Soil science
M. Gheitasi; Sh. Kiani; A. Hosseinpur
Abstract
Introduction: Large amounts of nitrogen (N) fertilizers are being applied to optimize yield in vegetable production. Nitrogen use efficiency in vegetable fields is low due to high application of N fertilizers in frequent cultivation, short growth cycles and their shallow rooting system. Nitrification ...
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Introduction: Large amounts of nitrogen (N) fertilizers are being applied to optimize yield in vegetable production. Nitrogen use efficiency in vegetable fields is low due to high application of N fertilizers in frequent cultivation, short growth cycles and their shallow rooting system. Nitrification inhibitors (NI) are compounds that retard the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in soil. In different studies, the positive effects of these compounds on the reduction of N losses from soil and increase of N use efficiency and crop yield have been demonstrated. The 3,4-dimethylpyrazole phosphate (DMPP) is a very popular nitrification inhibitor around the world. The efficacy of this molecule depends on climatic conditions and soil properties including of texture, pH, organic matter, moisture, temperature and mineral nitrogen. In this experiment, the effects of NI 3, 4-dimethylpyrazole phosphate on the N use efficiency of two spinach varieties were investigated in different soils.
Materials and Methods: A pot experiment was conducted in a completely randomized design with a factorial arrangement with three replications at Shahrekord University. Experimental factors were different N fertilizer sources, soil types and spinach varieties. Three N fertilizer sources consisted of urea, ammonium sulfate nitrate (ASN) and ASN plus DMPP (0.8 %). A no added N fertilizer treatment was considered as the control. The soil factor contained three different soils with different physical and chemical characteristics. The textures of the soils No. 1, 2 and 3 were loamy sand, loam and silty clay, respectively. Three selected soils were non-saline (EC1:2=0.14-0.31 dS m-1) and alkaline (pH1:2=7.9-8.0). Organic carbon and calcium carbonate equivalent (CCE) ranged from 0.26 to 0.35%, and 28.5 to 36.2%, respectively. Two spinach varieties were smooth-leaf (Giant Santos) and wrinkled-leaf (Viking). The used soils were mixed homogenously with 100 mg P kg−1 soil as triple super phosphate, 5 mg Fe kg−1 soil as Fe-EDDHA, 15 mg Zn kg−1 soil as ZnSO4.7H2O, 5 mg Mn kg−1 soil as MnSO4.H2O and 2.5 mg Cu kg−1 soil as CuSO4.5H2O. Nitrogen was applied at the rate of 150 mg kg-1 soil in two split doses before sowing and after one month. Twelve seeds were sown in 7 kg soil in plastic pots, and then placed in a greenhouse. The pots were thinned to 7 seedlings per pot after plant establishment. One week before harvesting, 10 measurements were done using a chlorophyll content meter to determine chlorophyll content index of leaves. At the end of the experiment, shoot dry weight was determined and plants were mixed and dried to measure N concentration. Finally, shoot N uptake and N use efficiency were calculated in different treatments.
Results and Discussion: In the present study, spinach plants fertilized with ASN+DMPP had a better appearance (dark green color) than those grown without DMPP. The results indicated that application of ASN with DMPP led to significant increase of leaf chlorophyll content index in comparison of ASN and urea fertilizers in all studied soils. Application of DMPP slowed down the process of ammonium oxidation to nitrite. Thus, this increase may be due to the role of ammonium in N nutrition of spinach plants treated with DMPP. This may be explained by the fact that ammonium has a positive effect on the synthesis of polyamines, cytokinins and gibberellins. The presence of these two phytohormones retarded senescence and chlorophyll degradation in plants. However, adding ASN to DMPP resulted in a significant decrease of shoot dry weight as compared with the ASN and urea fertilizers in soils No. 1 (loamy sand) and 2 (loam). In soil No. 3, shoot dry weight was not affected in plants fertilized with ASN+DMPP. Also, agronomic and physiological efficiencies of N significantly decreased by applying ASN+DMPP in comparison with ASN. It seems that application of DMPP strongly delayed the ammonium nitrification to nitrate, and consequently the soil nitrate availability appears not to be synchronized with spinach N needs. Due to short growth cycle of spinach, low availability of nitrate resulted in decreased shoot dry weight of spinach. The highest N use efficiency was observed is soil No. 2 (loam) and Giant Santos had more N use efficiency than Viking.
Conclusion: The results demonstrated that using ASN+DMPP led to yield loss, and we cannot recommend its application as a nitrogen fertilizer for spinach. However, application of ASN+DMPP is an effective strategy for improving qualitative appearance (dark green color) of spinach. Also, all studied indices were not affected in plants fertilized with ASN and urea. Therefore, application of both fertilizers is recommended for spinach production under similar conditions of the present study.
Mahbubeh Gheitasi; Ali Reza Hosseinpur
Abstract
Introduction: Leafy vegetables such as spinach (Spinaciaoleracea L.) contain high levels of nitrate. Using nitrification inhibitors (NIs) such as 3,4-dimethylpyrazole phosphate (DMPP) is one of the strategies for reducing nitrate accumulation. Nitrification inhibitors are compounds that delay the biological ...
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Introduction: Leafy vegetables such as spinach (Spinaciaoleracea L.) contain high levels of nitrate. Using nitrification inhibitors (NIs) such as 3,4-dimethylpyrazole phosphate (DMPP) is one of the strategies for reducing nitrate accumulation. Nitrification inhibitors are compounds that delay the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in soil. Soil properties such as texture, pH, organic matter, moisture, temperature and mineral nitrogen have important effects on the efficiency of NIs to delay nitrification. A pot experiment was conducted to investigate the effects of NI 3,4-dimethylpyrazole phosphate (DMPP) on soil mineral nitrogen (ammonium and nitrate) content, yield and nitrate concentration of spinach.
Materials and Methods: A completely randomized factorial design was carried out employing three factors consisted of nitrogen fertilizer type, soil type and spinach variety with three replications at Shahrekord University. Nitrogen fertilizers included urea, ammonium sulfate nitrate (ASN) and ASN plus DMPP (0.8 %). A no N fertilizer application was considered as control treatment. The soil factor contained 3 different soils with different physical and chemical characteristics. Two spinach varieties were smooth-leaf (Giant Santos) and wrinkled-leaf (Viking). The dose of applied nitrogen in all experimental treatments was 150 mg kg-1 soil that was applied in two split doses before sowing and after one month. The textures of three selected soils were loamy sand, loam and silty clay for the soils number 1, 2 and 3, respectively. Three selected soils were non-saline (EC1:2=0.14-0.31 dS m-1) and alkaline (pH1:2=7.9-8.0). Organic carbon and calcium carbonate equivalent (CCE) ranged from 0.26% to 0.35% and 28.5% to 36.2%, respectively. At 30 and 60 days after sowing, soil subsamples were taken to determine ammonium and nitrate content. The ammonium and nitrate concentrations (extracted with 0.5 M K2SO4) were determined calorimetrically using a spectrophotometer at a wavelength of 667 and 410 nm, respectively. At the end of the experiment, shoot fresh weight was determined and plants was mixed and dried to measure nitrate accumulation.
Results and Discussion: The results indicated that the application of ASN with DMPP led to significant increase of ammonium compared with ASN and urea fertilizers in three soils. At 30 days after sowing, the amount of this increase for ASN plus DMPP in comparison of ASN and urea were 182% and 78% for the soil number 1 (loamy sand), 105% and 65% for the soil number 2 (loam) and 89% and 74% for the soil number 3 (silty clay), respectively. By contrast, the application of ASN with DMPP led to significant decrease of soil nitrate in comparison of ASN and urea fertilizers in three soils. At 60 days after sowing, the amount of this decrease for ASN plus DMPP in comparison of ASN was 52%, 40% and 27% for the soils number of 1, 2 and 3, respectively. It means that the application of DMPP has slowed down the process of ammonium oxidation to nitrite. In fact, the addition of DMPP retained soil nitrogen as ammonium form for longer time. The application of NI DMPP also had positive effect on decrease of nitrate concentration in the soil. Unlike nitrate, ammonium is less susceptible to leaching and thus the application of DMPP can reduces nitrogen loss from the soil. However, the application of ASN with nitrification inhibitor DMPP in soils No. 2 (loamy sand) and No. 3 (loamy) significantly reduced shoot fresh weight of both spinach varieties compared with the similar treatment but without NI. This decrease was due to the toxic effects of high level of soil ammonium on the plant growth. While, in the soil No. 3 (silty clay) in Viking variety, the use of ASN plus DMPP resulted in significant increase of spinach shoot fresh weight to 29% in comparison with the same treatment but without NI. The highest and lowest values of shoot fresh weight (229 and 16.2 g pot-1, respectively) were obtained by Giant Santos variety in soil No. 3 (silty clay) with ASN plus DMPP and soil No. 1 (sandy loam) with no added N fertilizer. The application of ASN with nitrification inhibitor DMPP induced significant decrease of shoot nitrate concentration in spinach in comparison of ASN and urea. The amounts of this decrease for ASN plus DMPP in comparison with ASN and urea were 25.7% and 31.5% for the soil number 1 (loamy sand), 29.1% and 37.1% for the soil number 2 (loam) and 33.9% and 34.0% for the soil number 3 (silty clay), respectively. This decrease was due to ammonium nutrition of spinach plants.
Conclusion: In all studied soils, application of ASN with nitrification inhibitor DMPP is recommended for diminishing nitrate content in both spinach varieties (Giant Santos and Viking).
F. Mohammadi Navchinejad; A. R. Hosseinpur; H. R. Motaghian
Abstract
Introduction: Application of organic fertilizers such as vermicompost to agricultural calcareous soils with low organic matter content is a way to add nutrients to these soils. Different organic fertilizers have different effects on soil nutrient availability. Moreover, the study of nutrients distribution ...
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Introduction: Application of organic fertilizers such as vermicompost to agricultural calcareous soils with low organic matter content is a way to add nutrients to these soils. Different organic fertilizers have different effects on soil nutrient availability. Moreover, the study of nutrients distribution in the soil allows us to investigate their mobility and bioavailability. Zinc (Zn) deficiency is an important problem in many calcareous soils due to its effect on increasing the yield of agricultural products. Organic fertilizers can improve availability of Zn by impact on its fractionation. On the other hand, their interaction with chemical fertilizers requires careful consideration of availability and fractionation of Zn in soils treated with organic and chemical fertilizers. The aim of this research was to investigate the interaction effect of zinc sulphate, and vermicompost on availability and fractions of Zn in a calcareous clay soil.
Materials and Methods: This study was performed as a completely randomized factorial design including two levels of vermicompost (0 and 1% w/w) and three levels of Zn (0, 2, and 5 mg kg-1 as ZnSO4) with three replications. All treated soils were incubated for 120 days at 22 ± 1 0C and constant moisture (17% w/w). Zinc availability (DTPA-TEA) and other fractions (BCR method) were determined at the beginning of experiment, 60 days, and 120 days after incubation. The soil samples were sequentially extracted using an operationally defined sequential fractionation procedure, based on that employed by BCR in which increasingly strong extractants were used to release Zn associated with different soil fractions. Four Zn -fractions were extracted in the following sequence: Step 1: soluble, exchangeable, and associated with carbonates fraction (a 40 ml of 0.1 M CH3COOH for 16 h at room temperature), Step 2: iron-manganese oxides-associated fraction (40 ml of 1 M NH2OH.HCl in 1.5 M HNO3 for 16 h at 22 0C), Step 3: organic matter-associated fraction (50 ml of 1 M CH3COONH4 in 1.5M HNO3 for 16 h at 85 0C) and Finally step 4: residual fraction was determined using 4 M HNO3 (a 12.5 ml volume of 4 M HNO3, for 16 h at 80 0C). Concentrations of Zn in all extractants were determined by Atomic absorption spectroscopy..
Results and Discussion: The results of this study showed that the mean of Zn extracted by DTPA-TEA after vermicompost application increased significantly (P<0.05). The interaction between vermicompost and time on Zn extracted by DTPA-TEA was not significant (P>0.05). Zinc extracted by DTPA-TEA decreased with increasing incubation time. All forms of Zn increased by vermicompost application in soil samples treated with ZnSO4. Soluble, exchangeable, and bound to carbonates Zn and Zn associated to Fe-Mn oxides fractions (except vermicompost with 5 mg kg-1 Zn at 60 days after incubation) increased with increasing incubation time. Zinc associated to organic matter increased 60 days after incubation compared to the beginning of the experiment. However, difference between Zn associated to organic matter at 120 days after incubation and beginning of the experiment was not significant (except vermicompost with 5 mg kg-1 Zn at 60 days after incubation). The results of this study showed that residual Zn decreased with increasing incubation time. Results of this study demonstrated that the fractions of Zn in the soil samples treated with ZnSO4 were modified after vermicompost application and its availability increased. Therefore, the application of chemical fertilizers with organic fertilizers leads to increase Zn in the soil. The results of correlation study showed that the relation between available Zn and Zn associated to Fe-Mn oxides at 1 h (r=0.77 p<0.05), 60 days after incubation (r=0.95 p<0.05), and 120 days after incubation (r=0.95, p<0.05) was significant. There was a significant correlation between available Zn and Zn in forms of solution, exchangeable and associated with carbonates, associated with Fe-Mn oxides, and associated with organic matter, which indicate the effective role of these fractions in supplying the required Zn to plant.
Conclusion: Vermicompost application in calcareous soils increased available Zn and the effect of vermicompost was not dependent on time. Over time, there was a decrease in available Zn in the presence of chemical fertilizer. Vermicompost application in calcareous soils increased all Zn fractions. According to these results, the Zn fractions in the soil treated with zinc sulfate had been changed and its availability increased during incubation time. The results of this study demonstrated that the fractions of Zn in the soils treated with ZnSO4 and vermicompost were modified and its availability increased. Therefore, the application of chemical fertilizers with organic fertilizers can increase Zn in calcareous clay soils.
Parvin Kabiri; hamid reza motaghian; Alireza Hosseinpur
Abstract
Introduction: Anthropogenic activities have transformed the global geochemical cycling of heavy metals. Mine tailings are of great concern due to the detrimental effects of toxic inorganic elements causing environmental risks. Zinc (Zn) as an essential element is required in small amounts for various ...
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Introduction: Anthropogenic activities have transformed the global geochemical cycling of heavy metals. Mine tailings are of great concern due to the detrimental effects of toxic inorganic elements causing environmental risks. Zinc (Zn) as an essential element is required in small amounts for various biochemical reactions and physiological functions. However, high concentrations of Zn can induce oxidative stress. Applying an organic amendment is a promising, in situ phytostabilization approach to alleviate the phytotoxic effects of heavy metal in contaminated soils. The application of biochar as an amendment may be a solution to reduce the risk of pollutant diffusion. Biochars is a fine-grained biological residue combusted under low oxygen conditions, resulting in a porous, stable carbon-based material. The potential biochar applications include carbon sequestration, soil fertility improvement, and pollution remediation; therefore, it can reduce pollutants mobility and bioavailability.
Materials and Methods: Results of this research indicated that biochars decreased Zn concentration in maize shoots and roots. They reduced Zn concentration in the shoot/root of maize. Zinc concentration in shoots and roots of maize (Zea mays L.) harvested at 60 days after sowing, decreased with increasing thermochemical temperature and application rate of biochar. In treated soil with 2% (w/w) biochar prepared at 600 °C, Zn concentration in shoots and roots decreased by 21.6 and 33.0 % respectively (p
elham sadeghi; fayez raiesi; Alireza Hosseinpour
Abstract
Introduction: Soil, as an important component of terrestrial ecosystems, plant growth media, and a habitat of diverse living organisms commonly encounters a variety of abiotic stresses. Soil microorganisms play an important role in maintaining soil quality and functioning, since they are responsible ...
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Introduction: Soil, as an important component of terrestrial ecosystems, plant growth media, and a habitat of diverse living organisms commonly encounters a variety of abiotic stresses. Soil microorganisms play an important role in maintaining soil quality and functioning, since they are responsible for the decomposition of dead organic material, nutrient cycling and degradation of hazardous organic pollutants. Metal toxicity and salinity are the major abiotic stresses affecting soil microbial activity and community structure in many areas of the world, in particular arid regions. Anthropogenic activities have increased the concentration of heavy metals and soluble salts in soil, resulting in a major constrain for soil microbial performance and functions. Furthermore, soil microbial activity and biochemical processes are often limited by substrate availability in arid areas due to the low organic inputs. Although the individual effects of salinity and metal toxicity stresses on soil biological activity are generally well-known, their combined effects on microbial growth, population and functions are largely uncertain. The main aim of this study was to investigate the interactive effects of salinity and cadmium (Cd) Pollution on microbial respiration and biomass in a calcareous soil treated with plant residue. It was hypothesized that salinity would increase mobility and availability of Cd with subsequent reductions in microbial activity and biomass, and that addition of plant residue would modify these salinity effects.
Materials and Methods: This study was conducted under controlled laboratory conditions at Shahrekord University. A factorial experiment with two levels of cadmium (0 and 30 mg kg-1), three levels of salinity (1.35, 7.5 and 10 dS m-1) and two levels of plant residue (with and without alfalfa residue) was conducted using a completely randomized design with four replications. Using cadmium chloride salt, the soil was contaminated, and subsequently amended with alfalfa residue (1%, w/w). After thorough mixing of soil and plant residue, salinity treatments were applied using NaCl salt. To reactivate the microbial population and for the aging effect, soil moisture was set at 70% of field capacity, and containers were pre-incubated at room temperature for 4 weeks. The samples were then incubated at 25±1 oC for 98 days. Soil carbon (C) mineralization (microbial respiration) was measured weekly, and available Cd and microbial biomass C were measured at monthly intervals. In this experiment, the Bliss independence model was used to determine the type and nature of the interaction between salinity and pollution (synergistic and antagonistic).
Results and Discussion: The results showed that NaCl salinity increased the concentration of soil available Cd in both polluted and unpolluted soils over the experimental period, and the increases were greater at high than low salinity levels. This effect of salinity was less pronounced in residue-amended and unamended soils. In general, a strong synergistic effect of both stresses upon Cd availability was observed in residue-unamended soils while this effect was mostly antagonistic in residue-amended soils. This indicates that addition of plant residue to enhance soil organic matter may indirectly repress or lower salinity effect on Cd toxicity. Soil salinity decreased microbial biomass C and respiration with subsequent increases in specific respiratory quotient due to the increases in Cd solubility and availability. However, the changes in microbial properties were much lower in residue-amended and unamended soils. Addition of plant residue decreased the negative effects of both the individual and combined salinity and Cd pollution on microbial biomass and respiration. The interactive effect of these two stresses was mainly synergistic in residue-treated soils while it was antagonistic in residue-untreated soils. Overall, a strong synergistic effect occurred when both stresses were combined in the absence of plant residue while this effect was antagonistic in the presence of plant residue.
Conclusion: This study provided evidence that salinity could synergistically increase the mobility, bio-availability, and toxicity of Cd in Cd-polluted soils with C limitation. This was reflected by synergistic reductions in soil microbial biomass and respiration. However, addition of plant residue to increase soil organic matter lowered this effect of salinity, resulting in the antagonistic effects of salinity and pollution on soil microbial biomass and respiration. The reason for increase in the microbial activity in soils treated with plant residue was the increase of available substrate. As a result, using the plant residue increased the stimulatory effect of microbial activity. These findings point to the importance of providing adequate organic residues to enhance soil microbial performance and agricultural sustainability in polluted soils under salinity stress. However, further information on responses of microbial indicators to the joint effect of salinity and Cd toxicity is required.
Materials and Methods: This study was conducted under controlled laboratory conditions at Shahrekord University. A factorial experiment with two levels of cadmium (0 and 30 mg kg-1), three levels of salinity (1.35, 7.5 and 10 dS m-1) and two levels of plant residue (with and without alfalfa residue) was conducted using a completely randomized design with four replications. Using cadmium chloride salt, the soil was contaminated, and subsequently amended with alfalfa residue (1%, w/w). After thorough mixing of soil and plant residue, salinity treatments were applied using NaCl salt. To reactivate the microbial population and for the aging effect, soil moisture was set at 70% of field capacity, and containers were pre-incubated at room temperature for 4 weeks. Next, the samples were incubated at 25±1 oC for 98 days. Soil C mineralization (microbial respiration) was measured weekly, and available Cd and microbial biomass carbon were measured at monthly intervals. In this experiment, the Bliss independence model was used to determine the type and nature of the interaction between salinity and pollution (synergistic and antagonistic).
Results and Discussion: The results showed that NaCl salinity increased the concentration of soil available Cd in both polluted and unpolluted soils over the experimental period, and the increases were greater at high than low salinity levels. This effect of salinity was less pronounced in residue-amended and unamended soils. In general, a strong synergistic effect of both stresses was observed on Cd availability in residue-unamended soils while this effect was mostly antagonistic in residue-amended soils. This indicates addition of plant residue to enhance soil organic matter may indirectly repress or lower salinity effect on Cd toxicity. Soil salinity decreased microbial biomass carbon and respiration with subsequent increases in specific respiratory quotient due to the increases in Cd solubility and availability. However, the changes in microbial properties were much lower in residue-amended and unamended soils. Addition of plant residue decreased the negative effects of both the individual and combined salinity and Cd pollution on microbial biomass and respiration. The interactive effect of these two stresses was mainly synergistic in residue-treated soils while it was antagonistic in residue-untreated soils. Overall, a strong synergistic effect occurred when both stresses were combined in the absence of plant residue while this effect was antagonistic in the presence of plant residue.
Conclusions: This study provided evidence that salinity could synergistically increase the mobility, bio-availability, and toxicity of soil Cd in Cd-polluted soils with carbon limitation. This was reflected by synergistic reductions in soil microbial biomass and respiration. However, addition of plant residue to increase soil organic matter lowered this effect of salinity, resulting in the antagonistic effects of salinity and pollution on soil microbial biomass and respiration. The reason for increase in the microbial activity in soils treated with plant residue was the increase of available substrate. As a result, using the plant residue increased the stimulatory effect of microbial activity. These findings point to the importance of providing adequate organic residues to enhance soil microbial performance and agricultural sustainability in polluted soils under salinity stress. However, further information on responses of microbial indicators to the joint effect of salinity and Cd toxicity is required.
Mohamad Rahmanian; AliReza Hosseinpour; Ebrahim Adhami; Hamidreza Motaghian
Abstract
Introduction: Rhizosphere is commonly defined as the zone where root activity significantly influences the biological and chemical properties of the soil. Biological, physical and chemical characteristics of rhizosphere, especially metal availability and metal chemical forms are different than the bulk ...
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Introduction: Rhizosphere is commonly defined as the zone where root activity significantly influences the biological and chemical properties of the soil. Biological, physical and chemical characteristics of rhizosphere, especially metal availability and metal chemical forms are different than the bulk soil. Plant roots continuously release compounds such as sugars, amino acids, and carboxylic acids. Plant roots have the ability to transform metal fractions for easier uptake through root exudation in the rhizosphere. This study was conducted to investigate change in availability and fractions of Copper in the rhizosphere of sunflower (Helianthus annuus L.) in a sandy contaminated soil treated with chelators (EDTA, citric acid and poultry manure extract (PME)) in greenhouse condition.
Materials and Methods: In this study, EDTA and citric acid were used at concentrations of 0, 0.5 and 1 mmol kg-1 soil and PME was used at concentrations of0, 0.5 and 1 g kg-1 soil. Three seeds of sunflower were planted in the rhizobox. After 10 weeks, plants were harvested and rhizosphere and bulk soils were separated. Dissolved organic carbon (DOC), microbial biomass carbon (MBC), available Cu (by using 7 chemical procedures including DTPA-TEA,AB-DTPA, Mehlich1, Mehlich3, CaCl2 0.01 M, rhizosphere-based method and distilled water) and Cu-fractions were determined in the rhizosphere and bulk soils.
Results and Discussion: Rhizosphere soils properties were different with bulk soils. The results showed that the mean of DOC and MBC in the rhizosphere soils were higher than the bulk soils, but this difference was significant in some treatments. The mean value of pH in the rhizosphere soils was significantly (p
Akram Farshadirad; Alireza Hosseinpour; Shojae ghorbani; hamidreza motaghian
Abstract
Introduction: In recent years, because of the presence of industrial factories around the Isfahan province of Iran and high concentrations of heavy metals in the vicinity of them, and the gradual accumulation of heavy metals from various sources of pollution in urban areas over time, including gasoline ...
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Introduction: In recent years, because of the presence of industrial factories around the Isfahan province of Iran and high concentrations of heavy metals in the vicinity of them, and the gradual accumulation of heavy metals from various sources of pollution in urban areas over time, including gasoline combustion, and use of urban waste compost and sewage sludge as fertilizer, there has been widespread concerned regarding the human health problems with increasing heavy metals in soils around the Isfahan city. The variation of composition in the soil matrix may lead to variation of composition and behavior of soil heavy metals. Soil is a heterogeneous body of materials and soil components are obviously in interaction. Studies tacking this complexity often use aggregate measurements as surrogates of the complex soil matrix. So, it is important the understanding soil particle-size distribution of aggregates and its effects on heavy metal partitioning among the size fractions, the fate of metals and their toxicity potential in the soil environment. Therefore, the present study aimed to determine the Cu release potential from different size fractions of different polluted soils by different extractants and their availability for corn plant.
Materials and Methods: Five soil samples were collected from the surface soils (0–15 cm) of Isfahan province, in central of Iran. The soil samples were air-dried and ground to pass a 2-mm sieve for laboratory analysis. Air dried samples fractionated into four different aggregate size fractions 2.0–4.0 (large macro-aggregate), 0.25–2 (small macro-aggregate), 0.05–0.25 (micro-aggregate), and
Hanye Jafari Vafa; Fayez Raiesi; Alireza Hosseinpur; Zohre Karimi
Abstract
Introduction: Earthworms are among the most important organisms in soil and their activities can be an indicator of soil quality. These organisms may be influenced by organic wastes application such as sewage sludge and subsequently affect soil quality. One of the quick and easy methods for soil quality ...
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Introduction: Earthworms are among the most important organisms in soil and their activities can be an indicator of soil quality. These organisms may be influenced by organic wastes application such as sewage sludge and subsequently affect soil quality. One of the quick and easy methods for soil quality monitoring is the use of biological indicators such as microbial activity. It is due to their quick response to changes in the environment. The purpose of this study was to evaluate the effect of earthworms on nitrification rate and arginine ammonification as microbial activity in a calcareous soil amended with urban sewage sludge.
Materials and Methods: The studied soil was sampled from Shahrekord University land and sewage sludge belonged to the refinery sludge ponds of shahrekord. Based on dry weight, this organic waste had carbon and nitrogen, approximately 67 and 110 times more than tested soil, respectively. The organic waste in terms of quality and heavy metal concentrations was in class A. Experimental treatments were sewage sludge (without and with 1.5% sewage sludge) and earthworm (no earthworm, Eiseniafoetida from epigeic group, Allolobophracaliginosa from endogeic group and a mixture of the two species) as 2×4 full factorial experiment arranged in a completely randomized design with three replications. After applying sewage sludge, the pots were irrigated three months to achieve a balance in the soil. An adult earthworm per kg of soil was added and in the mixed treatments comparison species were 1:1. To prevent the exit of earthworms, the pots was closed with a thin lace. At the end of the experiment, soil was completely mixed. Part of it was stored in the refrigerator to measure the microbiological parameters. Chemical properties were measured by the air-dried soil. The effectiveness of a factor in the observed changes is shown by partial effect size (Tabachnick and Fidell 2012). So, partial effect size (Eta2p) for each source of variation (SS, earthworm and SS×earthworm) was calculated.
Results Discussion: According to Eta2p, the role of sewage sludge application to increase total nitrogen was almost twice the earthworm and had a greater effect on the property. Because of low concentrations of heavy metals and high nutrient in sewage sludge, it increased nitrification rate and arginine ammonification by 16.7 and 62.5 percent, respectively. Considering that the indices represent microbial biomass activity, so we can say sewage sludge application increased theri activities. Sewage sludge application increased total nitrogen, because provided the substrate for heterotrophic bacteria. Consequently, ammonium production improved and stimulated activity of Nitrosomonas and Nitrobacter. There was a positive and significant correlation between total nitrogen, arginine ammonification and nitrification rate, that confirmed the occurrence of this process. Earthworm inoculation affected these two indicators (p
hamid reza motaghian; alireza hosseinpuor; Shahram Kiani
Abstract
Introduction: Use of organic fertilizers such as vermicompost in agricultural soils with low organic matter content is almost considered as a one way for adding nutrients in these soils. However, application of these fertilizers may affect micronutrient release characteristics. Micronutrient release ...
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Introduction: Use of organic fertilizers such as vermicompost in agricultural soils with low organic matter content is almost considered as a one way for adding nutrients in these soils. However, application of these fertilizers may affect micronutrient release characteristics. Micronutrient release Kinetics in soils especially in amended soils give information about potential of amended soils to release these elements into solution. Although it is important to study kinetics of micronutrient release from soils to identify soil micronutrients buffering capacity, little attention has been paid to micronutrients desorption rate studies especially in amended soils. The rate of release micronutrients from soil solid phase by considering micronutrients as adsorbed ions or in mineral forms is an important parameter in nutrition of plants by microelements and a dynamic factor that regulates its continuous supply to growing plants; nonetheless, little attention has been paid to micronutrients kinetics inrelease studies.
Material and Methods: In this study, kinetics of zinc (Zn) and copper (Cu) were compared in one calcareous soil amended with 0, 0.5, and 1% (w/w) of manure and vermicompost in a completely randomized design and then amended and un-amended soils were incubated at field capacity, for 30 days. After incubation period, amended and un-amended soils were air-dried and were prepared to kinetics study. Kinetics of Zn and Cu release were studied by successive extraction with DTPA-TEA solution. Two grams of the amended and un-amended soils, in triplicate, suspended in 20 ml DTPA-TEA solution were equilibrated at 25±10C for 1, 8, 24, 48, 72, 96, 120, 144, 168, 336 and 504 h by shaking for 15 min. before incubation and 15 min. before the suspensions were centrifuged. Seven drops of toluene were added to each 1000 ml of extractant to inhibit microbial activity. Zinc and copper desorption with time was fitted by using different equations (Zero-order, First-order, Parabolic diffusion, Simplified Elovich, and Power function).
Results and Discussion: Results showed that released Zn in soils amended with manure and vermicompost compared to control soil significantly increased (p0.05) and released Cu in soil amended with vermicompost decreased significantly (p
Alireza Hosseinpur`; hamid reza motaghian
Abstract
Introduction: Application of organic fertilizers in agricultural soils with low organic matter content is one of the best ways of nutrientsaddition to these soils. Different organic fertilizers have different effects on nutrient availability in soil. Moreover study of the distribution of nutrients in ...
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Introduction: Application of organic fertilizers in agricultural soils with low organic matter content is one of the best ways of nutrientsaddition to these soils. Different organic fertilizers have different effects on nutrient availability in soil. Moreover study of the distribution of nutrients in the soil allows investigating their mobility and bioavailability. The nutrients availability and kinetics of nutrients desorption into the soil solution is often closely related to the distribution of nutrients to different fractions in the soil. It has been assumed that the factors influencing metal fractionation and availability in soil include rate of amendment application, amount of nutrients in amendment, root-induced pH changes, metal binding by root exudates, root-induced changes of microbial activities, and metal depletion because of plant uptake.
Materials and Methods: In this study, availability and fractionation of Zinc (Zn) and Copper (Cu) were compared in one calcareous soil amended with 0, 0.5, and 1% (w/w) of cow manure and vermicompost in a completely randomized design. Also, wheat was planted in treated and untreated soils in greenhouse condition.Available Zn and Cu were determined using different methods (DTPA-TEA, AB-DTPA, and Mehlich 3). For Zn and Cu fractionation, the soil samples were sequentially extracted using an operationally defined sequential fractionation procedure, based on that employed by Tessier et al. (1979) in which increasingly strong extractants were used to release Zn and Cu associated with different soil fractions. Five Zn and Cu -fractions were extracted in the following sequence: Step 1: exchangeable fraction (a 8 ml volume of 1.0 MNaOAc (pH= 8.2) for 120 min. at room temperature)., Step 2: carbonate-associated fraction (a 8 ml volume of 1.0 MNaOAc adjusted to pH 5.0 with acetic acid for 6 h at room temperature, Step 3: iron-manganese oxides-associated fraction (20 ml of 0.04 M NH2OH.HCl in 25% (v/v) HOAc for 6 h at 96 0C)., Step 4: organic matter-associated fraction (3 ml of 0.02 N HNO3 adjusted to pH 2 and 5 ml 30% H2O2 (adjusted to pH 2.0 with HNO3) and at 85 0C for 2 h in sequence, followed by 3 ml of 30% H2O2 (adjusted to pH 2.0 with HNO3) the sample was heated to 85 0C for 3 h with intermittent agitation. After cooling, 5 ml of 3.2 M NH4OAc in 20% (v/v) HNO3 was added and agitated continuously for 30 min. Finally step 5: residual fraction was determined using 4 M HNO3 (a 12.5 ml volume of 4 M HNO3, for 16 h at 80 0C). Concentrations of Zn and Cu in all extractants were determined by AAS.
Results and Discussion: The results showed that the effect of treatments on amount of extracted Zn by different methods were significant (P0.05). The minimum and maximum of extracted Zn by DTPA-TEA were in untreated soil (0.73 mg/kg) and treated soils with 1% manure (1.30 mg/kg) and treated soils with 1% manure (1.17 mg/kg), respectively. The results showed that the effect of treatments on Zn associated with Fe-Mn oxides and Zn associated with organic matter was significant (P0.05). The correlation between extracted Zn and Cu by DTPA-TEA and AB-DTPA with Fe-Mn oxides fraction were significant (P
T. Raiesi; A. Hosseinpur; F. Raiesi
Abstract
Introduction: The biological and chemical conditions of the rhizosphere are known to considerably differ from those of the bulk soil, as a consequence of a range of processes that are induced either directly by the activity of plant roots or by the activity of rhizosphere microflora (16). Municipal sewage ...
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Introduction: The biological and chemical conditions of the rhizosphere are known to considerably differ from those of the bulk soil, as a consequence of a range of processes that are induced either directly by the activity of plant roots or by the activity of rhizosphere microflora (16). Municipal sewage sludge (MSS) applied to agricultural soils is a well known reusable source of phosphorus (P), nitrogen (N) and other macro- and micro-nutrients (33). Sludge provides a short-term input of plant-available nutrients and stimulation of microbial activity, and it contributes to long term maintenance of nutrient and organic matter pools (33). Availability of P following application of MSS can be influenced by microbial and chemical properties of the soil, MSS composition, and rhizosphere processes. The specific interrelationships between these components have proven to be complex and, despite continued study, a thorough understanding of the interactions among plant roots, manure P, and P solubility has yet to be achieved (42). Little quantitative information is available about the chemical and biological properties in the rhizosphere of bean plant growing in soils un-amended and amended with MSS. Therefore, the objectives of this research were to evaluate the rhizospheric effects of bean on chemical and biological properties in 10 calcareous soils as amended with municipal sewage sludge (MSS) or unamended (control) under rhizobox conditions.
Materials and Methods: Ten surface soil samples (0–30 cm) were collected from Chaharmahal-Va-Bakhtiari province, in the central Iran. Municipal sewage sludge was used from the refinery of Shahrekord city, central Iran. Air dried and sieved (
A. Taheripur; Sh. kiani; A. Hosseinpur
Abstract
Introduction: Mining and smelting activities have contributed to increasing levels of copper (Cu) and zinc (Zn) in soils around of Sarcheshmeh copper mine (Kerman, Iran). Soil chemical analysis showed that the available of Cu and Zn (extracted with DTPA-TEA) were 260.1 and 9.2 mg kg-1 soil, respectively. ...
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Introduction: Mining and smelting activities have contributed to increasing levels of copper (Cu) and zinc (Zn) in soils around of Sarcheshmeh copper mine (Kerman, Iran). Soil chemical analysis showed that the available of Cu and Zn (extracted with DTPA-TEA) were 260.1 and 9.2 mg kg-1 soil, respectively. Phytoextraction is one of the most popular and useful phytoremediation techniques for removal of heavy metals from polluted soils. For chemically-assisted phytoextraction, different chelating agents such as EDTA and citric acid are applied to soil to increase the availability of heavy metals in soil for uptake by plants. A pot experiment was conducted to elucidate the performance of chelating agents addition in improving phytoextraction of Cu and zinc Zn from a naturally contaminated soil by maize (Zea mays L.) cultivars.
Materials and Methods: A factorial experiment in a completely randomized design was carried out bythree factors of chelate type, chelate concentrations and maize cultivars with three replications in 2012 at ShahreKord University. Chelating agents were Ethylene Diamine Tetra Acetic Acid (EDTA) and citric acid (CA). They were applied in concentration levels of 0, 0.75 and 1.5 mmole kg-1 soil with irrigation water. The three maize cultivars used were single cross 704 (SC-704), three v cross 647 (TVC-647), and single cross 677 (SC-677). The pots were 23 cm in diameter and 23 cm deep, and were filled with 4 kg of a silty loam, calcareous soil taken from the surface layer of Sarcheshmeh copper mine area. Maize plant s was grown under greenhouse conditions over 90 days. After the harvest, soil available Cu and Zn contents (extracted with DTPA-TEA) were determined by atomic absorption spectrophotometry (AAS). Plant samples (shoot and root) were dried for 48 h at 70ºC to determine their dry matter content (yield). Total Cu and Zn concentrations in root and shoot of maize were measured after digestion plant samples by AAS method. The shoot and root uptakes were calculated by multiplying Cu and Zn concentrations by dry mass. The effects of chelating agents and maize cultivars over the measured properties were evaluated using the two-ways ANOVA. The least significant difference (LSD) was used to compare means of treatments using SAS 8.02.
Results and Discussion: The results revealed that applying both chelates caused an increase of soil available Cu and Zn contents. The maximum of soil Cu (401.9 mg kg-1 soil) and Zn (17.1 mg kg-1 soil) were obtained by using EDTA with 1.5 mmole kg-1 soil in TVC-647 and SC-704 cultivars, respectively. This was due to formation of water-soluble complexes between EDTA with Cu and Zn in soil and help in their desorption from soil particles. EDTA was more effective than CA at increasing Cu and Zn available in the soil. The results indicated that EDTA-addition in 1.5 mmole kg-1 soil significantly reduced root and shoot fresh weight in all maize cultivars compared with the control (except root fresh weight in SC-677). This reduction was due to increasing soil available Cu and Zn contents and their toxic effects on plant growth as well as toxic impacts of EDTA on soil microorganisms and growth of plant.on the other hand0.75 mmole kg-1 soil CA addition induced significant increases in root fresh weight as compared to the control (except root fresh weight in TVC-647). Application of CA in concentration level of 0.75 mmole kg-1 soil led to the greatest quantity of shoot (12.85 g pot-1) and root (21.38 g pot-1) fresh weight in TVC-647 and SC-704 cultivars, respectively. Citric acid has a natural origin and is easily biodegraded in soil. It is not toxic to plants; therefore plant growth is not limited. The highest Cu concentration in root and shoot of maize (2506.1 and 335.6 mg kg-1 dry weight, respectively) were obtained in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA – 62.2% and 422.9% greater than those obtained with control. The highest shoot Cu (871.1 μg pot-1) and Zn (76.7 μg pot-1) accumulations were recorded in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA and CA, respectively.
Conclusion: Due to importance of Cu contamination in studying soil, it is suggested that EDTA-addition at 1.5 mmole kg-1 soil can be an appropriate chelator candidate for TVC-647 maize cultivar for environmentally safe phytoextraction of Cu in soil. It is noticed that application of EDTA in soil for long time has not recommended for phytoextraction of heavy metals. Because EDTA is non biodegradable substance and can leach into ground-water and causes other environmental hazardous risks.
F. Aghababaei; F. Raiesi; alireza hosseinpuor
Abstract
Soil biota such as earthworms and arbuscular mycorrhizal fungi (AMF) play an important role in the stability of ecosystem, and the bioavailability of soil elements, in particular heavy metals, in soils. To examine the effects of these organisms, a 3×2×3 factorial experiment arranged as randomized complete ...
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Soil biota such as earthworms and arbuscular mycorrhizal fungi (AMF) play an important role in the stability of ecosystem, and the bioavailability of soil elements, in particular heavy metals, in soils. To examine the effects of these organisms, a 3×2×3 factorial experiment arranged as randomized complete design was set up to study the individual and combined influence of earthworms (Lumbricus rubellus L.) and AMF (Glomus mosseae and Glomus intraradices) on soil organic matter (OM), dissolve organic carbon (DOC), soil respiration, microbial biomass carbon (MBC), soil enzyme activity and glomalin production in a calcareous soil contaminated with 0, 10, 20 mg of Cd kg-1 soil cropped with sunflower (Helianthus annuus L.) with three replications. Both earthworms and mycorrhizal fungi were able to survive in all the treatments with added Cd. Results showed that Cd pollution decreased all the measured microbial activities and properties in soil. Earthworm treatment increased DOC by 4-10% at all Cd levels. The amount of soil MBC in mycorrhizal treatments was greater (1.9-2.4 times) than that in non-mycorrhizal treatment, and AMF inoculation increased MBC/TOC ratio from 23% to 53% in Cd-polluted soils. Earthworm and AMF enhanced soil enzyme activity/MBC ratio, 10-18 and 40-54% for soil alkaline phosphatase and 4-9 and 40-55% for soil urease, respectively. The glomalin production increased at 20 mg kg-1 and was about 15% greater in G. mosseae than in G. intraradices species. Although soil respiration was decreased substantially with Cd pollution, inoculation of either earthworms or AMF enhanced soil respiration when compared with the corresponding controls.
A. Falahati Marvast; alireza hosseinpuor; Seyed Hassan Tabatabaei
Abstract
The objective of this study was to evaluate the effect of soil salinity on the availability and uptake of cadmium(Cd), lead(Pb), nickel(Ni), zinc(Zn) and copper(Cu) in a soil treated with municipal sewage sludge (MSS). Soil was salinized (2, 4, 8 and 12 dSm-1 soil paste extract) with NaCl + CaCl2 (1:1ratio), ...
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The objective of this study was to evaluate the effect of soil salinity on the availability and uptake of cadmium(Cd), lead(Pb), nickel(Ni), zinc(Zn) and copper(Cu) in a soil treated with municipal sewage sludge (MSS). Soil was salinized (2, 4, 8 and 12 dSm-1 soil paste extract) with NaCl + CaCl2 (1:1ratio), and incubated at soil field capacity (FC) for 1 month. The soil was treated with a 1.5 percent of MSS and incubated again at FC for 1 month. Before planting,soluble and DTPA-TEA extractable of heavy metals and soluble Chloride(Cl-) were determined. Then barley seeds were planted and, plants were harvested 10 weeks after germination. The plant indices (dry weight, heavy metal concentration and heavy metal uptake) were measured. The results showed that all salinity levels significantly increased soluble and availability of Cd, Pb, Ni, Zn and Cu. Soil salinity had a significant effect on concentrations and absorption of Cd and Pb in plant (P
H.R. Motaghian; A. Hosseinpour
Abstract
Change in microorganism activity and chemical properties can be affect on availability and fractionation of Copper (Cu). This research was conducted to investigate the availability and fractionation of Cu in the bean rhizosphere and bulk soils in 10 calcareous soils using rhizobox at greenhouse. Total ...
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Change in microorganism activity and chemical properties can be affect on availability and fractionation of Copper (Cu). This research was conducted to investigate the availability and fractionation of Cu in the bean rhizosphere and bulk soils in 10 calcareous soils using rhizobox at greenhouse. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), pH, available Cu (by using 7 chemical extractants) and Cu-fractions were determined in the rhizosphere and bulk soils. The results indicated that in the bean rhizosphere soils, TOC, DOC and MBC increased significantly (p
M. Hajhashemkhani; M. Ghobadi Nia; Seyed Hassan Tabatabaei; A. Hosseinpour; S. Houshmand
Abstract
Recently, wastewater is one of the water resources for irrigation due to the scarcity of water resources. In this regard, using adsorbents such as zeolites is recommended to improve the characteristics of the wastewater. Although the results show that natural zeolite decrease amount of pollutions but ...
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Recently, wastewater is one of the water resources for irrigation due to the scarcity of water resources. In this regard, using adsorbents such as zeolites is recommended to improve the characteristics of the wastewater. Although the results show that natural zeolite decrease amount of pollutions but at the same time decreases the permeability of the soil, which could adversely affect the soil. This study was done in 2012 at the Shahrekord University, 27 PVC columns were used to study the effect of modified zeolite particles on permeability and quality of the wastewater. The experiment consisted of two factors the type of the microzeolite (natural zeolite, modified zeolite) and application procedure of the micro zeolite (mixed, layer) with three replications and in total had 7 treated. Injection of wastewater into the soil was through waterlogging and repeated fifteen times with a weekly frequency. Volume of wastewater used in each injection is equal "nv". In frequency injections of 1,3,5,7,11,15 infiltration was measured using Falling Heads. The results showed that treatment of modified zeolite included mixed, middle layer and layer on the surface had the highest infiltration rate respectively and treatment with natural zeolite included mixed, middle layer, layer on the surface had lowest infiltration rate. Further modified treatments decreased Ca effluent rate 111% with respect to natural Zeolite and therefore caused modified treatments to decrease SAR amount 45% with respect to control treatments and 132% with respect to natural zeolite.
alireza hosseinpuor; H.R. Motaghian
Abstract
The amount of available micronutrients such as zinc (Zn) is a primary concern in treated soils with sewage sludge. This study was performed to evaluate Zn availability (DTPA-TEA, Mehlich 1 and Mehlich 3) and its fractionation in soils before and after treated with sewage sludge (1% w/w) and after wheat ...
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The amount of available micronutrients such as zinc (Zn) is a primary concern in treated soils with sewage sludge. This study was performed to evaluate Zn availability (DTPA-TEA, Mehlich 1 and Mehlich 3) and its fractionation in soils before and after treated with sewage sludge (1% w/w) and after wheat plantation in greenhouse conditions. The results of this study showed that mean of Zn extracted by using chemical extractants after sewage sludge application increased significant (P0.05). The results of fractionation showed that residual Zn, exchangeable Zn, Zn associated with organic matter, Zn associated with iron-manganese oxides, and Zn associated with carbonates increased 11, 26, 94, 172, and 279% respectively. The results of mean comparison showed that different between mean of Zn fractions (except Zn associated with iron-manganese oxides) before and after planting was significant (P
H.R. Motaghian; A. Hosseinpour
Abstract
Sewage sludge uses as a low coast fertilizer to rectify deficit of elements such as zinc (Zn). A suitable extractant for estimation of bean-available Zn in calcareous soils amended with sewage sludge has not yet been introduced. The aim of this research was to assess several chemical extractants for ...
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Sewage sludge uses as a low coast fertilizer to rectify deficit of elements such as zinc (Zn). A suitable extractant for estimation of bean-available Zn in calcareous soils amended with sewage sludge has not yet been introduced. The aim of this research was to assess several chemical extractants for the estimate of available Zn in sewage sludge-amended calcareous soils. For amended soils, 1% (w/w) of sewage sludge was added to 10 calcareous soils, and the soils (amended and un-amended) were incubated at field capacity for 30 days. At the end of incubation, soils were air-dried and available Zn was determined using 7 chemical extractants (DTPA-TEA, AB-DTPA, Mehlich 1, Mehlich 2, Mehlich 3, 0.1 N HCl and 0.01 M CaCl2). Zinc concentration in shoots, Zn uptake, and shoot dry weight of bean were determined in a pot experiment in amended and un-amended soils. The results show that Mehlich 3 and Mehlich 1 extractants extracted the highest and the lowest concentrations of Zn in both amended and un-amended soils, respectively. Furthermore, all three studied indices and Zn extracted by using different methods increased in amended soils. In addition, results indicated that significant correlations were found between extracted Zn using AB-DTPA, DTPA-TEA and Mehlich 3 and plant indices in un-amended soils. On the contrary, in sewage sludge-amended soils only the correlation between extracted Zn using DTPA-TEA and Mehlich 1 with Zn uptake and shoot dry weight and Mehlich 2 with Zn concentration was significant. The results of this study showed that DTPA-TEA could estimate bean-available Zn in the sewage sludge-amended and –un-amended calcareous soils.
T. Raiesi; A. Hosseinpur
Abstract
The objective of this research was to evaluate the rhizospheric effects of wheat on phosphorus (P) release kinetics in 10 calcareous soils under rhizobox conditions. The kinetics of P release in the bulk and the rhizosphere soils were determined by successive extraction with 0.5 M NaHCO3 in a period ...
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The objective of this research was to evaluate the rhizospheric effects of wheat on phosphorus (P) release kinetics in 10 calcareous soils under rhizobox conditions. The kinetics of P release in the bulk and the rhizosphere soils were determined by successive extraction with 0.5 M NaHCO3 in a period of 2 to 840 h at 25 ± 1°C. The results of kinetics study showed that mean of released P after 840 h of extraction period in the rhizosphere soils (192 mg/kg) was significantly lower than the bulk soils (207 mg/kg). A plot of cumulative amount of P released from both the rhizosphere and the bulk soils showed a discontinuity in slope at 168 h. Thus, two equations were applied to segments of the total reaction time (2 to 168 and168 to 840 h). Release kinetics of P from the rhizosphere and the bulk soils conformed fairly well to parabolic diffusion, simplified Elovich, power function and first order models in two segments. The correlation results showed that P released after 168 and P release rate constants of simplified Elovich, parabolic diffusion and first order equations in the rhizosphere and the bulk soils were significantly correlated (p≤0.05) with wheat plant indices. In second segment, P release rate constants of Elovich, and parabolic diffusion equations in the rhizosphere and the bulk soils were significantly correlated with wheat plant indices (p≤0.1). The results of this research indicated that wheat rhizosphere caused decrease of the P release rate and P release amount and release rate of P are important factosr in supplying available P to plants.
T. Raiesi; A. Hosseinpur; F. Raiesi
Abstract
The objective of the present study was to evaluate several chemical extractants to estimate available phosphorus (P) for bean growing in calcareous soils from Chaharmahal-Va-Bakhtiari province. The amount of available P was measured by Olsen, Colwell, ammonium bicarbonate-DTPA, 0.01 M calcium chloride, ...
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The objective of the present study was to evaluate several chemical extractants to estimate available phosphorus (P) for bean growing in calcareous soils from Chaharmahal-Va-Bakhtiari province. The amount of available P was measured by Olsen, Colwell, ammonium bicarbonate-DTPA, 0.01 M calcium chloride, BrayІ, ІІ, Mehlich І and ІІ extractants. In addition, soil organic P and total P were determined. A pot experiment consisting of a completely randomized design with three replications was conducted to evaluate the plant performance in association with chemical extractants. After the harvest, dry weight, P concentration and P uptake were determined. The results showed that the amount of extractable P decreased in the following order: Colwell> Mehlich ІІ> Bray ІІ> Olsen> Ammonium bicarbonate -DTPA> Mehlich І> Bray І> 0.01M Chloride calcium. Organic and total P and phosphorus extracted by Colwell, Olsen and Mehlich ІІ methods correlated significantly with plant indices. In addition, the results of stepwise regression analysis showed that the organic P, Colwell and Olsen extractants could explain more variation in the indices of bean plant. The results of this research showed that Colwell, Olsen and MehlichІІ extractants could be used to estimate plant-available P in the studied calcareous soils.
F. Ehsanpour; Sh. Kiani; alireza hosseinpuor
Abstract
Low phosphorus use efficiency in calcareous soils is one of the problems of wheat production in the fields, all over the world. This experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP) and phosphorus (P) levels on the yield and P use ...
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Low phosphorus use efficiency in calcareous soils is one of the problems of wheat production in the fields, all over the world. This experiment was conducted to elucidate the effects of nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP) and phosphorus (P) levels on the yield and P use efficiency of wheat (Triticum aestivum L.). A factorial experiment in randomized complete block design was carried out with two factors of type of nitrogen fertilizer (1- control: with no added N fertilizer, 2 and 3- ammonium sulfate fertilizer (ASF) with and without nitrification inhibitor DMPP, 4 and 5- ammonium sulphate nitrate fertilizer (ASNF) with and without nitrification inhibitor DMPP with rate of 100 mg N Kg-1 soil) and different levels of P (0, 30, 60 and 90 mg P kg-1 soil) on spring wheat cv. Pishtaz during 2010 at ShahreKord University with three replicates. According to results, application of nitrification inhibitor DMPP with both of ASF and ASNF resulted to meaningful increase of soil available P at the end of experiment as well as significant increase of NH4+ and also significant decrease of NO3- in the soil during experiment as compared to similar treatments but without NI. The results indicated that application of nitrification inhibitor DMPP with ASNF at all P applied led to significant increase (P
H.R. Motaghian; A. Hosseinpour; jahangard mohammadi; Fayez Raiesi
Abstract
Rhizosphere is a small zone and has quite different chemical, physical and biological properties from bulk soil. This research was conducted to investigate the availability and fractionation of copper in the wheat rhizosphere and bulk soils by using rhizobox at greenhouse conditions. Three seeds of wheat ...
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Rhizosphere is a small zone and has quite different chemical, physical and biological properties from bulk soil. This research was conducted to investigate the availability and fractionation of copper in the wheat rhizosphere and bulk soils by using rhizobox at greenhouse conditions. Three seeds of wheat were plant in the rhizobox. After 8 weeks, plants were harvested and rhizosphere and bulk soils were separated. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and available Cu (by using 7 chemical procedures) and Cu-fractions were determined in the rhizosphere and bulk soils. The results indicated that TOC, DOC and MBC in the rhizosphere were increased significantly (p
F. Nemati; F. Raiesi; A.R. Hosseinpur
Abstract
Abstract
Soil salinity in huge parts of the world, especially in arid and semi-arid regions, is a factor limiting growth of plant and other organisms. Earthworm can be considered as an indicator of soil quality in agroecosystems, because of a positive correlation between earthworm abundance and the ...
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Abstract
Soil salinity in huge parts of the world, especially in arid and semi-arid regions, is a factor limiting growth of plant and other organisms. Earthworm can be considered as an indicator of soil quality in agroecosystems, because of a positive correlation between earthworm abundance and the productivity of cropped plants. The main objective of this study was to realize the interaction between soil salinity and organic amendments on the growth and populations of anecic earthworm (Lumbricus terrestris L.) under controlled greenhouse conditions. The experiment was a 4×4 factorial consisting of three levels of salinity (2, 4 and 8 dSm-1) obtained using NaCl (plus a control) and three organic amendments (alfalfa and corn residues, cow manure and control) arranged in a completely randomized design replicated three times. The experiment lasted 15 weeks. Results showed that increasing soil salinity caused a significant reduction (P ≤ 0.001) in all the earthworm's growth indices. The increase in salinity from 0.49 dS m-1 (control) to 8 dS m-1 reduced the number of earthworms (32%), fresh weight of worms (54%), dry weight of worms (54%), worms length (25%) and the number of cocoon (35%), suggesting the harmful effect of salinity on earthworms growth. The application of organic amendments has, to some extent, alleviated salinity effects on earthworms, and resulted in increases in earthworm growth rates at all salinity levels. Soils amended with alfalfa residues showed the highest alleviating outcomes. In summary, salinity reduced the growth and activity of earthworms L. terrestris and the added organic materials, however, lowered the detrimental effects of salinity on earthworms in the studied soil.
Keywords: Earthworm, Growth index, Organic amendments, Salinity, Saline environments, Lumbricus terrestris L