Research Article
sabah mohamadi; Rasool Ghobadian; mahmood kashefipoor
Abstract
Introduction: It is so important for engineers to be able to predict the places in which deposition and scouring occurs. In recent two decades using the numerical models arecommon for simulating flow and sediment transport. Numerical models are valuable tools for estimating flow conditions and sediment ...
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Introduction: It is so important for engineers to be able to predict the places in which deposition and scouring occurs. In recent two decades using the numerical models arecommon for simulating flow and sediment transport. Numerical models are valuable tools for estimating flow conditions and sediment transport, and are widely applied in water resources management. For this reason, many researches focus on modeling and simulation of flow on a mobile bed in natural and alluvial rivers. Analyzer of sediment transport is one of the most complicated topics in sediment and river hydraulic.
Material and Methods: In this research a one dimensional, unsteady, hydrodynamic model is developed which can be used for simulating flow and sediment transport as semi-coupled model in river systems. In this research, the Saint- Venant’s first order partial differential hyperbolic equations are numerically solved using the Visual Basic program for river systems. In this research study a semi implicit finite difference scheme is developed to solve the Saint- Venant equations for unsteady flow. The linear equations are produced based on the partial differential equations and the staggered technique, so it is possible to employ the tri-angular matrix algorithm (TDMA) to solve them, with this algorithm the time of running model being minimum due to the least mathematical computations. The matrix form of the linearized momentum and continuity equations for a channel with upstream and downstream boundary conditions is provided. Another technique used to solve the matrix of the linear equations is Influence Line Technique (ILT). Base flow discharge and depth in each branch are introduced into the model as the initial conditions. To avoid divergence in numerical calculations, the downstream end discharge of each branch is calculated using initial flow depth and stage-discharge or Manning’s relationship. At the junctions, the upstream discharge is calculated using the algebraic sum of the discharges of the downstream branches and vice-versa; this process is continued up to the last branches at the upstream of the river system. After solving the above equations, the computed hydraulic parameters in this part are sent to the sediment transport segment. In the sediment subroutine the bed and suspended dynamic equations are discretized by finite volume method, and solved with flow equations as semi-coupled scheme. In this study the bed and suspended load rates are individually solved. The dynamic advection- dispersion equation and the bed load differential equation were applied to calculate the suspended sediment concentration and bed load transport, respectively. The Exner equation is then used to predict the changes in the river bed elevations innon-equilibrium conditions. Because ofthe nature, the sediment transport is often in non-equilibrium form, in this study, the non-equilibrium Exner equation is used to compute the bed elevations, unlike many of the known models. The use of non-equilibrium method due to the complexity of the solution and the presence of non-equilibrium parameters such as coefficients of the adaptation length and recovery is very difficult.
Results and Discussion: In non-equilibrium conditions, the numerical models have high sensitivity to two parameters including, the adaptation length coefficient for bed load and recovery coefficient for suspended load, with the sensitivity analysis for these coefficients being carried out in this research. In this study, a sensitivity analysis was performed on these parameters using developed numerical model. The developed model has this ability to simulate flow and sediment transport in complex and loop river systems. Finally, the model was simulated for the Chaudhry loop river systems. Thisriver system has 9 branches that form the loop. All channels have rectangular sections and their flows are sub-critical. The upstream boundary condition is an unsteady hydrograph with peak discharge of 250 cubic meters per seconds and base time of 8 hours. The calculated stage and discharge by the model (using Manning’s equation) was supplied to the model as a downstream boundary condition at last node. The model outputs are discharged hydrographs on different sections of each channel. The developed model has good ability to simulate the flow and sediment transport in river systems. The result showed that by selecting the adaptation length coefficient, equivalent to a multiple of 1 to 3 times the distance between cross sections, the results of the numerical model can be more realistic. Also it was concluded that empirical equation of Lin(1984) used for the recovery factor of the suspended load.
Research Article
Hojjat Ahmadi; Mohammad Hemmati; Mehdi Motallebian
Abstract
Introduction: Coastal aquifers are major source of freshwater in many parts of the world. Saltwater intrusion is a serious environmental issue since 80% of the world’s population live along the coast and utilize local aquifers for their water supply.Under natural conditions, these coastal aquifers ...
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Introduction: Coastal aquifers are major source of freshwater in many parts of the world. Saltwater intrusion is a serious environmental issue since 80% of the world’s population live along the coast and utilize local aquifers for their water supply.Under natural conditions, these coastal aquifers are recharged by rainfall events, and the recharged water flowing towards the ocean would prevent saltwater from encroaching into the freshwater region. However, over exploitation of coastal aquifers has resulted in reducing groundwater levels (hence reduced natural flow) and this has led to severe saltwater intrusion. Saltwater intrusion from the sea into below the freshwater of aquifer impairs the quality of these resources. Cause ofthe complexity of saltwater intrusion issues and generally they cannot be solved analytically, so numerical methods can be useful tools for simulation and prediction of salt water intrusion.
Materials and Methods: CTRAN/W is a finite element software product that can be used to model the movement of contaminants through porous materials such as soil and rock. The comprehensive formulation of CTRAN/W makes it possible to analyze problems varying from simple particle tracking in response to the movement of water, to complex processes involving diffusion, dispersion, adsorption, radioactive decay and density dependencies. SEAWAT is a three-dimensional variable density groundwater flow and transport model developed by the USGS based on MODFLOW and MT3DMS. SEAWAT is based on MODFLOW and MT3DMS. SEAWAT includes two additional packages: Variable-Density Flow (VDF) and Viscosity (VSC).In this study, the precision of CTRAN / W and SEAWAT models to simulation and prediction of saltwater wedge were investigated in three states: a) steady state salt-wedge data observed underdifferenthydraulic gradient conditions; b) transient salt-wedge data observed underintruding-wedge conditions; and c) transient salt-wedge data observed under receding-wedge conditions. Both models were initially calibrated and then the models were performed for the above conditions. The simulation results of the two models with the experimental results of Goswami and Clement (2007) have been compared. For comparing the measured data and simulated data, statistical indicators were used: root-mean-square error (RMSE), a measure of Nash-Sutcliffe (CE), the Correlation Coefficient (R^2), the ratio of difference (r) and the General Standard Deviation (GSD).
Results and Discussion: In this study, the precision of CTRAN / W and SEAWAT models to predict saltwater wedge wasinvestigated. At first step, both models were calibrated and the best values for longitudinal and transverse dispersion were obtained 0.5 and 0.05, respectively.Then simulation was performed with both models for all three modes(a- steady state salt-wedge data observed underdifferenthydraulic gradient conditions; b- transient salt-wedge data observed underintruding-wedge conditions; and c- transient salt-wedge data observed under receding-wedge conditions). The results showed thatCTRAN/W and SEAWAT models have high precision for simulation of position and movement of saltwater wedge in steady state with average of root mean square error (RMSE) equal to 1.05 and 1 cm, respectively and Both models have a higher estimate than the actual value for a steady state. As well as for transient state under the underintruding-wedge conditionsCTRAN/W and SEAWAT models have high precisionwith average of root mean square error (RMSE) equal to 0.65 and 0.44 cm, respectively and other statistical indicators were acceptable. The results of prediction of position and movement of saltwater wedgeunder receding-wedge conditionswith average of root mean square error (RMSE) equal to 0.54 and 0.56 cm, respectively provided acceptable estimates of both models. Finally, in order to determine the accuracy of the models in estimating the flow rate from the source of fresh water to the source of salt water, a comparison was made between the results of the models and the laboratory data, which showed that The CTRAN/W revealed appropriate estimation of amount of transferring discharge from freshwater reservoir to saltwater reservoir in compared with SEAWAT model. In general, according to statistical indicators, the results of both models were acceptable
Conclusion: The results showed thatCTRAN/W and SEAWAT models have high precision for simulation and prediction of position and movement of saltwater wedge with average of root mean square error equal to 0.67 and 0.58 cm (less than 10% of the average of measured data), respectively. The CTRAN/W revealed appropriate estimation of amount of transferring discharge from freshwater reservoir to saltwater reservoir in compared with SEAWAT model. In general, according to statistical indicators, the results of both models were acceptable.
Research Article
ommolbanin bazrafshan; zahra gerkani nezhad moshizi
Abstract
Introduction: Agriculture sector, as the key consumer of fresh water resources throughout the world, is progressively more squeezed by the requirements ofother contemporary society areas and threatened by potential climatic change. Irrigation is the major part of agricultural water usage in Iran, which ...
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Introduction: Agriculture sector, as the key consumer of fresh water resources throughout the world, is progressively more squeezed by the requirements ofother contemporary society areas and threatened by potential climatic change. Irrigation is the major part of agricultural water usage in Iran, which consumes 90% of total agricultural water use. Increasing competition for water resources use, in conjunction with climate factors change may have significant effects on water availableness for agricultural production. Climate change has already affected components of the hydrologic cycle, such as precipitation redistribution, runoff and groundwater cycling. The water footprint of a crop is the volume of freshwater both consumed during the crop production process, and it has three components consist of green water footprint (the volume of the precipitation consumed in crop production); blue water footprint (the volume of runoff or groundwater consumed in crop production); grey water footprint (the volume of freshwater that is required to assimilate the load of pollutants during the crop production process) and white water footprint (the volume of water losses during the irrigation process).
Materials and Methods: The Hormozgan is located in a hyper -arid region that is impressionable to the potential impact of climate. The data used in this research consist of climate data and agriculturaldata. The climate data (2002-2016) was taken from the Iran Islamic Republic Meteorological Organization including monthly average maximum temperature, monthly average minimum temperature, relative humidity, precipitation, wind speed and sunshine hours. The agricultural data consists of, cultivation area, crop yield and soil type weretaken from the Agricultural-Jihad Bureau of Hormozgan Province. CROPWAT model is used to estimate crop water and crop irrigation requirements using meteorological, crop and soil dates. Effective precipitation (Pe) values were calculated by USDA method and crop evapotranspiration (ETc) was calculated by FAO-Penman-Montieth method. The WFGreen (effective precipitation), WFBlue (net irrigation requirement) and WFWhite (irrigation water losses) water footprints (WF) of potato production were estimated for Hormozgan. The Mann-Kendall (M-K) trend test is used to analyze the trends and abrupt changes of the climatic factors.
Results and Discussion: The total tomato WF was estimated 0.639 m3/kg in the Hormozgan province that Jask and Bastak have maximum and minimum with 1.54 and 0.66 m3/kg, respectively. The share of green, blue and white water footprint estimated 5, 18 and 77 percent, respectively. The largest shares of water footprint were observed in Bandar- Abbas (27%). The sum of the water footprint it is 19.2 MCM, which is more than 95% of the total water footprint (70.2 MCM) in the whole province. In Bashagard a large share of water footprint is related to the blue water footprint despite having a considerable amount of seasonal precipitation. Regarding the dominance of autumn precipitation in it, changing the vegetation genotype and cultivation of varieties resistant to water deficit will increase the plausibility of dry farming and increases share of the green water footprint. The white water footprint has the largest shares (77%) of while subsidence is so serious in more than 36 plains. Hormozgan province has low precipitation and high water demand. On the other hand, improper irrigation management (number of events and the volume of irrigation) has led to decreased tomato performance in these regions and larger water footprint. The share of blue water footprint is 18% that 4 times more than from WFGreen. The considerable amounts of precipitation in this province, strategies such as cultivation of new genotypes more adapted to the wet periods, shortening the flowering period of Saffron with the aim of avoiding the dry period at the end of the growing season can be considered to reduce the share of the blue water footprint and reduce the share of the green and white water footprints. Total consumed and exported virtual water volume from the region are 10.8 MCM to 28 million Rials per year. The export of these crops imports the most pressure on groundwater and surface water resources of the region. The M-K test results of climatic factors throughout the 2002–2016 study periods in Hormozgan showed that sunshine hours during the tomato growth period experienced downward trends for the M-K statistics values were less than zero and the downward temperature trend reached statistical significance. The declining temperature and sunshine hours would result in lower crop evapotranspiration (ETc) and agricultural water consumption, while CWR donot have any trend. The trend analysis shows that the green, blue and white water footprint had significant increasing trends in the central part. Increasing theyield would result in lower water footprint.
Conclusion: Ground water depletion and water shortage are two problems in Hormozgan province which have occurred due to the irregular use and inappropriate management of demand and supply of water in agricultural sector. The water footprint (WF) of crop production is a comprehensive indicator that can reflect water consumption types, quantities and environmental impacts during the crop growth period. This study assesses interannual variability of green, blue and white WFs of tomato production in Hormozgan from 2001 to 2015. The share of green, blue and white WFs in the region is 5, 17 and 77 percent and 10.5 MCM year-1. Under the combined influence of climate change and water footprint variation, WFCs weredecreasing trends. In contrast, sunshine hours had decreasing trend. The statistical analysis revealed that interannual variabilities of WFCs were caused by both climatic and non-climatic factors.
Research Article
Hadis Hatami; Amir Fotovat; Akram Halajnia
Abstract
Introduction: After nitrogen, phosphorus is the second most frequently limiting macronutrient for plant growth. It participates in metabolic processes such as photosynthesis, energy transfer and synthesis and breakdown of carbohydrates. H2PO4- and HPO42- are two forms of this element which are present ...
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Introduction: After nitrogen, phosphorus is the second most frequently limiting macronutrient for plant growth. It participates in metabolic processes such as photosynthesis, energy transfer and synthesis and breakdown of carbohydrates. H2PO4- and HPO42- are two forms of this element which are present in the soil solution in the available form. Due to phosphorus reactions with soil components (oxy or hydroxides of Fe and Al in acidic soils and Ca2+ and Mg2+ ions in calcareous soils), the availability of this element is a limiting factor for production of agricultural crops in the whole world. To minimize this problem it is needed to improve the recycling of phosphorus and develop new technologies to reduce phosphorus losses and increase its effectiveness. In the recent decades, layered double hydroxides (LDH) have been extremely used as an effective sorbent for organic and inorganic anions sush as phosphate. Furthermore, some studies have suggested that the phosphate form LDH is applicable as a slow release phosphate fertilizer. Therefore, the objective of the present study was to compare the effect of using Zn-Al LDH and triple superphosphate (TSP) as fertilizers on the availability of phosphorus over time in a calcareous soil.
Materials and Methods: At the first, nitrate containing Zn-Al LDH (N-LDH) was synthesized by urea hydrolysis method and then ion exchange method was used for the phosphate anions intercalation into N-LDH. In this process, 5.0 g of the N-LDH was suspended in 1000 mL of a solution 0.05 mol/L of K2HPO4. The suspension was kept for 12 h at room temperature (25 °C) under stirring. Afterwards, the material was filtered, washed with distilled water and dried at 70 °C for 18 h. The LDH sample produced by the ion exchange method was nominated as P-LDH. To compare the effects of P-LDH and TSP application on the availability of soil phosphorus, an incubation experiment was carried out using a completely randomized factorial design with two sources of phosphorus (P-LDH and TSP), four levels of phosphorus (0 (control), 18, 45 and 90 mg P kg-1), eight levels of time (1, 5, 10, 20, 40, 70, 100 and 150 days) and three replications. Available phosphorus and zinc, pH and EC of samples were measured at the end of each time period. Available phosphorus was extracted with 0.5 M sodium bicarbonate and phosphorus concentration was determined using the ascorbic acid method. Available zinc content was determined by atomic absorption spectrometry following extraction of the sample by DTPA-TEA method. Also, pH and EC were measured in water (soil/water ratio 1:2). Data analysis was performed by MSTAT-C software, and the means were compared at α꞊5% by Duncan test.
Results and Discussion: The results showed that the use of P-LDH and TSP significantly improved available phosphorus compared to control treatment. However, in contrast to TSP, available phosphorus in P-LDH treatments increased with increasing of time, up to significant difference which was observed between the two sources after 150 days. This result is probably due to slow release of phosphorus from P-LDH and reduction of phosphorus reactions with different soil components. Moreover, available zinc was higher for P-LDH treatments than TSP treatments as dissolution of P-LDH may concurrently release zinc ions into the soil solution. It seems that the application of P-LDH not only increased the availability of phosphorus but also improved available zinc. Therefore, due to the zinc deficiency in calcareous soils, P-LDH can be used as a suitable dual purpose fertilizer for these soils. However, the possibility of Zn toxicity risk due to higher level of LDH application in soil is not ruled out. It is worth mentioning that the variation of pH and EC values in P-LDH treatments showed no significant difference compared to TSP tratments. In other words, application of P-LDH increased soil available phosphorus and zinc without any negative effect on soil pH and EC.
Conclusions: The results of this study illustrated that the P-LDH probably can be used as a slow release phosphate fertilizer to increase the phosphorus efficiency; however, care should be taken as the high levels of this fertilizer may not be recommended due to the high zinc content. It should be noted that the high levels of phosphorus are not appropriate for all phosphorus fertilizers but in the present study we used the different levels of fertilizers because the behavior of P-LDH was not clear for us.
Research Article
fateme Hasanzadeh Naranjboni; reza ebrahimi; B. Moradi; T. Raiesi
Abstract
Introduction: Type and source of fertilizer in fruit trees nutrition play an important role in increasing yield and fruit quality, shelf-life prolonging and reducing waste in harvested fruit. Evaluation of the possibility of integrated use of organic and inorganic fertilizers or gradual replacement of ...
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Introduction: Type and source of fertilizer in fruit trees nutrition play an important role in increasing yield and fruit quality, shelf-life prolonging and reducing waste in harvested fruit. Evaluation of the possibility of integrated use of organic and inorganic fertilizers or gradual replacement of chemical fertilizers with organic manures is necessary in nutrition of kiwi vines, due to environmental issues resulted due to application of chemical fertilizers as well as increasing market value of organic fruits. Studies in this regard, especially comparison between organic manure and chemical fertilizer effects in kiwi fruit production is very limited. Therefore,this research was performed to investigate the short-term effects of four types of organic fertilizers as compared to chemical fertilizers over the amount of nutrients in leaves and fruits in Kiwi- Hayward variety.
Materials and Methods:This short-term field research was conducted in a randomized complete block design with six treatments including (azola, azocompost,vermicompost, cow manure, chemical fertilizer and control treatments) and four replications inHorticultural Science Research Institute, Citrus and Subtropical Fruits Research Center in Ramsar.Fertilizers were mixed with topsoil in canopy,weed control and drop irrigation was performed. The amount of nutrients, including nitrogen, phosphorus, potassium, calcium and magnesium in kiwi leaves and fruits were measured. In addition, relationship between nutrients in leaves and fruit yield was examined. The correlation analysis between mineral elements and the characteristics of qualitative and quantitative fruit firmness, dry matter, total soluble solids, titratable acidity and ratio of soluble solids to titratable acidity was performed. Stepwise regression equation between treatments with nitrogen, phosphorus, potassium and calcium was written on kiwifruit leaves and fruit. In addition, stepwise regression, the overall equation between yield and nutrient content of kiwifruit were reported.
Result and Discussion: The results showed that concentration of nitrogen, phosphorus, potassium, calcium and magnesium in leaves and fruits in Kiwi trees are higher than control treatment and the amounts of these elements in leaves and fruit werein optimum condition. Fertilization increased the amount of nitrogen, phosphorus, potassium, calcium and magnesium in leaves and fruit of kiwifruit trees in fertilizer treatments, compared to the control. Azocompost treatment had the highest amount of nitrogen and calcium in leaves and fruit compared to other treatments. Azocompost and vermicompost treatments had the highest potassium content in the leaf. As well as cow manure, vermicompost and Azocompost treatments resulted in the highest amount of potassium in fruit. Increasing theamount of nutrients in the leaves of kiwifruit had a direct impact. The correlation between the amount of elements in the leaves and fruit showed a direct and significant relationship between nitrogen, phosphorus and potassium leaves and nitrogen, phosphorus and potassium in fruits. Increasing of nutrients in kiwifruit leaves had a direct and positive impact on fruits. In stepwise regression equation there was a significant relationship between the yield andamounts of nitrogen, phosphorus and potassium and kiwi fruit trees, and by increasing of these elements and yield wasincreased. Correlation analysis between minerals and firmness in kiwifruit showed that there are negative correlations between the nitrogen content in mature fruit and firmness at harvest time at probability level 5 percent. In addition, positive and significant correlation between the calcium content in mature fruit and firmness, as well as between the percentage of dry matter and phosphorus and potassium contents of mature fruit at harvest time was obtained. Results showed that a significant negative correlation was between soluble solids with calcium and between titratable acidity with phosphorus, and of soluble solids ratio to titratable acidity with nitrogen and phosphorus the mature fruit at harvest mature fruit.
Conclusion: In general, according to these research results we can say that use of organic fertilizers like chemical fertilizers in kiwifriut orchards increasethenutrient amounts in leaves and fruit of kiwifruit. In addition,there was a significant positive correlation between quantitative and qualitative characteristics of kiwifruit and its leaf and fruit nutrients. Nitrogen, phosphorus and potassium have significant positive effect in increasing fruit yield.Chemical fertilizers leaching and environmental problems caused by the consumption of these fertilizers, motivated to useof organic fertilizers, such as vermicompost and azocompost in kiwifruit orchards, in order to produce fruit in north of the country.
Research Article
Mahboobeh Tayebi; Mahdi Naderi; jahangard mohammadi; Mahdieh Hosseinjani Zadeh
Abstract
Introduction: Soil texture is one of the majorphysical properties of soils thatplays important roles inwater holding capacity, soil fertility, environmental quality and agricultural developments. Measurement of soil texture elements in large scales is time consuming and costly due to the high volume ...
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Introduction: Soil texture is one of the majorphysical properties of soils thatplays important roles inwater holding capacity, soil fertility, environmental quality and agricultural developments. Measurement of soil texture elements in large scales is time consuming and costly due to the high volume of sampling and laboratory analysis. Therefore, assessing and using simple, quick, low-cost and advanced methods such as soil spectroscopy can be useful. The objectives of this study were to examine two statistical models of Partial Least Squares Regression (PLSR) and Principal Component Regression (PCR) to estimate soil texture elements using Visible and Near-Infrared (VNIR) and Short-Wave Infrared (SWIR) reflectance spectroscopy (400-2450nm).
Materials and Methods: A total of 120 composite soil samples (0-10 cm) were collected from the Kafemoor basin (55º 15' - 55º 25' E; 28º 51' - 29º 11' N), Sirjan, Iran. The samples were air dried and passed through a 2 mm sieve and soil texture components were determined by the hydrometer method (Miller and Keeny 1992). Reflectance spectra of all samples were measured using an ASD field-portable spectrometer in the laboratory. Soil samples were divided into two random groups (80% and 20%) for calibration and validation of models. PLSR and PCR models and different pre-processing methods i.e.First (FD) and Second Derivatives (SD), Multiplicative Scatter Correction (MSC) and Standard Normal Variate (SNV) were applied and compared to estimate texture elements. The cross‐validation method was used to evaluate calibration and validation sets in the first part (80%) and coefficient of determination (R2), Root Mean Square Error (RMSE) and Residual Prediction Deviation (RPD) were also calculated. For testing predictive models, the second part of data (20%) was used and R2 and RMSE of predictive accuracy were calculated.
Results and Discussion: The results of applying two statistical models for estimatingLogClay (%) showed that R2of calibration (R2CV) and validation (R2VAL) datasetranged from 0.22 to 0.72 and 0.12 to 0.54, respectively. The lowest RMSE was computed for PLSR model with SD pre-processing. The highest RPD of calibration (RPDCV) and validation (RPDVAL) were obtained for PLSR with SD pre-processing technique which was classified as a very good and good model, respectively. The results indicated possible prediction of soil clay content by using PCR model with SD pre-processing techniques. In addition, the PCR predicted soil texture elements poorly according to RPD values while the PLSR model with SD pre-processing was the best model for predicting soil clay content. The R2CV and R2VAL of PLSR models for LogSilt (%) varied from 0.34 to 0.73 and 0.27 to 0.58, respectively. The RMSECV varied from 0.14 for FD pre-processing to 0.23 for no-preprocessing and the RMSEVAL rangedbetween 0.18 and0.24. The highest RPDCV (2.07) and RPDVAL (1.59) were obtained for PLSR with FD pre-processing which were classified as very good and good models, respectively. The results of PCR model developments for estimating LogSilt (%) indicated that the highest RPDCV and RPDVAL were, respectively, 1.31 and 1.25 for MSC pre-processing techniques which were rated as poor models. On the contrary to PLSR models, PCR models were not reliable for predicting LogSilt (%).Theresultsof PLSR models for estimatingLogSand (%) revealedthat the highest R2CV and R2VAL were 0.56 and 0.47, respectively and the lowest RMSECV and RMSEVAL were 0.14 and 0.16, respectively which were obtained for SD pre-processing. The RPDCV and RPDVAL values for SD pre-processing in PLSR model were 1.59 and 1.39 which were rated as good and poor performance of predictions, respectively. The highest RPDCV and RPDVALfor PCR models were obtained with the MSC pre-processing indicating poor model. Therefore, PLSR model with SD pre-processing techniques was superior model for estimation of LogSand(%).Overall, PLSR model with SD pre-processing techniques performed better in estimatingclay and sand and PLSR model with FD pre-processing gave better estimate of silt content.
Conclusions: Our finding indicated thatclay and silt contentcan be estimated by using electromagnetic spectrum between VNIR-SWIR region. Further, spectroscopy could be considered as a simple, fast and low cost method in predicting soil texture and PLSR model with SD and FD pre-processing seems to be more robust algorithm to estimateLogClay and LogSilt, respectively.
Research Article
zohreh mosleh; Mohammad hasan Salehi; azam jafari; Abdolmohammad Mehnatkesh; Isa Esfandiarpoor Borujeni
Abstract
Introduction: There is a concern with assessment of land performance when used for specific purposes. Land evaluation analysis is considered as an interface between land resources and land use planning and management. However, the conventional soil surveys are usually not useful for providing quantitative ...
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Introduction: There is a concern with assessment of land performance when used for specific purposes. Land evaluation analysis is considered as an interface between land resources and land use planning and management. However, the conventional soil surveys are usually not useful for providing quantitative information about the spatial distribution of soil properties that are used in many environmental studies. Development of the computers and technology lead to digital and quantitative approaches have been developed. These new techniques rely on finding the relationships between soil and the auxiliary information that explain the soil forming factors or processes and finally predict soil patterns on the landscape. Different types of the machine learning approaches have been applied for digital soil mapping of soil classes, such as the logistic and multinomial logistic regressions, neural networks and classification trees. To our knowledge, most of the previous studiesapplied land suitability evaluation based on the conventional approach. Therefore, the main objective of this study was to assess the performance of digital mapping approaches for the qualitative land suitability evaluation in the Shahrekord plain of Chaharmahal-Va- Bakhtiari province.
Materials and Methods: An area in the Shahrekord plain of Chaharmahal-Va-Bakhtiari Province, Iran, across 32º13′ and 32º 23′N, and 50º 47′ and 51º 00′E was chosen. The soils in the study area have been formed on Quaternary shale and foliated clayey limestone deposits. Irrigated crops such as wheat, potato, maize and alfalfa are the main land uses in the area. According to the semi-detailed soil survey, 120 pedons with approximate distance of 750 m were excavated and soil samples were taken from different soil horizons. Soil physicochemical properties were determined. The average of soil properties was determined by considering the depth weighted coefficient up to 100 and 150 centimeters for annual and perennial crops, respectively. Qualitative land suitability evaluation for main crops of the area including wheat, maize, alfalfa and potato was determined by matching the site conditions (climatic, hydrology, vegetation and soil properties) with studied crop requirement tables presented by Givi (5). Land suitability classes were determined using parametric method. Land suitability classes reflect degree of suitability as S1 (suitable), S2 (moderately suitable), S3 (marginally suitable) and N (unsuitable). Different machine learning techniques, namely artificial neural networks (ANNs), boosted regression tree (BRT), random forest (RF) and multinomial logistic regression (MLR) were used to test the predictive power for mapping the land suitability evaluation. Terrain attributes, normalized difference vegetation index (NDVI), clay index, carbonate index, perpendicular vegetation index (PVI), geology map, existing soil map (1:50000 scale) and geomorphology map were used as auxiliary information. Finally, all of the environmental covariates were projected onto the same reference system (WGS 84 UTM 39 N) and resampled to 50 * 50 m since the soil samples were collected with approximate distance of 750 m (1:50,000 scale). According to the suggested resolutions for digital soil maps, the pixel size 50 *50 m fits to a 1:50,000 cartographic scale. Training the models was done with 80% of the data (i.e., 96 pedons) and their validation was tested by the remaining 20% of the dataset (i.e., 24 pedons) that were split randomly. The accuracy of the predicted soil classes was determined using error matrices and overall accuracy.
Results and Discussion: The results showed that climatic conditions are suitable (S1) for wheat and potato whereas the most important limiting factors for maize and alfalfa were the average of minimum temperature and average temperature, respectively. Results demonstratedthat among the studied models, random forest showed the highest performance to predict the land suitability classes and subclasses. However, different models had the same ability for prediction. In addition, the overall accuracy decreased from class to subclass for all of the crops. The terrain attributes and remote sensing indices (normalized difference vegetation index and perpendicular vegetation index) were the most important auxiliary information to predict the land suitability classes and subclasses.
Conclusion: Results suggest that the DSM approaches have enough accuracy for prediction of the land suitability classes that affecting land use management. Although digital mapping approaches increase our knowledgeabout the variation of soil properties, integrating the management of the sparse lands with different owners should be considered as the first step for optimum soil and land use management.
Research Article
davoud davani; majid nabipour; habibollah roshanfekr
Abstract
Introduction: Maize (Zea mays L.) which belongs to the Poaceae family is the third important cereal crop of the world after wheat and rice. Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity. Planting method is a crucial factor for ...
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Introduction: Maize (Zea mays L.) which belongs to the Poaceae family is the third important cereal crop of the world after wheat and rice. Salinity is one of the major environmental factors limiting plant growth and productivity. Maize is sensitive to salinity. Planting method is a crucial factor for improving crop yield. Planting methods in saline and non-saline conditions are different. Kinetin is one of the cytokinins known to significantly improve the growth of crop plants grown under salinity. Indole acetic acid (IAA) is also known to play a significant role in plant tolerance to salt stress. However, little information appears to be available on the relationship between salinity tolerance and auxin or cytokinin levels in plants. In this respect, the objective of this study was to study the effects of foliar application of cytokinin and auxin hormones on distribution and accumulation of chlorine and some macro elements in different parts of maize in salinity conditions.
Materials and Methods: The experiment was carried out at Bushehr Agricultural and Natural Resources Research and Education Center, Dashtestan station with 29° 16´ E latitude and 51° 31´ N, longitude and 70 m above the see surface during the 2014 growing season. Dashtestan region is a warm-arid region with 250 mm precipitation per year. The field plowed inApril 2014 and then prepared and sowed inAugust 2014. There were five rows with 75 cm distance. The experiment was conducted as a split-plot design based on complete randomized blocks with three replications. Planting pattern (ridge planting, double rows of planting on a ridge in zigzag form and furrow planting) as the main factor and use of hormone (not consumption (control), application of cytokinin hormone in the time of V8-V10 and application of auxin hormone at the silking stage) was considered as the sub-factor. Cytokinin (Benzyl Adenine, Merck) and Auxin (Indole-3-Butiric Acid, Merck) were sprayed on the entire plant in the evening with concentration of 50 and 10 g. l-1, respectively. All traits measured on 10 randomly selected plants of each plot. Data analyzed using the SAS (Ver.9.1) and comparing of the means was conducted using Duncan’s multiple range test.
Results and Discussion: The measured salinity of soil at a depth of 0 to 30 cm in different locations of planting patterns and in different time period showed that in different planting patterns because salt movement by capillary ascent and its accumulation in the ridges, salinity center stack was the highest and the lowest salinity belonged to the furrow planting. The highest Potassium (K+) and Calcium (Ca2+) ions were obtained with pattern of furrow planting, while the highest sodium ions (Na+), Chlorine ions (Cl-) and Na+/K+ were devoted to the pattern of conventional planting (ridge planting). Foliar application of benzyladenine (BA) and indole-3-butyric acid (IBA) sodium ions (Na+) and Na+/K+. The results showed that in all three planting pattern the most sodium leaf was obtained without the use of hormone auxin, but the lowest amount of sodium leaf was observed with auxin treatment. In each pattern, use of hormone leading to increased potassium of shoot, but the largest increase was cytokinin hormone, of course, the greatest increase was achieved by application of cytokinin hormone. In furrow planting use of hormone reduced the amount of leaf chlorine so that most leaf chlorine was obtained without the use of hormones. While, use of cytokinin and auxin hormones reduced the amount of leaf chlorine by 6.86 and 21.24 percent, respectively. Use of hormone in all planting methods reduced the amount of shoot chlorine but the greatest reduction was achieved by application of cytokinin hormone.
Conclusions: In general, it can be concluded that increasing concentrations of sodium, magnesium and chlorine in leaves and shoots in row planting compared to planting two rows and furrow planting could be related to higher concentrations of these elements in the soil and in the location of the plant and as a result decrease of plant growth and therefore higher concentration of elements in various parts of the plant in the row planting. It is concluded that use of cytokinin and auxin especially in the furrow planting reduced the concentration of sodium, chloride and sodium to potassium ratio and increased plant potassium and calcium concentration.
Research Article
Esmaeil Esfandiary Ekhlas; Mohsen Nael; Mohsen Nael; Javad Hamzei; Ali Akbar Safari Sinegani
Abstract
Introduction: Soil is a finite natural resource and non-renewable under agricultural production without implementation of sustainable management practices. Ecological sustainability of agroecosystems can be comparatively assessed by soil quality evaluation, which in turn is assessed by soil quality indices. ...
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Introduction: Soil is a finite natural resource and non-renewable under agricultural production without implementation of sustainable management practices. Ecological sustainability of agroecosystems can be comparatively assessed by soil quality evaluation, which in turn is assessed by soil quality indices. Soil quality is the general term used to refer to “the continued capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain biological productivity, maintain the quality of air and water environments, and promote plant, animal, and human health”. Conservation tillage and use of cover crops are some of the sustainable agriculture practices that can improve the soil quality by adding organic matter and nutrients, and by acting as scavengers to trap leftover nutrients that otherwise might leach out. Cover crops are used as ground cover, mulches, green manure, nurse crops, smother crops, and forage and food for animals or humans. Given the significant role of tillage practices and crop residue management in soil quality improvement and crop production, a four-year field experiment was conducted to determine selected soil quality indices and Cucurbitapepo yield under different tillage and legume cover crop managements in Hamadan.
Materials and Methods: A four-year field experiment (2011-2014) was carried out at Bu-Ali Sina University experimental field in Dastjerd, Hamadan, as a factorial experiment in randomized complete block design with three replications. The area is located at 37 km of Hamadan, on 35◦ 01' N latitude and 48◦ 31' E langitude with 330 mm annual rainfall and 1690 m altitude. The treatments consisted of three levels of tillage practices (NT: no-till (direct seeding), MT: minimum tillage (chisel plowing + disk) and CT: conventional tillage (moldboard plowing + disk)) and two levels of cover cropping (C1: with legume cover crop (lathyrus sativus) and C0: without cover crop). These treatments were applied for four consecutive years in a way that lathyrus sativus as cover crop were planted in late winter for each year and returned to the soil surface with a trowel when 30% of the field was flowered. One week later, and prior to the cultivation of main crop, the mentioned tillage treatments were implemented. In the fourth year of the project,Cucurbita pepo was planted as the main crop. Soil and plant (Cucurbita pepo) were sampled early autumn (2014) and were analyzed for soil organic carbon, soil active carbon, macro and micro-aggregate carbon, mean weighted diameter of water stable aggregates, soil bulk density, basal microbial respiration and grain yield. Obtained data were analyzed using statistical software SAS 9.4 and the means were compared using LSD multiple range test at 5 percent level.
Results and Discussion: The results revealed that total organic carbon, active carbon, aggregate carbon, mean weighted diameter of water stable aggregates, bulk density, porosity and basal respiration were significantly affected by cover crop and tillage system so that the highest amount of these indicators were obtained in no-tillage system with cover crop treatment (NT-C1) and the lowest amounts were observed in the conventional tillage without cover crop (CT-C0). For instance, mean soil organic carbon increased from 0.4 percent in CT-C0 to about 0.7 percent in NT-C1. For majority of soil quality indices, no significant difference was observed between minimum and no-till; moreover, the application of cover crop in conventional tillage improved some aspects of soil quality. For instance, MWD was the highest (2.14 mm) in NT-C1, and was not significantly different with that of MT-C1 treatment. On the contrary, this index was significantly the lowest (0.48 mm) in CT-C0. The C. pepo grain yield was also significantly affected by tillage system, cover crop and their interactions. The highest grain yield (142.1 g.m-2) was obtained in MT-C1 treatment, which did not show significant difference with NT-C1 treatment. The lowest C. pepo grain yield (115.3 g.m-2) was observed in conventional tillage without cover crop (CT-C0) treatment, but it was in a same statistical group with NT-C0, MT-C0 and CT-C1 treatments. Cover crop increased organic carbon, active carbon, porosity, bulk density, microbial biomass activity and MWD by enhancing soil organic matter, probably; conservation tillage on its part further improved these effects by preventing the rapid decomposition of organic matter by reduced soil destruction, which eventually increased soil organic carbon, active carbon and production of stable aggregates.
Conclusions: Generally, after four years of applying different tillage practices and cover cropping, it was demonstrated that the integrated management of the conservation tillage (either no-tillage or minimum tillage) with legume cover cropping was the most appropriate management in the semi-arid region of Hamadan in view of selected soil quality indices and crop yield improvements.
Research Article
Somayeh Sefidgar; Mojtaba Barani Motlagh; farhad khormali; Esmael Dordipour
Abstract
Introduction: Soil pollution with heavy metals have become a global concern because of its damaging effects on the environment, including human health, toxicity in plants and long-term effects on soil fertility. Heavy metals stress in plants is characterized by decrease in photosynthesis, nutrient uptake, ...
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Introduction: Soil pollution with heavy metals have become a global concern because of its damaging effects on the environment, including human health, toxicity in plants and long-term effects on soil fertility. Heavy metals stress in plants is characterized by decrease in photosynthesis, nutrient uptake, damaging of roots and finally plant death. Lead (Pb) is found to be the most dangerous heavy metal, responsible for reduced soil fertility and elevated environmental pollution. Lead toxicity causes the inhibition of seed germination and exerts adverse effects on growth and metabolic processes of plants, which retards plant and crop production. The overproduction of reactive oxygen species (ROS) is the best indicator for secondary stress, which results in a number of toxic effects on biochemical processes in many plant cells. The overproduction of ROS due to Pb stress brings about changes in cellular membrane permeability, which in turn damages organelles such as nuclei, mitochondria, and chloroplasts in plant cells which decreased plant growth and yield. Chemical stabilization is an in situ remediation method that uses inexpensive amendments to reduce contaminant availability in polluted soil. The aim of this study was to investigate the immobilization of lead in a calcareous contaminated soil using two types of biochar as organic and Pumice, Leca, Zeolite and Bentonite as inorganic amendments.
Materials and Methods: In order to investigate the effect of organic amendments (biochar 640°C, and biochar 420°C) and inorganic amendments (Pumice, Leca, Zeolite and Bentonite) on Pb stabilization in a contaminated soil (1500 mg/kg), a greenhouse experiment using maize plant was carried out. This experiment was conducted in a completely randomized design consisting of 6 types of amendments (Pumice, Leca, Zeolite, Bentonite, Biochar 420°C, and Biochar 640°C) and at 1% and 5% levels of each amendment (12 amendments plus 1 control). The experimental treatments were incubated for 3 months. At the end of incubation time, the potential bioavailability of Pb in non-amended and amended soils was assessed by chemical extractions, as: extraction with DTPA, with ammonium acetate and with ethylenediaminetetraacetic acid (EDTA). After the end of incubation time, the pots were transferred to a greenhouse and in each pot five maize seeds were planted and then reduced to three seedlings in each pot after germination. After 3 months, all the plants were harvested. The Pb concentration in each plant, its biomass, its chlorophyll and its antioxidant enzyme activities levels were analyzed. All statistical analyses were performed using SAS software. Means of different treatments were compared using LSD (P ≤0.05) test.
Results and Discussion: The results indicated that the addition of amendments to soils reduced the concentration of Pb extracted with DTPA and EDTA. The 5% biochar 640 had the greatest reduction effect on DTPA-extractable Pb. The smallest concentration of Pb in the leaves and root of maize plant was observed in treated soil with organic amendments (biochar 640°C, and biochar 420°C) and treated with 5% zeolite, respectively. The highest increase in plant growth parameters like SPAD value, leaf area, plant height, number of leaves per plant, dry biomass yield and dry matter of roots were observed in organic amendments compared to the control. The application of 5% amendments in soil caused a significant increase in plant height and number of leaves as compared to control. The increase in growth and biomass of zea mays L. under various amendments might be due to decreased bioavailable Pb concentrations in soil amended which may be attributed to reduced Pb toxicity through improvement of soil fertility. Also, the application of amendments resulted in a significant increase in antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT), peroxidase (PX), and ascorbate peroxidase (ASP) in maize plants compared to the control. The increase of leaves enzyme activities with addition amendments may be due to a lower Pb accumulation in leaves because excess Pb generates free radicals and reactive oxygen species (ROS) those causes oxidative stress in plants.
Conclusions: The results indicated that the application of amendments were successful in lowering the potential bioavailability of Pb in the soils. The 5% biochar 640 treatment had the greatest reduction effect on extractable Pb. The application of amendments decreased the uptake and accumulation of Pb in maize plants, via the reduction of DTPA- extractable Pb. The amendments also significantly increased leaves antioxidant enzyme activities and photosynthetic pigments compared to the control.
Research Article
Majid Basirat; Hassan Haghighatnia; Seyed Majid Mousavi
Abstract
Introduction: Fertilizer recommendation in orchards based on soil testing is not accurate because findings showed that there is not significant correlation between nutrients concentration in the soil and plant. Therefore, studying the nutritional status in orchards is usually based on the plant testing. ...
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Introduction: Fertilizer recommendation in orchards based on soil testing is not accurate because findings showed that there is not significant correlation between nutrients concentration in the soil and plant. Therefore, studying the nutritional status in orchards is usually based on the plant testing. In order to evaluate the nutritional status ofplants, different methods, such as Compositional Nutrients Diagnosis (CND), Diagnosis and Recommendation Integrated System (DRIS), Deviation from Optimum Percentage (DOP), Critical Value Approach (CVA) and Sufficiency Range Approach (SRA) were used. In the CND method, a determination coefficient measured which is considered as the relative superiority of this method to the others. Generally, through the CND method, a correct perception on nutritional status of plantsmay be obtained.
Materials and Methods: The nutritional status of orange orchards, Valencia cultivar, in south of Fars province (Darab town) was studiedusing the compositional nutrient diagnosis and multivariate statistical analysis methods. For this, 80 orange orchards, Valencia cultivar were selected and 30 trees in each orchard were signed. Plant samples were taken from the selected trees in the proper session and concentration of N, P, K, Ca, Mg, Mn, Zn, Fe, Cu and B weremeasured using the standard methods. Then the average yield was measured atharvest. Based on the CND method, total concentration of the nutrients in the plant was considered as a variable (Sd) plus a residual portion (Rd) that "d" is defined as the number of nutrients in the equation and Rd is defined as the residual value. Which sum of the equation equals 100 and it is based on percent. The residual/un measured nutrients and estimated by using the equation of " Rd = 100- (N+P+K+…)". Thereafter, by using the standard equations, which they were perfectly explained and presented in the material and methods section, the geometric mean of nutrients, nutrients index, nutrient balance index, and average yield and finally the reference norms were determined. In addition to the CND method, by using the Multivariate Statistical Analysis and PrincipalComponent Analysis methods, the effective and important nutrients in the yield were determined and also, ability of the CND method was evaluated. The SPSS software was used for variance analysis the data.
Compositional nutrient diagnosis (CND) analysis and multivariate analysis methods are used to study the nutritional diagnosis of Valencia orange orchards in south of Fars province. 80 valencia orange orchards were selected in the region and in each of them, 30 uniform trees were marked and sampled were taken in proper time and referenced method. Leaf elemental compositions and mean yield also were measured from selected trees for each orchard. Data analysis divided all orchards into two low and high yield groups.
Results and Discussion: The results showed that 11 orchards were as high yielding group and 69 orchards were as low yielding group and the average of optimum yields, 113 Kg tree-1, was determined as the yield goal. By using the average of measured nutrients norms for the high yielding community the concentration of the 10 studied elements was obtained which comprised: N 3.00± 0.18; P 0.17± 0.01; K 1.37± 0.12; Ca 3.32± 0.78; Mg 0.36±0.07; Mn 23± 3.35; Zn 17.3± 2.3; Fe 75± 7.3; Cu 7.81± 1.44; B 76± 19.4. Through comparison with the obtained reference norms of optimum yielding orchards, more than 50% of the studied orchards had lower N, Ca and Mn content than the obtained norm and B concentration in the high yielding group was more than 50% less than the low yielding group. Generally, the results of Multivariate Statistical Analysis and PrincipalComponent Analysis showed that N, Ca, Fe and Zn had the highest effect in changes of yield.
Conclusion: Resultsof this work showed that 13% of the studied orchards were in the high yielding group and 86% of themwere in thelow yielding group which shows the imbalance nutritional condition in the studied region. The positive effect of N and Ca on the yield may be due to the dilution effect which these nutrients can reduce the B toxicity. Abundance of Mn deficiency in the studied orchards may be due to the high concentration of Zn and Fe in the plants and antagonistic relations may be considered as the main reason. Multivariate statistical analysis methods may be used as an important tool to study the nutritional conditions of plants. Dominant percentage of the studied orchards showed low yield which may be due to the B toxicity which probably N and Ca application may be alleviated the negative effect of this element.
Research Article
Bahman Khoshru; Mohammad Reza Sarikhani
Abstract
Introduction: Application of chemical and organic carrier and its integration with useful microorganisms including phosphate solubilizing bacteria (PSB) has facilitatedproduction of phosphate microbial fertilizers (PMFs), which are used in granular or powder form. One of the major limitation of thesebiofertilizers ...
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Introduction: Application of chemical and organic carrier and its integration with useful microorganisms including phosphate solubilizing bacteria (PSB) has facilitatedproduction of phosphate microbial fertilizers (PMFs), which are used in granular or powder form. One of the major limitation of thesebiofertilizers is decline or loss of PSB viable cell in the granule preparation process. Accordingly, in this study, isolation of temperature resistant phosphate solubilizing bacteria was performed and temperature tolerance and ability to dissolve phosphate from rock phosphate (RP) and tricalcium phosphate (TCP) sources were evaluated.
Materials and Methods: Firstly, each soil samples incubated for 16 hours at 55 °C, then dilution series were prepared and 100 μl of four final dilutions (10-6, 10-7, 10-8, and 10-9) were used to spread on Sperber solid medium. After spreading the microbial suspensions from the dilutions in the Sperber solid culture medium and the appearance of colonies, screening based on the resistance to soil temperature treatment and, subsequently, the ability to grow in a solid Sperber solid medium and dissolution of low solubility phosphate (formation of transparent halo), was done to isolate PSB. In order toprepare PMF, each of screened PSB were cultured in NB, andthen 1 ml of overnight culture wasmixed with 9 ml sterile distilled water and added to the basal formulation of rock phosphate (45 g), bagasse (30 g) and sulfur (15 g) with initial temperature of20°C.Temperature treatments (55 °C for 16 hours) of bacteria were performed in three steps: a) on sampled soils, b) pure-culture of bacteria and c) bacteria added to the carrier. Microbial population in provided microbial fertilizer was countedin two ways a) half of the microbial fertilizer was kept at normal temperature by maintaining the initial conditions, b) another half after the temperature applied (55 ° C for 16 hours). The semi-quantitative and quantitative test of insoluble inorganic phosphate solubility was performed by isolates in solid and liquid Sperber medium. The 16S rRNA molecular method was used to identify the isolated bacteria by general primers 27F and 1492R.
Results and Discussion: Five bacteria (RPS4, RPS6, RPS7, RPS8, RPS9) out of nine isolated bacteria were able to solubilize mineral phosphate (TCP and RP) but only two isolates (RPS7 and RPS9) were resistant to temperature (55 °C for 16 h). In tricalcium phosphate medium, the RPS9 and RPS7 bacteria had a high ability to solubilize insoluble inorganic phosphate with average of 2.60 and 2.27 for a ratio of (HD / CD) after 12 days, respectively. There was no halo in Sperber medium containing rock phosphate. The amount of solution in the quantitative methods was also obtained to be 563.8 and 324.1 mg / l for RPS9 and RPS7 bacteria, respectively. The prepared microbial fertilizer was counted in two ways (a): half of the sample fertilizer was kept at normal temperature by maintaining the initial conditions; (b):after the maintaining temperature at 55 °C for 16 hours, the population of other half was determined. During counting the initial microbial population (zero time) at normal temperature, all bacteria used in microbial carrier had an acceptable population. During examining the populationsof microbial in the initial carrier, RPS4, RPS6, RPS7, RPS8 and RPS9 bacteria were 3.6, 3.5, 3.6, 3.5, 3.6 and 3.5 (×106 CFU/g), respectively. After 4 months the populations were 4.6, 6.3, 9.6, 7.4 and 8.6 (×105) and in the 6th month, the populations were 3.9, 3.8, 12.3, 4. 7 and 9.2 (×104) seeming to be favorable for the tested bacteria. It seems that this survival time for the tested bacteria is desirable. During countingactive population of temperature treated microbial fertilizers, the initial population of the microbial carrier (at zero time) decreased 10 times with respect to the non-treated carrier. Active population ofRPS9 and RPS7 (temperature-resistant treatments) in the zero time was 4.5 and 4.3 (×105), respectively. Although the RPS9 and RPS7 microbial populations were able to survive in non- temperature treatments for 6 months, it was observed that in the treatment, this viability practically reduced to 4 months. Molecular identification of the isolates RPS7 and RPS9 revealed that they belonged to Pantoeaagglomerans.
Conclusions: According to the findings of this research, using phosphate solubilizing bacteria and temperature resistant Pantoeaagglomerans RPS9, recently isolated and identified, can be considered toindustrially produce granular microbial fertilizers. It is worth mentioning thatfurther studies are required to be carried out on the effectiveness of this formulation with these bacteria infield scale.
Research Article
Samaneh Abduolrahimi; Nasrin Ghorbanzadeh; Hasan Ramezanpour; Mohammad Bagher Farhangi
Abstract
Introduction: Rapid development of industrialization, heavy metal and radionuclide contaminants from industrial activities have posed a major threat to the environment owing to their toxicity, non-biodegradability and persistent accumulation. So various ecosystems are continuously contaminated with high ...
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Introduction: Rapid development of industrialization, heavy metal and radionuclide contaminants from industrial activities have posed a major threat to the environment owing to their toxicity, non-biodegradability and persistent accumulation. So various ecosystems are continuously contaminated with high levels of high-risk chemicals with different structures and levels of toxicity. Cadmium is one of the high-risk elements that enters the environment and can accumulate in the body of fish and other aquatic organisms, plants and livestock and be transferred to the human body. Therefore, the remediation of contaminated soils with cadmium in order to protect human health is very important. One method for remediation of pollutants is immobilization of them in the soil by adsorbents. Among the absorbents, bentonite has been identified for its unique properties, including high surface area and cation exchange capacity and adsorptive affinity for organic and inorganic ions, low cost and ease of access. If the physical and chemical properties of natural bentonites are improved by a special modification process, the adequate supplies for environmental purposes can be obtained. Among the biosorbents, rice husk has also been reported to be suitable for adsorption of cadmium and other heavy metals. This research was designed with the aim of decreasing the amount of cadmium in the soluble and exchangeable phase of a polluted soil under laboratory conditions in the presence of bentonite and rice husk. Considering that biological properties of the soil are an indicator of soil health and quality, so, after application of adsorbents, biological properties and some soil ecophysiological indices were also investigated.
Materials and Methods: The experiment was done with 13 treatments and 3 replications in a completely randomized design. Treatments were bentonite (B) and modified bentonite with iron (B-Fe), manganese (B-Mn), iron and manganese together (B-Fe-Mn), rice husk (RH), modified rice husk with phosphoric acid (RH-P) in two levels (2 and 5%) and control treatment (without adding adsorbent). Modification of bentonite was done with iron chloride (FeCl3.6H2O), manganese chloride (MnCl2.6H2O) and a mixture of FeCl3.6H2O and MnCl2.6H2O. Some of the characteristics of bentonite and rice husk adsorbents including pH, electrical conductivity, cation exchange capacity and organic carbon were measured. The contaminated soil with CdCl2 was treated with adsorbents and incubated for 2 months under constant lab conditions. After the incubation time, soil biological properties such as basal respiration, substrate-induced respiration (SIR), microbial biomass carbon (MBC), activity of some enzymes and also some ecophysiological indexes were measured.
Results and Discussion: The results showed that the basal respiration, SIR, MCB, activity of phosphatase, dehydrogenase and urease were less in the control treatment. The basal respiration and phosphatase activity in RH-P 5% treatment were 2.6 and 2.25 times more than those in the control, respectively. SIR and urease activity were highest in RH-P 5% treatment. The application of adsorbents to contaminated soil reduced soluble and exchangeable cadmium fraction. The lowest amount of soluble and exchangeable fraction of cadmium was in RH-P 5% treatment that showed 2.5 times reduction in comparison to control. In other words, immobilization of cadmium from these fractions improved soil conditions and caused increasing of biological soil properties and activity of microorganisms. The metabolic quotient was higher in the control treatment, probably due to lower microbial content, and decreased by adding adsorbents. Microbial quotient in control treatment was lower than other treatments which prove again the lower biomass carbon of control treatment. Carbon availability that is the ratio of basal respiration to SID, also was more in control in comparison to other treatments, perhaps due to the suppress or inhibition of dormant or zymogenous microbes by cadmium in the control treatment which can be stimulated to growth in the SIR experiment.
Conclusions: The results of this study revealed that cadmium with concentration of 30 mg kg-1has a toxic and inhibitory effect on the microbial activity of the soil. The addition of bentonite and rice husk adsorbents in particular modified form reduced mobility of cadmium and thus improved the biological properties of the soil and also had a positive effect on ecophysiological indexes.
The use of these adsorbents can be a cost effective, succeeded, and operative management strategy for immobilization of cadmium in contaminated soils that reducing the risk of plant reclamation, washing and entry into groundwater and food cycle.
Research Article
Sahar Taghdis; Mohammad Hady Farpoor
Abstract
Introduction: Soil magnetic properties reflect the complex chemical, geological and biological interactions occur in the soil. Thus, knowledge about the factors affecting soil magnetic properties helps better understanding and interpreting the results.. The lithogenic magnetic minerals are often found ...
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Introduction: Soil magnetic properties reflect the complex chemical, geological and biological interactions occur in the soil. Thus, knowledge about the factors affecting soil magnetic properties helps better understanding and interpreting the results.. The lithogenic magnetic minerals are often found in the coarse soil fractions (sand and silt) and they have inherited from parent rocks. Weathering and soil formation factors may lead increasing or decreasing of magnetic susceptibility. Climate and vegetation type are among the other factors affecting magnetic susceptibility too. Amount and distribution of magnetic susceptibility may also be affected by land use. The main objective of this research was to study the effect of different land uses and vegetation types on the magnetic susceptibility of topsoil related to soil properties.
Materials and methods: The study area was located in MahoonakeZiba around the Bardsir region, Kerman Province. The moisture and temperature regimes of the study area were sub aridic and mesic, respectively. The study area is located in the alluvial plain with igneous parent material originated from andesite, volcanic tuff, anddacite. Four land uses including farmland, well-covered pasture, disturbed pasture and degraded dryland farm with similar climate, topography, and parent material were selected. Overall, 60 complex surface samples were collected from the depth of 0-15 cm. The physicochemical analyses were done on the samples after that the soils were air dried, crushed, and passed through a 2 mm sieve. The soils magnetic susceptibility (ᵡ) in low (0.46 kHz) and high (4.6 kHz) frequencies were measured using the Bartington MS2 dual frequency sensor in two replications. The frequency depended magnetic susceptibility (ᵡfd %) was calculated as a development index of soil forming factors reflecting ferrimagnetic particle sizes.
Results and discussion: The pH of studied soils were in the range of neutral to alkaline and had the lowest coefficient of variance between measured parameters. The average of soil EC was 1.76 dS/m with a high coefficient of variance. The lowest amount of organic matter was in land use ofdegraded drylandfarm (0.26 %) and the highest was in farmland (2.15 %). The lowest amount of calcium carbonate with the coefficient of variance 12.37 % measured in the degraded pasture and its maximum was in the farmland. The loamy sand and sandy loam textural classes were found in the area under study. The minimum and maximum amounts ofᵡlf were determined in farmland (134.8× 10-8 m3 kg-1)and well-coveredpasture (1778.9 ×10-8 m3 kg-1 ), respectively and the relatively high mean value was 695.83 × 10-8 m3 kg-1. The topsoil of the study area was formed on alluvial deposits with a parent material originated from igneous andesite, tuff and dacite rocks. The high values of magnetic susceptibility of all soils under study could be attributed to the existence of initial magnetic minerals inherited from the parent material. The statistical analysis revealed a significant difference among ᵡlf values (p
Research Article
saman fashkhorani; mohammad salighe; mehry akbari
Abstract
Introduction: The effect of climate factors plays an important role on agricultural products. In this case, there is not enough knowledge about the role of climatic elements in agricultural planning, therefore, there wouldnot be much achievements because it is proved that in most cases, the low yield ...
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Introduction: The effect of climate factors plays an important role on agricultural products. In this case, there is not enough knowledge about the role of climatic elements in agricultural planning, therefore, there wouldnot be much achievements because it is proved that in most cases, the low yield of agricultural products is the result of not keeping and being unable to create a balanced climate. Temperature stresses are one of the most important factors in plant growth. In most plants, when the plant is exposed to extreme temperatures, physiological changes may prevent optimal plant growth. Therefore, plants need a specific temperature range for optimum growth and stepping outside of range is considered as a stress. Strawberries are generally herbaceous plants that are one of the most sedentary, dense, isolated petals without stems, more or less articulate with lower leaves and narrow stolon that are sensitive to temperature stresses. This temperature fluctuation causes major annual damage. Therefore, this study was carried out to investigate the extreme temperatures in the strawberry growing area in Kurdistan province (Sanandaj-Marivan-Kamyaran) and the effect of these stressful temperatures on strawberry yield, as well as future temperature prediction and future effects were investigated.
Methods and Approaches: In this study, the average daily temperature, maximum daily temperature and minimum daily temperature duringthe years 1381-1395 were obtained from Iran Meteorological Organization and the occurrence date of the last temperature (spring minimum temperature) for strawberry (5 ° C), which is actually the date of the beginning of the strawberry growth period. Also, the date of occurrence of the first stress temperature (maximum summer temperature) for strawberry (35 ° C) and the length of growth period of strawberry were estimated in the studied years. Data from the production and yield of strawberries were collected from the Jihad Agriculture Organization in Kurdistan province during this 15-year period. In order to study the effect of extreme temperature and the occurrence date of this temperature on the yield of strawberry, using Spearman correlation coefficient (SPSS), correlation between severe temperature and strawberry yield was calculated. Finally, in order to investigate the effect of climate change on the maximum and minimum temperature data in the future, using the SDSM model under the rcp26 scenario, CMIP5 climate scenarios were produced in the 2050-2020 and 2099-2099 periods.
Results and Discussion: The results indicated that the date of the extreme temperature did not change much and the latter extreme temperatures have tended to be more prevalent in the spring. The onset of the first extreme temperatures is also early in the summer of late July and we see an almost short (four-month) growth season for the growth of outdoor strawberries. Minimum temperature has the greatest effect on the yield of strawberries in April and the maximum temperature has the greatest impact in July. This issue is justified by the unfavorable temperature for growing strawberries and low yields in these months. The highest correlation between monthly average temperature and monthly yield of strawberries is in May and June. The simulated future data shows that in the months of the growing season (spring and summer), the temperature increases one to two degrees and the early minimum temperature and the maximum summer temperature will be lower than the base period.
Conclusion: The results of the correlation calculation between the date of the last event and the first critical temperature indicate a weak correlation, and it can be concluded that the occurrence of the first and the last extreme temperatures does not affect each other. The results of the study of the effect of the monthly average temperature on the monthly yield of strawberries in May and June showed that the average daily temperature of 12 to 25 °C, especially 17 to 20 °C, is higher on strawberries. Temperature higher and lower than this range (12 to 25 °C) reduces or stops growth. According to the data produced, the final temperature (minimum spring temperature) occurs a little earlier, and strawberries begin to grow in early March, but this could be risky and a sudden cold time causes a lot of damage. The maximum summer temperatures are also higher. This is true especially in June, when strawberries have the highest yield, it is not good and it stops plant growth. The strawberry growth season is expected to begin in March and end in June. Therefore, measures should be taken to prevent possible damage by raising awareness of the subject.
Research Article
Aliakbar Sabziparvar; ALI KARIMI
Abstract
Introduction: Exposure of human, animal and plants to sunlight has a major role for their growth. One of the most important applications of solar radiation is the agricultural sector. Photosynthesis is a photobiological phenomenon that depicts the ability of plants to convert light energy into chemical ...
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Introduction: Exposure of human, animal and plants to sunlight has a major role for their growth. One of the most important applications of solar radiation is the agricultural sector. Photosynthesis is a photobiological phenomenon that depicts the ability of plants to convert light energy into chemical energy. In fact, if we provide suitable water and temperature, plant growth and consequently crop yields are directly dependent on photosynthetic active radiation (PAR). Regarding the importance of monitoring of PAR flux in agriculture, unfortunately, in most meteorological stations, this parameter is not routinely measured, as its determination is acostly process.
Materials and Methods: In this study, the radiation parameters were measured in a meteorological station located at the faculty of Agriculture, Bu-Ali Sina University in Hamedan. The station has a geographical position of 34 degrees and 47.91 minutes North latitude, 48 degrees and 28.98 minutes Eastern longitude and 1851 meters above sea level in an open space land inside the university campus (Hamedan, Iran). The climate of Hamedan is cold and semi-arid.Geonica Data Logger (GDL) and the PAR detector asradiation devices wereused in this study. The scientific name Pyronometer light sensor which is connected to GDL is LPO2 (Huksellux). The sensitivity of the sensor is between zero to 2000 watts per square meter, and its spectroral response rangesfrom 305 to 2800 nm. The intensity of the irradiance measured by the PAR device is from zero to 2000 µmols/(m2.sec) and its spectroral response covers 380 nm to 750 nm. The method used inthis workwas to measure daily PAR data from a PAR device (ELE) at least four times a day at a local time from April 2016 to February 2017. At the same time, the TSR data was also recorded bythe Geonica Loggerin nearby meteorological site. In this study, simple linear regression and exponential regression wereemployedto investigate the relationship between the TSR data(independent variable, predectors) and the PAR variable (a dependent variable). Using SPSS software, 70%of the data was used to construct the regression relationships and the remainder for evaluating the accuracy of the obtained relationships. Due to the different weather conditions, the measured data are divided into four groups: Clear Sky, Partly Cloudy Sky, Overcast, and All Condition (All sky). To report the cloudiness, Okta unit is used parts (e.g. each Okta corresponds to about 12.5% cloud coverage).
Results and Discussion: The analysis of regression relationshipbetween TSR and PAR in the clear sky, partly cloudy sky, overcast and all sky wasperformed for monthly, seasonal and annual scales. There wasa linear relationship between TSR and PAR fluxes. This linear relationship decreasedwith increasing cloudiness for both monthly and seasonal scales. These results were compared with those ofEscobedo et al. (2009) whomodelled hourly and daily fractions of UV, PAR and NIR to global solar radiation under various sky conditions at Botucatu, Brazil. Our findings were also in good agreement with their results, as they also observed a linear correlation between PAR and TSR fluxes at Botucatu. Moreover, the ratio between PAR and TSR was determined for all time scales. Our results showed that the highest and lowest ratio of PAR /TSR occurs in July (0.448) and February (0.407), respectively. Onseasonal and annual scales, the ratio PAR /TSR increasedas the sky conditions changed from the clear sky to the cloudy sky, mainly because of the effect of cloudiness. Cloudy sky absorbs longer wavelength radiation of solar spectrum (such as infrared radiation) ascompared withshort wavelengths (such as PAR and UV). This increases the radiation proportions from the clear sky to the cloudy Sky. Our results are in good agreement with the results of Alados et al. (southeast Spain), Papaioannou et al. (Athens), Jacovides and et al. (Eastern Mediterranean basin) and Udo and Aro in central Nigeriawhoexamined the PAR/TSR ratio.
Conclusion: In the present study, the following results were achieved:
In monthly, seasonal and annual time scales, there wasa linear regression relationship between PAR and TSR varying with the change in clouds cover. The best correlations were observed in June and July, but the correlation coefficients decreased from October to February (autumn and winter) due to the increased cloudiness.
The PAR/TSRratio in the seasonal time scale showed an increment as the cloud cover increased. On annual scale, the ratio of photosynthetic active radiation (PAR) to total global irradiance (TSR) increased from 0.430 in clear sky to 0.489 in overcast condition.
