N. Azadi; F. Raiesi
Abstract
Introduction: Heavy metals contamination of soils is an important environmental concern which has specially long-term hazardous effects on soil biogeochemical and microbiological properties (including microbial and enzyme activity, microbial community structure, and the contents of organic compounds). ...
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Introduction: Heavy metals contamination of soils is an important environmental concern which has specially long-term hazardous effects on soil biogeochemical and microbiological properties (including microbial and enzyme activity, microbial community structure, and the contents of organic compounds). Among heavy metals, cadmium (Cd) and lead (Pb) are the two highly toxic, non-biodegradable and often coexisted anthropogenic pollutants in contaminated sites. Numerous earlier studies have demonstrated a detrimental influence of Cd and Pb, both individually and jointly, on microbial and biochemical properties through reduction of microbial activity, microbial biomass and enzyme activity in polluted soils. Metal co-contamination has a greater negative effect on soil microbial community and enzyme activity compared to individual ones. Although the individual effects of Cd and Pb on soil biological functions 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 Cd and Pb pollutants on biochemical and microbiological properties in a contaminated soil. It was hypothesized that combined Cd and Pb would increase mobility and availability of Cd and Pb, which subsequently results in further reductions in soil biochemical and microbiological properties. Materials and Methods: The study was conducted under controlled laboratory conditions. A factorial experiment with two levels of cadmium (0 and 10 mg kg-1) and two levels of lead (0 and 150 mg kg-1) was conducted using a completely randomized design with three replications. The soil was artificially spiked with cadmium chloride and lead chloride to attain the above mentioned concentrations. 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 20 days. Soil samples were incubated under standard conditions (70% of field capacity and 25±1 oC) for 120 days. At the end of the soil incubation the concentration of DTPA-TEA (diethylene triamine penta acetic acid-triethanol amine)-extractable Cd and Pb, biochemical and microbiological properties including nitrification rate (NR), cumulative N mineralization (CNM), cumulative C mineralization (CCM), microbial biomass C (MBC), microbial biomass N (MBN), arginine ammonification (AA), basal respiration (BR), substrate (glucose)-induced respiration (SIR), metabolic quotient (qCO2) and the activities of soil urease (URE), alkaline phosphatase (ALP), arylsulphatase (ARY), dehydrogenase (DEH), catalase (CAT) and fluorescein diacetate hydrolysis (FDA) were determined. In this experiment, the Bliss independence model was used to determine the type and nature of the interaction between Cd and Pb pollution (i.e., synergistic and antagonistic). Results and Discussion: Results showed that the DTPA-extractable metal (Cd and Pb) concentrations were considerably higher under the combined metals compared with the single-metals. In co-contaminated soils, a metal may contribute to release of other metals to soil solution and consequently would enhance the availability of the released metals. Compared to individual metal, the qCO2 was greater in Cd+Pb contaminated soil. Microbial and biochemical properties (MBC, MBN, AA, NR, CNM, CCM, BR, SIR) and enzyme activity (URE, ARY, ALP, DEH, CAT and FDA) significantly decreased in the presence of Cd or Pb pollutant than the control. Generally, the negative effects of Cd and Pb co-existence on biochemical and microbiological properties were higher than Cd or Pb alone because of synergistic interaction in the metal combinations. The results of Bliss independence model indicated the synergistic effect of Cd and Pb on microbial and biochemical functionalities in metal-co-contaminated soils. In soil ecosystem, heavy metals exhibit toxicological effects on soil microbes which may lead to the decrease of their function and activities. Conclusion: Heavy metals can effectively change the soil biochemical and microbiological properties. This study provided strong evidence revealing that combined Cd and Pb can increase the mobility and availability of heavy metals, and intensify their toxicity effects on microbial community and enzyme activity in co-contaminated soils. The co-existence of Cd and Pb reduced soil biochemical and microbiological properties more than their individual presence. Soil microorganisms are an important indicator of soil fertility and health and thus would improve the accuracy of the ecological risk assessment of toxic metals at multi-metal contaminated sites. However, further information on responses of microbial indicators to the joint effect of heavy metals under long-term and realistic field conditions is required.
Mina Nazarizadeh; Fayez Raiesi; Hamid reza Motaghian
Abstract
Introduction: Salinity and pollution are two environmental stresses that individually influence the population, growth and activity of earthworms as soil bioengineers. It is well-known that the population and activity of these organisms are mostly reduced or even their activity and growth can be stopped ...
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Introduction: Salinity and pollution are two environmental stresses that individually influence the population, growth and activity of earthworms as soil bioengineers. It is well-known that the population and activity of these organisms are mostly reduced or even their activity and growth can be stopped in polluted and saline soils. The individual effects of these abiotic stresses on earthworms, however, depend on the level of salinity, pollution and organic matter. Nonetheless, the joint or combined effect of these stresses on earthworms, especially in arid and semi-arid areas, is poorly known. Because of the importance of earthworms in soil ecosystem, the study of salinity and pollution interactions on earthworm population and activity to reduce their detrimental effects using organic materials is essential. The aim of this study was to examine how salinity and lead (Pb) stresses simultaneously affect the earthworms in soil ecosystem.
Materials and Methods: In this research, the interaction effect of salinity stress using sodium chloride (NaCl) and Pb stress using lead nitrate (PbNO3) on the population, weight and activity of the earthworm Eisenia fetida was studied under greenhouse conditions. This factorial experiment was carried out using 3 factors, including Pb pollution (control and 30 mg kg-1 Pb), salinity (control, 4 and 8 dS m-1) and cow manure (control and 4% by weight) arranged in a completely randomized design with four replicates. The experiment lasted 13 weeks and earthworm’s population and activity including the number of adult worms, total earthworms, wet and dry weights, and wet and dry weights of casts produced by earthworm were measured at the end of the experiment. Concentration of DTPA (di-ethylene-triamine-pentaacetic acid) extractable Pb was also determined to assess how salinity influences the accessibility of this metal in the soil. The Fisher’s least significant difference test was used to determine the significance of any difference between the means values at 5% level with the STATISTICA 8 software. The Bliss Independence Model was used to determine the type of interaction between salinity and Pb pollution for each manure treatment.
Results and Discussion: The current results showed that increasing salinity level enhanced the accessibility of Pb and subsequently its toxicity for earthworms. In contrast, addition of cow manure reduced the accessibility of Pb by 22-50% at all salinity levels. Earthworm population, wet and dry body weights, and wet and dry weights of casts produced by worms were all significantly (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.
Hanye Jafari Vafa; Fayez Raiesi
Abstract
Introduction: Land application of organic wastes and biosolids such as municipal sewage sludge has been an important and attractive practice for improving different properties of agricultural soils with low organic matter content in semi-arid regions, due to an increase of soil organic matter level and ...
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Introduction: Land application of organic wastes and biosolids such as municipal sewage sludge has been an important and attractive practice for improving different properties of agricultural soils with low organic matter content in semi-arid regions, due to an increase of soil organic matter level and fertility. However, application of this organic waste may directly or indirectly affect soil bio-indicators such as microbial and enzymatic activities through a change in the activity of other soil organisms such as earthworms. Earthworms are the most important soil saprophagous fauna and much of the faunal biomass is attributed to the presence of these organisms in the soil. Therefore, it is crucial to evaluate the effect of earthworm activity on soil microbial and biochemical attributes, in particularly when soils are amended with urban sewage sludge. The purpose of this study was to evaluate the earthworm effects on biochemical and microbiological properties of a calcareous soil amended with municipal sewage sludge using Factor Analysis (FA).
Materials and Methods: In the present study, the experimental treatments were sewage sludge (without and with 1.5% sewage sludge) as the first factor and earthworm (no earthworm, Eiseniafoetida from epigeic group, Allolobophracaliginosa from endogeic group and a mixture of the two species) as the second factor. The study was setup as 2×4 full factorial experiment arranged in a completely randomized design with three replications for each treatment under greenhouse conditions over 90 days. A calcareous soil from the 0-30 cm layer with clay loam texture was obtained from a farmland field under fallow without cultivation history for ten years. The soil was air-dried and passed through a 2-mm sieve for the experiment. Sewage sludge as the soil organic amendment was collected from Wastewater Treatment Plant in Shahrekord. Sewage sludge was air-dried and grounded to pass through a 1-mm sieve for a uniform mixture with soil matrix.Heavy metals concentrations were found to be below the maximum permissible limits for municipal sewage sludge. After applying sewage sludge treatments, the pots were irrigated (70% soil field capacity) for three months to achieve a relative equilibrium condition in the soil. Eight adult earthworms with fully-developed clitellum were added to each pot. In the pots with both earthworm species, 4 specimen of each earthworm species was added. At the end of the experiment (90 days), soil samples were collected from treatments and were separately air-dried for chemical analysis or kept fresh and stored (4oC) for microbial analysis. Finally, data obtained from the study were analyzed using multivariate analysis.
Results and Discussion: Factor analysis led to the selection of three factors with eigen value greater than 1. The first, second and third factors were accounted for 62, 17.7 and 9.2% of the variability in soil data, respectively. The three factors together explained 89% of the original variability (i.e., variance) in the soil dataset. Consequently, three factors were retained to represent the original variability of the dataset. The first factor had 16 highly weighted variables with a negative loading for soil pH and positive loadings for other variables. The first factor, which included most soil indicators as input variables, clearly separated sewage sludge treatments. Most of the soil microbial characteristics were increased by sewage sludge application due to the high contents of organic matter and nutrients in sewage sludge, as well as low concentrations of heavy metals. Fungal respiration, bacterial respiration and microbial biomass carbon loaded heavily on the second factor with a negative loading for fungal respiration and positive loadings for bacterial respiration and microbial biomass carbon. The second factor, which included microbial biomass and community composition, noticeably discriminated earthworm treatments. In sewage sludge treatments, the dependence of E. foetidaspecies on soil microorganisms as a food source declined, because of the consumption of organic waste by this epigeic species. However, the activity and impact of A. caliginosa species from endogeic group was only related to soil microbial biomass probably due to selective feeding of soil microorganisms.
Conclusion: Factor analysis was used successfully in discriminating the effects of sewage sludge and earthworm either alone or in combination on soil microbial and biochemical parameters. A. caliginosa species in soils amended with sewage sludge had a positive effect on microbial community and biomass, while E. foetidaspecies had no such effect. A. caliginosa species indirectly benefited from sewage sludge application following the increase of soil microbial biomass. In summary, A. caliginosa species positively affected microbiological and biochemical properties in soils amended with sewage sludge due to its less dependence on this organic resource.
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
J. heidary; Sh. Ghorbani Dashtaki; F. Raiesi; Pejman tahmasebi
Abstract
Annual fires might change many soil physical properties in semi steppe rangeland.The objective of this study was to investigate the impact of fire on soil physical properties and soil water infiltration parameters in semi-steppe rangeland of Karsanak region in Chaharmahal and Bakhtiari province. Therefore, ...
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Annual fires might change many soil physical properties in semi steppe rangeland.The objective of this study was to investigate the impact of fire on soil physical properties and soil water infiltration parameters in semi-steppe rangeland of Karsanak region in Chaharmahal and Bakhtiari province. Therefore, several sites were chosen which were affected by fire at three, two and one years prior to this study (i.e. 2008, 2009 and 2010, respectively). Soil water infiltration was measured using tension infiltrometer in 54 points of the study sites. Since the soil samples were taken from to depth (0-10 cm and 15-25 cm) of each site, the numbers of soil samples for laboratory analysis were 108. Independent t-test and principle component analysis (PCA) was used to assess the difference between the measured properties at the burned and control sites. The results showed that aggregates stability coefficients (MWD and GMD) in the surface layer significantly reduced in 1 and 2 years after fire compared with control areas. Water dispersible clay (WDC) and bulk density significantly increased in surface layer of all burned areas compared with control areas. Saturation hydraulic conductivity significantly decreased in burned areas in 1, 2 and 3 years after. The results showed that annual fires occurs have meny negative effects on soil physical properties cause to shallow, low water retention capacity and high risk of erosion in semi steppe rangeland.
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 (
J. Givi; F. Raeisi; F. Dehghani
Abstract
Purpose of this research was evaluationof organic matter unstability (ripening) of Histosolsof south-west Shahrekord,using humusunstability indices, including ratios of humic acid (HA) to fulvic acid (FA), sum of organic material types, soluble in alkali (AE=FA+HA) to humin fraction (HUM) and also ratio ...
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Purpose of this research was evaluationof organic matter unstability (ripening) of Histosolsof south-west Shahrekord,using humusunstability indices, including ratios of humic acid (HA) to fulvic acid (FA), sum of organic material types, soluble in alkali (AE=FA+HA) to humin fraction (HUM) and also ratio of optical density at 465 (E4)tooptical density at 665 nanometer (E6) of organic matter and its components.The studied area has cool and semi-arid climate. Some of the soils formed in the studied area are Histosols.Five soil profiles were described down to depth of 2 m and soil samples were collected from their different horizons. Chemical fractionation of organic matter to fulvic acid, humic acid and humin was done and the content of each of these three components and the amounts of E4and E6 were measured.In all of the soil profiles, variations of the fulvic acid, humic acid and humin contents are similar to variations of organic matter contents. More than 94 percent of the soil organic matter has changed to humus. Increase of HA/FA with increase of soil depth indicates high degree of polymerization and humification (stability) of organic matter in underlying layers and higher rate of humic material decomposition (unstability) in surface layers. Lower rate of humic material decomposition in underlying layers is due to increase of clay content with increase of soil depth and adsorption of humin by clay particles. E4/E6 of the whole soil also decreased regularly from soil surface towards soil depth. This decrease is another evidence for increase of organic matter stability. Highest organic matter unstability was observed in the profile 5. This profile contains hemic but the others have sapric organic material.
Mohammad Reza Naderi; A. Danesh Shahraki; F. Raiesi; F. Nikookhah
Abstract
This study was performed in order to isolate lead (Pb)-tolerant plant growth promoting rhizobacteria in Pb-contaminated soils and to evaluate their potential for production of plant promoting substances. The isolated Pb-tolerant rhizobacteria were identified as Rhodococcus sp., Bacillus stearothermophilus ...
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This study was performed in order to isolate lead (Pb)-tolerant plant growth promoting rhizobacteria in Pb-contaminated soils and to evaluate their potential for production of plant promoting substances. The isolated Pb-tolerant rhizobacteria were identified as Rhodococcus sp., Bacillus stearothermophilus strain A, Corynebacterium sp., Bacillus pumilus, Mycobacterium sp., Bacillus stearothermophilus strain B, Bacillus licheniformis and Bacillus sp. The results showed that all isolates were able to tolerate high concentrations of Pb. The minimum inhibitory concentration (MIC) of these bacteria was in the range of 1100-1720 mg l-1 (3.3-5.19 mM). In addition, all isolates produced IAA (ranging from 3.53 to 43.64 mg l-1) and siderophore (ranging from 57.74 to 86.24%). However, only two isolates (i.e., Bacillus licheniformis and Mycobacterium sp.) had the ability to produce bacterial enzyme ACC-deaminase. Inoculation of medium containing poorly soluble PbCO3 with bacterial strain Corynebacterium sp. significantly increased the available concentration of Pb.
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.
Mohammad Reza Naderi; A. Danesh-Shahraki; F. Raiesi
Abstract
The right selection of an appropriate cultivar, which can be adapted with a particular pollutant and environmental conditions, is a crucial factor for a successful phytoremediation technology. Sunflower might be a suitable plant to remove the toxic metals from soil of polluted sites due to its rapid ...
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The right selection of an appropriate cultivar, which can be adapted with a particular pollutant and environmental conditions, is a crucial factor for a successful phytoremediation technology. Sunflower might be a suitable plant to remove the toxic metals from soil of polluted sites due to its rapid growth and high biomass production. In order to evaluate the efficiency of six sunflower cultivars in lead (Pb) phytoextraction from a contaminated soil, an experiment was carried out using a completely randomized design with three replications in Research Station of Shahrekord University. Sunflower cultivars used in this experiment were Alestar, Serena, Sanburu, Hysun 33, Record and Euroflor. Results showed that there was a significant difference in shoot lead concentration, translocation factor and total lead harvested by shoot among sunflower cultivars at 1% probability level. Generally, due to translocation factor of all cultivars was less than 1, this can be stated that none of cultivars had the proper efficiency for extraction of lead from contaminated soil. However, high root lead concentration and low translocation factor of these cultivars show that efficiency of them for use in phytostabilization technique is more than phytoextraction technique.
M. Riahi Samani; F. Raiesi
Abstract
The study of soil C dynamics and factors controlling this important soil process in rangeland ecosystems may provide an insight into understanding and evaluating changes in the global C cycle. The primary objective of this study was to quantity the effects of pasture management (i.e., grazing, controlled ...
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The study of soil C dynamics and factors controlling this important soil process in rangeland ecosystems may provide an insight into understanding and evaluating changes in the global C cycle. The primary objective of this study was to quantity the effects of pasture management (i.e., grazing, controlled grazing and ungrazing) on soil C levels and mineralization in three natural rangeland sites of Chaharmahal Va Bakhtiyari province. Three range management regimes including: (a) long-term ungrazed, (b) controlled grazed and (c) free (over) grazed in close vicinity were selected at three sites including SabzKouh (protected from grazing for 18 years), Boroujen (protected from grazing for 23 years) and Sheida (protected from grazing for 2 years). Soil samples were collected from 0-15 cm depth and organic C, total N and C mineralization were measured using standard methods. Results show that SabzKouh and Sheida sites had the highest (14.6 mg g-1) and the lowest (4.80 mg g-1) soil organic C contents, respectively. Soil total N and organic C contents at SabzKouh were significantly higher when compared to other sites, probably due to more rainfall and humid climate. The effect of range management on soil C mineralization was evident at two of the three sites. Results indicate that the exclusion of grazing animals resulted in an increase in soil C mineralization at SabzKouh and Boroujen sites, probably through the addition of plant residues and animal excrements to the soil. However, ungrazed management did not improve plant cover and soil properties in Sheida area, due likely to dry climate conditions, less biomass production and the history of cultivation and agricultural uses. It is, therefore, concluded that the effect of grazing on soil C mineralization depends primarily upon the plant community and climatic conditions and also upon the type of rangeland management and even land use history involved.
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.
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
S. Fallah; Fayez Raiesi
Abstract
The effects of organic and inorganic N sources on nutrient (N and P) efficiency under the water-stressed conditions have not yet been determined. Thus, a field study was conducted to determine the influence of N from different sources along with drought stress on nutrient efficiencies of maize. Main ...
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The effects of organic and inorganic N sources on nutrient (N and P) efficiency under the water-stressed conditions have not yet been determined. Thus, a field study was conducted to determine the influence of N from different sources along with drought stress on nutrient efficiencies of maize. Main plots consisted of two irrigation treatments (i.e., optimum irrigation and cut-off irrigation at silking stage for two weeks), and subplots comprised N fertilizers (cattle manure: 40.8 Mg ha-1, poultry manure: 13.3 Mg ha-1, urea fertilizer: 435 kg ha-1, cattle manure + urea fertilizer: 20.4 Mg ha-1and 20.4 Mg ha-1, respectively) and control (without fertilizer). Results indicated that the imposition of water deficit and fertilizer type had a significant effect on N uptake while P uptake was significantly affected only by fertilizer type. The highest N and P uptake were obtained with poultry manure. Similarly, significant differences in N and P use efficiency and N physiological efficiency were observed between the water deficit and fertilizer type (P
S. Rajaei; F. Raiesi; S.M. Seyedi
Abstract
The contamination of ecosystem components with petroleum and its derivatives is considered as one of the most crucial environmental threat in Iran, particularly in southern areas. Bioremediation has frequently been regarded as an appropriate and more practical alternative to clean-up petroleum hydrocarbons ...
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The contamination of ecosystem components with petroleum and its derivatives is considered as one of the most crucial environmental threat in Iran, particularly in southern areas. Bioremediation has frequently been regarded as an appropriate and more practical alternative to clean-up petroleum hydrocarbons in the contaminated environments. Bioremediation optimizes conditions for microbial hydrocarbon degradation and uses the microorganisms and plants potential to metabolize contaminants resulting in their removal or attenuation in situ. This study aims at remedying an aged petroleum-contaminated soil using bioaugmentation and phytoremediation techniques. A consortium has been prepared using oil-degrading bacteria; 10% oil-contaminated soil was then inoculated with the consortium. Additionally, oat and/or barley were planted in certain treatments to separately evaluate the effects of plant-bacteria interaction on Total Petroleum Hydrocarbon (TPH) degradation and inoculum's efficiency. TPH degradation value under unplanted and uninoculated conditions was only 2.4% in the studied petroleum -contaminated soil after 4 months. However, the presence of the two plants elevated TPH degradation up to 30%, and bacterial inoculation resulted in only 20% TPH degradation. The significance of the plants in enhancing TPH degradation could be probably explained by promoting microbial populations, growth and activities. The highest amount of TPH degradation recorded was 44% and was observed with inoculated plants. The presence of plants in petroleum-contaminated soils promoted microbial populations and activities with increased microbial respiration and biomass well developed petroleum-degrading microbial population and decreased microbial metabolic quotient (qCO2), hence, increased biodegrading of hydrocarbons.
F. Raiesi; F. Aghababaei
Abstract
Abstract
Soil microbial activity and biochemical processes are often limited by carbon availability in arid- and semi-arid regions, probably due to the low organic matter content. Consequently, return of plant residues to soil is a convenient and effortless practice for increasing microbial activities ...
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Abstract
Soil microbial activity and biochemical processes are often limited by carbon availability in arid- and semi-arid regions, probably due to the low organic matter content. Consequently, return of plant residues to soil is a convenient and effortless practice for increasing microbial activities and biochemical reactions. The primary objective of this study was to evaluate the effect of various plant residues on soil microbial respiration and biomass, and enzymatic activities as well. The experiment consisted of a completely randomized design (CRD) with three replications under laboratory conditions. Experimental treatments consisted of seven plant residues including wheat, alfalfa, corn, rice, almond, walnut and grape, common in agro-ecosystems of Chaharmahal va Bakhtiari province, with a control soil without plant residue addition. Results show that the added plant residues brought about a significant increase in microbial activity (soil respiration) and biomass with concurrent increases in enzyme activities in the studied soil. The results of the current study indicate that enzyme activities would alter with changes in substrate quality during the course of plant residue decomposition. However, the extent to which, soil microbial activity and biomass, and enzyme activities fluctuate depended largely upon the type and quality of plant residues used, and the stage of residue decomposition.
Keywords: Litter chemical composition, Soil respiration, Soil Microbial biomass, Soil Enzyme Activities, Cropping systems
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
F.S, Moosavi; F. Raiesi
Abstract
Abstract
Earthworms are an important component of soil fauna, and play a crucial role in the improvement of soil properties. However, very little is known of the interactive influence of earthworms and organic materials on soil enzyme activities, particularly in arid and semi-arid soils. The low organic ...
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Abstract
Earthworms are an important component of soil fauna, and play a crucial role in the improvement of soil properties. However, very little is known of the interactive influence of earthworms and organic materials on soil enzyme activities, particularly in arid and semi-arid soils. The low organic matter content and the significant role of earthworms in stimulating microbiological and biochemical properties of arid and semi-arid soils may justify researches on the interactive effects of organic materials and earthworms on soil enzymes. Thus, the main objective of this study was to identify the interactive effects of an anecic earthworm (Lumbricus terrestris L.) and various organic materials on soil urease, alkaline phosphatase, invertase, β-glucosidase and arylsulphatase activities. The experiment consisted of a 2×5 factorial treatment arranged in a completely randomized design with four replications under controlled greenhouse conditions. The first factor was soils inoculated with and without earthworm, and the second factor was soils amended with alfalfa, compost, cow dung, and a mixture of alfalfa and compost, in addition to a non-amended soil as the control. Potential soil enzyme activities were assayed 30, 60 and 90 days after the initiation of the experiment using the appropriate substrate for each enzyme under standard conditions. Results showed that the activities of most soil enzymes were markedly greater in the presence of earthworms than in the absence of earthworms. The addition of organic materials to soil also resulted in higher enzyme activities compared with the non-amended soils. Nevertheless, the simultaneous effect of earthworm inoculation and organic material additions was much more effective in increasing soil enzyme activities. Yet, the activities of soil enzymes showed fluctuations and varied during the experiment. We found that the averaged increase in soil enzyme activities over 60-90 days in treatments without earthworms was often more remarkable than in treatments with earthworms, indicating that earthworm activity may shorten the time period to attain the maximum enzyme activities (over 30-60 days).
Keywords: Soil enzymes, Earthworm activity, Organic materials, Arid and semi-arid soils
L. Dayani; F. Raiesi
Abstract
Abstract
Cadmium is one of the heavy metals with a considerable importance for its potential toxic effects on soil microbial activities and composition. Although, the toxic effect of cadmium on soil microbial activities is somewhat well-known, but the extent to which Cd affects soil biota depends largely ...
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Abstract
Cadmium is one of the heavy metals with a considerable importance for its potential toxic effects on soil microbial activities and composition. Although, the toxic effect of cadmium on soil microbial activities is somewhat well-known, but the extent to which Cd affects soil biota depends largely on soil properties and conditions, particularly soil organic matter contents. Thus, the aim of this research was to study the effect of increasing cadmium levels on soil microbial biomass and activities, and to examine the role of compost materials in the alleviation of Cd effects. A 2×5 factorial experiment consisting of two levels of compost (0 and 2.5 t ha-1) and five levels of cadmium (0, 50, 100, 150 and 200 mg Cd kg-1) arranged in a completely randomized design with three replicates was carried out under laboratory conditions. The responses of soil microbiological properties consisting of C mineralization, microbial biomass C; and acid and alkaline phosphatase activities to cadmium and compost additions were evaluated during 10 weeks of laboratory soil incubation. Results show that cadmium additions had a significant, negative effect on all the measured microbiological properties. The accumulated C mineralization reduced with increasing cadmium concentrations. Nonetheless, compost addition lowered the detrimental and inhibiting effect of cadmium on soil microbial activities. Results demonstrate that in spite of a significant correlation (r=0.96) between the two Cd fractions, the added Cd at the beginning of soil incubation was not reflected totally in the total Cd concentrations determined at the end of soil incubation. Data also indicated that the fraction of available Cd had a stronger negative (cor)relation with soil microbial activities than the other fractions had. In summary, the results of the current study illustrate that even a lower concentration of Cd (50 mg kg-1) may inhibit soil microbial activities due to it toxicity in the studied soil, and that the addition of organic materials could be effective in reducing the toxicity of cadmium via lessening its bioavailability to soil biota.
Keywords: Cadmium, Soil microbial activity, Soil C dynamics, Compost, Soil enzymes
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
M. Boyrahmadi; F. Raiesi; J. Mohammadi
Abstract
Abstract
Soil microbiological criteria are a complex reflection of interactive metabolic processes that may not be evaluated only by measuring a single parameter but rather it requires the simultaneous determination of more parameters and combining them. The objective of this research was to study enzyme ...
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Abstract
Soil microbiological criteria are a complex reflection of interactive metabolic processes that may not be evaluated only by measuring a single parameter but rather it requires the simultaneous determination of more parameters and combining them. The objective of this research was to study enzyme activities: microbial biomass carbon ratios in salinized and none-saline soils in the presence and absence of plant's rooting system. This ratio indicates the amount of enzyme activity per unit of microbial biomass. In this study, five levels of salinity using NaCl, CaCl2, MgCl2 and KCl; with 2:1:1:1 ratio and three soils (unplanted soil, soil planted with wheat and clover) replicated three times consisted our factorial experiment arranged in a completely randomized design. Results showed that salinity caused significant reduction in enzyme activities: microbial biomass ratio in all three soils. Furthermore, at all salinity levels, unplanted and planted treatments had a significant effect on urease activity: microbial biomass carbon ratio and arylsulphatase activity: microbial biomass carbon ratio. However, there were no significant differences in ß-glucosidase: microbial biomass carbon ratio and alkaline phosphatase: microbial biomass carbon ratio among the three soils at all salinity levels. In the other words, the presence of plant did not have any substantial effect in increasing or reducing microbial ability to produce and synthesize these enzymes. The effect of planted and un-planted treatments on the ratio of L-glutaminase, saccharase and acid phosphatase to microbial biomass carbon in different salinity treatments were variable. In summary, results showed that the presence of plants may support the synthesis of some enzymes by soil microorganisms. But the synthesis of some other enzymes is not affected by the presence and absence of plants living roots. In other words, the effect of roots and its exudates on moderating the effect of salinity on the amount of the enzymes synthesized by soil microbes depends on the salinity level, plant type and enzyme.
Keywords: Salinity, Soil enzyme activity, Microbial biomass carbon ratio, Uncultivated soil, Planted soil, Wheat, Clover
M. Fereidooni Naghani; F. Raiesi; S. Fallah
Abstract
Abstract
The addition of manures and chemical fertilizers as soil amendments for the improvement of soil fertility and quality could affect the seasonal changes in the activity of soil microbes and enzymes. This study aimed at investigating the effect of different levels of nitrogen from broiler litter ...
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Abstract
The addition of manures and chemical fertilizers as soil amendments for the improvement of soil fertility and quality could affect the seasonal changes in the activity of soil microbes and enzymes. This study aimed at investigating the effect of different levels of nitrogen from broiler litter and urea sources on the trend of urease, alkaline phosphatase and saccharase activities in a clay loam calcareous soil cultivated with maize (Zea Mays L.) under field conditions. The treatments were a control (no fertilizer and broiler litter), 100, 200, 300 kg N ha-1 from broiler litter and 100, 200, 300 kg N ha-1 from urea, using a split-plot experiment arranged in a completely randomized block design with four replications. The activity of soil enzymes was monitored at five different stages after treatments imposition with 20-day intervals during the growth period. Results of this research show that the activity of urease, alkaline phosphatase and saccharase in broiler litter- and urea- treated soils were significantly greater than that in the control soil (no broiler litter and urea added). The level of broiler litter and urea fertilizers and time had a significant effect (P