphere soils of three varieties of cabbage [Brassica oleracea var. acephala L. (Ornamental cabbage), Brassica oleracea var. italica L. (Broccoli cabbage) and Brassica oleracea var. capitata L. (Cabbage)] and (b) five species of PGPR consisting of Pseudomonas putida PTCC 1694, Bacillus megaterium PTCC 1656, Proteus vulgaris PTCC 1079, Bacillus subtilis PTCC 1715 and Azotobacter chroococcum and control (without rhizobacteria) used to inoculate the rhizosphere soils. The experiment had 18 treatments and there were 54 experimental units and three seedlings of cabbage were planted in each pot. In all treatments inoculated with rhizobacterial species, 2 ml of a bacterial suspension with 107-108 (cfu ml-1) were used to inoculate the soil of root area. The data obtained in this study were statistically analyzed by SAS software (version 9.4) and the mean comparison was performed by Duncan’s multiple range test at 1 and 5 percent probability levels.
Results and Discussion: The analysis of variance (ANOVA) showed that the cabbage varieties, bacterial inoculation and their interactions had significant effects (p < 0.01) on organic acids concentration, fresh and dry biomass of plant, concentrations of Pb and Cd in root and shoot of cabbage plant. The results showed that inoculation of the rhizosphere soils with PGPR species increased organic acids concentration of rhizosphere. The highest concentration of malic and citric acids in rhizosphere soil (9.59 and 118.34 mg dl-1, respectively) was obtained when the rhizosphere soils of the broccoli were inoculated with Pseudomonas putida PTCC 1694 and the highest concentration of acetic acid in rhizosphere (233.88 mg dl-1) was determined when the rhizosphere of broccoli were inoculated with Bacillus megaterium PTCC 1656. Inoculation of the rhizosphere with PGPR species also increased the fresh and dry biomass of plant, and Pb and Cd concentrations in cabbage root and shoot. The highest fresh and dry biomass of cabbage (416.77 and 76.96 g in the plot, respectively) were obtained when the rhizosphere soils of cabbage were inoculated with Bacillus megaterium PTCC 1656, the highest concentration of Pb in the root and shoot and Cd in the root of cabbage (12.20, 90.77 and 9.01 mg kg-1, respectively) were obtained when the rhizosphere soils of the ornamental cabbage were inoculated with Pseudomonas putida PTCC 1694. Inoculation of the rhizosphere soils of the ornamental cabbage, broccoli and cabbage by B. megaterium PTCC1656 caused an increase in the DOC concentration by 137, 150 and 120%, respectively, compared to uninoculated rhizosphere soils. Bacterial inoculation also increased the concentrations of available phosphorus in the rhizosphere soils and the highest concentration of phosphorus was measured in the treatments inoculated by P. putida PTCC1694. Furthermore, the concentrations of available phosphorus in the rhizosphere soils of the ornamental cabbage, broccoli and cabbage increased by 79, 71 and 111%, respectively, relative to uninoculated rhizosphere soils.
Conclusion: It is concluded that inoculation of Pb and Cd contaminated soils by PGPR species, especially Bacillus megaterium PTCC 1656 and Pseudomonas putida PTCC 1694, enhances the tolerance of host plants, metal uptake performance and thus phytoremediation process by increasing the metal bioavailability and biomass production of the plant. As the distribution and accumulation of heavy metals in plant tissues are important factors for evaluation of plant role in phytoremediation of polluted soils, the PGPR inoculation of rhizosphere soils can be used as a biotechnological tool to enhance biomass production and plant uptake and thus the efficiency of phytoextraction.
A. Nemati; A. Golchin; A. Ghavidel
Abstract
Introduction: Crude oil is one of the most important sources of energy and its large scale production, transmission, consumption and disposal, making it one of the most important and common types of environmental pollution worldwide. Oil extraction and various oil products have led to spread of pollution ...
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Introduction: Crude oil is one of the most important sources of energy and its large scale production, transmission, consumption and disposal, making it one of the most important and common types of environmental pollution worldwide. Oil extraction and various oil products have led to spread of pollution in the soils around oil extraction and refining sites. During the production and transportation of crude oil, unsuitable operation and leakage may result in contamination of soil with petroleum hydrocarbons. Great concern in this case is the environmental risks of these pollutants. During the past decades, bioremediation of petroleum contaminated soil has been a hot issue in environmental research, and many bioremediation strategies have been developed and improved to clean up petroleum polluted soil. The aim of this study was to compare the effects of co-using of different bioremediation strategies on remediation of crude oil contaminated soil.
Materials and Methods: In order to investigate the effects of co-using phytoremediation and bioremediation in a crude oil contaminated soil, a factorial experiment in completely randomized design with three replications was conducted. The factors were three levels of crude oil contamination (0 wt% (C0), 2 wt% (C1) and 4 wt% (C2() and four treatments of remediation (Grass (B1), Alfalfa (B2), Grass + Pseudomonas Putida+ Phanerochaete Chrysosporium (B3), Alfalfa + Pseudomonas Putida+ Phanerochaete Chrysosporium (B4), control (B0)). For amendment of contaminated soil, soil samples were artificially contaminated with crude oil (from Tabriz Oil Refinery) and blended to soil (10% total quantity of soil spiked) then spiked soils were progressively mixed with unpolluted soil and homogenized. After preparation of the crude oil-spiked soil microbial inoculation were done and then the samples were packed into soil columns and then plants cultivation was done in soil columns (P.V.C pipes). At the end of growth period, some parameters were measured including residual Total Petroleum Hydrocarbons (TPHs) concentration, microbial basal respiration and dry weight of root and shoot.
Results and Discussion: The results showed that TPHs concentration in C1 crude oil level by B3 and B4 remediation treatments decreased by 59% and 57%, respectively, and in C2 level B3 and B4 remediation treatments decreased TPHs content by 41% and 39%, respectively. B3 remediation treatment had the highest shoot and root dry weight and the lowest root and shoot dry weight observed from B2 remediation treatment. Shoot and root dry weight decreased with increasing crude oil contamination levels. The highest basal respiration rate was observed in B3 and B4 remediation treatments. In all of crude oil levels, there was not significant difference between B1 and B2 remediation treatments and control (B0) in basal respiration rate. In the highest crude oil contamination level (C2) the amount of carbon produced as CO2 increased because this level has higher concentration of oil pollutants and therefore has more required substrate for the activity of microorganisms, and consequently more microbial activities increased CO2 production. Compared to the control, the levels of crude oil contamination (C1 and C2) decreased dry weight of root by 46% and 61%, respectively and dry weight of shoot by 53% and 63%, respectively. Considering that the high concentrations of oil contaminants in the soil can lead to toxicity for plants and microorganisms and also hydrophilic properties of these compounds can decrease the availability of moisture and nutrients for plants root, therefore the growth of root decreased in oil contaminated soil. In lower level of crude contamination (C1), remediation treatments have more effective role in refining crude oil. This results from more plant growth and then more plant roots which increase the bioavailability of hydrocarbons by reducing the volume of soil micro pores. Also plants root release organic compounds which would increase the population and activity of soil microbes and these cause to increase of oil compounds degradation and elimination.
Conclusion: Experimental results showed that remediation treatments which contained bacteria and fungi with plants caused to more oil compounds elimination, microbial basal respiration and dry weight of root and shoot. Therefore, it can be found the importance of the presence of microorganisms and the microbial activity with plants in order to degrade and remove the soil oil compounds.
Keywords: Bioremediation, Oil pollution, Residual oil compounds, Microbial basal respiration
Fatemeh Rakhsh; Ahmad Golcchin
Abstract
Introduction: Mobilization and stabilization of organic matter in soils represent a set of complex processes involving the processing and decomposition of organic matter by diverse communities of soil fauna and microorganisms, as well as chemical-physical interactions with mineral particles of soil. ...
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Introduction: Mobilization and stabilization of organic matter in soils represent a set of complex processes involving the processing and decomposition of organic matter by diverse communities of soil fauna and microorganisms, as well as chemical-physical interactions with mineral particles of soil. Clay minerals have high effects on the soil organic matter dynamics. Clay minerals with the physical protection of organic matter play an important role in reducing the rate of decomposition of organic matter. The effects of soil texture on the soil organic matter dynamics have been investigated in many studies, but the effects of exchangeable cations and clay types on mineralization of organic nitrogen and microbial biomass nitrogen have not been given much attention. For this reason, the aim of this study was to evaluate the effects of types and clay contents and exchangeable cations on the mineralization of organic nitrogen and microbial biomass nitrogen.
Material and Methods: Appropriate amounts of homoionic Na-, Ca- and Al- clays from Georgia kaolinite, Illinois illite and Wyoming montmorillonite were mixed with pure sand to prepare artificial soils with different clay contents, exchangeable cations, and clay types. The artificial soils have zero, 5 and 10% clay from Georgia kaolinite, Illinois illite and Wyoming montmorillonite that their clay minerals saturated with Ca, Na and Al. Alfalfa plant residues were incorporated into the artificial soils and the soils were inoculated with microbes from a natural soil and incubated for 60 days and concentration of NH4-N and NO3-N were measured every 15 days. In the artificial soil samples, microbial biomass nitrogen was measured by the fumigation-extraction method in the end time of incubation period.
Results and Discussion: The results of this study showed that the percentage of mineralized nitrogen in the two-month incubation period, was higher in the pure sand than in soils containing 5% and 10% clay, indicating that clay contents influence the capacity of soils to protect and store organic nitrogen. Microbial biomass nitrogen increased as the amount of clay in the soil increased. The highest and lowest amounts of microbial biomass nitrogen measured in soils with 10% clay (9.26 mg per 50 g dry soil) and pure sand (4.31 mg per 50 g dry soil), respectively. There was a significant influence of exchangeable cations on the percentage of mineralized nitrogen and microbial biomass nitrogen. The microbial biomass nitrogen and the percentage of mineralized nitrogen were highest in Ca-soils and lowest in Al-soils. The percentage of mineralized organic nitrogen in two months of incubation period was highest in soils with Georgia kaolinite clay and lowest in soil with Wyoming montmorillonite clay. The amounts of microbial biomass nitrogen in soils with Wyoming montmorillonite clay were lower than soils with Georgia kaolinite and Illinois illite clays. The percentage of mineralized organic nitrogen increased as the incubation period increased. The results of this study indicated that organic nitrogen mineralization rates and microbial biomass nitrogen were affected by types and clay contents and exchangeable cations and interaction of organic matter with clays and is an important process as it slows soil organic matter decomposition.
Conclusions: Mixing the alfalfa residues with artificial soils and incubation samples allowed to study the effects of types and clay contents and exchangeable cations on the percentage of NH4+-N, NO3--N, mineralized nitrogen, and microbial biomass nitrogen. Soils with different clay contents have different surface areas and cation exchange capacities; therefore, it is concluded that organic nitrogen storage of soils is, partly, controlled by the surface areas, cation exchange capacity and physical protection provided by the soils. Nitrogen mineralization and the amounts of microbial biomass nitrogen were different in soils with different exchangeable cations. It is concluded that exchangeable cations exert their influence on microbial biomass and hence nitrogen dynamics by controlling the size and activity of the microbial population through modifying the physicochemical characteristics of microbial habitats. Since various clay minerals have different specific surface areas and cation exchange capacity and the physicochemical changes induced in the soil environment as a result of variations of exchangeable cations is much greater in soils with higher cation exchange capacity and specific surface area. It seems the effects of clay mineralogy on the dynamics of organic materials and microbial biomass, in part, arise from the type of exchangeable cations present on the exchange sites of the clay minerals.
zeinab bigdeli; ahmad golchin; saeid shafiei
Abstract
Introduction: Dynamics of organic carbon and nitrogen are controlled by several factors, including physical, chemical and biological properties of soil. Heavy metals contaminate soils and change soil properties and affect organic carbon and nitrogen dynamics. Since toxicities of heavy metals are different ...
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Introduction: Dynamics of organic carbon and nitrogen are controlled by several factors, including physical, chemical and biological properties of soil. Heavy metals contaminate soils and change soil properties and affect organic carbon and nitrogen dynamics. Since toxicities of heavy metals are different and organic carbon and nitrogen dynamics are affected by available concentrations of these metals, the aims of this experiment were to assess the effects of different levels of soil cadmium on mineralization of organic carbon and nitrogen.
Materials and Methods: To assess the effects of different levels of soil cadmium on mineralization of organic carbon and nitrogen, a factorial pot experiment was conducted using litter bag method. The factors examined were different levels of soil cadmium (0, 10, 20, 40, and 80 mg kg -1soil) and incubation periods (1, 2, 3 and 4 months) that were applied in three replications. Soil samples were artificially contaminated with cadmium to desirable levels using cadmium sulfate and the samples were placed in plastic pots and the pots incubated at constant moisture and temperature for one month. Then litter bags containing 15 g wheat residues were buried in pots and incubated for different periods of time. At the end of incubation periods, the remaining amounts of plant residues were measured and analyzed for organic carbon and nitrogen concentrations using Walkley and Black and Kjeldahl methods respectively. The decomposition rate constants of organic carbon and nitrogen were calculated using Mt = M0 e –kt equation. Organic carbon and nitrogen losses were calculated by subtracting the remaining amounts of organic carbon and nitrogen in one incubation time interval from those of former one.
Results and Discussion: The results showed that the effects of soil cadmium levels and incubation periods were significant on organic carbon and nitrogen mineralization. The losses of organic carbon and nitrogen from wheat residues decreased as the levels of soil cadmium increased. The highest and the lowest organic carbon and nitrogen losses were measured in control and treatments with 80 mg Cd kg -1 soil respectively. Increase in soil cadmium levels decreased the losses of organic carbon and nitrogen from wheat residue. The losses of organic carbon for a period of four months were 37.54, 37.21, 36.11, 35.12 and 33.69 (%) in treatments with soil cadmium levels of 0, 10, 20, 40 and 80 mg kg -1 respectively. The loss of organic carbon in the first month of incubation was (30.78%) and in the other three months of incubation was (9.74%) with a sum of (40.52%) for a period of 4 months. Similarly, the loss of organic nitrogen in the first month of incubation was 23.69% and in the other three months of incubation was 8.56% with a sum of 32.25 (%) for a period of 4 months. The highest losses of organic nitrogen from wheat straw residue were measured in treatment of control cadmium (31.64 percent) and lowest losses of organic nitrogen (23.86percent) related to treatment with 80 mg of cadmium / kg of soil. The losses of organic nitrogen, after 4 months were 31.64, 30.69, 28.68, 26.25, and 23.86 (%) when treatment of cadmium contamination of soil was 0, 10, 20, 40 and 80, respectively. The decomposition rate constants for organic carbon were 0.0076, 0.0075, 0.0073, 0.0070 and 0.0066 day -1 when soil cadmium levels were 0, 10, 20, 40, and 80 mg kg -1 respectively. The rate constants for organic nitrogen at the mentioned soil cadmium levels were also 0.0061, 0.0059, 0.0054, 0.0048 and 0.0044 day -1 respectively.
Conclusions: The results of this research indicate that contamination of soils by heavy metals increases the residence time of organic carbon and nitrogen in soils and slows down the cycling of these elements. The mineralization rate of organic nitrogen was affected by soil cadmium levels more than that of organic carbon. The amounts of organic carbon and nitrogen losses are higher in the first month of incubation than those of other months and decomposition of wheat residue had a fast and a slow stage. The results of this study indicate that due to the adverse effects of heavy metals on soil organisms, mineralization rate of plant residue carbon is slower in polluted soils compared with non polluted soils.
tahereh mansouri; Ahmad Golchin; Mohammad Babaakbari
Abstract
Introduction: Arsenic (As) is the twentieth element in earth's crust and the contamination of soils and ground waters by it is common and disturbing. In addition to geological factors and soil parent material, human activities such as mining and smelting, coal combustion and the use of arsenic-containing ...
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Introduction: Arsenic (As) is the twentieth element in earth's crust and the contamination of soils and ground waters by it is common and disturbing. In addition to geological factors and soil parent material, human activities such as mining and smelting, coal combustion and the use of arsenic-containing compounds such as insecticides, pesticides, wood preservations and etc lead to the accumulation of high levels of this metal in the soils. Long-term exposure to As can lead to skin, bladder, lung, and prostate cancers.The presence of As in soil and water causes its transfer to different parts of the plant. Because of the crucial role of corn in human nutrition, investigation of the uptake, transport and accumulation of As in different parts of this plant is very important, thus this study was carried out with the aims of evaluating the response of corn to the presence of As in the environment and its impact on concentrations of phosphorus (P), iron (Fe), zinc (Zn) and manganese (Mn) in this plant.
Materials and Methods: Soil samples were collected and after air drying, passed through a 2 mm sieve and analyzed for some physico-chemical properties. The samples were then artificially contaminated by different levels of arsenic (0, 6, 12, 24, 48 and 96 mg/kg) using Na2HAsO4.7H2O salt and incubated for 6 months, and then planted to corn. Before planting, the concentration of available As was determined. At the end of growth period, mean height of plants was measured and then the above and below ground parts of plants were harvested, washed, dried and digested using a mixture of HNO3 and H2O2. The concentrations of As, P, Fe, Zn and Mn in plant extracts were measured. Statistical analyses of data were performed using SAS software and comparison of means carried out using Duncan's multiple range test.
Results and Discussion: The results indicated that As concentration increased both in root and in shoot with increasing As concentration. The highest As concentrations in corn root and shoot were 383.41 and 59.56 mg/kg, respectively. Arsenic accumulation in root was higher than the shoot, so that the concentrations of arsenic in the roots of plants grown at 6, 12, 24, 48 and 96 mg As/ kg of soil, were 1.88, 1.99, 3.13, 4.96 and 6.44 times higher than their concentrations in shoot, respectively. Corn was sensitive to As stress and growth of it reduced by increasing the level of soil As. Mean heights of plants grown in soils polluted with 6, 12, 24, 48 and 96 mg As/kg decreased compared to control by 10.74, 25.30, 38.99, 59.71 and 76.66%, respectively. The rate of reduction of dry weights of roots of plants grown in soils polluted with 6, 12, 24, 48 and 96 mg As/kg were 10.66, 30.20, 54.64, 81.65, 95.94 % and ones of shoot were 11.30, 27.25, 47.14, 77.66 and 95.22%, respectively, which showed corn root was more sensitive to As than shoot. Arsenic uptake by root and shoot increased with increasing the As levels to 48 and 24 mg/kg, respectively, but at higher levels of As it decreased, this showed that up to these levels, increasing arsenic concentrations in plant parts surpassed from the decreasing dry weights of them and the amount of uptake obtained by multiplying these two factors, increased. Phosphorus concentrations in root and shoot increased and decreased, respectively, with increasing soil As concentration, and this matter showed As reduced P translocation from the root to the shoot of plants. Iron and Zinc concentrations in root and shoot decreased but Manganese concentration increased with increasing soil As concentration.
Conclusions: The results of this study showed that the corn plant is very sensitive to arsenic and its growth decreased even in the presence of low concentrations of arsenic. Arsenic accumulation in root was higher than the shoot. Arsenic changed the concentration of nutrients in the soil and the corn, So that increased the available P concentration and reduced the available concentrations Fe, Zn and Mn. It also reduced the translocation of P, the concentration of Fe and Zn in the root and shoot. The statement that toxicity limits plant As uptake to safe levels was not confirmed in our study. If corn plants are exposed to a large concentration of As, they may accumulate residues which are unacceptable for animal and human consumption.
tahereh mansouri; Ahmad Golchin; Zahra Rezaei
Abstract
Introduction: Selecting the right source of nutrient in a particular cropping situation requires a consideration of economic, environmental, and social objectives. One of the objectives is to keep all nutrient losses to a minimum. Since the use of nitrogen chemical fertilizers began more than 100 years ...
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Introduction: Selecting the right source of nutrient in a particular cropping situation requires a consideration of economic, environmental, and social objectives. One of the objectives is to keep all nutrient losses to a minimum. Since the use of nitrogen chemical fertilizers began more than 100 years ago, it has been recognized that it can be lost as gaseous ammonia when an ammonical fertilizer is applied to calcareous soil. A process by which nitrogen exit from the soil in form of ammonia and enter to the atmosphere is called volatilization. Agricultural practices (use of chemical and animal fertilizers) are known as major sources of ammonia volatilization into the atmosphere. Nitrogen losses not only economically but also in terms of environment pollution is important. Ammonia volatilization is one way of the nitrogen losses from agricultural and non-agricultural ecosystems. A variety of soil chemical properties interact with environmental conditions at the site of the fertilizer application to determine the extent of NH3 loss. This article study some of the major factors that contribute to NH3 loss from N fertilizer. The aims of this study were to evaluate the impacts of concentrations of soil calcium carbonate (experiment 1), plant residue application (experiment 2), nitrogen fertilizer rate and source on volatilization of ammonia from soil.
Materials and Methods: Two factorial experiment with 36 treatments, three replications and 108 experimental unit for 25 days at a constant temperature of 30 ° C were conducted using a completely randomized design. The experimental treatments were three concentrations of soil calcium carbonate (20, 27 and 35% in experiment 1), three alfalfa plant residue application rates (0, 2.5 and 5% w/w in experiment 2), three rates of nitrogen (0, 200 and 400 kg/ha), four sources of nitrogen (urea, ammonium nitrate, ammonium sulfate and urea- sulfuric acid). Fertilizers were added to soil samples in form of solution and the moisture of soils was brought to field capacity. Samples were placed into special jars and amount of nitrogen volatilization were measured.
Results and Discussion: The results showed that ammonia volatilization from soil increased as the concentration of soil calcium carbonate, rates of nitrogen and alfalfa plant residues application increased. In first experiment the highest amount of nitrogen volatilization rate, as ammonia (33.21 µgr N/gr soil) was measured from 400kgN/ha soil for urea fertilizer and 35 percent calcium carbonate. Also the lowest amount (11.99 µgrN/gr soil) was obtained from 20 percent calcium carbonate without application of any nitrogen fertilizer. In this experiment, with an increase in the amount of soil calcium carbonate by 15%, the amount of volatilized nitrogen in the form of ammonia were six times. By increasing the amount of soil calcium carbonate of from 20 to 27% the amount of nitrogen losses as ammonia slightly increased but with a further increase of calcium carbonate (from 27 to 35%) the amount of nitrogen losses increased a lot and this increase was higher than the initial increase. The presence of calcium carbonate in the soil increase soil pH and ammonia volatilization. In second experiment the highest amount of nitrogen volatilization rate, as ammonia (32.28 µgr N/gr soil) was measured from 400kgN/ha soil for urea- acid sulfuric fertilizer and 5 percent of plant residues. Also the lowest amount (0.33 µgrN/gr soil) was obtained from soil without application of any nitrogen fertilizer and plant residues. The most of nitrogen losses in the form of ammonia in the amount of 15.34 micrograms per gram of soil was obtained from level of 5% of alfalfa residue. With the 2.5 percent increase in the alfalfa residue rate, ammonia volatilization from soil increased in rate of 3.24 micrograms per gram of soil and by increasing it from 2.5 to 5%, nitrogen volatilization increased in the amount of 8.88 micrograms per gram of soil.
Conclusion: The loss of nitrogen as ammonia with application of nitrogen fertilizers and without application of residues was as urea> ammonium sulfate> ammonium nitrate > urea-sulfuric acid and with application of crop residues was as urea-sulfuric acid
P. Mohajeri; P. Alamdari; A. Golchin
Abstract
Introduction: Topography is one of the most important factors of soil formation and evolution. Soil properties vary spatially and are influenced by some environmental factors such as landscape features, including topography, slope aspect and position, elevation, climate, parent material and vegetation. ...
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Introduction: Topography is one of the most important factors of soil formation and evolution. Soil properties vary spatially and are influenced by some environmental factors such as landscape features, including topography, slope aspect and position, elevation, climate, parent material and vegetation. Variations in landscape features can influence many phenomena and ecological processes including soil nutrients and water interactions. This factor affects soil properties by changing the altitude, steepness and slope direction of lands. In spite of the importance of understanding the variability of soils for better management, few studies have been done to assess the quality of soils located on a toposequence and most of these studies include just pedological properties. The aim of this study was to investigate physical and chemical properties of soils located on different slope positions and different depths of a toposequence in Deilaman area of Gilan province, that located in north of Iran.
Materials and Methods: The lands on toposequence that were same in climate, parent material, vegetation and time factors but topographical factor was different, were divided into five sections including steep peak, shoulder slope, back slope, foot slope and toe slope. In order to topsoil sampling, transverse sections of this toposequence were divided into three parts lengthways, each forming one replicate or block. 10*10 square was selected and after removing a layer of undecomposed organic residues such as leaf litter, three depths of 0 to 20, 20 to 40 and 40 to60 cm soil samples were collected. physical and chemical characteristics such as soil texture, bulk density, aggregate stability, percent of organic matter, cation exchange capacity, available phosphorous and total nitrogen were measured.
Results and Discussion: The results showed that, because of high organic matter content and fine textured soils on the lower slope positions including foot slope and toe slope, aggregate stability, cation exchange capacity, available phosphorous and total nitrogen were maximum in these positions, whereas, bulk density had a reverse trend and was higher in the upper slope positions than the lower slope positions. The high content of organic carbon, phosphorus and total nitrogen in the soil of foot and toe slope positions, can be attributed to soil erosion and transferred from top of the slope and their accumulation in these situations. The results also revealed that, with increasing depth, aggregate stability, organic carbon content, cation exchange capacity, available phosphorous and total nitrogen content of soils decreased, whereas, clay content and bulk density had a reverse trend and increased with increasing the depth. Reducing the amount of organic carbon with increasing depth was because of the remains of plants and roots in the surface horizons and the presence of more organic carbon. Since phosphorus and nitrogen in the soils are highly dependent on organic matter, Thus, changes in these indicators are mainly obeys from this materials.
Conclusion: In general, it became appears from this study, that the topography factor had important effect on studied soil properties. The changes observed in the quality of soils located on different slope positions can be attributed to the differences of the soil in erosion rate and moisture content and different sediment receptions in different positions of toposequence as affected by the amount and distribution of rainfall. Considering the effect of the position of the landscape on the physical and chemical properties of soil, recommended analysis of the landscape is better to be done in the sustainable land management and also for soil and water conservation programs. Because of the different management practices in different parts of landscape is difficult and perhaps impossible, in order to maintain soil, conservation management must be done based on soil quality in areas with maximum damage and minimum quality.
T. Mansouri; A. Golchin; J. Fereidooni
Abstract
Introduction: Soil contamination by heavy metals is one of the most important environmental concerns in many parts of the world. The remediation of soil contaminated with heavy metals is necessary to prevent the entry of these metals into the human food chain. Phyto-extraction is an effective, cheap ...
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Introduction: Soil contamination by heavy metals is one of the most important environmental concerns in many parts of the world. The remediation of soil contaminated with heavy metals is necessary to prevent the entry of these metals into the human food chain. Phyto-extraction is an effective, cheap and environmental friendly method which uses plants for cleaning contaminated soils. The plants are used for phytoremediation should have high potential for heavy metals uptake and produce enormous amount of biomass. A major problem facing phyto-extraction method is the immobility of heavy metals in soils. Chemical phyto-extraction is a method in which different acids and chelating substances are used to enhance the mobility of heavy metals in soil and their uptake by plants. The aims of this study were: (a) to determine the potential of radish to extract Pb from contaminated soils and (b) to assess the effects of different soil amendment (EDTA and H2SO4) to enhance plant uptake of the heavy metal and (c) to study the effects of different levels of soil Pb on radish growth and Pb concentrations of above and below ground parts of this plant.
Materials and Methods: Soil samples were air dried and passed through a 2 mm sieve and analysed for some physico-chemical properties and then artificially contaminated with seven levels of lead (0, 200, 400, 600, 800 and 1000 mg/kg) using Pb(NO3)2 salt and then planted radish. During the growth period of radish and after the initiation of root growth, the plants were treated with three levels of sulfuric acid (0, 750 and 1500 mg/kg) or three levels of EDTA (0, 10 and 20 mg/kg) through irrigation water. At the end of growth period, the above and below ground parts of the plants were harvested, washed, dried and digested using a mixture of HNO3, HCl, and H2O2. The concentrations of Pb, N, P and K in plant extracts were measured. Statistical analysis of data was performed using MSTATC software and comparison of means was carried out using duncan's multiple range test.
Results and Discussion: The results showed that the effects of the type and rate of soil amendment and Pb levels of polluted soils were significant on dry weight and Pb concentrations of above and below ground parts of radish (p< 0.01). The dry weights of above and below ground parts of radish decreased as the Pb levels of polluted soils increased. By increasing the soil pollution level (1200 mg Pb/kg soil), the total dry weight of plant decreased by %47.3 which was probably due to phytotoxicity of lead and deficiency of several essential nutrients such as phosphorus. When the Pb levels of the polluted soils increased up to 400 mg/kg soil, the concentrations of Pb in above and below ground parts of the plant increased. But when the Pb levels of the polluted soils were higher than 400 mg/kg soil, the Pb concentration in above ground part of the plant decreased but in below ground part of the plant significantly increased. The decrease in Pb concentration in above ground part of radish was probably due to formation of insoluble lead complexes in soil. the use of soil amendments increased the concentrations of Pb in above and below ground parts of radish. The Application of EDTA increased the concentration of Pb in aerial part of radish more than the application of H2SO4. Also, the application of EDTA and H2SO4at low concentrations increased dry weight of plant since, the availability of micro- and macro elements enhanced and plant uptake of nutrients increased. But at the high concentrations of these amendments the increased availability of lead caused the reduced plant growth due to phytotoxicity. But the ability of the low level of sulfuric acid to absorb lead was more than EDTA. An antagonistic effect between phosphorus and lead uptake was also observed.
Conclusion: The results of the experiment showed that the Radish plant had the ability to absorb and accumulate the high concentration of lead in its tissues and so can be used for the phytoremediation of lead-contaminated soils. The EDTA application had higher potential for enhancing lead mobility and phytoavailability than H2SO4, But the ability of the low level of sulfuric acid to absorb lead was more than EDTA. The rate of amendment also had a significant effect on phyto-extraction process and the process was adversely affected by high concentrations of the amendments.
hashem aram; A. Golchin
Abstract
Introduction: Soil contaminations with heavy metals represent a potential risk to the biosphere and leads to increased concentration in ground and surface water. Therefore metals mobility in soil has been extensively studied in the last decades. Use of agrochemicals such as synthetic fertilizers and ...
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Introduction: Soil contaminations with heavy metals represent a potential risk to the biosphere and leads to increased concentration in ground and surface water. Therefore metals mobility in soil has been extensively studied in the last decades. Use of agrochemicals such as synthetic fertilizers and pesticides has resulted in soil and water pollution, and loss of biodiversity. Cadmium is a heavy metal with a strong effect on crop quality. Moreover, it is a very mobile element in the environment. Plants can easily uptake cadmium and transfer it to other organs. Experiments on the effects of cadmium on the contents of macro elements in plants are scarce and therefore the mechanism of its effect has not yet been fully explained. Contaminated soil can be remediated by chemical, physical or biological techniques. Mycorrhiza is the mutualistic symbiosis (non-pathogenic association) between soil-borne fungi with the roots of higher plants. Arbuscular mycorrhizal fungi (AMF) are obligate biotrophs, which can form mutualistic symbioses with the roots of around 80% of plant species. Arbuscular mycorrhiza have been observed to play a vital role in metal tolerance and accumulation. Many workers have reported enhancement of phosphate uptake and growth of leguminous plants by vesicular arbuscular mycorhizal fungi (AMF).
Materials and Methods: One study performed the factorial experiment based on completely randomized design (CRD) with three replications in the greenhouse of Agriculture Faculty of Zanjan University. The examined factors include different levels of arbuscular mycorrhizal fungi inoculation (Glomus mosseae) (with and without inoculation), and different levels of soil contamination by cadmium (0, 5, 10, 20, 40 and 80 ppm). In this study, arbuscular mycorrhizal fungi Glomus mosseae species were used. These fungi were prepared by the Plant Protection Clinic in Iran – Hamedan. The soil was prepared of arable land of depth of 0-20 cm at the University of Zanjan, after the complete analysis of soil and obtaining the chemical and physical properties in the laboratory. 6 kg of soil was weighed for each pot and then the soil was contaminated. Cadmium sulfate was used in this experiment. The mycorrhizal fungi weighed 150 grams and was mixed with the soil. After mixing the soil with mycorrhizal fungi, the soil was put in pots and then it was cultivated with clover. In this study, clover seeds weighed 0/5 grams and were disinfected with 10% hydrogen peroxide solution and were added to each pot. Distilled water was used for irrigation. After the completion of growth of plants (about 70 day), plant aerial parts and roots were harvested and before measuring, they were washed with distilled water and then were dried in the oven for 72 hours. Plant aerial parts were harvested. Data were analyzed by SAS (version 9) and MSTATC (version 2.10) software, and obtained variance analysis tables. Mean comparison of different treatments was conducted by Duncan test. Charts were obtained by excel software.
Results and Discussion: The results showed that the effects of arbuscular mycorrhizal fungi were significant on all traits measured (P< 0.01). With increasing cadmium concentration in soil, dry matter of 37% and 39%, nitrogen concentration of 35% and 28%, Potassium 9/27% and 37%, and phosphorus concentration of 37% and 39%, reduced in root and aerial, respectively. Also the results showed that arbuscular mycorrhizal fungi increased dry matter amount by 42% and 26%, nitrogen concentration by 40.3% and 30%, phosphorus concentration by 6% and 15.4%, potassium concentrations by 54% and 91.2% in root and aerial, respectively. Interaction between cadmium levels and mycorrhizal fungi in statistics was significant on dry matter aerial, nitrogen concentration in aerial and root, and potassium concentrations in plant root (P< 0.01).
Conclusion: The results showed that mycorrhizal fungi were significant on all traits measured in one percent level. Cadmium reduced the concentration of nutrients in the plant; but mycorrhizal fungi increased nutrient concentrations of nitrogen, phosphorus and potassium in the plant. Previous studies have shown that external hyphae of mycorrhizal fungi are able to provide their symbiotic plant potassium, nitrogen and phosphorus. Ghazala reported that nutrient uptake of mycorrhizal plants was higher when compared with non-mycorrhizal. It seems that the ability of arbuscular mycorrhizal fungi in concentration of nutrients depends on fungal species, soil condition, and host plant.
R. Jenabi Haghparast; A. Golchin; E. Kahneh
Abstract
Heavy metals are entered to the environment by mining and by applying sewage sludge and agricultural inputs to soils. These metals have detrimental effects on environment and soil organisms. An experiment was conducted to determine the cadmium affects on earthworms (Eisenia fetida) in a calcareous soil ...
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Heavy metals are entered to the environment by mining and by applying sewage sludge and agricultural inputs to soils. These metals have detrimental effects on environment and soil organisms. An experiment was conducted to determine the cadmium affects on earthworms (Eisenia fetida) in a calcareous soil amended with 0 and 5% organic matter. The concentrations of Cd in soils were 0,10,20,40, 60 and 80 mg kg-1 and growth parameters of the earthworms were measured with 15 day intervals over 75 days. Survival, growth and cocoon production of earthworms were determined. The results showed that addition of organic matter to soils reduced the toxic effects of cadmium to earthworms. In soils contaminated with Cd the weights of the earthworms decreased with increasing the concentrations of this metal and cadmium had the highest negative effects on cocoon production. The highest earthworm’s mortality was recorded in soils contaminated with cadmium.
H.R. Samaei; A. Golchin; Mohammad Reza Mosaddeghi; Sh. Ahmadi
Abstract
Organic matter improves soil structure and any factor that decreases soil organic matter content causes soils structural instability. In soils with low organic matter content, soluble polymers can be used to increase the soil structural stability. In order to study the effects of polymer type and concentration ...
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Organic matter improves soil structure and any factor that decreases soil organic matter content causes soils structural instability. In soils with low organic matter content, soluble polymers can be used to increase the soil structural stability. In order to study the effects of polymer type and concentration on physical properties of soils with different texture, factorial experiment ..was ..conducted.. within ..completely ..randomized design ..with ..three replication. Three types of polymer (R790, TC108 and NC218) and three polymer concentration (1:1, 1:3 and 1:10 V/V polymer: water) were used in factorial combinations. Samples from soils with different texture were sprayed with different concentrations of the polymers and physical properties of polymer- treated soil samples were measured and compared with the control. Polymers application significantly enhanced the physical conditions of the soils. It increased the soil saturated hydraulic conductivity and dry and wet structural stabilities of the polymer-treated samples when compared with the control. The application of polymers decreased the dispersible clay and soil density of the polymer-treated soil samples. Increase of the soil saturated hydraulic conductivity and structural stability of the polymer-treated samples was greater for high polymer concentrations. The TC108 and R790 polymers were more effective than the NC218 polymer in improving the physical properties of the soils.
A. Beheshti Ale Agha; F. Raiesi; A. Golchin
Abstract
Abstract
In this study the effects of land use changes from pasturelands to croplands on soil microbiological and biochemical properties were studied in Kangaver, Dehno and Soltanye regions. Composite soil samples from 0-20 and 20-40 cm depths of pasture and cultivated lands were taken from Kangaver, ...
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Abstract
In this study the effects of land use changes from pasturelands to croplands on soil microbiological and biochemical properties were studied in Kangaver, Dehno and Soltanye regions. Composite soil samples from 0-20 and 20-40 cm depths of pasture and cultivated lands were taken from Kangaver, Dehno and Soltanye regions, and soil microbial respiration, microbial biomass C and N, and urease, alkaline phosphatase, saccharase and arylsulfatase activities were determined. Results showed that land use changes from pasture to arable lands resulted in a significant reduction of microbial respiration in Kangaver (36-64%), Dehno (45-60%) and Soltanye (34%) regions. Similarly, substrate-induced respiration (SIR) decreased between 13 to 37% due to land use changes in all the three regions studied. The microbial biomass C (30-60%), N (18-56%) and C/N ratios (9-17%) in the two soil depths of cultivated sites were lower than those of forest sites in the three regions while metabolic quotient (36-95%), the portion of carbon (4-60%) and nitrogen (3-76%) of microbial biomass in total soil and percentage mineralized C (36-95%) in all the three regions increased due to land use changes. The assay of enzyme activities showed that alkaline phosphatase in both soil depths did not change substantially for each region. In Soltanye region, urease activity decreased (18%) only in the 0-20 cm depth and land use effects were not significant for the other enzymes. Conversion of pastures to agricultural lands in Kangaver region resulted significant decreases in urease (20%), saccharase (33%) and arylsulfatase (11%) activities in the surface layer, but not in the 20-40 cm depth. In Dehno, increased urease and arylsulfatase activities in both soil depths due to land use changes from pastures to cultivated lands were significant, but increased saccharase activity was significant only in the 0-20 cm depth. Overall, it is concluded that a change in land use from pastures to croplands with widespread agricultural practices, specifically long-term intensive tillage activities, may lead to enhanced availability of oxygen and substrate to microorganisms, which could result in increased microbial activity including soil respiration.
Keywords: Land use change, Agricultural practices, Soil organic matter, Soil enzyme activity, Soil microbial respiration, Soil quality
S. Seyed Dorraji; A. Golchin; Sh. Ahmadi
Abstract
Abstract
Agriculture is the largest consumer of water resources in Iran. One of the best options for increasing the irrigation efficiency and better application of precipitation in arid and semi-arid areas is employing of superabsorbent polymers to soil. Polymers can absorb rain and irrigation water, ...
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Abstract
Agriculture is the largest consumer of water resources in Iran. One of the best options for increasing the irrigation efficiency and better application of precipitation in arid and semi-arid areas is employing of superabsorbent polymers to soil. Polymers can absorb rain and irrigation water, decrease deep percolation and increase water use efficiency. In order to investigate the effects of different rates of hydrophilic polymer superab A200 on water holding capacity and the porosity of soils with different salinity and textures, three factorial experiments were conducted using a completely randomized design with three replications. The polymers were applied to soils of different textures (sand, loam and clay) at the rates of 0.0, 0.2, 0.4 and 0.6 % w/w and salinity of the soils was adjusted at the levels of initial soil salinity (blank), 4 and 8 dS/m. The application of 0.6% w/w of polymer at the lowest salinity level increased available water content by 2.20 and 1.20 times greater than those of controls in the sandy and loamy soils, respectively. Thus application of polymers to soils especially in the sandy soils may increase water holding capacity, may decrease salinity and may help to improve irrigation projects in arid and semi-arid areas.
Keywords: Soil texture, Salinity, Superabsorbent polymer, Available water, Soil porosity