Research Article
A. Arabi-Yazdi; A. Alizadeh; F. Mohamadian
Abstract
Demand and supply of water in Iran is unbalanced. This situation has caused a great challenge in water resources management. In order to overcome this problem, the role of international trade of virtual water has been ignored. Virtual water trade is one of the key solutions for water scarcity. Each country ...
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Demand and supply of water in Iran is unbalanced. This situation has caused a great challenge in water resources management. In order to overcome this problem, the role of international trade of virtual water has been ignored. Virtual water trade is one of the key solutions for water scarcity. Each country should adapt virtual water trade based upon its socio-cultural, economical, and climatic condition of the country. However, before any action is implemented, there is a need to evaluate ecological water footprint (EWF) of the country. EWF is the amount of water which is needed for the population and consumptive use and remediation of all pollution related to this consumption. In this study EWF of Iran has been calculated for the year 2007. The results showed that EWF in Iran is 104 billion cubic meter (bcm) of water in agricultural section. In 2007, Iran has imported 12 bcm of water due to virtual water trade. In this computation, irrigation efficiency has not been included. Considering the amount of 60% for irrigation efficiency virtual water trade in the above mentioned year was 20 bcm. Without this trade, the country had to spend 112 bcm of water for producing all required food in the country which was out of reach.
Research Article
F. Fahalian; R. Moazenzadeh; M.R. Nori Emamzadeie
Abstract
A precise estimation of water consumption throughout a crop's growth season and of the amount of water consumed in each growth stage may play an important role in water resources management, integrated water and soil management, and proper irrigation scheduling. In a greenhouse, this faces with the conditions ...
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A precise estimation of water consumption throughout a crop's growth season and of the amount of water consumed in each growth stage may play an important role in water resources management, integrated water and soil management, and proper irrigation scheduling. In a greenhouse, this faces with the conditions specific to this environment. This study was conducted to propose a model to make an appropriate and accurate prediction of evapotranspiration (ET) for greenhouse cucumber. Two same microlysimeters with 28 cm diameter and 30 cm height were deployed simultaneously in the greenhouse for the cucumber culture. Amount of ET was measured daily by the weighing method in both mycrolysimeters. The data from the first microlysimeter were used to derive, and those from the second to validate the proposed models. The developed models were evaluated by root mean square error (RMSE), drawing measured versus predicted ET values, and t-statistics. The proposed model was initially developed in the form of a single regression equation with independent variables such as vapor pressure curve slope and relative humidity for the whole growth season; further however, a separate equation was developed for each of the four growth stages, as the initial model did not perform well (RMSE= 46.61%). The results showed that the proposed models made appropriate predictions of greenhouse cucumber ET. Average amount of cucumber ET were obtained with proposed models 0.398, 1.79, 3.428 and 2.061 mm for four growth stages. RMSE values also were obtained 15.78, 11.48, 9.11 and 7.08 percentage for four growth stages. Correlation coefficient from measured and predicted values of cucumber ET varied from 0.4 (using single equation) to 0.95 (using variable equations for different growth stages). All of the proposed models were significant (p
Research Article
M. Mossadeghi; A. Lakziyan; Gh. Haghnia; A. Fotovat; A. Halajnia
Abstract
Dissolved Organic nitrogen (DON) is an important constituent of Dissolved Organic Matter (DOM). It has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. Dissolved inorganic nitrogen, which is another form of ...
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Dissolved Organic nitrogen (DON) is an important constituent of Dissolved Organic Matter (DOM). It has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. Dissolved inorganic nitrogen, which is another form of total soil dissolved nitrogen, includes NO3, NO2 and NH4, which is very important for plant nutrient. Soil managements such as fertilizer application affects the flux and concentration of DON and DIN in soils. The purpose of this study was to evaluate the effects of different N-fertilizers application on DON and DIN content of two Alfisols located in near the Caspian Sea in the north of Iran. An experiment carried out using complete randomized design with factorial arrangements. Four level of N-fertilizers (Urea, Ammonium nitrate, Ammonium sulfate with Control)) and six different times (0, 7, 14, 28, 42, 60 day) with three replications in two different soils. Changes in DON, DIN, pH and soil respiration were monitored during the period of 60 days. The results showed that dissolved organic nitrogen decreased significantly by N- fertilizer application in both soil samples however, NO3, NO2 and NH4 increased. Ammonium sulfate showed the maximum effect on DON reduction and it can be due to the pH reduction. Changes in DON during the experiment varied from 11 to 75 % in both soil. At the end of experiment, NO3 + NO2 formed a major part of total Dissolved nitrogen in soils.
Research Article
A. Halajnia; Gh. Haghnia; A. Lakziyan; A. Ramezanian
Abstract
Elevated atmospheric carbon dioxide and other green house gases have increased the Earth temperature in recent century, which it affects all biochemistry cycles in soils. To examine the effect of atmospheric CO2 concentration and temperature on N forms in soil solution in a calcareous soil, an experiment ...
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Elevated atmospheric carbon dioxide and other green house gases have increased the Earth temperature in recent century, which it affects all biochemistry cycles in soils. To examine the effect of atmospheric CO2 concentration and temperature on N forms in soil solution in a calcareous soil, an experiment was conducted in a completely randomized design with factorial arrangement in the laboratory conditions. Initially, soil was treated with one percentage of cattle manure compost and 200 kg ha-1 of urea, then changes in forms of soil nitrogen (total dissolved nitrogen, dissolved inorganic nitrogen, dissolved organic nitrogen, sum of nitrate and nitrite and ammonium) were evaluated in two levels of temperature (25 and 35 oC) and two different carbon dioxide concentrations (350 and 700 ppm) during 60 days of incubation with three replications. The results showed that the effect of carbon dioxide on nitrogen forms was different at 25 and 35 oC. Carbon dioxide increased dissolved organic nitrogen but dissolved inorganic nitrogen and nitrate and nitrite decreased at 25oC treatment. While total dissolved nitrogen, dissolved inorganic nitrogen and NO2 + NO3 increased at 750 ppm of carbon dioxide treatment, it had no effect on dissolved organic nitrogen. Changes in dissolved organic nitrogen were higher than other forms of nitrogen during the experiment. The maximum and minimum dissolved organic nitrogen were occurred faster than other nitrogen forms at 35 oC treatment. The results of this experiment showed that elevated carbon dioxide with increasing temperature increased the rate of nitrogen biochemical reactions in soil.
Research Article
K. Davary; S.H. Nemati; B. Ghahraman; N. Sayari; P. Shahinrokhsar
Abstract
This experiment was conducted at research greenhouse of college of agriculture, Ferdowsi University of Mashhad in 1381-1382. The experiment was designed based on the splitted plots in the form of completely randomized design and in four replications. Irrigation intervals were in three levels of 12, 4, ...
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This experiment was conducted at research greenhouse of college of agriculture, Ferdowsi University of Mashhad in 1381-1382. The experiment was designed based on the splitted plots in the form of completely randomized design and in four replications. Irrigation intervals were in three levels of 12, 4, and 2 times per day at primary plots, and three substrates of new perlite, used perlit, and rice bran at secondary plots. We used Paris Island as the lettuce seed. Wet weight, dry weight, and height were influenced from irrigation interval. Accordingly which 4- and 12-day irrigation intervals resulted in 466.39 and 386.94 g corresponding to highest and lowest dry weight, respectively and 12-day irrigation interval arose increase in lettuce height. Significant differences for wet and dry weights were found under different substrates. High wet and dry weights were due to used perlit and rice bran substrates, respectively. There were no significant interactions between irrigation interval and substrate on all of the growth properties of lettuce.
Research Article
R. Moazenzadeh; B. Ghahraman; K. Davary; A.A. Khoshnood Yazdi
Abstract
Soil moisture retention curve (SMRC) is an important soil property which expresses reaction between matric potential and moisture of soil. Direct measurement of soil matric potential and moisture is labour- and time-consuming. In order to prevail this problem, indirect methods are used for SMRC prediction. ...
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Soil moisture retention curve (SMRC) is an important soil property which expresses reaction between matric potential and moisture of soil. Direct measurement of soil matric potential and moisture is labour- and time-consuming. In order to prevail this problem, indirect methods are used for SMRC prediction. Pedotransfer functions (PTFs) are one of these indirect methods. This study was carried out to evaluate three internal pedotransfer functions, first and second models of Ghorbani and Homaee (1381) and Sepaskhah and Bondar (2002) derived in Iran, to predict SMRC in some Iranian soils. Also we tried to develop new different PTFs with better performance using the available information. Therefore 42 soil samples with spatial distribution from northern region of Iran, Amol, Babol and Karaj were selected and divided in Loam (20 samples) and Clay Loam (22 samples) texture classes. In evaluation of all existing PTFs, all 42 soil samples, and in developing new PTFs, 36 soil samples were used. The remaining six samples (three samples in each texture class) were used for validation of the new developed PTFs. In evaluation of the existing PTFs, results showed that the first and second models of Ghorbani and Homaee had alike and appropriate prediction of moisture in whole range of matric potential, whereas Sepaskhah and Bondar did not show an appropriate prediction. By the way, none of these PTFS had noticeable preference in specific texture classes in comparison with the others. New developed PTFS were highly significant (p
Research Article
M. Dayani; J. Mohammadi; M. Naderi
Abstract
Generally heavy metals exist in all soils, but soil pollution is rising by time due to human activities. Soils in the proximity of mines are more pruning to pollution of heavy metals due to mine exploring and excavation. This research was carried out to evaluate the soil pollution of Sepahanshahr Suburb ...
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Generally heavy metals exist in all soils, but soil pollution is rising by time due to human activities. Soils in the proximity of mines are more pruning to pollution of heavy metals due to mine exploring and excavation. This research was carried out to evaluate the soil pollution of Sepahanshahr Suburb with Pb, Zn and Cd. During a field work campaign 100 soil samples were selected randomly from 9000 ha area. The soil samples were treated with 4 M HNO3. Total amounts of Pb, Zn and Cd were measured using Atomic Absorption Spectrometer. The results indicated that concentration of Pb and Zn were beyond the defined soil pollution thresholds (
Research Article
A.A. Montazar; E. Zadbagher; N. Heydari
Abstract
The main objective of this study was to develop an assessment model for the virtual water of irrigation networks using analytical hierarchy process. For this purpose, 14 modern irrigation networks of Iran were selected. Also, 14 effective factors on the virtual water of these systems were considered ...
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The main objective of this study was to develop an assessment model for the virtual water of irrigation networks using analytical hierarchy process. For this purpose, 14 modern irrigation networks of Iran were selected. Also, 14 effective factors on the virtual water of these systems were considered as decision criteria. Expert choice software was used for ranking the virtual water values of the proposed irrigation networks. The average virtual water of irrigation networks with regard to the 5-year data, 2002-2006, was determined. The results showed that the actual virtual water of the Nekooabad irrigation network was the highest (17.04 m3 kg-1) and the Sefidrood irrigation network had the lowest amount (2.17 m3 kg-1). The results of the AHP model indicated that the Saveh and Dez irrigation networks with a relative weight of 0.112 and 0.045 had the most and the least virtual water content, respectively. The sensitivity analysis of the proposed model demonstrated that the cultivated area and crop water demand had a significant effect and water quality and water price had a low effect on this index. Comparisons showed that the results of AHP model were in good agreement with actual virtual water results. The findings revealed that AHP model is an efficient approach to assess the virtual water of irrigation networks. Hence, the proposed model, as a user-friendly model, can be also applied to assess the global water productivity of irrigation networks.
Research Article
M. Memarian fard; H. Beigi
Abstract
Abstract
Cation Exchange Capacity (CEC) is an important characteristic of soil in terms of nutrient and water holding capacities and contamination management. Measurement of CEC is laborious and time-consuming. Therefore, CEC estimation through other easily - measured properties is desirable. In this ...
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Abstract
Cation Exchange Capacity (CEC) is an important characteristic of soil in terms of nutrient and water holding capacities and contamination management. Measurement of CEC is laborious and time-consuming. Therefore, CEC estimation through other easily - measured properties is desirable. In this study, PTFs for estimation of cation exchange capacity from basic soil properties such as particle-size distribution, organic carbon, percentage saturation and pH were developed and validated using artificial neural network (ANN) and multiple-linear regression methods and the predictive capabilities of the two methods was compared using some evaluation criteria. Total of 200 soil samples was divided into two groups as 165 for the development and 35 for the validation of PTFs. Accuracy of the predictions was evaluated by the criteria of coefficient of determination (R2) and the root mean square error (RMSE) between the measured and predicted CEC values. Clay (%), OC (%), SP and sand (%) predicted CEC better than other models with an R2=0.81 and RMSE=3.05 cmol.kg-1 when a neural networks model with one hidden layer and seven nodes was used. The R2 and RMSE varied from 0.66 to 0.69 and from 4.26 to 4.69 for regression, and varied from 0.78 to 0.81 and from 3.05 to 3.29 for ANN, respectively. Results showed that neural networks predictions is better than regression-based functions.
Key words: Artificial neural networks, Cation Exchange Capacity, Chaharmahal - Bakhtiari
Research Article
I. Esfandiarpour Borujeni; N. Toomanian; M.H. Salehi; J. Mohammadi
Abstract
Abstract
Geopedology is a systematic approach of geomorphic analysis for soil mapping which focuses the field operation mainly on sample area. The purpose of this study is to determine the credibility of generalization of the results of geopedological approach for similar landforms in the Borujen region, ...
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Abstract
Geopedology is a systematic approach of geomorphic analysis for soil mapping which focuses the field operation mainly on sample area. The purpose of this study is to determine the credibility of generalization of the results of geopedological approach for similar landforms in the Borujen region, using diversity and similarity indices in a soil taxonomic hierarchical structure. After a primary interpretation of the study area on air photos (1:20000 scale), the largest delineation of Pi111 geomorphic unit was selected and 19 pedons with an approximate 125 m interval were excavated, described and sampled. The credibility of generalizing the results of the geopedological approach for the studied unit was tested by comparison with 15 pedons in a similar unit outside the sample area, named the validation area. Results showed that as the category decreases from order to soil family, the Shannon's diversity index increases in both the sample and validation areas. A significant difference at 95% confidence level was observed for pedodiversity mean values of two areas at family level. Soil diversity also remains high through the soil taxonomic hierarchy when we change the understanding level and consider the horizon/genetic diversity in both the sample and validation areas. Jaccard index and proportional similarity also indicated that up to subgroup level, the geopedological approach can be used for generalization of the similar geomorphic unit results and it does not have a good efficiency for lower soil taxonomic levels (family and series). Therefore, the use of landform phases and also phases of soil families and/or series for each of landform phases is recommended to increase the accuracy of geopedological results.
Key words: Geopedology, Pedodiversity, Similarity index, Sample area, Validation area
Research Article
M. Bannayan Aval
Abstract
Abstract
Radiation, water and CO2 are three major resources requirement for crops growth and development and within a wide range, increasing each of them would increase the biosphere productivity. Higher usage of fossil fuels is increasing the atmospheric CO2 and according to known crop physiological ...
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Abstract
Radiation, water and CO2 are three major resources requirement for crops growth and development and within a wide range, increasing each of them would increase the biosphere productivity. Higher usage of fossil fuels is increasing the atmospheric CO2 and according to known crop physiological functions, such conditions should increase the crops production. However there is a possibility that these functions forced to modify as well due to such a change in atmosphere. In order to realize such a change, robust models are required which in turn demands high quality data and complete test of the models. Most climate change studies benefit from crop models however, all models are structured and developed based on current conditions. Our objectives in this study are verification of two crop models for such a possible future climate change and to find whether there are any required modifications for these crop models. Required data for this study were obtained from two international studies on rice plant under FACE experiment in Japan and on peanut crop in USA. Rice experiment included the effects of nitrogen and elevated CO2 and peanut experiment was looking for the effects of CO2 and temperature. Observed data were employed within CSM-DSSAT for peanut and Oryza2000 model for rice plant. The results showed that both models wrongly simulated the magnitude and direction of crops responses mostly for interaction of CO2 and nitrogen and/or temperature which indicated the requirement of modification of some relationships in the crop models in order to be used for any future recommendation under climate change.
Key words: Climate change, Crop models, Rice plant, Peanut crops
Research Article
M. Fereidooni Naghani; F. Raiesi; S. Fallah
Abstract
Abstract
The addition of manures and chemical fertilizers as soil amendments for the improvement of soil fertility and quality could affect the seasonal changes in the activity of soil microbes and enzymes. This study aimed at investigating the effect of different levels of nitrogen from broiler litter ...
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Abstract
The addition of manures and chemical fertilizers as soil amendments for the improvement of soil fertility and quality could affect the seasonal changes in the activity of soil microbes and enzymes. This study aimed at investigating the effect of different levels of nitrogen from broiler litter and urea sources on the trend of urease, alkaline phosphatase and saccharase activities in a clay loam calcareous soil cultivated with maize (Zea Mays L.) under field conditions. The treatments were a control (no fertilizer and broiler litter), 100, 200, 300 kg N ha-1 from broiler litter and 100, 200, 300 kg N ha-1 from urea, using a split-plot experiment arranged in a completely randomized block design with four replications. The activity of soil enzymes was monitored at five different stages after treatments imposition with 20-day intervals during the growth period. Results of this research show that the activity of urease, alkaline phosphatase and saccharase in broiler litter- and urea- treated soils were significantly greater than that in the control soil (no broiler litter and urea added). The level of broiler litter and urea fertilizers and time had a significant effect (P
Research Article
H.A. Alizadeh; A. Liaghat; F. Abbasi
Abstract
Abstract
Water and nitrogen are the main limiting factors affecting agricultural production in arid and semiarid regions. Therefore, improving the efficiency of these factors is very important. The method of fertilizer application is affecting water and fertilizer use efficiency. The objective of this ...
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Abstract
Water and nitrogen are the main limiting factors affecting agricultural production in arid and semiarid regions. Therefore, improving the efficiency of these factors is very important. The method of fertilizer application is affecting water and fertilizer use efficiency. The objective of this study was to investigate the effect of furrow fertigation on fertilizer use efficiency (FUE), water use efficiency (WUE), and corn yield. A field experiment was carried out in furrows which have 165m length and 0.006 (m/m) slope in Karaj. The corn Hybrid 370 double-cross was planted on June 2008. A factorial design based on randomized complete block design with 4 replicates. Four levels (0, 60, 80 and 100%) of the recommended fertilizer value and four levels (60, 80, 100, and 120%) of the irrigation water requirement were applied. These 16 treatments were compared with traditional fertilizer application method. Fertilizer treatments were accomplished in four critical stages of the growth (before cultivation, in seven leaves stage, shooting stage and Flowering stage) for fertigation treatments and two stages (before cultivation and seven leaves stage) for the traditional method. Results showed that effects of levels of different water and fertilizer on yield component were significant. Water use efficiency (WUE) was significantly affected by nitrogen rate. On the other hand, water treatments significantly affected fertilizer use efficiency. Increasing fertilizer increased water use efficiency. Increasing water levels to 100% of ETC resulted in increasing fertilizer use efficiency. Highest yield was obtained from the full irrigation treatments (W100%). Albeit the difference among W120%, W100% and W80% was not significant (P=0.05), because W100% was always higher than W120%, treatment of W80% recommends as optimum water level for arid and semi arid region. The maximum and minimum WUE was 2.24 and 0.66 (kg/m3) in W80%N100% and W100%N60%, and The maximum and minimum FUE was 29.85 and 8.52 (kg/kg) in W100%N100% and traditional method, respectively.
Key words: Fertigation, Fertilizer use efficiency, Productivity, Corn
Research Article
R. Ghobadian; K. Khodaei
Abstract
Abstract
Among activities that can be used to prevent piping phenomena and reduce seepage and exit gradient are installation of cutoff wall and drain under hydraulic structures. Hence in this study, to investigating the influence of each mentioned parameter on uplift force and exit gradient a computer ...
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Abstract
Among activities that can be used to prevent piping phenomena and reduce seepage and exit gradient are installation of cutoff wall and drain under hydraulic structures. Hence in this study, to investigating the influence of each mentioned parameter on uplift force and exit gradient a computer model has developed in which general equation of fluid flow into the isotropic and anisotropic soil was solved numerically by Gauss-Seidel method. Verify model, experimental result and result of WinMseep model that is an acceptable model was used. One of the relative advantages of this model is consideration of permeability value for cutoff curtain. The result of this study showed, bye construction of one cutoff curtain in any location values of exit gradient relative to basic exit gradient (without cutoff) reduces. Also, maximum uplift force and minimum exit gradient is observed when cutoff curtain is located in toe. For situation with two cutoff walls in toe and heel of dam and one drain in between it is observed that when drain is located at far distance whit respect to heel influence of it on uplift force and exit gradient increases. Additionally with increasing upstream cutoff depth in comparison to downstream cutoff, values of exit gradient decreases and intensity of this decrease for shallow downstream cutoff is more sensible. Distribution of uplift pressure and calculated exit gradient for isotropic and anisotropic condition are very consistences to those are computed by WinMseep model.
Key words: Hydraulic structure, Cutoff wall, Uplift pressure, Exit gradient, Finite volume
Research Article
A. Alizadeh; M.H. Najafimood; J. Moosavi; B. Alizadeh
Abstract
Abstract
Environmental pollution has made urban citizens to focus on landscapes. In this respect Lown is very important plant. From the other hand water resources in many arid and semi-arid region is saline. For this purpose a research was conducted to study the effect of sprinkling irrigation with ...
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Abstract
Environmental pollution has made urban citizens to focus on landscapes. In this respect Lown is very important plant. From the other hand water resources in many arid and semi-arid region is saline. For this purpose a research was conducted to study the effect of sprinkling irrigation with saline water on growth parameters of three Lown varieties. These varieties were Poa partensis, Festuca arundianca and Lolium prenne. A complete randomized block with 3 irrigation treatments and 9 replications were used. The salinity of irrigation waters were EC=2.4 and EC= 5.3 dS/m. growth parameters were followed for 7 months. After this period of time, germination rate, height of plant, dry weight of ground canopy and length of roots were measured. The results showed that Festuca is resistance to salinity while Poa could not tolerate and dried immediately after increasing air temperature.
Key words: Salinity, Sprinkling irrigation, Lown varieties, Lolium, Festuca, Poa
Research Article
F. Khayamim; H. Khademi; A. Khoshgoftar manesh; Sh. Ayoubi
Abstract
Abstract
Mineral weathering is a major source of most essential nutrients including potassium. It is well known that potassium plays an important role in improving the quality of agricultural products and micaceous minerals, as the major source of potassium, are abundant in Iranian soils. No information ...
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Abstract
Mineral weathering is a major source of most essential nutrients including potassium. It is well known that potassium plays an important role in improving the quality of agricultural products and micaceous minerals, as the major source of potassium, are abundant in Iranian soils. No information is available on the role of micaceous minerals in supplying K to barley as the second major crop in Iran. The objective of this research was to demonstrate the ability of barley (Hordeum vulgare L.) to take up structural potassium from muscovite and phlogopite. The experiment was carried out in a completely randomized design with factorial combinations and three replicates. Culture medium was a mixture of quartz sand (as filling material) and K-bearing minerals including muscovite or phlogopite. Pots were irrigated with different nutrient solutions (+K and -K) during a period of four months. Barley Govhar cultivar was used which is widely cultivated in the Isfahan province. At the end of experiment, shoots and roots were separated and plant samples were prepared with dry ashing method and their K content was determined with flame photometer. In K-free treatments, total plant K uptake was significantly higher in phlogopite treated medium as compared to muscovite. No significant difference was found between control and muscovite amended treatment under K-free solution. In pots amended with phlogopite, K concentration was in sufficient limit, even under K-free nutrient solution. This indicates the importance of the type of micaceous minerals in plant K availability, particularly in soils where minerals structural K is the only source of K supply.
Key words: Muscovite, Phlogopite, Barley, Rhizospheric effections, Potassium release
Research Article
J. Ahadiyan; S.H. Musavi Jahromi
Abstract
Abstract
In the present article, effective parameters of the buoyant jets have been evaluated in the stagnant ambient fluid. The jet parameters, geometry parameters and environmental parameters are investigated. Using dimensional analysis, a set of dimensionless functions was obtained. To achieve the ...
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Abstract
In the present article, effective parameters of the buoyant jets have been evaluated in the stagnant ambient fluid. The jet parameters, geometry parameters and environmental parameters are investigated. Using dimensional analysis, a set of dimensionless functions was obtained. To achieve the exact functions, a physical model was built in the hydraulic laboratory of Shahid Chamran University, Iran (SCU). 215 experiments were set on base of different jet diameter, different concentration of jet injection and different convergence angle of jets. To precede the goals of the present study, the positive mixing length and trajectory characteristics from a buoyant jet and the maximum length of upper and inferior limits of trajectory have been considered. The velocity profiles of adjacent sections near and far field of location jet injection was measured using profiler acoustic, UVDP. The velocity profiles were compared with the theoretical normal Gaussian distribution. Finding shows that the gathered data in this field have been satisfactory correlated. In addition the concentration and dilution in the different sections along the jet flow were measured. Findings show there are satisfactory correlation between experimental data and theoretical formula. The lengths of falling jet trajectory were analyzed as the ratio of trajectory length to port diameter (x/dp) versus relative trajectory elevation ((Z0-Zu)/x). According to the results, increasing on concentration of jet flow causing a density gradient between jets and receiving fluid and change in the buoyancy forces involved, has major influence on the lengths of falling trajectory. Findings show there is a nonlinear correlation between the trajectory characteristics and jet flow properties. As change of contraction angle, from 15 to 90 degrees, upper limit of trajectory increased to 25 percents. While contraction angle increase from 15 to 90 degrees, the inferior limit increase to 28 percents.
Key words: Buoyant jet, Contraction angle, Trajectory, Flow pattern, Spreading Coefficient
Research Article
J. Tabatabee-Yazdai; H. Rezaee- Pazhand; H. Khatami-Mashhadi
Abstract
Abstract
This papare is resaults of analysing the data which reported from a harvesting project. The site for collecting data is buildings' roofs of Azad Islamic University of Mashhad. A rain gauge and a small reservoir (capacity is 4 cubic meters) were set at this site. Then the amount of precipitation ...
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Abstract
This papare is resaults of analysing the data which reported from a harvesting project. The site for collecting data is buildings' roofs of Azad Islamic University of Mashhad. A rain gauge and a small reservoir (capacity is 4 cubic meters) were set at this site. Then the amount of precipitation and its runoff were measured during two years (from 1386, Dey, 23 to 1388, Tir, 3).The sample size is 35 observations. The relationship between runoff and rainfall was estimated by regression methods. The best model was chosen by analyzing residuals and testing the Models. Then the runoff were estimated through this model. The 55-year annual rainfalls of Mashhad synoptic station (1951-2005) were selected and frequency analysis was done on them. Then the roofs' runoff was estimated by this frequency analysis for both wet and dry years. The total area of roofs and their mean annual runoff in ordered are 18680 square meters and 8428 cubic meters.
Key words: Water harvesting, Roof, Runoff, Azad Islamic University of Mashhad
