Research Article
Mohammad Nazeri Tahrudi; Keivan Khalili; Farshad Ahmadi
Abstract
Introduction: Climate change has been one the most important subject in studies in the recent decades. Precipitation is an effective climatic parameter in the municipal and rural studies and in the industry, architecture, agriculture, climate and other fields. Trend analysis of average monthly and yearly ...
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Introduction: Climate change has been one the most important subject in studies in the recent decades. Precipitation is an effective climatic parameter in the municipal and rural studies and in the industry, architecture, agriculture, climate and other fields. Trend analysis of average monthly and yearly rainfall investigated in many studies, but less researches probe regional rainfall analysis. In this study average yearly precipitation data measured at 31 synoptic stations of Iran in the period of 1961 to 2010 used to study regional variations of precipitation. In this order station divided to five regions by fuzzy clustering. Then, using the regional Kendall method, trend of precipitation investigated at five regions and all of Iran.
Materials and Methods: Iran with an area of over 16480000 square kilometers is situated in the northern hemisphere and southwest of Asia. Almost all parts of Iran have four seasons. In general, a year can be divided into two warm and cold seasons. Iran with range annual precipitation of 62.1-344.8 mm is located between two meridians of eastern 44° and 64° and two orbits of northern 40° and 25°. In order to investigate trend of precipitation two Mann-Kendall and Regional Kendall tests used. Also to evaluate the regional trends the Fuzzy method applied to clustering the studied region. The classic form of Mann-Kendall test has been used in many studies. The null hypothesis (no trends) is accepted when , otherwise H0 is rejected and its opposite hypothesis, i.e. the existence of a trend is accepted (5, 13). To estimate regional trend, the mean S statistic of Regional Mann-Kendall introduced that was presented by Douglas et al (7). Fuzzy Clustering: Clustering the studied area was done using the Fuzzy clustering method. One of the first clustering methods that were based on the objective function and Euclidean distance was presented by Dunn in 1974 and then was generalized by Bezdak in 1981.The FCM clustering algorithm is modified type of K-Means clustering algorithm. This algorithm minimizes the variance of clusters (1). The assumption of this algorithm is that data are in a vector space and the objective of this algorithm is to minimize the sum of variance in the D v cluster.
Results and Discussion: In this section the results of decreasing and increasing trend of annual precipitation of Iran can be observed in order to the data that recorded at provinces synoptic stations in the 1 and 5 percentage significance levels. Isfahan Synoptic station detected an increasing trend insignificant level of 5 percentages and the East Azerbaijan synoptic station followed a significant and severe decreasing trends. In order to investigate regional trend it is needed to use the clustering methods. After investigation the trend of mean annual precipitation at each station, the studied area was clustered using the Fuzzy clustering method and then the regional trend of Iran’s precipitation was evaluated. At first the number of different clusters investigated using the geographic properties and mean annual precipitation of the studied area and then with attention to the correlation of precipitation series in each cluster, five clusters selected to investigate the regional trend of precipitation. Overall the results showed that about 67 percentages of synoptic stations in center of provinces detected decreasing trend in the recent half century. Increasing the precipitation almost accrued in the center and northern part of Iran and other areas detected a decreasing precipitation trend in the studied data period that this subject is corresponded with Azerakhshi and et al (2). The observed trends over Iran and almost all stations and provinces were downward trend. This decreasing trend of precipitation also observed in Iran in the two past decades by Khalili et al (13).
Conclusion: Result showed decreasing trend in the west, north of Iran at each station and regional scale. Results indicated also a significant downward trend at northwest, central and south-west of the country, non-significant downward trend in western of Iran and non-significant upward trends in northern regions and Caspian Sea margins in the regional analysis. The most decreasing trend of precipitation observed at the north west of Iran because of increasing temperature and climate changes in the recent years.
Research Article
Majid Montaseri; Babak Amirataee; Keyvan Khalili
Abstract
Introduction: Droughts are natural extreme phenomena, which frequently occur around the world. This phenomenon can occur in any region, but its effects will be more severe in arid and semi-arid regions. Several studies have highlighted the increasing of droughts trend around the world. The majority of ...
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Introduction: Droughts are natural extreme phenomena, which frequently occur around the world. This phenomenon can occur in any region, but its effects will be more severe in arid and semi-arid regions. Several studies have highlighted the increasing of droughts trend around the world. The majority of studies in assessing the trend of time series are based on basic Mann-Kendall or Spearman's methods and no serious attention has been paid to the impact of autocorrelation coefficient on time series. However, limited numbers of studies have included the lag-1 autocorrelation coefficient and its impacts on the time series trend. The aim of this study was to investigate the trend of dry and wet periods in northwest of Iran using Mann-Kendall trend test with removing all significant autocorrelations coefficients based on SPI and RAI drought indices.
Materials and Methods: Study area has a region of 334,000 square kilometers, with wet, arid and semiarid climate, located in the northwest of Iran. The rainfall data were collected from 39 synoptic stations with average rainfall of 146 mm as the minimum of Gom station, and the highest annual rainfall of 1687 mm, in the Bandaranzali station. In this study, Standardized Precipitation Index (SPI) and Rainfall Anomaly Index (RAI) were used for trend analysis of dry and wet periods. SPI was developed by McKee et al. in 1993 to determine and monitor droughts. This index is able to determine the wet and dry situations for a specific time scale for each location using rainfall data. RAI index was developed by Van Rooy in 1965 to calculate the deviation of rainfall from the normal amount of rainfall and it evaluates monthly or annual rainfall on a linear scale resulting from a data series. Then, correlation coefficients of time series of these drought indices with different lags were determined for check the dependence or independence of the SPI and RAI values. Finally, based on dependence or independence of the time series values, trend analysis of wet and dry periods was conducted in different stations using one of the basic or modified Mann-Kendall tests. Also, the magnitude of the trends was derived from the Theil- Sen’s slope estimator.
Results and Discussion: Time series of SPI and RAI drought indices for a given annual rainfall as an example for three stations of Marivan, Gom and Maku show that during 1991 to 1994 and from 2002 to 2007 are in wet period and during 1987 to 1990 and 1998 to 2001 are in the dry period. It is clearly show that, dry and wet periods in RAI index are more severe than SPI. Comparison the correlation between Lag-1 autocorrelation coefficients values of SPI and RAI time series and Lag-1 autocorrelation coefficients of annual rainfall data indicate that these correlations are high and about 0.97 and 0.99, respectively. This difference is due to the different classification of SPI and RAI drought indices. The results of trend analysis indicate a decreasing trend in most of stations. Also, Mann-Kendall statistic has been declining while eliminating the effect of all significant correlation coefficients of dry and wet periods. This result in both SPI and RAI indices are similar and have a high correlation with R = 0.99. According to results, west of the study area have a significant decreasing (negative) trend. The spatial distribution of dry and wet periods showed that the difference between Mann-Kendall statistics of SPI and RAI indices is minimal. Also, The results show that, the slope of the trend line based on the SPI and RAI drought indices is negative in most of stations and correlation between these two indices in determining the slope of the trend line is high. But, this correlation compared with the trend statistics of SPI and RAI time series is less.
Conclusions: In this study, first the time series of SPI and RAI time series based on annual precipitation and common quantitative classification of mentioned two drought indices were determined. Then, trends of dry and wet periods of selected stations in northwest of Iran were evaluated based on these indices using the Mann-Kendall trend test with removing all significant autocorrelation coefficients. The results from this study indicate that using Mann-Kendall test with removing all significant autocorrelation coefficients effects are essential in assessing trend in time series. Although, according to various studies available in the literature, SPI is known as more accurate than RAI in drought mitigation, but according the results of this study, can solely be used both RAI and SPI index for trend detection.
Research Article
Shirko Ebrahimi Mohammadi; Mahmood Azari; Esmaeel Manoochehri
Abstract
Introduction: Forest herbs due to decrease of runoff coefficient and the kinetic energy of raindrops, is known as a key factor in controlling runoff and soil conservation. Many physical (hydrophobicity, electrical conductivity, pH, particle size distribution, color and temperature regimes), chemical ...
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Introduction: Forest herbs due to decrease of runoff coefficient and the kinetic energy of raindrops, is known as a key factor in controlling runoff and soil conservation. Many physical (hydrophobicity, electrical conductivity, pH, particle size distribution, color and temperature regimes), chemical (quality and quantity of organic matter, nutrient availability) and biological (Microbial biomass, soil invertebrates living community) soil properties can be affected by forest fires. Fire not only reduces forest herbs, vulnerability against splashing rain but also has strong effects on the hydrological cycle and soil loss. despite of repeated fires, there are very few studies about fire impact on natural resources of the west of the country, especially the city of Marivan, in Kurdistan province so this study aimed to investigate the short-term fire impacts on soil properties, Hydrologic regime, soil erosion and sedimentation of Zrebar Lake watershed in west of Iran.
Materials and Methods: Considering the importance of the slope on the hydrological response of the watershed, slope classes of the Zrebar Lake watershed were mapped. Therefore, effects of fire on hydrological characteristics, erosion and sedimentation were studied by the establishment of twelve 0.25 square meter plots in three replications at two dominant slope classes (0 to 30 and 30 to 60%) in burned and natural areas . The first plots in the burned and natural sections, was established randomly and two other plots with the similar conditions at a distance of 1.5 meters from each other were established. Garden Spray Simulator with constant pressure was used to fall rain from half a meter height for thirty minutes with an intensity of about 2 mm min-1 and 1 mm droplet diameter according to the general weather conditions of the studied area. For every five minutes, runoff and sediment were collected. Runoff volume by weighting and suspended sediment concentration by drying at 105°c were measured. Infiltration and interception by water balance assessment and subtracting the simulated rainfall volume and runoff were calculated. Soil samples were also collected in triplicate by auger drilling method to assess the effects of fire on different characteristics of topsoil (depth of 5 cm) asthe samples 1 and 2 in the slope class of 30 to 60%, and samples 3 and 4 in slope class of 0 to 30%, at the burned and natural sections respectively. In the laboratory, after determination of soil texture, the moisture content, pH and EC by portable laboratory instruments, the percentage of total organic carbon and organic matter bye wet oxidation were measured. Soil water repellency by Water Drop Penetration Times (WDPT) method in the field was calculated. Statistical analysis for comparing the average hydrophobicity of the soil, runoff and sediment of both natural and burned treatments by independent t-test and for equality of variances by the Levene test was performed using SPSS 21 software.
Results and Discussion: The results showed no effect of fire on soil texture because the fire severity was low to moderate as the color of ash was black. The fire caused to 46 percent reduction of soil moisture and also 24 percent reduction of soil organic matter and 29 percent reduction of total organic carbon at 0% to 30% and 30% to 60% slope classes respectively. Slight increase in pH and electrical conductivity were another effects of fire. At the slope of less than 30%, the average water drop penetration time were 1.24 and 0.70 S in burned and natural treatments and at the slope of 30 to 60 % slope class were 4.52 and 1.04 S respectively. Independent t-test results showed that, the water repellency differences of natural (t=3.466, p=0.003) and burned (t=7.364, p=0.000) treatments were significant. Levene test and independent t-test results showed significant difference in the average of runoff at confidence level of 95% in both slope classes. At the slope of less than 30%, differences of sediment average of burned and natural plots with a significant level of 0.012 were significant. But in slope class of 30% to 60%, despite of large different sediment concentration output from the burned and natural plots at the beginning of the experiment, there was no significant difference between them. The results showed that fire leads to low soil moisture content, total organic carbon and soil organic matter. Slight increase of pH and EC and also lack of effect on soil texture, in both slope classes were also observed. Ash on the forest floor caused to soil water repellency and therefor decreased soil infiltration and increased runoff and soil erosion.
Research Article
rouhollaah vafaeezadeh; shamsollah Ayoubi; mohamamdreza mosaddeghi; maryam yousefifard
Abstract
Introduction: Land use changes are the most reasons which affect natural ecosystem protection. Forest soils have high organic matter and suitable structure, but their land use management change usually affects soil properties and decreases soil quality. There are several outcomes of such land use changes ...
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Introduction: Land use changes are the most reasons which affect natural ecosystem protection. Forest soils have high organic matter and suitable structure, but their land use management change usually affects soil properties and decreases soil quality. There are several outcomes of such land use changes and intensification: accelerated soil erosion and decline of soil nutrient conditions, change of hydrological regimes and sedimentation and loss of primary forests and their biodiversity. Establishing effects of land use and land cover changes on soil properties have implications for devising management strategies for sustainable use. Forest land use change in Yasouj caused soil losses and decreased soil quality. The objectives of this study were to assess some soil physical and chemical properties and soil magnetic susceptibility changes in different land uses and slope position.
Materials and Methods: Soil samples were taken from natural forest, degraded forest and dryland farm from different slops (0-10, 10-20 and 20-30 percent) in sout east of Yasouj. They were from 0–10 cm depth in a completely randomized design with five replications. Soil moisture and temperature regimes in the study area are xeric and mesic, respectively. Particle size distribution was determined by the hydrometer method and soil organic matter, CaCO3 equivalent and bulk density was determined using standard procedures described in Methods of Soil Analysis book. Magnetic susceptibility was measured at low and high frequency of 0.46 kHz (χlf) and 4.6 kHz (χHf) respectively with a Bartington MS2D meter using approximately 20 g of soil held in a four-dram clear plastic vial. Frequency dependent susceptibility (χfd) is expressed as the difference between the high and the low frequency measurements as a percentage of χ at low frequency.
Results and Discussion: Soil texture was affected by land use change from silty clay loam in forest to silty loam in dry land farm. Declining of organic matter and aggregate stability caused soil surface loss by erosion. The bulk density increased from 1.12 to 1.54 gcm-3 when forest changed to dry land farms. Soil compaction by tillage and lower amount of organic matter in farm lands are some of the reasons for increasing bulk density. Another possible reason could be decreasing of biological activity and parent material with greater calcite mixed with soil surface layer during land use change. Thus, the maximum and minimum amount of calcite was observed in dry land farm in 20-30 % slopes (57.46 %) and forest in 0-10 % slopes (13.37 %), respectively. In addition during soil formation calcite was translocated to lower horizons in natural forest. The greatest organic matter was 7.45 % and related to natural forest in 0-10 % slopes. Overall, the organic matter content was greater in all forest slopes than all other land use. In mineral soil, total organic carbon is not a proper factor in soil physical behavior. Complex and noncomplex organic carbon influence the soil physical behavior. Organic carbon in degraded forest and dry land farming was in complex form but in forest land use it was observed in two complex and noncomplex forms. Noncomplex organic matter was 53% and complex organic matter was 47%. It means that forest soil have better quality than degraded forest and dry land farm, respectively. Sedimentary rocks have rather low concentration of magnetic minerals with magnetic susceptibility from 0.1 (10-8 m3 kg-1) in the limestone to approximately 20 (10-8 m3 kg-1) in the siltstone. Low magnetite susceptibility in natural forest was more than degraded forest and dry land farm. Mean magnetite susceptibility values were 61.8, 48.6 and 42.4 10-8 m-3 kg-1, respectively which probably related to magnetic minerals formation during pedogenesis. Frequency magnetite susceptibility (χfd) was more than 3% in the most soils, significantly in forest soil (from 4.63-5 percent). Greater frequency magnetite susceptibility (χfd) values are suggested to be indicative of the dominance of super-paramagnetic grains and fiug single domain particles. χfd in soils reflects significant pedogenic magnetic minerals which formed during soil formation from calcitic parent materials.
Research Article
Marzieh tavanaei; somayeh bakhtiari; mehran shirvani
Abstract
Introduction: Heavy metals contamination due to natural and anthropogenic sources is a global environmental concern. Lead (Pb) is one of the very toxic heavy metals. Industrial production processes and their emissions, mining operation, smelting, combustion sources and solid waste incinerators are the ...
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Introduction: Heavy metals contamination due to natural and anthropogenic sources is a global environmental concern. Lead (Pb) is one of the very toxic heavy metals. Industrial production processes and their emissions, mining operation, smelting, combustion sources and solid waste incinerators are the primary sources of lead. This heavy metal has aberrant effects on the environment and living organisms. Hence, proper treatment of lead from soil and industrial wastewaters is very important. In order to remove toxic heavy metals from contaminated water systems, conventional methods such as chemical precipitation, coagulation, ion exchange, solvent extraction and filtration, evaporation and membrane methods are being used. These conventional methods generally have high costs and technical problems. Therefore, biosorption processes, in which microorganisms are used as sorbents, have been considered as economical and environmentally friendly options for removal of heavy metals from aqueous solution. Clay minerals are another group of sorbents used in removal of heavy metals from polluted environments. Furthermore, bacterial cells can be attached on clay mineral surfaces and form bacteria-mineral composites. These composites adsorb heavy metals and convert them into forms with low mobility and bioavailability. Pseudomonas putida is a unique microorganism with a high tendency to sorb and/or degrade certain environmental pollutants. Palygorskite and sepiolite are the fibrous clay minerals of arid and semiarid regions; their structures consist of ribbons and channels. These fibrous minerals have various applications in industry and the environment because of its large surface area and high adsorption capacity. The present study was conducted in order to determine the ability of Pseudomonas putida (P168), and its composites with palygorskite and sepiolite in lead sorption.
Materials and Methods: The bacterial strain used in the present study was Pseudomonas putida (P168) grown and maintained on Nutrient Broth (NB). The population of living and non-viable bacteria in suspension was determined by an optical microscope. The minerals used in this study were palygorskite from Florida (the Source Clay Minerals Repository, Purdue University, IN) and sepiolite from Yazd (Iran). The clay samples were ground and passed through 0.05 mm (mesh #270) sieve. The clays were then saturated with calcium chloride (0.5 M) and washed free of salts. Batch experiments were performed to measure Pb sorption by Pseudomonas putida. For this purpose, 10-ml aliquots of bacterial suspension (7.24×107 cells ml-1) were added to10 ml solutions containing Pb with concentration ranged from15-110 mg L-1. The mixtures were gently shaken at 30 ◦C for 24 h and centrifuged at 3000 rpm for 20 min. The concentration of Pb in the supernatants was finally measured by atomic absorption spectrometer. The percentage of sorbed Pb was determined by subtracting the amount of unabsorbed Pb from that initially added. Various hybrids of P. putida and clays were also exposed to solution of 0.5 mM Pb in 0.01 M KNO3 to determine the role of composites in sorption of Pb. Langmuir and Freundlich adsorption isotherms were chosen to describe the biosorption equilibrium data. GraphPad Prism 5.0 was used for determining the isothermal parameters using non-linear regression analysis. Data were analyzed with the Statistical Analysis System (SAS). Experimental design was factorial in form of complete randomized block.
Results and Discussion: Pseudomonas putida showed a considerable capacity to sorb Pb ions. Lead sorption isotherms were sufficiently fitted with the Langmuir and Freundlich models. The Pb sorption isotherms by P. putida were L-type showing a high affinity of P. putida for Pb ions. Lead sorption capacity (qmax) of P. putida was estimated to be 582.4 mg g-1 and its Langmuir constant (KL) was found to be 0.11 mg L-1. The experimental data of lead sorption (7.5-55.5 mg L-1 initial concentration) by P.putida (P168) demonstrated that about 31.5% to 78.4% of the intial concentration of Pb was taken up by these bacteria. Sorption of Pb decreased with the increase of bacteria in the bacteria-clay composites, which may be due to the occupation of adsorption sites on the clay surface by the bacteria. Composites of bacteria-sepiolite were more effective than bacteria-palygorskite in Pb sorption due to the larger channel dimensions, greater surface area, and more functional groups of sepiolite than palygorskite. LSD test showed that there were significant differences between the hybrid sorbents with different ratios and single bacterial cells in Pb sorption.
Conclusion: The results showed that P. putida and its composites with palygorskite and sepiolite clays exhibited a high potential for the removal of Pb from aqueous solutions.
Research Article
Elham Malekzadeh; Jafar Majidi; Nasser Aliasgharzad; Jalal Abdolalizadeh
Abstract
Introduction: Glomalin is known as a specific fungal glycoprotein belonging to the order Glomerales in phylum Glomeromycota and has been introduced as a heat shock protein. We hypothesised that increasing the level of Pb would lead to increase in glomalin production. Glomalin is usually determined by ...
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Introduction: Glomalin is known as a specific fungal glycoprotein belonging to the order Glomerales in phylum Glomeromycota and has been introduced as a heat shock protein. We hypothesised that increasing the level of Pb would lead to increase in glomalin production. Glomalin is usually determined by two methods, the Bradford protein dye-binding assay and the enzyme-linked immunosorbent assay (ELISA). Since many laboratories are not equipped to carry out the ELISA assay, many studies have measured glomalin-related soil protein using the Bradford colorimetric total protein assay. While, the ELISA method specifically measures glomalin by using monoclonal antibody MAb32B11.
Materials and Methods: The pot experiment was conducted in the sterile free-glomalin sand with Trifolium repens L. mycorrhized by Rhizophagus irregularis fungus and treated with the Pb levels of 0, 150, 300 and 450 µM. Thus, in vitro experiment was performed in two-compartments plates containing of the transformed carrot roots (Daucus carota L.) mycorrhized with the same fungus in root compartment and hyphal compartment treated with the Pb levels of 0, 0.01, 0.1 and 1 mM as Pb(NO3)2. For glomalin extraction, hyphal or root samples were autoclaved at 121 ⁰C with 50 mM sodium citrate buffer for 60 min in three cycles. Protein concentrations in the extracted samples were determined using a modified Bradford protein assay. Also, glomalin content in the samples were determined by indirect ELISA using monoclonal antibody MAb32B11. The percentages of the total root length were colonised by mycorrhizal fungi in pot culture and both hyphal and spore densities in the metal-containing hyphal compartment were determined.
Results and Discussion: In the in vitro culture the percentage of total hyphae and spore frequency decreased, while Bradford reactive total hyphal protein (BRHP) and Immunoreactive hyphal protein (IRHP) in hyphal compartment increased as the concentrations of Pb increased. Also, there was positive and significant correlation between immunoreactive hyphal protein (IRHP) and Bradford reactive total hyphal protein (BRHP) in hyphal compartment of in vitro culture (r= 0.941**). In the pot culture, the percentage of the total mycorrhized root length in all the treatments increased compared to the unleaded control as the concentrations of Pb raised. In general, Bradford reactive total protein and Immunoreactive protein in both the hyphal and root compartments of pot culture increased with increasing the Pb levels. Also, there were positive and significant correlations between immunoreactive hyphal protein (IRHP) with Bradford reactive total hyphal protein (BRHP) (r= 0.845 **) and immunoreactive root protein (IRRP) with Bradford reactive total root protein (BRRP) (r= 0.706 **) in pot experiment. Some previously researches had reported correlation between ELISA with Bradford contents, whether, Bradford and ELISA values were nearly the same, this means that the extraction process mostly separates glomalin. The results of non-mycorrhizal roots indicated that a small proportion of root protein is cross-reactive with the MAb32B11 antibody. There are some evidences that MAb32B11 is slightly cross-reactive with plant compounds, non-AMF species, and non-target proteins present in large concentration, such as BSA. Additionally, we found the increasing of BRRP contents of AMF-colonized root compared to the non-mycorhizal roots. This may be as a result of uptake and storage of arginine within AMF intraradical hyphae. Considering IRHP to BRHP ratio indicates that immunoreactivity percentage enhances by rising Pb levels. Immunoreactivity indicates a molecular configuration similar to the configuration of glomalin on hyphae. Our findings are in agreement with previous observations confirming that the toxicity-induced stress by metals may be enhancing glomalin production by AMF. The sequence of the glomalin gene revealed that is likely a 60-KDa heat-shock protein (Hsp) homolog. Glomalin relation with the heat shock proteins clarifies how stress is imposed by heavy metals may rapidly increase glomalin production by AMF and its concentrations in polluted soils.
Conclusion: The high contents of glomalin along with the increasing of Pb concentrations may be explained by the overexpression of this protein. This suggests that under Pb-induced stress and the toxic effect of Pb, the fungus exerts a protective mechanism against toxicant. Therefore, glomalin as a heat shock protein can involve in the reduction of possible cytosolic damages and the transfiguration of proteins under Pb toxicity. We can conclude that glomalin may reduce toxic elements availability via their stabilization and decrease their toxicity risk to other microorganisms and plants in heavy metal polluted sites.
Research Article
Mohsen Hamidpour; Leila Akbari; Hossein Shirani; Ali akbar Mohammadi
Abstract
Introduction: Soil contamination by heavy metals is a major concern throughout the world, due to persistence of metals in the environment and their toxicity and threat to all living organisms. Several strategies have been used to immobilize heavy metal ions in soils. Immobilization can be achieved by ...
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Introduction: Soil contamination by heavy metals is a major concern throughout the world, due to persistence of metals in the environment and their toxicity and threat to all living organisms. Several strategies have been used to immobilize heavy metal ions in soils. Immobilization can be achieved by adding natural and synthetic amendments such as zeolites and organic materials. Because of large specific surface area, high cation exchange capacity (CEC), low cost and wide spread availability, zeolites are probably the most promising materials interacting with many heavy metal ions in contaminated soils and water. Organic amendments such as vermicompost contains a high proportion of humified organic matter (OM), may decrease the bioavailability of heavy metals in soil by adsorption and by forming stable complexes with surface functional groups, thus permitting the re-establishment of vegetation on contaminated sites. Recent studies showed that the co-application of zeolite and humic acids could be effective in reducing the available fraction of Pb in a garden polluted soil. Fractionation of heavy metals cations in amended polluted-soils is needed to predict elemental mobility in soil and phyto-availability to plants. Therefore, the objective of this study was to investigate the effects of co-application of zeolite and vermicompost on Zn redistribution in a contaminated soil.
Material and Methods: A contaminated soil was collected from the top 20 cm in the vicinity of zinc mine in Zanjan province, western north of Iran. The soil sample was air-dried, passed through 2-mm sieve and stored at room temperature. The soil sample was thoroughly mixed to ensure uniformity. Sub-samples were then digested using the hot-block digestion procedure for total Zn concentration. The experiment was conducted under greenhouse condition. The polluted soil was put in polyethylene pots and mixed well vermicompost and zeolite at the rate of 0, 50 and 100 g kg-1 soil. The treatments were evaluated in a 3 × 3 factorial design and were arranged in a randomized block design with three replications. After incubation for 45 days, five seeds of corn were sown in each pot. After germination the seedlings were thinned to 3 per pot. Plants were grown for 2 months under control conditions. After the corn had been harvested, soil samples were air-dried, and analyzed for pH, cation exchange capacity (CEC), and electrical conductivity (EC). Chemical fractionations of Zn in soils collected after the pot trial were investigated using the procedure of Salbu et al. (1998). This procedure subdivides the heavy-metal distribution into an water-extractable+exchangeable fraction, a form bound to carbonates, a form bound to Fe and Mn oxides, a form bound to organics, and a residual form. An analysis of variance was used to test significance (P≤0.05) of treatment effects and Duncan multiple range test (P≤0.05) was used to compare the means (SAS, 2002).
Results and Discussion: Soil pH gradually decreased with application of both vermicompost and zeolite amendments. This may be due to degradation of organic matter and releasing of organic and inorganic acids such as carbonic, citric and malic acids as well as H+ produced from mineralization of nitrogen in the organic matter. Electrical conductivity (EC) of soils increased with increasing amounts of vermicompost and zeolite applications. The highest EC was observed in pots containing 10% w/w zeolite and 10% w/w vermicompost. Addition of zeolite significantly increased soil CEC. The overall distribution of Zn in different fractions was in the sequence residual (38.6%)> Fe and Mn oxides bound (31.0 %) > carbonated (21.6%)> organic (4.3%)≈exchangeable +water soluble (4.4 %). The application of vermicompost significantly decreased concentration of Zn in water+exchangeable fraction as compared to the control soil. Although singly zeolite amendment had not significant effect on water+exchangeable Zn concentration, this form decreased significantly with co-application of vermicompost and zeolite. This may be due to redistribution of Zn from this form to less available forms (e.g. organic and residual fractions). The addition of vermicompost had not significant effect on the carbonated fraction of Zn, whereas co-application of zeolite and vermicompost significantly decreased concentration of Zn bound in carbonates. Singly zeolite and co-application of amendments decreased the concentration of Zn in Fe and Mn oxides bound. Although singly compost and zeolite amendments increased concentration of Zn bound to organics, this form decreased furthest with co-application of them. Zeolite and vermicompost alone had not significant effect on mobility factor (MF) of Zn over the un-amended soil. Co-application of vermicompost and zeolite to polluted soil resulted in a significant decrease in MF values of Zn compared to control.
Conclusion: Co-application of vermicompost and zeolite to polluted soil resulted in redistribution of Zn from available forms (exchangeable +water soluble) to less available form (e.g. organic), thus may be useful for the immobilization of Zn from polluted sites.
Research Article
hamid reza motaghian; alireza hosseinpuor; Shahram Kiani
Abstract
Introduction: Use of organic fertilizers such as vermicompost in agricultural soils with low organic matter content is almost considered as a one way for adding nutrients in these soils. However, application of these fertilizers may affect micronutrient release characteristics. Micronutrient release ...
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Introduction: Use of organic fertilizers such as vermicompost in agricultural soils with low organic matter content is almost considered as a one way for adding nutrients in these soils. However, application of these fertilizers may affect micronutrient release characteristics. Micronutrient release Kinetics in soils especially in amended soils give information about potential of amended soils to release these elements into solution. Although it is important to study kinetics of micronutrient release from soils to identify soil micronutrients buffering capacity, little attention has been paid to micronutrients desorption rate studies especially in amended soils. The rate of release micronutrients from soil solid phase by considering micronutrients as adsorbed ions or in mineral forms is an important parameter in nutrition of plants by microelements and a dynamic factor that regulates its continuous supply to growing plants; nonetheless, little attention has been paid to micronutrients kinetics inrelease studies.
Material and Methods: In this study, kinetics of zinc (Zn) and copper (Cu) were compared in one calcareous soil amended with 0, 0.5, and 1% (w/w) of manure and vermicompost in a completely randomized design and then amended and un-amended soils were incubated at field capacity, for 30 days. After incubation period, amended and un-amended soils were air-dried and were prepared to kinetics study. Kinetics of Zn and Cu release were studied by successive extraction with DTPA-TEA solution. Two grams of the amended and un-amended soils, in triplicate, suspended in 20 ml DTPA-TEA solution were equilibrated at 25±10C for 1, 8, 24, 48, 72, 96, 120, 144, 168, 336 and 504 h by shaking for 15 min. before incubation and 15 min. before the suspensions were centrifuged. Seven drops of toluene were added to each 1000 ml of extractant to inhibit microbial activity. Zinc and copper desorption with time was fitted by using different equations (Zero-order, First-order, Parabolic diffusion, Simplified Elovich, and Power function).
Results and Discussion: Results showed that released Zn in soils amended with manure and vermicompost compared to control soil significantly increased (p0.05) and released Cu in soil amended with vermicompost decreased significantly (p
Research Article
MirHassan Rasouli-Sadaghiani; Habib Khodaverdiloo; Mohsen Barin; Solmaz Kazemalilou
Abstract
Introduction: Heavy metals (HMs) are serious threat for environment due to their dangerous effects. These metals as contaminants that can be accumulated in soil and after absorption by plants, finally will be found in food chains. Cadmium (Cd) is one of the dangerous HMs that threats the health of plants, ...
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Introduction: Heavy metals (HMs) are serious threat for environment due to their dangerous effects. These metals as contaminants that can be accumulated in soil and after absorption by plants, finally will be found in food chains. Cadmium (Cd) is one of the dangerous HMs that threats the health of plants, living organisms and human. Physicochemical remediation methods may cause large changes in different characteristics of soils . Recently environmental-friendly strategies including phytoremediation have been emphasized by researchers. Phytoremediation that refers to the use of plants and their assistance with microorganisms for remediation of contaminated soils is an effective and low cost method for reclamation of heavy metals polluted soils. The most important limitation of phytoremediation is low availability of heavy metals and sensitivity of plants to contamination. There are evidences that soil microbes can help to overcome these limitations through several ways. Plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) are known to enhance plant growth and survival in heavy metal contaminated soils through different mechanisms including producing promoting metabolites, auxin, siderophore and antibiotics. In this study the role of some strains of PGPR (a mixture of Pseudomonas species including P. putida, P. fluorescens, and P. aeruginosa) and AMF (a mixture of Glomus species including G. intraradices, G. mosseae and G. fasciculatum), on uptake and accumulation of Cd, Fe, Zn and Cu as well as some physiological properties of Onopordon (Onopordon acanthium L) were evaluated.
Materials and Methods:This study was carried out under greenhouse condition as a factorial experiment based on a randomized complete block design with two factors including Cd concentration (four levels) and microbial treatment (three levels) in three replications. Consequently, a soil was selected and spiked uniformly with different concentrations of Cd (0, 10, 30 and 100 mg Cd kg-1 soil) at greenhouse of agricultural college in Urmia University. The contaminated soils were then sterilized and subsequently inoculated with arbuscular mycorrhizal fungi (a mixture of Glomose species including G. intraradices, G. mosseae and G. fasciculatum) and plant growth promoting rhizobacteria (a mixture of Pseudomonas species includeing P. putida, P. fluorescens, and P. aeruginosa). The seeds of Onopordon plants were grown in 2.5 kilogram pots under greenhouse condition. At the end of growing season the shoot dry weight, Cd, Fe, Zn and Cu concentration and element contents and some of physiological parameters of plant as well as microbial properties were analyzed. Furthermore, the effect of soil Pb level on population, activity and efficiency of the inoculated microbes was studied.
Results and Discussion: Significant difference was observed for plants’ dry weights. At different Cd levels, the yield of inoculated plants was higher than that of control plants. Furthermore, at elevated Cd concentration, plant height, biomass, relative yield, chlorophyll a, b, carotenoids, relative water content (RWC) decreased significantly (P < 0.05), however, plants inoculated with plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi showed considerable amount of dry matter, chlorophyll a, b as well as RWC. Mycorrizal and bacterial inoculation and Cd treatment also had significant effect on leaf photosynthetic pigments concentration and plant relative water content. In general, concentrations of photosynthetic pigments and RWC were higher in inoculated plants at every level of soil Cd. The microbial inoculation effectively decreased the inhibitory effects of Cd on plant growth. Shoot yield of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria plants increased by 2.7 and 2.1 times as well as microbial respiration increased by 2.17 and 2.01 times compared to control treatment. The results showed inoculated plant absorbed more Cd than non-inoculated plants. Plant growth promoting rhizobacteria were more effective than arbuscular mycorrhizal fungi inoculation in shoot Cd concentration. Cd contamination reduced soil microbial population and basal respiration. Results showed that with increasing soil Cd concentration shoot Fe, Zn and Cu concentrations significantly decreased. Root colonization rates decreased significantly with 10 mg kg-1 Cd addition for AMF treatments, and drastically with 100 mg kg-1 Cd added. Plant roots in the control and PGPR treatment were not colonized.
Conclusion: It is concluded that plant growth promoting rhizobacteria and arbuscular mycorrhizal fungi inoculation could be sustained and promoted plant growth in phytoremediation processes. Therefore, under Cd contamination it can be use PGPR and AMF as growth promoters and finally enhance phytoremediation efficiency.
Research Article
Mohammad Akbar Bahoorzahi; Mohammad Hady Farpoor; Azam Jafari
Abstract
Introduction: The optimum and sustainable use of soil is only possible with correct and complete understanding of its properties. The objectives of the present research were to study 1) genesis and development of soils related to different geomorphic surfaces in Kouh Birk Area (Mehrestan City), 2) Soil ...
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Introduction: The optimum and sustainable use of soil is only possible with correct and complete understanding of its properties. The objectives of the present research were to study 1) genesis and development of soils related to different geomorphic surfaces in Kouh Birk Area (Mehrestan City), 2) Soil classification according to Soil Taxonomy (2014) and WRB (2014) systems, and 3) physicochemical properties, clay mineralogy and micromorphology of soils.
Materials and Methods: Mean annual rainfall and soil temperature in the selected location are 153.46 mm and 19.6 oC, respectively. From geological point of view, the studied area is a part of west and south west zones and Flysch zone of east Iran. Soil temperature and moisture regimes of this part are thermic and aridic, respectively. Eight representative pedons on different surfaces including rock pediment, mantled pediment, Alluvial fan and Upper terraces were selected, sampled, and described. Routine physicochemical analyses, clay mineralogy, and micromorphological observations performed on soil samples. Soil reaction, texture, electrical conductivity, calcium carbonate, and gypsum were identified. Four samples including Bt horizon of pedon 1, Bk1 horizon of pedon 4, By2 horizon of pedon 5 and Bk1 horizon of pedon 7 were selected for clay mineralogy investigations. Four slides including Mg saturated, Mg saturated treated with ethylene glycol, K saturated, and K saturated heated up to 550 oC were analyzed. A Brucker X-Ray diffractometer at 40 kV and 30 mA was used for XRD analyses. Undisturbed soil samples from Bt horizon of pedon 1, Bk2 horizon of pedon 2, Btn horizon of pedon 3, By2 horizon of pedon 5, Bk1 horizon of pedon 7, and By1 horizon of pedon 8 were selected for micromorphological observations. A vestapol resin with stearic acid and cobalt as hardener was used for soil impregnation. Bk-Pol petrographic microscope was used for micromorphology investigations.
Results and Discussion: Due to the presence of argillic and petrocalcic horizons in rock pediment, soils of this surface were more developed compared to other landforms. High amount of CaCO3 (39.5%) was observed in pedon 4 on rock pediment geomorphic surface which is attributed to calcareous parent material. The presence of argillic horizon in this geomorphic position is due to the more available water of the past climate. The maximum salinity was observed in the mantled pediments. Calcic over gypsic horizons formed in pedon 7 on alluvial fan surface due to higher solubility of gypsum than calcium carbonate. Kaolinite, illite, chlorite, and palygorskite clay minerals were found in pedons 1 and 4 on rock pediment. Palygorskite in this position seems to be pedogenic, but kaolinite, illite, and chlorite are inherited from parent material. Mantled pediment and alluvial fan showed smectite, kaolinite, illite, chlorite, and palygorskite clay minerals. Pedogenic smectite in this position is probably formed from weathering of illite and chlorite. On the other hand, palygorskite stability decreased in mantled pediment surface. This is the reason why smectite was the dominant clay mineral in this landform. Clay and calcite coatings were investigated in Bt horizon of pedon 1 (rock pediment). Coatings and infillings of calcite in Bk2 horizon of the same geomorphic position caused a calcic crystallitic b fabric. A diffused clay coating due to the presence of Na in Btn horizon of pedon 3 in rock pediment was observed. Micromorphological observations of By2 horizon in pedon 5 (mantled pediment) showed gypsum interlocked plates and gypsum infillings. Interlocked plates formed due to re-solubility of gypsum crystals. Micro spars and infillings of calcite are among dominant pedofeatures found in Bk1 horizon of pedon 7 (alluvial fan geomorphic surface). A calcic crystallitic b fabric and Primary calcite mineral were also observed in this pedon. Release of Ca from calcareous parent material caused Ca+2 to SO4-2 ratio to be increased which could be a probable source of gypsum formation. Results of the study showed that more and less developed soils formed on rock pediment and upper terrace geomorphic surfaces, respectively. Illuviation of clay, gypsum, and CaCO3 together with formation of cambic, calcic, petrocalcic, gypsic, argillic, and natric horizons were among the dominant pedogenic processes in studied soils. Paleosols containing Bt horizons were only observed on rock pediment geomorphic surface. Kaolinite, illite, chlorite, and palygorskite clay minerals were observed in almost all surfaces. Smectite was not discovered in rock pediment, but was only investigated in mantled pediment and alluvial fan which could be attributed to higher available moisture of formation time in these surfaces. Secondary calcite and gypsum caused stability of pedogenic palygorskite in soils under study. Micromorphological observations proved the presence of clay and calcite coatings, calcite and gypsum infillings, and gypsum interlocked plates. Gypsum pedofeatures were not observed in rock pediment, but clay and calcite pedofeatures were only found. On the other hand, clay and calcite pedofeatures were not observed in upper terraces and gypsum pedofeatures were the only features determinded in this position.
Conclusion Results of the present research showed that difference in soil characteristics is highly affected by geomorphology.
Research Article
zahra dianat maharluei; ali akbar moosavi
Abstract
Introduction: In arid and semi-arid soils, low organic matter is one of the barriers to achieving optimal performance. The soils with more organic matter have a better structure and are more resistant to erosive factors such as water and wind. Soil organic matter has a particular importance and has significant ...
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Introduction: In arid and semi-arid soils, low organic matter is one of the barriers to achieving optimal performance. The soils with more organic matter have a better structure and are more resistant to erosive factors such as water and wind. Soil organic matter has a particular importance and has significant impact on the stability of soil aggregates, the extension of plant root system, carbon and water cycles and soil resistance to erosion. This substance acts as a cementing agent and plays an important role in soil flocculation and formation of resistant aggregates.Also, the addition of organic matter to the soil increases soil porosity and decreases soil bulk density.
Materials and Methods: In this research, the effect of the two types of organic matter (compost and the ripe fruit waste of fig) on some soil physical properties was studied. A factorial experiment based on completely randomized design, including the four levels of compost and the ripe fruit waste of fig (0, 1, 2 and 4 by weight %) and three soil types (loamy sand, loam and silty clay loam) with three replications was carried out. The soil samples were collected from the three territories of Fars Province: loamy sand soil from Shiraz, loamy soil from Maharlu and Silty clay loam soil from Zarghan area. The soil samples were air dried and passed through a 2 mm sieve. The physical properties including the bulk density, particle density, porosity, moisture content and soil crust strength was measured. In this research, the soil texture by hydrometer method, Electrical conductivity of the soil saturated paste extract by electrical conductivity meter, saturated paste pH by pH meter, seedling emergence test, soil crust strength by a pocket penetrometer (HUMBOLDT MFG.CO.) bulk density by cylindrical sample and particle density by pycnometer method were measured. The fig fruit treatments were prepared by thoroughly mixing the dried powder of ripe fig fruit passed through a 2 mm sieve (with the rates of 0, 1, 2, and 4 % by dry weight) with the air dried soils. Also, the compost treatments were prepared by thoroughly mixing the dried powder of compost passed through a 2 mm sieve (with the rates of 0, 1, 2, and 4 % by dry weight) with the air dried soils. The test measurement PVC cylinders with an inner diameter of 12.5 cm and a height of 20 cm were prepared. The bottom ends of the cylinders were closed with a screened PVC plate. These cylinders were uniformly filled with the treated soils and irrigated a few times to make a homogeneous soil column. About 3 cm of the top end of the cylinders were left empty.
Results and Discussion: The results showed that all the rates of the ripe fruit waste of fig and the compost treatments significantly decreased crust strength of all soils compared to control at 1% probability level. The results also showed nearly the greater effect of all the treatments on crust strength of loamy sand soil compared to the other soils. All the rates of the ripe fruit waste of fig and compost treatments significantly increased the moisture content of all the soils compared to control at 1% probability level. Moreover, the greater effect of all the treatments on the moisture content of silty clay loam soil compared to other soils was generally observed. All the rates of the ripe fruit waste of fig and compost treatments decreased the bulk density and particle density of all the soils compared to control. Tthe greatest impact was observed in the compost treatments at the level of 4% by dry weight and silty clay loam texture. Also, all the rates of the ripe fruit waste of fig and compost treatments increased the porosity of all the soils compared to control, and the greatest impact belonged to the compost treatments at the level of 4% by dry weight andsilty clay loam texture.
Conclusion: The results showed that the use of the ripe fruit waste of fig and compost in the soil increased moisture content and decreased crust strength significantly compared to the control. Also, the ripe fruit waste of fis and compost in the soil increased porosity and decreased bulk density and particle density compared to the control, but this increase and decrease were not significant.Reduction in crust strength caused by the ripe fruit waste of fig application was more than compost application. However, the effect of compost application on the soil bulk density, particle density, porosity and moisture content was more than the ripe fruit waste of fig application.
Research Article
roza kazemi; shahram kiani
Abstract
Introduction: Nitrification inhibitors (NIs) are compounds that retard the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in the soil. Many popular NIs such as nitrapyrine (NP), dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) are produced ...
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Introduction: Nitrification inhibitors (NIs) are compounds that retard the biological oxidation of ammonium to nitrite by depressing the activity of Nitrosomonas bacteria in the soil. Many popular NIs such as nitrapyrine (NP), dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) are produced and used in agricultural soils. Dicyandiamide is a very popular NI in some of the world countries. It delays nitrification process in the soil through its bacterial static property. It is easy to blend with commercial fertilizers such as urea, due to its low volatile nature. Application of urea in combination with nitrification inhibitor DCD lengthens nitrogen presence in soil as ammonium form. It has several beneficial effects for agriculture and enhances environmental protection. Studying the ammonium oxidation kinetics in the presence of nitrification inhibitor DCD can provide the experts in agriculture with very useful information regarding the ammoniumdurability in different soils. This research has been done to study the effect of using NI dicyandiamide on the kinetics of ammoniumloss in some calcareous soils of Chaharmahal Va Bakhtiari province, Iran.
Materials and Methods: This research was conducted as factorial using completely randomized design with two factors of nitrogen fertilizer type and soil type with three replications at laboratory conditions. In this experiment, nitrogen fertilizer type included 2 levels of: 1- urea 2- urea plus nitrification inhibitor DCD (3.2%). A no added nitrogen fertilizer was considered as control treatment.The soil factor also consisted of 5different soils with a wide variation in soil physical and chemical characteristics. Five selected soils were non-saline (EC1:2=0.14-0.76 dS m-1) and alkaline (pH1:2=7.5-8.2). Organic carbon and cation exchange capacity (CEC) ranged from 0.48 to 2.34% and 10 to 30 cmolc kg-1, respectively. The dose of applied nitrogen in all experimental treatments was 50 mg kg-1 N as urea. Forty-five containers containing different soils were incubated at 20°C for 105 days. At 1, 7, 14, 21, 28, 35, 49, 63, 77, 91 and 105 days after adding urea and urea+DCD, soil subsamples were extracted to determine ammonium content. The ammonium concentration (extracted with 0.5 M K2SO4) was determined colourimetrically using a spectrophotometer at a wavelength of 667 nm. Then zero, first and second order equations were calibrated on the residual ammonium in the soil using SAS 8.02 and the best equation was seleted on the basis of coefficients of determination (R2) and standard error of the estimate (SE). In addition, ammonium half-time and nitrification inhibitor index were calculated.
Results and Discussion: The results indicated that the first order equation was able to describe ammonium oxidation kinetics of the soil in all of the experimental treatments (control, urea and urea+DCD). The average values of R2 and SE of first order equationwere 0.915 and 1.51 in control, 0.903 and 4.98 in urea treatment and 0.863 and 4.92 in urea+DCD treatment, respectively. It means that ammonium oxidation kinetics is dependent on the ammonium concentration in soil. In all study soils, the slope of the first order equation in the urea treatment with DCD has been less in comparison to similar treatment but without NI. This may be explained by the fact that application of DCD has slowed down the process of ammonium oxidation to nitrite. The application of urea with DCD resulted in increase of ammonium half-life (calculated with first order equation) in the soil comparing to urea fertilizer without NI in all of the studied soils. The amount of this increase for DCD was 34.8, 31.6, 31.1, 25.1 and 40.4 days for the soils number of 1 2, 3, 4, and 5, respectively. Increasing the presence of ammonium in soil can be considerable for agricultural and environmental purposes. The maximum nitrification inhibitor indexes were 11.3% and 28.1% after 28 days of incubation in soils number 1 and 3, respectively. These nitrification inhibitor index values are in agreement with observations by other researchers.
Conclusion: The results showed that nitrification inhibitor DCD is compound with a high capacity for extending ammonium presence in studying soils under conditions of this experiment. However, its efficiency was dependent to physical and chemical properties of soil.According to the results, first order equation was the best equation for describing ammonium oxidation kinetics in tested soils fertilized with urea and urea+DCD.
Research Article
rahim motalebifard; Nosratollah Najafi; Shahin Oustan
Abstract
Introduction: In natural environments, plants are subjected to biotic (insects, bacteria, fungi, and viruses) and abiotic (light, temperature, water availability, nutrients, and soil structure) stresses that can have negative effect on growth, metabolism, and yield. Among these, drought is a major abiotic ...
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Introduction: In natural environments, plants are subjected to biotic (insects, bacteria, fungi, and viruses) and abiotic (light, temperature, water availability, nutrients, and soil structure) stresses that can have negative effect on growth, metabolism, and yield. Among these, drought is a major abiotic factor that limits agricultural crop production. Potato production has fourth rank in the world after rice, wheat, and maize with the production of 321 million tons from 19.6 million hectares. By about 3 percent of cultivation area, potato had 7.2 percent of total agricultural production (5.57 million tons) in our country (Iran). Limited studies have been conducted on the interactive effects of Zn and P on potato tubers quality under water deficit conditions.
Materials and Methods: This study was conducted for evaluating the effects of soil moisture, phosphorus (P) and zinc (Zn) levels on the chemical composition and nutrients content of potato (Solanum tuberosum L. cv. Agria) as a factorial experiment based on randomized complete blocks design with three factors under greenhouse conditions. The study was performed with factors of Zn at three levels (0, 10 and 20 mg Zn per kg dry soil as ZnSO4.7H2O), P at three levels (0, 30 and 60 mg P per kg dry soil as Ca(H2PO4)2.H2O (monocalcium phosphate)) and soil moisture at three levels (0.5FC-0.6FC, 0.7FC-0.8FC and 0.9FC-FC) using three replications and 81 pots. The soil moisture levels were imposed three weeks from the flowering (64th day) until harvest (85th day after planting). After imposing of soil moisture levels and at the harvest, the yield and yield components, reducing sugars concentration in fresh weight by di- nitro phenol method (Mostofi and Najafi, 2005) and starch by Antron method (Mostofi and Najafi, 2005), N, P, K, Mg, Na, Fe and Zn concentrations in dried potato tubers were measured. Data were subjected to analysis of variance as factorial 3×3×3 with n=3 by using MSTATC software. Duncan's multiple range tests at p≤0.05 probability level was applied to compare the mean values of measured attributes. The Excel software was used to draw Figures.
Results and Discussion: The results showed that water deficit significantly affected most of qualitative attributes and nutrients concentration of potato Tuber N, P and reducing sugar concentrations were significantly increased (p
Research Article
shahrzad kabirinejad; mahmoud kalbasi; amir khoshgoftar manesh; M. Hoodaji; Majid Afyuni
Abstract
Introduction: Preceding crops as a source of organic matter are an important source of micronutrient and can play an important role in the soil fertility and the micronutrients cycle of soil. In addition to the role of the organic matter in increasing the concentration of micronutrients in soil solution, ...
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Introduction: Preceding crops as a source of organic matter are an important source of micronutrient and can play an important role in the soil fertility and the micronutrients cycle of soil. In addition to the role of the organic matter in increasing the concentration of micronutrients in soil solution, attention also should be paid to the role of the kind and the quantity of the root’s exudates that are released in response to the incorporation of different plant residues in the rhizosphere. Present research was conducted with the objective of studying the effect of the kind of preceding crops: Trifolium (Trifolium pretense L), Sofflower (Carthamus tinectirus L), Sorghum (Sorghum bicolor L), Sunflower (Heliantus annus L) and control (fallow) on the chemical forms of copper in the wheat rhizosphere and the bulk soil and Cu uptake by wheat and also investigating the correlation between the fractions of Cu in soil and Cu uptake in wheat.
Materials and Methods: The present research was conducted as split plot in a Randomized Complete Block design (RCBD) with 3 replications and 5 treatments, in field conditions. In the beginning, the preceding crops were cultivated in the experimental plots and after ending growth, preceding crops were harvested. Then the wheat was cultivated in the experimental plots. Finally, after harvesting the wheat, soil samples were collected from the two parts of the root zone (the wheat rhizosphere and the bulk soil). The soil samples were air dried ground and passed through a 2-mm sieve and stored for chemical analysis. Soil pH (in the soil saturation extract) and organic matter (Walkley–Black wet digestion) were measured in standard methods (1). The Total Organic Carbon (TOC) was measured by Analyzer (Primacs SLC TOC Analyzer (CS22), Netherlands). The available Cu in soil was extracted by DTPA and determined using atomic absorption spectroscopy (2). The fractionation of soil Cu was carried out using the MSEP method (3).
Results and Discussion: The results showed that the preceding crops significantly decreased soil pH, also significantly increased the DOC and DTPA-extractable Cu.These changes were higher in the Trifolium preceding treatment in the rhizosphere soil. Also, the preceding crops significantly decreased Carbonate -Cuand Residual-Cu fractions in the wheat rhizosphere compared with the bulk soil. The preceding crops (except Trifolium) significantly increased Oxide-Cu fraction. The soil Oxide- Cu fraction was higher in the rhizosphere in comparison with the bulk soil. The preceding crops increased the Organic-Cu in both the wheat rhizosphere and the bulk soil and it was higher in Trifolium treatment. The preceding crops increased Cu uptake by wheat and Organic-Cu positively correlated with Cu uptake by wheat.
Conclusion: The Organic-Cu fraction increased in the rhizosphere compared with the bulk soil, whereas Oxide- Cu, Carbonate–Cu and Residual-Cu fractions decreased. According to the results, the observed increase in the copper concentration of organic fraction in the rhizosphere was due to the decrease in the copper concentration of carbonate, oxide and residual fractions. In fact, the main process is the transmission of copper from carbonate, oxide and residual fractions to another fraction. Also, the results showed that the root exudates of the preceding crops and wheat affected the different forms of copper in the soil solid phase. Furthermore, the results of copper forms correlation analysis with Cu uptake by wheat showed that the Organic-Cu fraction had more important role in supplying copper was needed for wheat. Therefore, the preceding crops increased the copper concentration of organic fraction in the rhizosphere compared with the bulk soil, and these changes are associated with increasing the amount of copper uptake in wheat.
Research Article
babak motesharezadeh; somayeh rezaezadeh; majid fekri
Abstract
Introduction: Boron is one of the seven essential microelements for the natural growth of plants. The toxicity of this element occurs in arid and semi-arid regions, which is because of its high level in soils and the irrigation water of mentioned regions. The aim of this study was to evaluate the effect ...
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Introduction: Boron is one of the seven essential microelements for the natural growth of plants. The toxicity of this element occurs in arid and semi-arid regions, which is because of its high level in soils and the irrigation water of mentioned regions. The aim of this study was to evaluate the effect of nitrogen application on boron toxicity tolerance in pistachio, Badami-Zarand variety. The effects of three nitrogen levels (0, 250, and 350 mg/kg of soil) on the reduction of toxicity due to the three levels of boron (0, 15, and 30 mg/kg of soil) were examined in Badami-Zarandi variety of pistachio under greenhouse conditions. After 7 months from sowing the seeds, pistachio seedlings were harvested and desired traits were measured. The results showed that by increasing boron application level, boron concentration in the shoot and root of seedlings increased whereas their dry weight decreased. Using of nitrogen reduced the negative effects of boron on the dry weight and led to increase dry weight and decrease boron concentration in the shoot and root of pistachio, Badami variety. Nitrogen application at the levels of 250 and 350 mg N per kg of soil reduced boron uptake in shoots by reinforcing plant vegetative system and increasing chlorophyll content by 13.5% and 30.2%, respectively and finally led to diluted boron concentration in the plant (dilution effect) and reduced the effects of boron toxicity. Hence, optimized nitrogen application is suggested as one of the management methods in controlling Boron toxicity under these conditions.
Materials and Methods: A factorial experiment based on randomized complete block design with four replications was carried out. Soil sampling was done in 0-30 cm depth in a zeekzack way from a pistachio garden that located in mahmoodiye area in Rafsanjan. The soil sample was air-dried and passed through a 2mm sieve. The soil chemical and physical properties were measured. In this study, badami-zarand cultivar seed was used because it is one of the most important pistachio cultivars. The seeds were soaked in water for 24 hours and disinfected by benomyl fungicide. When the seeds germinated, they were planted in the pots containing 4.5 kg soil and without drainage, so nutrients balance was kept during growing period. After 7 months, the seedlings were harvested and B was measured.
Results and Discussion: The results showed that increasing the boron levels from 0 to 30 mg kg-1 led to decrease shoot dry weight from 3.72 to 2.45 gram and root DM from 2.28 to 1.50 gram. Increasing 30 mg kg-1 boron led to 2.8 times increase of shoot boron concentration. The averages of shoot boron concentration in the levels of 15 and 30 mg kg-1 boron were 87.6 and 122 mg kg-1DM, respectively. The boron toxicity level in Badami-Zarand cultivar is 8.9 mg kg-1 DM (Sepaskhahet al, 1994), so these levels were the cause of boron toxicity and boron toxicity symptoms were seen as leaf burn, often at the margins and the tips of older leaves.
The results showed that increasing nitrogen levels led to decrease shoot boron concentration and increase their weight. The results also showed a significant negative correlation between the nitrogen levels and boron uptake. Boron uptake in the shoots of seedlings about 13.5 and 30.2 percent decreased when nitrogen levels increased. Shoot dry weight decreased when boron application increased, but it increased when nitrogen was used (Koohkan and Maftoun, 2009).
Conclusion: The reduction of dry weight and increasing boron concentration occurred when increased boron application. The Maximum of boron uptake was seen by leaves, and boron toxicity symptoms were appeared as leaf burn especially at the tips and margins of older leaves. Since, boron is immobile in pistachio; it is absorbed by mass flow, so the accumulation of boron at older leaves is persuaded. Nitrogen reduced the bad effects of boron on dry weight and the bad effects of increasing boron concentration by the synthesis of chlorophyll, so it was more useful in shoot than root. Boron uptake was also reduced by nitrogen application. This effect of nitrogen is probably concerned to the increase of dry weight more than boron concentration (Dilution effect). On the other hand, nitrogen caused to increase leaf index and increase the number of seedling leaves. The injured leaves due to boron toxicity were restored, because of high leaf chlorophyll. It is suggested that this study will be done under field conditions for fertilizer application recommendations and to be used for creation of tolerant cultivars of pistachio.
Research Article
javad seyedmohammadi; leila esmaeelnejad; hassan ramezanpour; kamran eftekhari
Abstract
Introduction: Paddy soils are important and the base of agriculture in Guilan province. It is necessary to recognize these soils for understanding of their limitations and optimum use. Unsaturated soil submerging is the cause of collection of chemical and electrochemical process that has significant ...
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Introduction: Paddy soils are important and the base of agriculture in Guilan province. It is necessary to recognize these soils for understanding of their limitations and optimum use. Unsaturated soil submerging is the cause of collection of chemical and electrochemical process that has significant effects on soil fertility. Eh, rH and pH are important indexes that are used to investigate oxidation and reduction condition in submerged soils and have abundant effects on activity and sorption rate of nutrients. Decrease of Eh and rH in poorly drainage of paddy soils affects availability and solubility of nutrient. Different Fe forms are used for analysis of soils evolution trend and submerging influences on changes of Fe forms. The aim of the present study was conducted to investigate the effect of redox potential changes on soil characteristics and analysis of soils evolutional trend in different physiographic units.
Materials and Methods: The study area with 40000ha (at the east of Rasht city) is located between 49° 31' to 49° 45' E longitude and 37° 7' to 37° 27' N latitude in North of Guilan Province, Northern Iran, in the southern coast of the Caspian sea with different water table depth. The climate of the region is very humid with the mean annual precipitation of 1293.6 mm. The mean annual temperature is 15.8°C. The soil moisture and temperature regimes are Aquic, Udicand Thermic, respectively. The parent materials are derived from river sediments. The soils formed on the plateaues and upper terraces, river alluvial plain and lowland physiographic units were classified as Inceptisols and the soils formed on coastal plain physiographic unit as Entisols. Air-dried soil samples were crushed and passed through a 2mm sieve. Particle-size distribution, organic carbon and cation exchange capacity were determined by hydrometric, wet oxidation and ammonium acetate methods, respectively. Eh by Eh electrode, total iron, free iron and amorphous iron were determined using nitric acid, dithionite-citrate-bicarbonate and ammonium oxalate methods, respectively. The means of different Fe forms values compared through LSD test.
Results and Discussion: It can be seen especial morphological and physicochemical characteristics in studied paddy soils with high groundwater table due to artificial submerging in rice growing seasonDifferent Fe mottles such as orange mottles include lepidocrocite mineral was observed in studied soils. Low redox potential with average 145/7mV and rH with average 19.6 in lowland and coastal soils implicate intense reduction condition. In lowland soils Eh was lower than other units and it was lower in top horizons than to sub horizons in all of units. Eh index had inverse relationship with organic matter, because of high organic matter amount caused high activity of anaerobic micro-organisms, increase of iron reduction and reduction soils degree decrease. rH index amounts showed that studied soils had reduction condition and presence of brown iron and black manganese minerals proved this condition. CEC was high in top soil of physiographic units due to high amount of organic matter and clay content. Clay particles in plateaues were lower than other units because of alteration and suitable aeration and showed high evolution in these soils. Clay coatings were not observed due to high ground water table and its alternative fluctuation. Results showed amorphous iron in surface horizons with average amount of 24.3g kg-1 was higher than subsurface in all soils and had positive correlation with organic matter, because of high activity of anaerobic micro-organisms that prevent from transformation of amorphous iron to crystallized iron, therefore amorphous iron amount increased in presence of organic matter. Pedogenic iron was high in A and B horizons with regard to BC and C horizons due to aeration and weathering. In lowland and coastal land Fed was lower than plateaues and upper terraces and river alluviums units because of ground water presence and its alternative fluctuation. Fed-Feo index showed crystallized iron oxides, high amount of Fed-Feo index proved soils evolution and high weathering. Feo/Fed ratio was related to amorphous pedogenic iron and high amount of this index showed few evolution of soil. Fed/Feo and Fed-Feo indexes indicated the lower rate of crystallized iron with average 6.8g kg-1 in lowland and coastal soils and implicated the lower evolution of these units' soils, due to higher surface groundwater and its more fluctuation than soils of plateaues, upper terraces and river alluviums unites with average amount of crystallized iron 15/8g kg-1.The comparison of different Fe forms using LSD method showed significant difference at the 0.01 level for different Fe forms values in different physiographic units.
Conclusion: Submerging, high groundwater table and severe fluctuation caused noticeable changes in morphological, physical, chemical and electrochemical properties of studied paddy soils. Noticeable organic matter amount added to soil and their burial by puddling operation and slow decomposition were effective factors in redox potential changes of studied wet soils. In equal anaerobic condition, more organic matter caused to decrease redox potential in surface horizons of soils with aquic condition and reverse, lower organic matter caused increasing in redox potential. lower amount of Eh and rH proved severe reduction condition in lowland. Investigation of Fed-Feo and Feo/Fed showed that their amount in lowland and coastal land were lower than plateaus and river alluviums, therefore lowland and coastal soils had lower evolution. Mean comparison of different Fe forms values using LSD method showed significant difference at the 0.01 level for different Fe forms in different physiographic units.
Research Article
M. Hashemi; Ahmad Gholamalizadeh Ahangar; Abolfazl Bameri; F. Sarani; A. Hejazizadeh
Abstract
Introduction: In order to provide a database, it is essential having access to accurate information on soil spatial variation for soil sustainable management such as proper application of fertilizers. Spatial variations in soil properties are common but it is important for understanding these changes, ...
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Introduction: In order to provide a database, it is essential having access to accurate information on soil spatial variation for soil sustainable management such as proper application of fertilizers. Spatial variations in soil properties are common but it is important for understanding these changes, particularly in agricultural lands for careful planning and land management.
Materials and Methods: To this end, in winter 1391, 189 undisturbed soil samples (0-30 cm depth) in a regular lattice with a spacing of 500 m were gathered from the surface of Miankangi land, Sistan plain, and their physical and chemical properties were studied. The land area of the region is about 4,500 hectares; the average elevation of studied area is 489.2 meters above sea level with different land uses. Soil texture was measured by the hydrometer methods (11), Also EC and pH (39), calcium carbonate equivalent (37) and the saturation percentage of soils were determined. Kriging, Co-Kriging, Inverse Distance Weighting and Local Polynomial Interpolation techniques were evaluated to produce a soil characteristics map of the study area zoning and to select the best geostatistical methods. Cross-validation techniques and Root Mean Square Error (RMSE) were used.
Results and Discussion: Normalized test results showed that all of the soil properties except calcium carbonate and soil clay content had normal distribution. In addition, the results of correlation test showed that the soil saturation percentage was positively correlated with silt content (r=0.43 and p
Research Article
M. Ghorbanian Kerdabadi; Hamideh Noory; A.M. Liaghat
Abstract
Introduction: Crop coefficient varies in different environmental conditions, such as deficit irrigation, salinity and intercropping. The effect of soil fertility and texture of crop coefficient and evapotranspiration of maize was investigated in this study. Low soil fertility and food shortages as a ...
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Introduction: Crop coefficient varies in different environmental conditions, such as deficit irrigation, salinity and intercropping. The effect of soil fertility and texture of crop coefficient and evapotranspiration of maize was investigated in this study. Low soil fertility and food shortages as a stressful environment for plants that makes it different evapotranspiration rates of evapotranspiration calculation is based on the FAO publication 56. Razzaghi et al. (2012) investigate the effect of soil type and soil-drying during the seed-filling phase on N-uptake, yield and water use, a Danish-bred cultivar (CV. Titicaca) was grown in field lysimeters with sand, sandy loam and sandy clay loam soil. Zhang et al (2014) were investigated the Effect of adding different amounts of nitrogen during three years (from 2010 to 2012) on water use efficiency and crop evapotranspiration two varieties of winter wheat. The results of their study showed. The results indicated the following: (1) in this dry land farming system, increased N fertilization could raise wheat yield, and the drought-tolerant Changhan No. 58 showed a yield advantage in drought environments with high N fertilizer rates; (2) N application affected water consumption in different soil layers, and promoted wheat absorbing deeper soil water and so increased utilization of soil water; and (3) comprehensive consideration of yield and WUE of wheat indicated that the N rate of 270 kg/ha for Changhan No. 58 was better to avoid the risk of reduced production reduction due to lack of precipitation; however, under conditions of better soil moisture, the N rate of 180 kg/ha was more economic.
Materials and Methods: The study was a factorial experiment in a completely randomized design with three soil texture treatment, including silty clay loam, loam and sandy-loam soil and three fertility treatment, including without fertilizer, one and two percent fertilizer( It was conducted at the experimental farm in Jey and Qahab district of Isfahan. Reference evapotranspiration and actual evapotranspiration of maize were measured by evaporation pan method and volumetric soil water balance method using micro lysimeters, respectively. In order to accommodate the growing field conditions, a ditch with a depth of 25 cm, length of 240 cm and width of 300 cm were dug and micro-lysimeters were placed it in three rows (three replications) with a distance of 75 cm. After preparing the treatments, four seed Maize with variety of NS540 were planted at a depth of 3-5 cm on 5 August. To reduce the oasis effect on evapotranspiration, the same corn was planted in the vicinity of the project area with 500 square meters..
Results and Discussion: The results showed that using fertilizer caused increasing of crop evapotranspiration and crop coefficient of maize. Maximum of the ten-day average evapotranspiration of maize in the silty clay loam soil with two percent fertilizer was obtained 8.76 (mm/ day) on the fifth decade of growth and this value was found 45.5 percent higher than the lowest mean evapotranspiration value of the ten-day. Comparison evapotranspiration of maize in different soil fertility treatments showed that the greatest impact on increasing of maize evapotranspiration in SLF2, SCLF2, SLF2 treatments were obtained that was equal %19.1, %14.3 and %10.6, respectively (table 4). Most of the effects of fertility the crop coefficient of maize at the middle stage of growth was influenced more than other stages by the different treatments of soil fertility. Adding one and two percent of the fertilizer to treatment SCLF0 increased maize crop coefficient about 3.5 and 9.7 percent at development stage, respectively, That measured %6 and 11% for LF1 and LF2 treatments, respectively, and about 1.6 and 5.6% for SLF2 SLF1 treatment, respectively (Table 6). Comparison of maize middle crop coefficient in SLF2 and SLF1 for different soil fertility treatments showed that effect of increasing soil fertility on middle Kc of maize was more than other stages of plant growth (Table 6). The obtained results showed that the addition of one and two percent fertilizer to the silty clay loam soil increased, the middle crop coefficient 13.3% and 27%, respectively in.
Conclusion: Maximum and minimum effect of soil fertility on increasing crop coefficient of maize in the middle stage was equal to 37.8% in the loamy soil and 18.3% in the sandy loam soil with two percent fertilizer. The greatest effect of soil fertility on crop coefficient of maize was measured 8.37% in the middle stage of growth in LF2. The effect of soil fertility on crop coefficient of maize in loam and silty clay loam soils more than sandy loam soil, Because can be a further organic matter in these soils (loam and silty clay loam and also decreasing evaporation in sandy loam soil.
Research Article
Nader Naderi; Ramin Fazl Oula; Mirkhaleg Ziatabar Ahmadi; Ali Shahnazari; Saeed Khavari Khorasani
Abstract
Introduction: Water shortage is the most important factor affecting crop production in the world. The deficit irrigation is a way to reduce water consumption in farming. The Partial Root- zone Drying (PRD) irrigation is a new improvement in deficit irrigation in which the half of the root zone is irrigated ...
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Introduction: Water shortage is the most important factor affecting crop production in the world. The deficit irrigation is a way to reduce water consumption in farming. The Partial Root- zone Drying (PRD) irrigation is a new improvement in deficit irrigation in which the half of the root zone is irrigated alternatively in scheduled irrigation events. In the fixed partial root zone drying (FPRD) the irrigation is fixed to one side of the root zone in the growing season. Maize is a drought sensitive crop. In maize, secondary traits related to drought resistance are considered in producing tolerate cultivars.
Materials and Methods: An experiment was conducted in order to investigate the effects of regulated deficit irrigation, variable partial root zone drying (PRD) and fixed partial root zone drying (FPRD) on the yield, physiological and photosynthetic parameters of forage maize (KSC 704) during the growing seasons of 2014 in Mashhad region. A factorial experiment based on randomized complete block design with four replications was carried out. The treatments included the full irrigation (FI) and the deficit irrigations (regulated deficit irrigation (DI) and the replacements of 80 % (DI80) and 60 % (DI60) of total water requirement, fixed PRD (FPRD) at 100% (FPRD100), 80% (FPRD80) and 60%(FPRD60) of water requirement, and variable PRD at 100% (PRD100), 80% (PRD80) and 60% (PRD60) of water requirement). Drip irrigation tapes were placed between plant rows. In the full irrigation and regulated deficit irrigation treatments, the plants were irrigated from two sides for every irrigation. In the PRD, one of two neighboring tapes was alternatively used for irrigation. In FPRD, a drip tape was used for two plant rows and irrigation was fixed to one side of the root. The irrigation interval was 3 days for all treatments. Dry and fresh forage yield, leaf area index (LAI), stomatal conductance, leaf relative water content (RWC) and chlorophyll content were measured.
Results and Discussions: All the measured traits were affected by the deficit irrigation. The highest fresh forage yield (72099 kg/ha) was produced by the full irrigation treatment. The statistical comparison showed that there was no significant difference between regulated deficit irrigation and PRD method for the fresh forage yield. But the FPRD treatment reduced the fresh forage yield. There was no significant difference between the fresh forage yield of FI and PRD80 treatments. The dry forage yield was affected by the different irrigation methods, irrigation levels and the interaction effects of the treatments (p
Research Article
samin ansari; Alireza Massah Bavani; Abbas Roozbahani
Abstract
Introduction: Nowadays, the issue of climate change and its related problems are fundamental crisis in water resource management. On the other hand, considering that groundwater is the most important water resources, determination of the effects of climate change on groundwater and estimation the amount ...
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Introduction: Nowadays, the issue of climate change and its related problems are fundamental crisis in water resource management. On the other hand, considering that groundwater is the most important water resources, determination of the effects of climate change on groundwater and estimation the amount of their recharge will be necessary in the future.
Materials and Methods: In this research, to analyze the effects of climate change scenarios on groundwater resources, a case study has been applied to the Sefid Dasht Plain located in Chahar Mahal and Bakhtiari Province in Iran. One of the three Atmospheric-Ocean General Circulation Models (AOGCM) which is called HadCM3, under the emission scenarios A2 and B1 is used to predict time series of climate variables of temperature and precipitation in the future. In order to downscale the data for producing the regional climate scenarios, LARS-WG model has been applied. Also, IHACRES model is calibrated and used for simulation of rainfall - runoff with monthly temperature, precipitation and runoff data. The predicted runoff and precipitation production in future have been considered as recharge parameters in the ground water model and the effects of climate change scenarios on the ground water table has been studied. To simulate the aquifer, GMS software has been used. GMS model is calibrated in both steady and unsteady state for one year available data and verification model has been performed by using the calibration parameters for four years.
Results and Discussion: Results of T- test shows that LARS-WG model was able to simulate precipitation and temperature selected station appropriately. Calibration of IHACRES model indicated the best performance with τw=6 و f=7.7 and the results shows that IHACRES model simulated minimum amount of runoff appropriately. Although it didn’t simulate the maximum amount of runoff accurately, but its performance and Nash coefficient is acceptable. Results indicate that changes of monthly precipitation in the future period are less than the base period in both scenarios A2 and B1. Precipitation increases about 26 and 33 percent under the scenario B1 and A2 respectively in the future compared to the base period. The monthly average temperature in the future compared to monthly average temperature in the base period has been increasing in both scenarios about 1 degree. Root Mean Square Error criteria for aquifer simulation was 1.6 in steady state and 1.9 in unsteady state. This result indicates that the aquifer has been accurately simulated. Assuming the same rate of pumping wells in the future period and in the base period, despite the increasing of recharge in the future period, water levels decrease notably in the central plains due to exceeding operation. At the end of the period (year 2035) the amount of cumulative groundwater recharges in the scenario A2 compared to scenario B1 increases about 10 cubic meters per second, which shows that the impacts of climate change in the A2 scenario compared to the B1 scenario is more.
Conclusion: Study the impact of climate change is important in our country because the major uses of water supply of groundwater. Enormous use of this resource has been defected aquifer problematically. So, it is necessary to survey impacts of climate change in future period on recharge and water levels aquifer by modeling and simulation. It is useful to predict the future conditions of groundwater. Although the recharge increases in future period, but with respect to high rate of groundwater use, it is impossible to achieve an equivalent level of aquifer without any planning. We need to control on pumping well and treatment of aquifer such as underground water dam, artificial recharge and etc. results of this research can be evaluated by other climatic scenarios, downscaling models and rainfall-runoff models. The results of this research, considerably helps to assess the effects of climate change scenarios on ground water resources as well as its proper planning and management.
Research Article
Vida Atashi; Mahmood Shafai-Bajestan; Ideh Golrokh
Abstract
Introduction: Flow patterns within the river bend is three dimensional. Occurrence of secondary flow due to centrifugal force and formation of helicoidally vortex in river bend usually causes the outer bank of river erodes whilst the sediment are deposited in inner bend which appears in the form of point ...
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Introduction: Flow patterns within the river bend is three dimensional. Occurrence of secondary flow due to centrifugal force and formation of helicoidally vortex in river bend usually causes the outer bank of river erodes whilst the sediment are deposited in inner bend which appears in the form of point bars. To reduce the river bank scour, many techniques have been developed which may be classified as covering technique and modified flow patterns methods. The W-weir is among such structures. In the present paper, by measuring three components of flow velocity with and without presence of W-weir, variation of flow patterns and shear stress distribution in a 90-degree sharp bend have been investigated. The main purpose of this study is to see the installation of different locations of W-weir in the bend on reduction of outer bank scour. In the present paper, by measuring three components of flow velocity with and without presence of W-weir, variation of flow patterns and shear stress distribution in a 90-degree sharp bend have been investigated. The analyses of data showed more uniform flow upstream of the weir and also revealed that the effect of transverse and centrifugal forces are modified in such a way that the secondary flow is diminished. The results showed that for 30, 60 and 90-degree bends maximum erosion depth in the vicinity of the outer bank with Froude number of 0.206 in comparison with 0.137 has increased up to 84, 90 and 118 % respectively. In both Froude numbers, installation of W-Weir in 30 degree has the most reduction in bed in comparison with 60 and 90 degree.
Materials and Methods: To reach the goal of this study a physical model of 90 degree sharp bend was constructed in the hydraulic lab of Shahid Chamran university of Ahvaz. The ratio of R(radius)/b(flume width) was less than 2 which shows a sharp bend. The W-weir was built with 1mm galvanized steel. Flume bed was covered with sediment of D50=1.5mm. The W-weir was installed at three different locations of 30, 60 and 90 degrees from the bend entrance. Two sets of tests were carried out with and without weir. For each location two different flow discharges (Fr= 0.137 and Fr=0.206) were studied. The flow depth for all tests were kept constant equal to 15cm. At the end of each test the flume was drained and bed topography was recorded using laser meter. Measured bed topographic data were used in SURFER and TECPLOT software to compare the results of the W-weir location
Results and Discussion:
a)W-weir in 60 degree location
b)W-weir in 30 degree location
a)W-weir in 90 degree location
Fig.1 Bed topography after W-weir installed(Q=10l/s)
The results showed that W-weir concentrated the flow toward the flume center thus the bed only will scour at the downstream of W-weir whilst the bed at upstream is neither of weir nor eroded. This is because the flow patterns within the bend has been modified in such a way that diminishes the strength of helicoidally vortex upstream of the weir thus the scour or deposition will not occur. The results of tests with Q=15 l/s also was similar with the exception that in these tests the Froude number is higher and the scour depth downstream of weir is much larger. The results also showed that the scour depth is much higher when the weir is installed at 60 degrees. The scour depth for weir at 90 degree location showed reduction of about 33% and 39% compare to the weir in 30 and 60 degree location respectively.
Conclusion: In this research, by assessing the cross velocities and the scour depth downstream of weir in 90 degree sharp bends and studying the impacts of w-shape weir on those parameters, following results were obtained: The W-weir can modify the flow patterns within the flume bend in which no scour and deposition is observed upstream of the weir. The scour downstream of weir with higher depth closed to the outer bank is observed in all tests. The scour depth is much higher when the weir is installed at 30 degree location whilst is minimum when the weir is installed at 90 degree location.
Research Article
aboalhasan fathabadi; hamed rouhani
Abstract
Introduction: In order to implement watershed practices to decrease soil erosion effects it needs to estimate output sediment of watershed. Sediment rating curve is used as the most conventional tool to estimate sediment. Regarding to sampling errors and short data, there are some uncertainties in estimating ...
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Introduction: In order to implement watershed practices to decrease soil erosion effects it needs to estimate output sediment of watershed. Sediment rating curve is used as the most conventional tool to estimate sediment. Regarding to sampling errors and short data, there are some uncertainties in estimating sediment using sediment curve. In this research, bootstrap and the Generalized Likelihood Uncertainty Estimation (GLUE) resampling techniques were used to calculate suspended sediment loads by using sediment rating curves.
Materials and Methods: The total drainage area of the Sefidrood watershed is about 560000 km2. In this study uncertainty in suspended sediment rating curves was estimated in four stations including Motorkhane, Miyane Tonel Shomare 7, Stor and Glinak constructed on Ayghdamosh, Ghrangho, GHezelOzan and Shahrod rivers, respectively. Data were randomly divided into a training data set (80 percent) and a test set (20 percent) by Latin hypercube random sampling.Different suspended sediment rating curves equations were fitted to log-transformed values of sediment concentration and discharge and the best fit models were selected based on the lowest root mean square error (RMSE) and the highest correlation of coefficient (R2). In the GLUE methodology, different parameter sets were sampled randomly from priori probability distribution. For each station using sampled parameter sets and selected suspended sediment rating curves equation suspended sediment concentration values were estimated several times (100000 to 400000 times). With respect to likelihood function and certain subjective threshold, parameter sets were divided into behavioral and non-behavioral parameter sets. Finally using behavioral parameter sets the 95% confidence intervals for suspended sediment concentration due to parameter uncertainty were estimated. In bootstrap methodology observed suspended sediment and discharge vectors were resampled with replacement B (set to 3000) times. Sediment rating curves equation was fitted to each sampled suspended sediment and discharge data sets. Using these sediment rating curve and their residual suspended sediment concentration were calculate for test data. Finally using the 2.5 and 97.5 percentile of the B bootstrap realizations, 95% bootstrap prediction intervals were predicted.
Results and Discussion: Results showed that Motorkhane and MiyaneTonelShomare 7 stations were best fitted by a sigmoid function and Stor and Glinak stations were best fitted by second order polynomial and liner function, respectively The first 50 of the B bootstrapped curves were plotted for all stations.with respect to these plots implied that bootstrapped curves more scattered whereas observed data were less. The suspended sediment curve parameters estimated more accurately where, the suspended sediments were sampled more, as a result of reduced uncertainty in estimated suspended sediment concentration due to parameter uncertainty. In addition to sampling density bootstrapped curves, uncertainty depends on the curve shape. For GLUE methodology to assess the impact of threshold values on the uncertainty results, threshold values systematically changed from 0.1 to 0.45. Study results showed that 95% confidence intervals are sensitive to the selected threshold values and higher threshold values will result in an increasing 95% confidence interval. However, the highest 95% confidence intervals obtained by GLUE method (when threshold value was set to 0.1) was little than those values obtained by Bootstrap.
Conclusions: The uncertainty of sediment rating curves was addressed in this study by considering two different procedures based on the GLUE and bootstrap methods for four stations in Sefidrod watershed.Results showed that nonlinear equation fitted log-transformed values of sediment concentration and discharge better than linear equation. Uncertainty result using GLUE depend on chosen threshold values. As threshold values increased, 95% confidence intervals decreased. Uncertainty results showed that 95% confidence intervals estimated by bootstrap were higher than the biggest 95% confidence intervals (when threshold value set to 0.1) estimated by GLUE method. Overall, in all stations, 95% confidence intervals arising from suspended sediment curve shapes (e.g, linear, second order polynomial and sigmoid function), data sampling density and uncertainty estimation methods (here were GLUE and Bootstrap).
Research Article
Ali Morshedi; Seyed Hassan Tabatabaei; Mahdi Naderi
Abstract
Introduction: Evapotranspiration (ET) is an important component of the hydrological cycle, energy equations at the surface and water balance. ET estimation is needed in various fields of science, such as hydrology, agriculture, forestry and pasture, and water resources management. Conventional methods ...
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Introduction: Evapotranspiration (ET) is an important component of the hydrological cycle, energy equations at the surface and water balance. ET estimation is needed in various fields of science, such as hydrology, agriculture, forestry and pasture, and water resources management. Conventional methods used to estimate evapotranspiration from point measurements. Remote sensing models have the capability to estimate ET using surface albedo, surface temperature and vegetation indices in larger scales. Surface Energy Balance Algorithm for Land (SEBAL) estimate ET at the moment of satellite path as a residual of energy balance equation for each pixel. In this study Hargreaves-Samani (HS) and SEBAL models ET compared to an alfalfa lysimeter data’s, located in Shahrekord plain within the Karun basin. Satellite imageries were based on Landsat 7 ETM+ sensor data’s in seven satellite passes for path 164 and row 38 in the World Reference System, similar to lysimeter sampling data period, from April to October 2011. SEBAL uses the energy balance equation to estimate evapotranspiration. Equation No. 1 shows the energy balance equation for an evaporative surface:
λET=Rn–G–H [1]
In this equation Rn, H, G and λET represent the net radiation flux input to the surface (W/m2), Sensible heat flux (W/m2), soil heat flux (W/m2), and latent heat of vaporization (W/m2), respectively. In this equation the vertical flux considered and the horizontal fluxes of energy are neglected. The above equation must be used for large surfaces and uniformly full cover plant area. SEBAL is provided for estimating ET, using the minimum data measured by ground equipment. This model is applied and tested in more than 30 countries with an accuracy of about 85% at field scale, and 95 percent in the daily and seasonal scales. In Borkhar watershed (East of Isfahan, IRAN) ASTER and MODIS satellite imageries were used for SEBAL to compare Penman-Monteith model. Results showed that estimated ET of SEBAL were about 20% less than sugar beet ET and about 15% more for maize ET by Penman-Monteith. He concluded the differences may be due to the limited number of satellite imageries which extrapolated ET through the entire growth period and the data obtained from the weather station far from 24 km in the studied area. In another study at Zayanderud Basin, the different irrigation networks were examined using Landsat 7 imageries to increase the spatial resolution of NOAA satellite to determine the energy balance components and actual evapotranspiration. In this study, data from a lysimeter to a depth of 2.5 m and a diameter of 3 meters planted with alfalfa in the Chahar-Takhteh agricultural research station (Agricultural and natural resources research center of Shahrekord, IRAN) was used. The lysimeter (LYS_REF) located in the in the middle of 25 × 40 m (1000 square meter) alfalfa cultivated farm, surrounded by other planted area. The lysimeter used to measure the reference evapotranspiration (ETr) and around alfalfa was used as cold pixels.
Materials and Methods: This study was conducted to evaluate SEBAL and Hargreaves-Samani estimated ET models against evapotranspiration measured by lysimeter within the Shahrekord plain. Meteorological data required for a period of 185 days (according to the lysimeter data period) includes minimum and maximum relative humidity (RHmax and RHmin), maximum and minimum air temperature (Tmax and Tmin), wind speed at two meters (U2), precipitation, evaporation rate, sunshine hours, air pressure and dew point temperature obtained from a weather station nearby lysimeter. In order to assess reference evapotranspiration (ETr) models, statistical indices such as the coefficient of determination (R2), mean absolute error (MAE), mean bias error (MBE), root mean square error (RMSE) and index of agreement (d) were used.
Results and Discussion: The results showed that RMSE, MAE and MBE for SEBAL model over the lysimeter data were 1.782, 1.275 and -0.272 mm/day and 0.700 for the d index, respectively. Similar indices for the Hargreaves-Samani model were 1.003, 0.580 and 0.290 mm/day and 0.917 for the d index. For HS model results show that RMSE, MAE and MBE values were 0.813, 0.477 and 0.206 mm/day, and 0.930 for the index of d, during the entire growing period (185 days).
Conclusion: However, results showed that the efficiency and reliability of the SEBAL model by processing satellite visible, near infrared and thermal infrared bands. The need for irrigation water requirements and ET estimation are noteworthy, during the growth of various plants, which vary and thus the complete time series of satellite imageries is required to estimate the total and annual evapotranspiration.
Research Article
Ahmad Fakheri Fard; Vahid Nourani; Faegheh Niazi
Abstract
Introduction: The influence of urbanization, as one important form of land use, on runoff and floods within watersheds has been a major topic of research during the past few decades. Urbanization affects the hydrology processes of a watershed by replacing the vegetated land cover with impervious surfaces. ...
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Introduction: The influence of urbanization, as one important form of land use, on runoff and floods within watersheds has been a major topic of research during the past few decades. Urbanization affects the hydrology processes of a watershed by replacing the vegetated land cover with impervious surfaces. This can have a substantial effect on the hydrological response of a watershed to rainfall, potentially resulting in faster response, greater magnitude of river flow, higher recurrence of small floods and reduced base-flow, and groundwater recharge. The direct runoff hydrograph generated by rain falling on a watershed reflects the characteristics of both the effective rain hyetograph and the relevant surface features that control the runoff generation and surface-water flow processes.
Materials and Methods: In this study, the effect of land use investigated using GUHCR model and adjusted GUHRLU model is presented. These models and Nash’s conceptual model used to investigate land use impacts for a small, well instrumented watershed consisting of two different land uses sub-watershed in the city of Sierra Vista, Cochise County, Southeastern Arizona. Geomorphological factors for the sub-watersheds extracted by GIS. In this study 13 storm events occurring on both sub-watersheds were selected to examine the proposed model’s performance. Nine events were selected for model calibration. The remaining four events were used to examine the simulated hydrographs for the outlet and the interior natural sub-watershed. The model parameter ( ) was estimated for each event using the moment method and the average of the calibrated values was used for evaluation of the model. The model's performance demonstrated through four popular criteria (i.e. The Nash–Sutcliffe efficiency (NE), the Correlation Coefficient (R), the ratio of the absolute error of peak flow (EP) and the ratio of the absolute error of hydrograph’s volume (Ev)) using available hydro-geomorphological data.
Results and Discussion: The results show that although all studied models forecast the outlet hydrographs with acceptable accuracy, only the presented GUHRLU model shows appropriate results at sub-watershed outlet considering the effect of land use. Clearly, accounting for land use properties in the model formulation leads to improved efficiency at the internal sub-watershed. The Nash model as a lumped model, calculates the hydrography just at the watershed outlet without any information about the hydrological behavior of the interior watershed. Therefore, internal hydrography estimation is impossible via this model. In general, urban runoff tends to have a sharper rising limb and higher peak values while runoffs in natural watersheds have smaller peak values and the rising limb climbs more slowly. The hydrographs show that the overall shapes of the urban sub-watershed hydrographs are similar to each other, while those in the natural sub-watershed tend to be more different, as expected. Simultaneous consideration of geomorphological and land use parameters in the formulation of the proposed model (GUHRLU) provides this capability. As indicated by Ep and Ev, the error of peak flow and the volume of hydrographs show acceptable accuracy. It can be noted that some events show high values of error of peak flows (Ep), however, the model results in small values of Ev that is of great importance in water resource management. Note that, the performance values obtained for the watershed outlet were, for most events, higher than those of the internal sub-watershed outlet in both formulations, which may be due to the use of outlet hydrographs for calculating the model parameter ( )., This might also be due to less uncertainty in urban watersheds where runoff to rainfall ratios is much larger than in the natural sub-watershed. The GUHCR model has slightly better performance at watershed outlet, but it is unable to detect land use variability in its model formulation and so to estimate the internal watershed hydrographs appropriately. Overall, peak discharge and runoff volume for the natural sub-watershed was over-estimated via GUHCR model. The average values for Nash-Sutcliffe criteria at the internal watershed outlet for GUHCR and GUHRLU models are 0.47 and 0.78 respectively. Over 40% improvement is achieved in simulated peak discharge and runoff volume at interior watershed outlet using GUHRLU in compared with GUHCR model.
Conclusion: GUHRLU model considers not only the geomorphologic properties of the watershed, but also the land use variation of the sub-watershed in parameter formulation. This model can also reflect the hydrological conditions of the internal parts of the watershed with divergent land uses. The GUHRLU model is able to improve the efficiency of geomorphological rainfall-runoff simulations at the interior part of the study watershed, located in southeastern Arizona, by taking into account land use. Consideration of land use in the model leads to acceptable results at both watershed and interior sub-watershed outlets, particularly for watersheds like the studied watershed where different land uses sub-watersheds have. The overall efficiency of prediction was slightly poorer for the internal sub-watershed than for the outlet. Application of three models reveals that only the presented GUHRLU model shows appropriate results at sub-watershed outlet in which the land use variation is considered in the model formulation.
Research Article
Farzin Parchami-Araghi; seyed majid mirlatifi; Shoja Ghorbani Dashtaki; Majid Vazifehdoust; Adnan Sadeghi-Lari
Abstract
Introduction: In order to provide more realistic representation of processes governing the water and energy balances as well as water quality and plant physiological processes, weather data are needed at finer timescales than currently are available at most regions. In this study, a physically based ...
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Introduction: In order to provide more realistic representation of processes governing the water and energy balances as well as water quality and plant physiological processes, weather data are needed at finer timescales than currently are available at most regions. In this study, a physically based framework was developed to disaggregate daily weather data needed for estimation of subdaily reference evapotranspiration, including air temperature, wind speed, dew point, actual vapour pressure, relative humidity, and solar radiation. In this paper, the results of performance comparison of the utilized disaggregation approaches are presented.
Materials and Methods: In developed framework, missing daily weather data are filled by implementation of a search-optimization algorithm. Meanwhile, disaggregation models can be calibrated using Unified Particle Swarm Optimization (UPSO) algorithm. Daily and subdaily solar radiation is estimated, using a general physically based model proposed by Yang et al. (YNG model). Long-term daily and three-hourly weather data obtained from Abadan (59 years) and Ahvaz (50 years) synoptic weather stations were used to evaluate the performance of the developed framework. In order to evaluate the accuracy of the different disaggregation models, the mean error (ME), mean absolute error (MAE), root mean square error (RMSE), and Pearson correlation coefficient (r), and model efficiency coefficient (EF) statistics were calculated. Different contributions to the overall mean square error was decomposed, using a regression-based method.
Results and Discussion: The results indicated that compared to the WAVE I, WAVE II, WCALC, ERBS, and ESRA models, the calibrated TM model had the best performance to disaggregate daily air temperature with a EF of 0.9775 to 0.9924. Compared to air temperature disaggregation models with an arbitrary value for the time of maximum and minimum air temperature, the models in which the above mentioned times are described as a function of sunrise and/or sunset had better performance in describing the diurnal variations of the air temperature. HUM III model (based on cosinusoidal disaggregation of daily actual vapour pressure) had the best performance to disaggregate daily dew point, actual vapour pressure, and relative humidity with an EF of 0.7266 to 0.8896. In addition, subdaily wind speeds were predicted with an EF of 0.3357 to 0.6300. The results showed high agreement between daily and sum-of-subdaily solar radiation (with an EF of 0.9801 to 0.9729). The use of the WAVE II and HUM II (based on linear disaggregation of relative humidity) models can be recommended for the regions with no subdaily weather data needed for calibration of the weather data disaggregation models. The results indicate the need for calibration of Green and Kozek model for disaggregation of the daily wind speed at different regions.
Research Article
Mona Golabi; M. R. Sikakinezhad; A. Shir Afrous; M. Albaji
Abstract
Introduction: Surface irrigation methods are the most common methods for irrigation of agricultural land. These methods are superior to sprinkler, drip and underground irrigation, because they have lower costs of funding and implementation, is inexpensive, needed maintenance of equipment is simple and ...
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Introduction: Surface irrigation methods are the most common methods for irrigation of agricultural land. These methods are superior to sprinkler, drip and underground irrigation, because they have lower costs of funding and implementation, is inexpensive, needed maintenance of equipment is simple and does not require skilled labor. New requirements for the use of municipal water, energy, industrial, and military intends to further improve the performance of surface irrigation systems. In other words, the low efficiency of surface irrigation is not related to the method of it, but the weakness is because of the design, implementation and management. Due to the special place of Khuzestan province in southwest of Iran in agriculture and applied surface irrigation for most of the farms in this province, in the present study was simulated water flow in furrow irrigation by using WinSRFR4.1 and the optimum length of furrow was determined in the experimental farm of the Water Sciences Engineering Shoshtar University. For this purpose, advance and recession of flow were simulated by Zero inertia and Kinematic wave model and result were compared with observed data.
Materials and Methods: In order to calculate and predicte advance and recession curves field measurement is necessary, but it takes a lot of time and cost. Therefore, the use of mathematical models and software for access information is important. In this research the amount of advance in furrow irrigation was measured and the results were compared with simulation of WinSRFR4.1.Field experiments was conducted in the research field of Water Sciences Engineering Shoshtar University. Data were collected from three furrows. The lengths of them were 60, 80 and 100 meters. Irrigation was performed under three discharges (1, 1.25 and 1.5 L/s), with three iterations. Three experiments furrows were provided which central furrow was for measurement data and side furrows were as buffer furrow. Before experiment in order to determine soil texture undisturbed soil samples were prepared from four depths 25-0, 50-25, 75-50 and 100-75 cm. Soil texture was determined in laboratory using the hydrometer method. The water supply was transported by pumping the water to the farm. This research was conducted in the winter of 2012 and spring of 2013. The end of furrow was opened. Input and output flows were controlled with W.S.C flume. Infiltration data were also measured according to two point method. Model using 27 set of field data was run and the results were compared with WinSRFR4.1 software. For evaluating the results of the model were used Esfandiari and Maheshwari’s statistical method.
Results and Discussion: For comparison between measurement and simulation data , , and indices were applied. The results of this study indicated that the phase advance of predicted values for all models is greater than the observed values. The average relative error rate of zero inertia models was 9.588 percent which indicated that Zero inertia models is the best model to predict the advance phase. The worst predictions were for Kinematic wave models with an average relative error equal to 33.21%. According to the results, the value of λ and for the Zero inertia model was 1.0912 and 98.76 respectively. The amount of error of field parameters such as; infiltration characteristic and hydraulic resistance are important for selection of model. So, for adjusting the amount of error in all models to predict an acceptable threshold tolerance was defined.
Conclusion: According to the results, Zero inertia and Kinematic wave models estimated advance time more than real condition. The results of the Zero inertia model were closer to measurement data than a Kinematic wave model. The maximum relative error was in discharge equal to 1.25 (l/s) in all models. With increasing the length of the furrow and input discharge the relative error of zero inertia models will be decreased. The results represented that in low discharge the infiltration depth was increased. Finally, it can be concluded thatthe zero inertia models are suitable for the study area and in study area, suitable length of the furrow is 100 (m).
