Soil science
P. Kabiri Samani; M.H. Salehi; H.R. Motaghian
Abstract
Introduction In addition to the minerals, weathering in soil which depends on soil forming factors and processes, plants rhizosphere release components which affect soil minerals and finally their weathering. If the soil is polluted by heavy metals, root exudates will be influenced resulting in ...
Read More
Introduction In addition to the minerals, weathering in soil which depends on soil forming factors and processes, plants rhizosphere release components which affect soil minerals and finally their weathering. If the soil is polluted by heavy metals, root exudates will be influenced resulting in decreasing microbial activity. Many studies showed minerals weathering in rhizospheric medium for both natural soils and pure clay minerals but information about the effect of pollution of rhizosphere on clay minerals weathering is limited. This study was conducted to investigate the effect of cadmium pollution on the transformation of clay minerals in wheat rhizosphere in a dominant soil of Shahrekord plain (Chaharmahal soil series).Materials and methods Soil samples were collected from 0-20 cm depth of Chaharmahal soil series based on the 1:50,000 scale soil map. A factorial experiment as completely randomized design with three replications and three cadmium levels (0, 5, and 10 mg kg-1 from cadmium) was performed in two environments including bulk soil and rhizospheric soil (18 samples in total) in greenhouse conditions for 16 weeks. Necessary care was taken during the growth period and the soil moisture was kept constant at the field capacity. At harvest time, the rhizosphere soil was separated from bulk soil. Then, the soil samples were air dried and passed through a 2 mm sieve. The mineralogy was examined by X-ray diffraction (XRD) in the studied soil after plant harvest (including rhizospheric soil and bulk soil) in unpolluted samples. Then, results were compared with minerals in polluted rhizosphere media. Dissolved organic carbon (DOC) and pH in the rhizosphere and bulk soils were also determined.Results and Discussion The results showed that the effect of contamination on soil pH was not significant but the pH value in rhizosphere soil was significantly lower than the bulk soil. The average pH in the soil was 7.8 and in the rhizosphere reduced to 7.5. The interaction of medium (rhizosphere and bulk soil) and contamination on the amount of dissolved organic carbon was significant (p < 0.01). The amount of dissolved organic carbon in the rhizosphere at 170.6 mg Kg-1 was significantly higher than the bulk soil (104.6 mg kg-1), which could be due to root secretions. In the rhizosphere, increasing the contamination level to 5 mg kg-1 decreased by 19% and contamination of 10 mg kg-1 caused a 21% decrease in dissolved organic carbon. The amount of dissolved organic carbon in the rhizosphere was 39% higher than the bulk soil. The average of dissolved organic carbon in the rhizosphere and bulk soil was 170.6 and 104.6 mg kg-1, respectively. Based on mineralogical results, mica, smectite, chlorite, kaolinite and palygorskite minerals were detected in the bulk soil. Comparison of clay minerals samples in the bulk soil and rhizosphere showed that the trioctahedral chlorite transformed to hydroxy-interlayer vermiculite (HIV) in the rhizosphere soil. The presence of HIV was identified by an increase in the intensity ratio of the 10 and 14 angstrom peaks after K-saturation. In rhizospheric soils, the intensity of the 14 angstrom peak decreases in K-550ºC treatment. Furthermore, in the rhizospheric soils, a clear increase in the intensity of the 10 angstrom peak was observed from K-air dried to K-550ºC treatments which can be related to the presence of HIV which can be attributed to the changing conditions of the rhizosphere, including reducing pH and increasing the dissolved organic carbon and the activity of microorganisms. Comparison of diffractograms for clay fraction of rhizospheric soil with different contamination levels after cultivation showed that the type of minerals in contaminated levels was similar to non-contaminated conditions, but the amount of trioctahedral chlorite was the highest in higher contaminated soil. The peak intensity of 14 angstrom in potassium saturated sample heated at 550°C was lower in non-contaminated soil. Also, at the level of 10 mg kg-1 cadmium contamination, the chlorite peak had the highest intensity which indicates less chlorite was transformed to HIV in the contaminated soils.ConclusionsThe results showed that DOC in the rhizosphere soil was significantly higher than the bulk soil, whereas pH significantly decreased in the rhizosphere soil compared to the bulk soil. In both the rhizosphere and the bulk soils, increasing the contamination caused a decreasing trend in dissolved organic carbon. Mineralogical results of the rhizospheric and the bulk soils showed that trioctahedral chlorite was transformed to hydroxy-interlayer vermiculite (HIV). In addition, rhizosphere contamination reduced the chlorite transformation. The results suggest that soil contamination with a negative impact on plant activity and soil could even prevent the availability of nutrients from the clay minerals structure.
Hassan Lotfi Parsa; Ghasem Asadian
Abstract
Introduction: Soil organic carbon (SOC) is released from decomposition of plant residues, while root secretion products in rhizosphere are also a substantial source of SOC input to soil. Binding SOC to clay minerals leads to increase aggregate stability and protect organic carbon against microorganisms. ...
Read More
Introduction: Soil organic carbon (SOC) is released from decomposition of plant residues, while root secretion products in rhizosphere are also a substantial source of SOC input to soil. Binding SOC to clay minerals leads to increase aggregate stability and protect organic carbon against microorganisms. Organo-mineral complexes have important role in decreasing organic carbon decomposition. Assessment of organic carbon particle size and biochemical fractionation is an appropriate approach to investigate organic carbon dynamics and durability against microorganisms in rhizosphere as a hot spot of activity.
Materials and Methods: The study area was a semi-arid rangeland with the main plants species including five perennial rangeland species: crested wheat grass (Agropyron cristatum), astragalus (Astragalus verus), sheep fescue (Festuca ovina), phlomis (Phlomis oliveri), feverfew (Tanacetum parthenium). Whole soil surrounding plant roots with all roots was taken for each plant. Three sample with different distances from root surface were taken by applying this procedure: sample A: The soil which is adhered to the root surface and separates quickly from roots after drying, sample B: The soil in root zone, which is not stuck and almost is so close to roots, sample C: The soil which is wholly far from root area and apparently not affected by roots. Intact samples removed from ground and transferred quickly to laboratory to separate roots and soils with different distances from root surface by drying the root system before shaking. Particle size fractionation was done by wet sieving of aggregates and SOC in different aggregate sizes was measured by wet combustion method. Biochemical fractionation of SOC was done by acid hydrolysis method to study organic carbon stability at different distances from root surface.
Results and Discussion: ANOVA results showed a significant effects of plants and distance from root surface on aggregate size classes. The results showed the increasing amounts of microaggregates at root vicinities compare to macroaggregates. By increasing distance from root surface, the >2 mm aggregates increased, but, the amount of <0.15 mm aggregates decreased significantly. Toward root surface from C to A locations, the mean weight diameter (MWD) of soil aggregates decreased due to decreasing macro-aggregates at root vicinity. Maenwhile, SOC increased approaching to root surface due to root exudates and rhizodeposits. The highest and lowest of SOC content were found in the A location of Feverfew and the C location of Astragalus (4.16 and 0.82%), respectively. The OC contents in root vicinity were higher than other locations due to high root exudates and rhizodeposits which had C-containing molecules. Soil OC contents had significant correlation with measured soil parameters. The highest SOC content was found in micro-aggregate and in vicinity of roots. Low-decomposed OC, which has crucial role in linking microaggregates to make macroaggregates, led to high OC contents in macroaggregates. Soil OC biochemical fractionation demonstrated higher OC contents in recalcitrant pool at further distances from root surface, while by going toward root vicinity the amounts of OC in water soluble and labile pool increased. In average for A locations, 66% of total OC was measured as water soluble fraction, while for C location, the average fraction of labile and recalcitrant pools from total OC were found 62.5% and 50%, respectively. As the root exudates had fresh OC such as carbohydrates and sugars, the concentration of OC in water soluble and labile pools were so high at root vicinity. Moreover, OC in labile and water soluble pools had high correlation coefficient and, contributed to high fractions of total OC in root vicinity. Whilst C in recalcitrant pool were found higher in further distances from root surface, because activities of microorganisms and the fresh OC were decreased toward bulk soil.
Conclusion: This study investigated the effect of root activities of five perennial rangeland plants on the particle size and biochemical fractionation of soil OC at different distances from root surface. In root vicinity due to addition of fresh OC from roots to soil and higher microorganisms’ activities, mineral particles were aggregated to micro-aggregates which contained a large fraction of soluble and labile Soil OC. But, recalcitrant OC were dominated in macro-aggregates far from root surface. Rangeland plants with various root systems and characteristics had strong impact on particle size and biochemical fractionation of soil OC which needs more investigation. Durability of biochemical C pools has important role in carbon dynamic and stability in soil.
MirHassan Rasouli-Sadaghiani; Roghayeh Vahedi; Mohsen Barin
Abstract
Introduction: Millions of tons of trees pruning waste are produced annually in Iran, which can contribute to supplying soil organic matter. Soils in arid and semi-arid regions, due to lack of sufficient vegetation and the return of low amounts of plant residues to the soil, contain little organic matter. ...
Read More
Introduction: Millions of tons of trees pruning waste are produced annually in Iran, which can contribute to supplying soil organic matter. Soils in arid and semi-arid regions, due to lack of sufficient vegetation and the return of low amounts of plant residues to the soil, contain little organic matter. These soils are often calcareous, and as a result, many plants in these soils are faced with nutritional problems, especially phosphorus deficiency. Phosphorus, as an essential element for plant growth, combines with soil components and changes into less soluble and insoluble compounds in calcareous soils with low amounts of organic matter. Organic matter and biological amendments can affect the solubility and mobility of nutrients in the rhizosphere and improve their bioavailability by creating different chemical and biological conditions. The pruning waste of trees can be used to produce biochar and compost and consequently improves soil physical and chemical properties and plays an important role in the dynamics and living of soil microorganisms. Biochar is a carbon-rich solid material produced during pyrolysis which is the thermal degradation of biomass under oxygen limited conditions. It has recently received much attention as a soil amendment which can be used to increase nutrient availability, improve the soil microbial diversity and biological activities such as enzyme activity in rhizosphere and sequester carbon in agricultural soils. In addition, compost is a chemical derived product from organic waste and contains many beneficial elements that are gradually released into soil and available to plants. Another approach to improve the bioavailability and mobility of phosphorus in the rhizosphere is the use of potential of phosphate-solubilizing microorganisms including arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR). Limiting the roots to examine the biological and chemical changes and the extent to which these properties have expanded in the rhizosphere are challenges that have been less addressed .Rhizobox is one of the systems used to study rhizosphere changes. The aim of this study was to investigate the effect of biochar and compost prepared from pruning waste of apples and grapes trees as well as microbial inoculation on phosphatase activity and phosphorus availability at wheat rhizosphere under rhizobox condition.
Materials and Methods: This study was carried out on a completely randomized design with a factorial arrangement in three replications, under greenhouse condition in rhizobox. The factors were organic matter (pruning waste biochar (PWB), pruning waste compost (PWC) and control (without organic matter)), microbial inoculation (AMF and PGPR) and soil type (rhizosphere and non-rhizosphere soil). For this purpose, a soil sample with light texture and low available phosphorus content was prepared. PWB used in the experiment was produced from mix pruning waste of apple and grape at the final temperature of approximately 350°C for 3 hours. Moreover, pruning waste compost of apple and grape trees was prepared from Department of Soil Science, Urmia University. The biochar and compost were ground and screened through a 0.5 mm sieve for the greenhouse experiment. The seeds of wheat were planted in 20 × 15 × 20 cm rhizobox (length, width and height). At greenhouse experiment, the biochar and compost were added to the boxes in terms of 1.5% pure organic carbon before planting (each box contained 5.8 kg of soil). In control treatments (without organic matter), sterile soil was used with microbial inoculation. Microbial strains used for inoculation included Pseudomonas aeruginosa, Pseudomonas fluorescens and Pseudomonas putida) and mycorrhizal fungus (Glomus fasciculatum). Wheat seeds (Triticum aestivum L. cv. Pishtaz) were grown in rhizobox. At the end of the vegetative growth period, acid phosphatase (ACP) and alkaline phosphatase (ALP) enzymes activities were asseyedassayed by spectrophotometry method. Soil available P was extracted with 0.5 M NaHCO3 (Olsen-P) in the rhizosphere and non-rhizosphere soils and phosphorus concentrations in the root and shoot were determined by the standard method.
Results and Discussion: The results showed that the application of PWC and microbial inoculation significantly increased ACP and ALP enzymes activity and the availability of phosphorus compared to the control. The highest increase in ALP enzyme activity and available phosphorus was observed in PWC treatment inoculated with PGPR. Furthermore, PWC increased the ACP and ALP enzymes activities in the rhizosphere soil by 1.39 and 1.33 times compared to non-rhizosphere soil, respectively. However, phosphorus availability in the non-rhizosphere soil of the PWC treatment was 21.19% higher than that in the rhizosphere soil. The lowest available phosphorus content was observed in rhizosphere soil of AMF treatment. In addition, the highest phosphorus concentrations in plant root and shoot were, respectively, found in the compost and biochar treatments inoculated with AMF. In PWB treatment, the inoculation of AMF increased shoot phosphorus concentration by 1.31 times relative to PGPR inoculation.
Conclusions: In general, applying organic matter and microbial inoculation had a significant positive effect on phosphorus availability and plant growth. Adding organic matter to the soil, such as compost and inoculation with microorganisms particularly PGPR bacteria in the root zone, led to increased soil available phosphorus. The activity of phosphatases in soil was influenced by using organic materials such as compost and microbial inoculation which enhance the bioavailability of inorganic phosphorus. More positive interaction of PWC and PWB with AMF than PGPR in the rhizosphere caused greater increase of phosphorus bioavailability in the root zone and plant phosphorus uptake. In general, according to the results of this study, it seems that the use of organic materials and biological potential of the microorganisms have a significant effect on phosphorus availability and improve plant growth.
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 ...
Read More
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
shahrzad kabirinejad; mahmoud kalbasi; amir khoshgoftar manesh; M. Hoodaji; Majid Afyuni
Abstract
Introduction: Preceding crops as a source of organic matter are an important source of micronutrient and can play an important role in the soil fertility and the micronutrients cycle of soil. In addition to the role of the organic matter in increasing the concentration of micronutrients in soil solution, ...
Read More
Introduction: Preceding crops as a source of organic matter are an important source of micronutrient and can play an important role in the soil fertility and the micronutrients cycle of soil. In addition to the role of the organic matter in increasing the concentration of micronutrients in soil solution, attention also should be paid to the role of the kind and the quantity of the root’s exudates that are released in response to the incorporation of different plant residues in the rhizosphere. Present research was conducted with the objective of studying the effect of the kind of preceding crops: Trifolium (Trifolium pretense L), Sofflower (Carthamus tinectirus L), Sorghum (Sorghum bicolor L), Sunflower (Heliantus annus L) and control (fallow) on the chemical forms of copper in the wheat rhizosphere and the bulk soil and Cu uptake by wheat and also investigating the correlation between the fractions of Cu in soil and Cu uptake in wheat.
Materials and Methods: The present research was conducted as split plot in a Randomized Complete Block design (RCBD) with 3 replications and 5 treatments, in field conditions. In the beginning, the preceding crops were cultivated in the experimental plots and after ending growth, preceding crops were harvested. Then the wheat was cultivated in the experimental plots. Finally, after harvesting the wheat, soil samples were collected from the two parts of the root zone (the wheat rhizosphere and the bulk soil). The soil samples were air dried ground and passed through a 2-mm sieve and stored for chemical analysis. Soil pH (in the soil saturation extract) and organic matter (Walkley–Black wet digestion) were measured in standard methods (1). The Total Organic Carbon (TOC) was measured by Analyzer (Primacs SLC TOC Analyzer (CS22), Netherlands). The available Cu in soil was extracted by DTPA and determined using atomic absorption spectroscopy (2). The fractionation of soil Cu was carried out using the MSEP method (3).
Results and Discussion: The results showed that the preceding crops significantly decreased soil pH, also significantly increased the DOC and DTPA-extractable Cu.These changes were higher in the Trifolium preceding treatment in the rhizosphere soil. Also, the preceding crops significantly decreased Carbonate -Cuand Residual-Cu fractions in the wheat rhizosphere compared with the bulk soil. The preceding crops (except Trifolium) significantly increased Oxide-Cu fraction. The soil Oxide- Cu fraction was higher in the rhizosphere in comparison with the bulk soil. The preceding crops increased the Organic-Cu in both the wheat rhizosphere and the bulk soil and it was higher in Trifolium treatment. The preceding crops increased Cu uptake by wheat and Organic-Cu positively correlated with Cu uptake by wheat.
Conclusion: The Organic-Cu fraction increased in the rhizosphere compared with the bulk soil, whereas Oxide- Cu, Carbonate–Cu and Residual-Cu fractions decreased. According to the results, the observed increase in the copper concentration of organic fraction in the rhizosphere was due to the decrease in the copper concentration of carbonate, oxide and residual fractions. In fact, the main process is the transmission of copper from carbonate, oxide and residual fractions to another fraction. Also, the results showed that the root exudates of the preceding crops and wheat affected the different forms of copper in the soil solid phase. Furthermore, the results of copper forms correlation analysis with Cu uptake by wheat showed that the Organic-Cu fraction had more important role in supplying copper was needed for wheat. Therefore, the preceding crops increased the copper concentration of organic fraction in the rhizosphere compared with the bulk soil, and these changes are associated with increasing the amount of copper uptake in wheat.
S. Bagheri; hossein mirseyed hosseini
Abstract
Zinc is an essential element for plant growth which its high concentrations can cause pollution and toxicity in plant. In this study, the effects of sorghum cultivation on some indicators of microbial activity and its association with increased zinc concentrations in two soils with relatively similar ...
Read More
Zinc is an essential element for plant growth which its high concentrations can cause pollution and toxicity in plant. In this study, the effects of sorghum cultivation on some indicators of microbial activity and its association with increased zinc concentrations in two soils with relatively similar physical and chemical properties, but different in concentration of heavy metals were investigated. In both soils zinc levels were added to obtain 250, 375 and 500 mg kg-1 (based on the initial nitric acid extractable) content. Using plastic boxes containing 8 kg of soil, growth boxes (Rhizobox) were prepared. The box interior was divided into three sections S1 (the rhizosphere), S2 (adjacent to the rhizosphere) and S3 (bulk soil) using nylon net plates. The results showed that at all levels of zinc in both soil types, BCF were bigger than units, so using this indicator, sorghum can be considered as a plant for accumulation of zinc. Microbial respiration and dehydrogenase activity was reduced in all sections adjacent to root in the polluted soil. It is generally understood that substrates and inhibitors (heavy metals) compete in the formation of substrate-enzyme and inhibitor-enzyme complexes, but the effects of sorghum cultivation in increasing biological and enzyme activity indexes in soil 1 (non-polluted) was higher than soil 2 (polluted), perhaps due to improvements in microbial activity in the vicinity of the roots, even in concentration higher than stress condition levels for zinc in soil.
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 ...
Read More
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
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 ...
Read More
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.
A. Golestani Fard; H. Mirseyed Hosseini; Gholam Reza Savaghebi; Gh.R. Savaghebi
Abstract
In this research chemical forms of lead and zinc in bulk and rhizosphere soil of different cultivars of maize and canola were determined by sequential and single step extraction methods. Some factors affecting chemical transformation of the two elements such as pH, dissolved organic carbon (DOC), their ...
Read More
In this research chemical forms of lead and zinc in bulk and rhizosphere soil of different cultivars of maize and canola were determined by sequential and single step extraction methods. Some factors affecting chemical transformation of the two elements such as pH, dissolved organic carbon (DOC), their uptake by plant and also cation exchange capacity in the rhizosphere and bulk soil were also assessed. Rhizosphere was obtained with gentle shaking and separating the soil around plant roots. Results showed that zinc uptake was more than lead in both plant cultivars. Zinc and lead accumulation in all cultivars roots were also more than shoots. Translocation index (The ratio of element concentration in shoot to root) in the corn cultivars was higher than canola cultivars (significant correlation= 1%) while the ratio was higher for lead in canola cultivars. Metal concentration in shoots to total metal concentrations in soil (Accumulation factor) showed a similar trend like the translocation index. In total, the corn ability in zinc and lead absorption and extraction in soil was higher compared to canola. There weren’t any significant changes in rhizosphere pH compared to bulk soil. Dissolved organic carbon in the rhizosphere of different cultivars was more than bulk soil and the amount of it in canola was significantly more than corn cultivars. Among each plant cultivars, the absorption rate increased with increasing root exudates. The results of sequential and single step extraction methods showed that the general trend and the soil system tendency (Root-Soil interface) is toward zinc availability in the rhizosphere. The amount of lead in rhizosphere showed no significant changes to bulk soil with none of the extractants in single step extraction method but with regards to the results of sequential extraction method, rhizosphere processes tend to reduce the availability of this element in both plant cultivars.
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 ...
Read More
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
