Research Article
L. Qasemi far; A. Golchin; F. Rakhsh
Abstract
Introduction: The accumulation of heavy metals in water, sediments, and soils has led to serious environmental problems. In recent years, several processes have been developed with the aim of reducing or recovering heavy metals from contaminated environments. Physical and chemical approaches are capable ...
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Introduction: The accumulation of heavy metals in water, sediments, and soils has led to serious environmental problems. In recent years, several processes have been developed with the aim of reducing or recovering heavy metals from contaminated environments. Physical and chemical approaches are capable of removing a broad spectrum of contaminants, but the main disadvantages of these methods lie in the increased energy consumption and the need for additional chemicals. In recent years, the processes such as bioleaching, biosorption, bioremediation, phytoremediation, and bio precipitation are all based on the use of microorganisms that have the ability to solubilize, adsorb, or precipitate heavy metals. Therefore, it is necessary to find some solutions to reduce the negative effects of heavy metals in soil. Materials and Methods: A factorial experiment was conducted in the greenhouse of the Faculty of Agriculture, the University of Zanjan, using a completely randomized design with three replications. In this experiment, the effects of different levels of soil cadmium (0, 5, 10, 25, and 50 mg/Kg) and soil inoculation (without inoculation and inoculation with Glomus mosseae, Glomus intraradices, Glomus mosseae + Rhizobium trifolii, Glomus intraradices + Rhizobium trifolii bacterium, Rhizobium trifolii, Glomus mosseae + Glomus intraradices and Glomus mosseae + Glomus intraradices + Rhizobium trifolii) on growth of berseem clover were assessed. Results and Discussion: The results of this study showed that the soil cadmium levels has a significant effect (p < 0.05 and p < 0.01) on fresh weights of aerial parts and roots, height, number of the plant in the pot, Fe, Zn and Cd concentrations in aerial parts and roots of berseem clover. The fresh weights of aerial parts and roots, height, number of the plant in the pot, Fe and Zn concentrations in aerial parts and roots of berseem clover decreased as the levels of soil cadmium increased. The lowest concentrations of iron and zinc were measured in treatment with 100 mg Cd/Kg. Also, Cd concentration in aerial parts and roots increased as the level of soil cadmium increased. The results of this experiment showed that soil inoculation with mycorrhizal fungi and Rihzobium trifolii had a significant effect (p < 0.05 and p < 0.01) on fresh weights of aerial parts and roots, height, number of plant per pot, Fe, Zn and Cd concentrations in aerial parts and roots of berseem clover. The inoculation of soil with mycorrhizal fungi and Rhizobium trifolii increased the fresh weights of aerial parts and roots, height and No. of plant per pot. The highest fresh weights of aerial parts and roots of berseem clover, height, and number of plant per pot were obtained in treatments co-inoculated with Glomus mosseae and Rhizobium trifolii. The highest and lowest concentrations of iron and zinc in aerial parts and roots of berseem clover were measured, respectively, for the treatment co-inoculated by Glomus mosseae and Rhizobium trifolii and control treatment (without inoculation). However, the opposite trends were found in Cd concentrations in the plant. The highest and lowest Cd concentrations in aerial parts and roots were measured in control treatment (without inoculation) and treatment co-inoculated by Glomus mosseae and Rhizobium trifolii (MT), respectively. Conclusion: Bioremediation and phytoremediation are considered as two very safe and necessary technologies which naturally occur in the soil by microbes and plants and pose no hazard to the environment and the people life. The procedure of bioremediation and phytoremediation can be simply carried out on site without initiating a major disruption of normal actions and threating the human life and the environment during transportation. Bioremediation and phytoremediation are used less than other technologies for cleaning-up the wastes and contaminated soils. Microorganisms and plants possess inherent biological mechanisms that enable them to survive under heavy metal stress and remove the metals from the environment. These microbes use various processes such as precipitation, biosorption, enzymatic transformation of metals, complexation and phytoremediation techniques of which phytoextraction and phytostabilization have been very effective. However, environmental conditions need to be adequate for effective bioremediation. The use of hyperaccumulator plants to remediate contaminated sites depends on the quantity of metal at that site and the type of soil. The results of this experiment showed that the Rhizobium trifolii and Glomus mosseae could be used to reduce the soil cadmium contamination. Also, the berseem clover is a hyperaccumulator plant for phytoremediation of cadmium in soils. According to the results of this study, co-inoculation of mycorrhizal fungus Glomus mosseae and Rhizobium trifolii can be recommended to improve the yield and uptake of micronutrients such as iron and zinc in cadmium contaminated soils.
Research Article
A.R. Vaezi; E. Mohammadi; N. Sadeghian
Abstract
Introduction: Rills are usually found on the sloping fields worldwide, especially in semi-arid slopes, where vegetation covers are often poor and soils are weakly aggregated. Rill erosion is recognized as an important process of water erosion on agricultural land in these regions and causes a grate amount ...
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Introduction: Rills are usually found on the sloping fields worldwide, especially in semi-arid slopes, where vegetation covers are often poor and soils are weakly aggregated. Rill erosion is recognized as an important process of water erosion on agricultural land in these regions and causes a grate amount of soil loss. Understanding rill erosion rate is important in the prediction of soil erosion and the prevention of soil loss in the lands. Rill erosion is often easy to observe but difficult to measure because of its complexity and stochastic nature. A common method used to determine rill erosion rate is measuring sediment concentration distribution of eroding rill flow under different flow rates. However, it is not only time-consuming but also had to measure. The volume Replacement Method is an easy method to estimate soil loss from rills in the sloped lands. Limited information is available concerning the ability of this method in different soil textures under slope gradients. Therefore, this study was conducted to evaluate the ability of the method to estimate rill erosion of semi-arid soils. Materials and Methods: This study was conducted on three different soil textures i.e. loam, clay loam and sandy clay loam under four slope gradients including 5, 10, 15 and 20% using factorial arrangement based on completely randomized block design with three replications in the laboratory. A flume with 0.3 m width and 4 m length was subdivided into strips of 0.1 m width and 4 m length to imitate eroding rills. Soil samples for each soil texture were passed from 8-mm sieve and packed into the flumes at its bulk density in the field. Prior to each experimental run, the soil materials were pre-wetted to reach to water-holding capacity. Tap water was introduced into the rill from the upper end, through a water supply tank and a pump at a constant flow rate of 0.5 L.min-1. After erosion, the flume was lowered to the horizontal position for the measurements of eroded rill volumes. The rill volume was determined using soil samples passed from a 2-mm sieve. Soil loss mass eroded from soil surface was computed using rill volume and original soil bulk density packed into the flume. This value was considered as estimated value using the Volumetric Replacement Method for each soil texture under different slope gradients. The performance of the method was assessed using the measured data for each soil and slope gradient using error measures such as root mean square error (RMSE) and mean absolute error (ME). Results and Discussion: Significant differences were found among soil textures and slope gradients as well as their interaction on rill erosion rate. The highest rill erosion rate was observed in clay loam (3.166 g.m-2.s-1), whereas sandy clay loam showed the minimum susceptibility to rill detachment (0.962 g.m-2.s-1). Higher fine particles (clay) and lower aggregation as well as weak aggregate stability are the major reasons for higher susceptibility of clay loam to rill erosion. The rill erosion was more sensitive to slope gradient than soil texture and the strongest dependency of rill erosion on slope gradient was found in clay loam (R2= 0.99). With an increase in slope gradient, rill erosion strongly increased except for loam. The Volumetric Replacement Method overestimated rill erosion in all soils and slope gradients. The highest overestimation was observed in sandy clay loam (RMSE= 2.72 g/m2.sec and ME= 7.02 g/m2.sec), whereas the lowest overestimation value was in loam (RMSE= 0.60 g/m2.sec and ME= 3.86 g/m2.sec). The performance of the Volumetric Replacement Method decreased in higher slope gradients and the highest overestimation was observed under 20% slope gradient (RMSE=1.86 g/m2.sec and ME= 3.84 g/m2.sec). Conclusion: Rill erosion is strongly affected by soil texture and slope gradient. Particle size distribution, aggregates percentage and their stability can control the soil’s susceptibility to detach by concentrated water flow. The Volumetric Replacement Method showed higher uncertainty as evaluated in the semi-arid soil textures especially under steep slopes. The change of soil physical properties by water flow especially bulk density result in errors in determination of rill volume by using this method. The higher change of physical properties by concentrated flow occurs in fine soil textures and steeper slopes. Additionally, continuous sedimentation along the rills imposes other errors in estimating soil loss mass from the rills.
Research Article
H.R. Rafiei; A. Jafari; A. Heidari; Mohammad Hady Farpoor; A. Abbasnejad
Abstract
Introduction: Soil carbon (C) sequestration is recognized as a potentially significant option to off-set the elevation of global atmospheric carbon dioxide (CO2) concentrations. Soils are the main sink/source of carbon and also, an important component of the global C cycle. Total soil carbon (C) comprises ...
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Introduction: Soil carbon (C) sequestration is recognized as a potentially significant option to off-set the elevation of global atmospheric carbon dioxide (CO2) concentrations. Soils are the main sink/source of carbon and also, an important component of the global C cycle. Total soil carbon (C) comprises of the soil organic C (SOC) and the soil inorganic C (SIC) components. The soil inorganic C (SIC) stock mainly consists of carbonates and bicarbonates. Processes governing the dynamics of the soil carbon stock differ among ecoregions and strongly interact with soil properties. Understanding the distribution of organic and inorganic carbon stocks in soil profiles is essential for assessing carbon storage at the regional and global scale. Although global estimates provide a general view of carbon stock levels, accurate local estimates and factors affecting soil carbon dynamics are very important. As a result, there is an essential requirement for accurately estimating the distribution of carbon reserves and their differences with regard to soil properties. Materials and Methods: The study area is located in the Sardooeyeh region, South of Kerman, under semiarid conditions. A total of 5 soil profiles were excavated. Percentage of coarse fragments (> 2 mm) using a 2 mm sieve, total organic C by the K2Cr2O7-H2SO4 oxidation method of Walkley-Black, soil inorganic carbon using the Gravimetric carbonate meter method were determined. Bulk density was measured by drying core samples in an oven overnight and dividing the weight of dry soil by the volume of the core occupied by the soil after correction for coarse fragments. Results and Discussion: Organic carbon in the surface horizons of all profiles is maximum due to vegetation and decreases with increasing soil depth. As the altitude increased, the amount of organic carbon increased in the surface horizons. Lower temperature and higher humidity at higher altitudes lead to the lower organic matter decomposition and consequently higher organic carbon content of the soil. Although the upper soil layers had the maximum soil organic C content, the maximum soil inorganic C content was observed in the sub-surface layers. The soil organic carbon storage was between 5.52 to 9.48 kg m-2 and the storage of soil inorganic carbon in profiles was between 14.41 and 91.34 kg m-2. The total soil carbon storage in the profiles varied between 19.92 to 100.83 kg m-2 and the average was 42.66 kg m-2. The average of soil organic carbon storage in 0-25, 25-60, 60-120 cm depths were 2.6, 1.97 and 1.26 kg m-2, respectively. The amount of soil inorganic carbon storage in 0 -25, 25-60 and 60-120 cm depths were equal to 2.7, 10.40 and 8.26 kg m-2, respectively. Therefore, it seems that more than 50% of the total soil inorganic carbon storage is stored at a depth of 25-60 cm from the soil surface. The portion of inorganic carbon storage of total soil carbon was 77.5%, and about 89% of it was stored in sub-surface horizons (below 25 cm). The portion of organic carbon storage of total soil carbon was 22.4%. It seems that an increase in the partial pressure of CO2 in soils leads to some dissolution of the pedogenic carbonate in the top soil. Dissolved pedogenic carbonate transfers to the deep soil and then re-crystallizes under relatively dry conditions and low CO2. Conclusion: The results showed that soil organic carbon storage was mostly higher in surface horizons, and soil inorganic carbon storage was higher in sub-surface horizons. On average, the ratio of soil inorganic carbon storage to soil organic carbon storage was 4.27. The high percentage of soil inorganic carbon storage in total soil carbon, shows that inorganic carbon plays a very important role in semi-arid regions. Almost 89% of the soil inorganic carbon content and about 80% of the total soil carbon were accumulated in the sub-surface horizon of soil (below 25 cm), indicating the importance of sub-surface soil for storing carbon in semi-arid regions.
Research Article
M. Niazkhani; B. Abdollahi Mandolkani; M. Jafari; M.H. Rasooli Sedghiani
Abstract
Introduction:The lack of micronutrients through a decrease in plant growth, which is related to human health, can be a global problem. Micronutrient deficiency reduces the immunological capacity of plant and animals by which they resist against several chronic diseases. This fact has been brought into ...
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Introduction:The lack of micronutrients through a decrease in plant growth, which is related to human health, can be a global problem. Micronutrient deficiency reduces the immunological capacity of plant and animals by which they resist against several chronic diseases. This fact has been brought into sharp focus in the last decade because of a large proportion of people being deficient in micronutrients. The micronutrients such as zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn) are more important than the others and therefore, they are essential to all living creatures. Zn deficiency is the most noticeable one since it has an influential effect on the production of agricultural products, and consequently, quality of people's life and health. One of the common methods to reduce the shortage of Zn is using Zn-efficient cultivars. These cultivars have more biomass than Zn-inefficient cultivars. However, some micronutrient supply strategies used by these cultivars could have a negative effect on the absorption process of the other micronutrients. Therefore, in the current study, an experimental approach was proposed to evaluate the effect of Zn deficiency on the concentrations of Zn, Cu, Fe, and Mn in the root, shoot, and grain of bread wheat cultivars with differential Zn efficiency. In addition, the capability of transferring the micronutrients from the root system to the shoot system was analyzed. Materials and Methods: A greenhouse study was conducted using a factorial experiment based on completely randomized design (CRD) with three replications. The first factor was two levels of Zn-efficient (data represent the average for Bayat and Niknejhad) and Zn-inefficient (data represent the average for Hirmand and Karaj1) cultivars, and the second factor was two levels of Zn, including Zn deficiency (no application of Zn) and Zn sufficient (application of 5 mg Zn per kg soil). Soil samples passed through a 2 mm sieve and washed five times with double-distilled deionized water to remove soluble salt and organic matter. Soil samples were dried at room temperature (20-25 oC), and the necessary nutrients were added. Seeds were sown in polyethylene pots containing 4.5 kg of prepared soil after disinfection. To prevent nitrogen (N) deficiency, ammonium nitrate (NH4NO3) was applied to the treatments every 14 days. Daily irrigation was carried out using double-distilled deionized water to maintain field capacity. Sampling of root and shoot was performed at 30% of the heading stage and from the seeds after complete ripening. Finally, the concentration of Zn, Fe, Cu and Mn was measured in root, shoot and grain. The relative ability of Zn, Fe, Cu and Mn translocation from root to the shoot was calculated in the studied cultivars. Analysis of variance was performed using SAS software and comparison of means was done at 1% Duncan’s multiple range test (DMRT). Results and discussion:The results revealed that the concentrations of root Fe and Cu increased by 37.97% and 7.9%, respectively, under soil Zn deficiency. There was also an increase in Fe and Mn concentrations of the grain by 24.58% and 6.33%, respectively. Furthermore, the decrease of Zn in soil resulted in a reduction of Mn concentration in the root by 15%, Fe, Cu, and Mn concentrations in the shoot by 39.44, 28.5, and 16.19%, respectively. Under Zn deficiency condition, Cu concentration in grain (24.51%) decreased. Zn, Cu and Mn concentrations of roots (13.4, 44.88 and 10.32%, respectively) and Fe concentration of grain (6.42%) in Zn-efficient cultivars were higher compared to Zn-inefficient cultivars. In the case of Zn deficiency, Zn-efficient cultivars had a higher concentration of root Fe (18.55%) and grain Zn (11%) than those of the Zn-inefficient cultivars. Comparison of the relative translocation ability of micronutrients from root to shoot in the studied bread wheat cultivars showed that Zn-efficient cultivars had less ability to transfer Zn (53.85%), Fe (29.69%), Cu (21.69%) and Mn (50.17%) compared to Zn-inefficient cultivars (79.77%, 37.68%, 27.65% and 70.91% respectively) under soil Zn deficiency. Conclusions: On average, the Zn-efficient cultivars of bread wheat contained higher concentrations of Zn, Fe, and Mn in root and grain. Moreover, the possibility of using micronutrients in their organs was higher compared to the Zn-inefficient cultivars. Zn-efficient cultivars also had less ability to transfer Zn, Fe, Cu and Mn from root to the shoot. The obtained results can be used for micronutrient biofortification and significant improvements of Zn content in wheat grain and to bring the improved varieties to the field.
Research Article
H. Neisi; A. Khademalrasoul; H. Amerikhah
Abstract
Introduction: Soil erosion is one of the most important forms of soil degradation which topographical characteristics are effective on its occurrence and spatial distribution. Actually, soil erosion is one form of soil degradation that includes on-site and off-site effects and the off-site effect is ...
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Introduction: Soil erosion is one of the most important forms of soil degradation which topographical characteristics are effective on its occurrence and spatial distribution. Actually, soil erosion is one form of soil degradation that includes on-site and off-site effects and the off-site effect is deposition and sedimentation. In recent decades, the potential of soil erosion has been recognized as a serious threat against soil sustainability. Topographical attributes such as slope gradient (S) and slope length (L) are considered as the most important land surface properties which control energy fluxes, overland and intra-soil transport of water and sediment, and vegetation cover distribution within a landscape. The L and S are two main factors in the USLE equation which are meaningfully effective on soil erosion. The development of modern techniques such as geomorphometry has made it possible to quantify these attributes in GIS environments. Geomorphometry or terrain analysis is a computer technology-based science in which morphometric and hydrological attributes are calculated by a series of mathematical algorithms from a digital elevation model (DEM). WaTEM/SEDEM is water and tillage erosion model/sedimentation which is possible to estimate water erosion and also different forms of sediments in the watershed and hydrographical network. The accuracy of DEM in this model is really important and effective on the quality of model outputs.
Material and Methods: Landscape planning tools might help simplify the complexity of soil erosional processes. Furthermore, using predictive tools open up for the possibilities to investigate the effectiveness of different management scenarios on soil erosional responses to make a decision for improving soil properties by application of BMPs. Soil erosion modelling as a landscape planning tool is an efficient way to investigate the on-site and off-site effects of erosion. At the same time this tool opens up for an opportunity to perform scenario analysis with the respect to the placement of structural BMPs such as buffer zones. The soil erosion model WaTEM has been used as a landscape planning tool. WaTEM is a spatially distributed empirical model to simulate both erosion and deposition by water explicitly in a two dimensional landscape. This soil erosion model has been used as a landscape planning tool. The Universal Soil Loss Equation (USLE) has been developed to predict sheet and rill erosion. Desmet and Govers (1996) showed that using the 2D-calculation of the LS-factor in WaTEM made it possible to predict rill, interrill, and ephemeral gully erosions. In this study the spatial distribution of soil erosion and deposition affected by different LS-factors were investigated using WaTEM/SEDEM model that including rainfall erosivity (R-factor), soil erodibility (K-factor), topography (LS-factor), crop cover (C-factor) and management (P-factor) as GIS layers (.rst format) in Zoji watershed located in Shush (Khuzestan province). The WaTEM/SEDEM includs three main input parts, the first part consist of DEM, parcel map and stream network. The second part is CP factor and the third part consist of LS algorithms. The variations of LS algorithms are a milestone of this model and provide the possibility to define different LS situations in the watershed. In order to evaluate the effectiveness of LS algorithms, in the simulation process Govers, McCool, Nearing and Wishmeier-Smith algorithms were defined for WaTEM/SEDEM model.
Results and Discussion: Results of correlation (R=0.78) showed that topography had the highest effect on soil erosion distribution. Also our results illustrated that the amount of deposition in forms of total sediment production (TSP), total sediment deposition (TSD) and total sediment export (TSE) between different LS algorithms were disparate. Based on prediction of rill and interrill erosion, Nearing algorithm was the best LS algorithm and Govers algorithm was convenient in order to monitor and evaluate gully erosion. This study results showed that Govers algorithm estimated the highest amount of TSP because the Govers algorithm basically estimate the sheet, rill, interrill and gully erosion, therefore the amount of sediment in this algorithms is the highest one. For Govers algorithm the estimated TRE was the highest because the Gully erosion also was in the calculations and mostly the volume discharge originated from Gully was significantly higher than sheet and rill erosion. Therefore, regarding the types of prevailing erosion in each case the type of selected LS algorithm to simulate soil erosion and deposition distribution should be different.
Conclusion: In general, WaTEM/SEDEM and its LS algorithms is a suitable tool to select and apply best management practices (BMPs) to control soil erosion at critical areas and hotspots. Our results confirmed that regarding the selection of each LS algorithm, the amount of sediment components and their distribution could be different.
Research Article
A. Fallah Nosrat Abad; M. Habibi
Abstract
Introduction: According to WHO and FAO studies, the diseases caused by contaminated foods are of the most widespread threats to human health in developing and developed countries. Therefore, in recent years, researchers have been trying to use soil microorganisms to solve this problem and maintain the ...
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Introduction: According to WHO and FAO studies, the diseases caused by contaminated foods are of the most widespread threats to human health in developing and developed countries. Therefore, in recent years, researchers have been trying to use soil microorganisms to solve this problem and maintain the health of plants and the environment. Phosphorus after nitrogen, is a major macronutrient in plants which controls the growth, seeding and fruit production and involves in basic biological functions such as cell division, nucleic acids synthesis, photosynthesis and respiration and energy transfer. However, high amount of soluble inorganic phosphate is annually applied to the soil as chemical fertilizer but a large portion of it is immobilized rapidly after application due to phosphate fixation by aluminum, calcium, iron, magnesium and soil colloids and becomes unavailable to plants. The use of biological agents especially phosphate solubilizing microorganisms, can play an important role in supplying plant nutrients and improves crop health and productivity without causing any harm in agricultural and natural ecosystems. Bacteria and fungi are the two important groups of phosphate solubilizing microorganisms. Phosphate solubilizing bacteria in soil include Rhizobium, Bacillus, Pseudomonas, Agrobacterium, Achromobacter, Enterobacter and Burkholderia, and the most important ones i.e., Bacillus sp. and Pseudomonas flourescens. Material and Methods: In order to evaluate the effect of Thiobacillus, sulfur and phosphorus applicationon population of phosphate solubilizing bacteria in soil, a field experiment was conducted at Zarghan Agricultural and Natural Resources Research Center of Iran in a factorial, based on complete randomized block design with 3 replications. Treatments consisted of three levels of sulfur fertilizer with biofertilizer containing Thiobacillus bacteria (without sulfur and biofertilizer containing Thiobacillus (S0), application of 500 kg S + 10 kg biofertilizer containing Thiobacillus (S1), 1000 kg S + 20 kg biofertilizer containing Thiobacillus (S2) and 2000 kg S + 40 kg biofertilizer containing Thiobacillus (S3) per hectare), three levels of triple super phosphate (without phosphorus (P0), 100% (P1) and 65% (P2) percent phosphorus recommended based on the soil test) in two corn planted and not planted states. After harvesting, 72 soil samples were collected from each plot and transferred to the biology laboratory of soil and water research institute of Karaj. Soil samples were stored in sterile conditions at 4◦C. In order to isolate phosphate solubilizing bacteria, 10 gram of soil from each sample was suspended in 90 ml of sterilized water to make 1:10 dilution. Then, series of dilution were made (101 – 107) and 0.1 ml of suspensions of the diluted soil sample were transferred to petri dishes containing pikovskaya medium and incubated at 28- 30˚C. To identify PSP from halos surrounding characterized colonies was used and counting was performed 1-14 days after cultivation. The colonies were isolated on the basis morphological characteristics such as shape, color and size and then purified by linear culture. Finally, 60 strains were purified that were used to compare phosphate solubilizing capability. Results and Discussion: The results of this study showed that the main and interaction effects of sulfur fertilizer and biofertilizer treatments of Thiobacillus, phosphorus and plants on the population of phosphate-solubilizing bacteria (cells per gram of dry soil) in Pikovskaya medium were significant at 0.01 level probability. The highest population of bacteria was obtained at the lowest level (S1). Increasing the level of sulfur fertilizer and Thiobacillus biofertilizer decreased the population of phosphate-solubilizing bacteria and the highest level of sulfur and Thiobacillus biofertilizer led to the lowest bacterial population. Also, the study of phosphorus application on the bacterial population showed that phosphorus fertilizer at both levels significantly increased the bacterial population compared to the control (no application phosphorus). The best fertilizer treatment for phosphorus application was P1 which had the greatest effect on bacterial population compared to P2 treatment in Pikovskaya environment. In this experiment, the population of bacteria in corn planted conditions was higher than in non-planted conditions and this population increase was observed in almost all different levels of sulfur and phosphorus fertilizers. The highest bacterial population was observed in combined treatment of S1P2 under corn planted conditions. The results of microscopic, physiological and biochemical tests of the strains showed that all 60 bacterial strains were capable to form clear zone in Pikovskaya medium. Among them, 15 strains (7, 3, 2 and 3 strains belonging to Bacillus megaterium, Bacillus subtilis, Bacillus cereus and Pseudomonas fluorescent, respectively) had higher phosphate solubility than the others.
Research Article
Irrigation
A. Aliverdi; S. Karami; H. Hamami
Abstract
Introduction: Since rainfall occurs often in the fall and winter, water is an important limiting factor to subsequent growing crops especially those in hot seasons like soybean. Therefore, there is a growing focus on increasing water use efficiency in crops in recent years. Recently, an irrigation technique ...
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Introduction: Since rainfall occurs often in the fall and winter, water is an important limiting factor to subsequent growing crops especially those in hot seasons like soybean. Therefore, there is a growing focus on increasing water use efficiency in crops in recent years. Recently, an irrigation technique so-called magnetized water has been introduced to increase water use efficiency. The researchers have reported that the physical and chemical properties of water including electrical conductivity, volatility, pH, solubility, surface tension, and viscosity can be affected by its passage through the magnetic field. Subsequently, these changes lead to alterations in soil electrical conductivity, soil nutrient mobility, soil water holding capacity, water passage through the soil profile and soil pH. Increased water use efficiency in soybean (11%) and many leguminous crops have been demonstrated through their irrigation with magnetized water. However, those studies have provided no information about the status of bacterial nodulation on legume root in such an irrigation method. Therefore, the main purpose of this study was to investigate the effect of irrigation with magnetized water on five soybean varieties on their symbiosis with specific bacteria (Bradyrhizobium japonicum). Materials and Methods: The experiment was conducted in the open air at the Bu Ali Sina University of Hamedan in 2018. A completely randomized design with two factors (soybean cultivar and irrigation water type) and eight replications was applied. The soybean cultivar had five levels (Amir, Zan, Saba, Kosar, and Hobbit) and irrigation water type had two levels (untreated and magnetically treated water). An equal volume of water (1 liter) was added to each pot every two days. Before adding water to pots for the irrigation with magnetized water, we passed it through a magnetic tube with a 35 cm long, 1-inch radius and a 0.68 T magnetic field intensity. On August 26, the plants of the half of replications were harvested to measure shoot dry weight, root dry weight, number of nodules, nodule dry weight, shoot nitrogen content and root nitrogen content. On September 10, the plants of the other half of replications were harvested to measure individual seed yield and its components (number of pods per plant, number of seeds per pod and 100-seed weight). By dividing the seed yield obtained from each pot to the total volume of water added to each pot during the growing season, water use efficiency can be calculated. Results and Discussion: The soybean seedlings irrigated with magnetized water were green 1 to 2 days earlier than those irrigated with untreated water. The number of seeds per pod was not affected by soybean cultivar, irrigation water type, and their interaction. In other traits, the simple effects of soybean cultivar and irrigation water type and their interaction were significant at the 5% level of probability. The cultivars of Amir and Saba irrigated with magnetized water led to a higher shoot dry weight to root ratio, indicating the allocation of more resources to the shoot than to the root. The number of nodules formed on the root of all soybean cultivars (Amir (33.7%), Zan (55.3%), Saba (40.1%), Kosar (62.7%) and Hobbit (51.6%)) increased when they were irrigated with magnetized water. However, only in Zan (0.70%) and Kosar (45.1%), irrigation with magnetized water significantly increased the dry weight of nodules. The individual seed yield in all soybean cultivars (Amir (34.8%), Zan (35.1%), Saba (43.4%), Kosar (26.8%) and Hobbit (21.3%)) was significantly increased by irrigation with magnetized water, indicating an improved water use efficiency in soybean irrigated with magnetized water. Based on previous research, the most suitable soil pH range for bacterial growth and activity was found to be between 6.5 and 7.0. On the other hand, other researchers have shown that irrigation with magnetized water reduces the soil pH by approximately 0.5 units. Hence, in our experiment, irrigation with magnetized water probably caused the initial soil pH which was 7.6 to be closer to the optimal range for bacterial activity. Also, according to previous study, bacterial activity is also dependent on soil dry conditions. On the other hand, other researchers have shown that irrigation with magnetized water increases soil water storage capacity due to reduced water vaporization. Therefore, in our experiment, irrigation with magnetized water probably provided good moisture conditions for bacterial activity. Conclusion: The results showed that the irrigation of soybean with magnetized water improved its symbiosis with its specific rhizobium. Improved symbiosis increased plant seed yield and water use efficiency. Therefore, improved symbiosis by irrigating soybean with magnetized water can reduce the reliance on nitrogen fertilizer application in this plant. It can also improve the status of soil fertility for other crops in crop rotation.
Research Article
Soil science
M. Zangiabadi; manoochehr gorji; P. Keshavarz
Abstract
Introduction: Soil quality can be considered as a comprehensive index for sustainable land management assessment. Studying the most important soil physical properties and combining them as an index of soil physical quality (SPQI) could be used as an appropriate criteria for evaluating and monitoring ...
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Introduction: Soil quality can be considered as a comprehensive index for sustainable land management assessment. Studying the most important soil physical properties and combining them as an index of soil physical quality (SPQI) could be used as an appropriate criteria for evaluating and monitoring soil physical changes. In this regard, this study was conducted to determine the most important soil physical properties and calculate the SPQI of medium to coarse-textured soils of Khorasan-Razavi province.
Materials and Methods: Torogh Agricultural and Natural Resources Research and Education Station of Khorasan-Razavi province is located in south-east of Mashhad city (59° 37' 33"-59° 39' 10" E, 36° 12' 31"-36° 13' 56" N). Soil texture variability in this research station is one of its outstanding features. The soil textures are classified into loam, silt loam, silty clay loam, clay loam, and sandy loam. More than 90% of agricultural soils in Khorasan-Razavi province are classified in these five texture classes. Using the available data, 30 points with different soil textures and OC contents were selected. The soil samples were collected from 0-30 cm soil depth at each point. Intact soil cores (5 cm diameter by 5.3 cm length) were used for sandbox measurements, and disturbed soil samples were used to determine other properties. Required laboratory analysis and field measurements were conducted using standard methods. In this research, 35 soil physical properties as total data set (TDS) including: soil moisture release curve (SMRC) parameters, particle size distribution and five size classes of sand particles, soil bulk and particle density, dry aggregates mean weight diameter (MWD) and stability index (SI), S-index, soil porosity and air capacity, location and shape parameters of soil pore size distribution (SPSD) curves, relative field capacity (RFC), plant available water measured in matric pressure heads of 100 and 330 hPa for the field capacity (PAW100 and PAW330), least limiting water range measured in matric pressure heads of 100 and 330 hPa for the field capacity (LLWR100 and LLWR330), integral water capacity (IWC) and integral energy (EI) of different soil water ranges were measured and calculated for 30 soil samples. The most important soil physical properties were selected using principal component analysis (PCA) method by JMP (9.02) software. Selected physical properties as minimum data set (MDS) were weighted and scored using PCA results and scoring functions, respectively. In this study, three types of linear scoring functions were used. The soil physical quality index (SPQI) was calculated by two scoring and two weighting methods for each soil sample and the differences between these four SPQIs were tested by sensitivity index.
Results and Discussion: Principal component analysis results showed that among 35 soil physical properties (TDS) which were studied at this research, six properties of mean pore diameter (dmean), PAW100, total porosity (PORT), EI LLWR330, SI and PAW330 accounted for about 90% of the variance between soil samples. Weight of the selected properties (MDS) was calculated by the ratio of variation in the data set explained by the PC that contributed the selected property to the total percentage of variation explained by all PCs with eigenvalue ˃ 1. In this research, the parameters of PAW100, total porosity (PORT), SI and PAW330 were scored using scoring function of more is better, EI LLWR330 was scored using scoring function of less is better and dmean was scored using scoring function of optimum by two scoring methods with score ranges of 0.1-1 and 0-1. Considering unweighted and weighted MDS and two ranges of scores, four SPQIs were calculated for each soil sample. The results showed that SPQIs which were calculated by the MDS derived from PCA method and scoring weighted MDS at the range of 0-1, had the highest sensitivity index and could represent the differences between the studied soil samples better than other SPQIs. By this method, maximum and minimum SPQI values for the studied soils were 0.82 and 0.12, respectively. SPQI is a relative comparison criterion to quantify the soil physical quality which could be applied only for the studied soils with specific characteristics.
Conclusion: The results of this research showed that minimum data set (MDS) explained about 90% of the variance between soil samples. Combining MDS into a numerical value called soil physical quality index (SPQI) could be used as a physical comparison criterion for the studied soils. From the SPQI based on the MDS indicator method, soil quality was evaluated quantitatively. Soil samples with grade I, II, III, and IV accounted for 10%, 36.7%, 30%, and 23.3% of the soil samples, respectively.
Research Article
M. Anoosha; A. Forghani
Abstract
Introduction: Copper and zinc are two of the most important microelements affecting plant growth which can be influenced by many factors. The adsorption processes play a determinative role in solubility of copper and zinc elements in the soil solution and, therefore, their availability to plants. Organic ...
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Introduction: Copper and zinc are two of the most important microelements affecting plant growth which can be influenced by many factors. The adsorption processes play a determinative role in solubility of copper and zinc elements in the soil solution and, therefore, their availability to plants. Organic matter is one of the most important factor that have an significant role on the absorption and desorption of elements in the soil. These materials are divided into humic and non-humic groups. Humic substances are divided into three groups of fulvic acid, humic acid and humic, based on their resistance and solubility in acid and base. Humic acid with a medium molecular weight and color is soluble into base and insoluble into acid, and has a medium resistance against the microbial attack. It forms the most important organic part of the soil and is capable to adsorb metals. The purposes of this study were to extract soil humic acid, study the adsorption of metals on the surface of humic acid and to determine the metals adsorption coefficients using adsorption isotherm models. Materials and Methods: Sampling was done from forest areas of northern Iran. Some physical and chemical properties of the studied soil were determined. Then, the humic acid of the soils was extracted by 0.1 M NaOH and 6 M HCl, and purified by 0.1M HCl+0.3M HF. Functional group, E4/E6 ratio (Optical density or absorption of dilute solutions at wavelengths of 465 and 665 nm), and humification index of the extracted humic acid were measured. Some other properties of the extracted humic acid have also been analyzed. To study the adsorption isotherms of Zn and Cu in the presence of humic acid, solutions with concentrations of 10, 20, 40, 60 and 80 mg/L of ZnCl2 (zinc adsorption testing) and CuSO4 (copper adsorption testing) were prepared, respectively in a 0.01M Ca(NO3)2 background solution, and added to 250 g of humic acid. The samples were shaken for 12 hours (based on the time of equilibrium) at pH=5 and 25 °C in incubator shaker, then the samples were centrifuged and the supernatant was passed through filter paper and measured using atomic adsorption spectrophotometer device. The difference between initial concentration and final concentration identified the amount of adsorbed element. Results and Discussion: The results of the acidic functional groups measurement in the humic acid samples revealed that the most of total acidity (60%) was due to the presence of phenolic groups while the carboxylic groups were responsible for the remaining (40%). Phenolic groups were abundant in the primary stages of the decomposition of humic materials. Since the soil used for extracting humic acid was covered with broad leaf trees and the continuous entry of organic matter into it (the fall of leaves) lasted for many years and due to the low temperature of the soil in part of the year, it can be said that a significant part of the soil organic matter is in the primary or middle stages of humification and the phenolic OH groups/carboxylic groups ratio in the humic acid extracted from them was high. The equilibrium time for adsorption of both metals occured at 12 h to achieve maximum adsorption level in the presence of humic acid. The obtained experimental data were fitted to three models of Langmuir, Freundlich, and Tampkin. The accuracy of mentioned models to fit data were estimated based on the detection coefficient (R2) and the roots of mean square error (RMSE). The results showed that the Freundlich model with higher detection coefficient and lower roots of mean squared error describes the adsorption of copper and zinc elements, well. To better compare the adsorption of the elements by humic acid, Langmuir's b parameter (Expresses maximum adsorption) can be used. The maximum adsorption of copper (23.04 mg/g) by humic acid was higher than zinc adsorption (13.8 mg/g). This trend is consistent with the Irving–Williams series of divalent elements: Mn < Fe < Zn < Co < Ni < Cu. It is generally believed that humic acid is a good complexing agent for many metal ions and its binding to metal ions can improve the adsorption. Significance differences were tested by a parametric 𝑡-test or 𝐹 statistics in ANOVA (analysis of variance). There was a significant correlation between the maximum adsorption of metals (b) and the properties of humic acid at a probability level of 5%.
Research Article
H. Bondar; Mohammad Mousavi baygi; B. Ghahraman
Abstract
Introduction: In arid and semi-arid regions such as Iran, water is the most important limiting factor in economic development, and its management is of high importance. In recent years, due to irrigation expansion, low productivity in agricultural sector, and the rainfall shortage, water resources have ...
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Introduction: In arid and semi-arid regions such as Iran, water is the most important limiting factor in economic development, and its management is of high importance. In recent years, due to irrigation expansion, low productivity in agricultural sector, and the rainfall shortage, water resources have been adversely affected in Iran. Undoubtedly, global warming in arid and semi-arid countries has increased the need for aquatic plants and the severity of drinking water shortages, making it more difficult to plan for limited resources. Studying the spatial and temporal changes of evapotranspiration is essential for the comprehensive planning of water management in Mashhad and providing an appropriate solution for optimal use of available water resources. However, spatiotemporal analysis of evapotranspiration regardless of the phenomenon of global warming and thermal island leads to unrealistic results. Therefore, the aim of this study was to address these shortcomings in previous studies in Mashhad. The specific objectives were: temporal analysis of evapotranspiration in the existing statistical period and estimation of annual evapotranspiration volume with respect to global warming, investigating the effect of global warming factors and thermal island on evapotranspiration and eventually water resources management in Mashhad. Materials and Methods: This study was carried out in Mashhad, city of Khorasan Razavi province with an area of 204 square kilometers, in northeastern Iran. Satellite imagery used for this research was a time series from Landsat 5 (TM sensor), Landsat 7 (ETM +) and Landsat 8 (OLI and TIRS sensors) from 1996 to 2016. The selected images for 2016 consisted of a time series of 13 images and a 16-day interval. After receiving satellite imagery, the performance of atmospheric corrections was evaluated based on FLAASH and TAC methods for reflective and thermal bands, respectively. The radiometric correction of images and reflection calculation of reflection was also conducted for bands 4 and 5 (values of ρ) and radiations of thermal bands10 and 11 (Lsen values) in the ILWIS software environment. Then, the temperature of the vegetation was calculated using different methods of determining the surface temperature (LST). Result and Discussion: The results showed that, on average, NDVI values in urban, mountainous and agricultural classes were 0.39, 0.37, and 0.4, respectively. However, the lowest and largest absolute value of NDVI were, respectively, 0.29 and 0.82, both of which are obtained in agricultural lands. The mean land surface temperature (LST) was 34.2 °C during days, which had a time and spatial variation between 17.9 to 49.4 °C in different regions. The highest and lowest mean LST was observed in urban and mountainous applications, respectively. Urban areas also had a significant difference in LST compared to other land uses due to the type of land cover in urban areas (mainly asphalt, stone, brick, cement, iron, etc.) and activities such as vehicle traffic, smoke and heat from factories and industries. The Split-Window (SW) method gave higher LST values compared with other methods. Then, the single-channel (SC), Improved Mono-Window (IMW) and single-window (MW) methods provided lower amounts of LST. The same trend was observed in almost all land use classes in the study area. It was also found that in urban areas, the strongest correlation between air temperature and LST was calculated by applying SC (R2 = 0.937). In mountainous regions, the highest correlation between air temperature and computed LST was found for the IMW (R2 = 0.951). Similarly, in the agro-rangeland areas, the highest correlation between air temperature and computed LST was obtained by IMW (R2 = 0.953). Conclusion: In the study area, the general trend of NDVI index was declining between 1996 and 2016. Reducing the percentage of vegetation cover in different sectors such as agriculture and rangeland, changing the type of vegetation (crop pattern) in agricultural sector and urban green spaces are the reasons for decreasing NDVI index in Mashhad region. The average LST was 34.2 °C in the days, which had a time and spatial variation between 17.9 to 49 °C in different regions. The maximum and minimum average LST was observed in urban and mountainous regions, respectively. The SW provided higher LST values compared to other methods. The SC, IMW and MW methods, however, provided lower LST values. The same trend was observed in almost all land use classes in the study area. It was also found that in urban areas, the highest correlation between air temperature and LST was found by using SC (R2=0.937). In mountainous regions, the strongest correlations between air temperature and LST was observed by using the Split Window Algorithm (SW) Improved Mono-Window (IMW) (R2=0.951). Similarly, in the agricultural and rangeland areas, the highest correlation between air temperature and LST was observed using the Split Window (SW) Improved Mono-Window (IMW) (R2 =0.953).
