Research Article
S. Hamzeh; AbdAli Naseri; H.A. Kashkuli
Abstract
Two issues of the drainage systems which are less studied in the literature are drainage in layered soils and bi-level derange systems. Hence, it is necessary to do more research in these topics. Therefore the present study was carried out under above conditions in the Imam Khomeini Farming and Industrial ...
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Two issues of the drainage systems which are less studied in the literature are drainage in layered soils and bi-level derange systems. Hence, it is necessary to do more research in these topics. Therefore the present study was carried out under above conditions in the Imam Khomeini Farming and Industrial Lands, located in the north of the Khuzestan province, Iran. In this area based on primary studies, lateral spacing was estimated about 70 m and they were installed at the depth of 2.1m. But after two years of establish these drainage systems, it was observed that due to existence a soil layer with a very low infiltration rate (less than 10 time in compare with its above and below layers) at the depth of 110 to 160 cm, drainage systems in 500ha of these fields had low performance. Then, in order to overcome with this problem, the implementation of bi-level drainage system was proposed. Hence, a new drain line was installed at the depth of 1.2m between the old drain lines. After establishment of these new drains one field was selected to evaluation the performance of this new system. In the selected field three rows of observation wells were installed (in total 20 observation wells). After equipment of these observation wells, water table fluctuation, inflow and outflow water values from the field were measured in 3 irrigation periods. Then the results of field observations were compared with the obtained results from analytical solution in the literature. Results show with establish new drain lines the problem of these fields are solved and the water table profile will drop-off to the below of root zone in less than 36hr. Also it was concluded that the rate of water table decline by moving from the end of field to the open collector of field will be increased and the discharge of deep drains are more than low-deep rains. Results show that analytical solution is not able to predict the water table profile with well accuracy and predicted values by this equation only in a small area of water table profile were consistent with the observed values in the field. The main reason of this difference was the specific situation of layers of the soil.
Research Article
Abstract
تصویر جلد نشریه
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تصویر جلد نشریه
Research Article
A. Abtahi; M. Hoodaji; M. Afyuni
Abstract
The objectives of this research were to study the effect of three kinds of biosolids applications such as urban compost, sewage sludge, cow manure and chemical fertilizers (sulphates of Zn, Fe) concentration on soil and corn plant. Two calcareous soils having different textures (sandy loam and clay loam) ...
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The objectives of this research were to study the effect of three kinds of biosolids applications such as urban compost, sewage sludge, cow manure and chemical fertilizers (sulphates of Zn, Fe) concentration on soil and corn plant. Two calcareous soils having different textures (sandy loam and clay loam) were used in order to study the uptake of the above zinc and iron by corn. This study was carried out in pots in a greenhouse using a factorial experiment design which was block completely randomized and each treatment was replicated three times. The levels of biosolids used were 0, 25, 50 Mg ha-1 and chemical fertilizers applied were as (Zn and Fe) sulphates. Seventy five days after corn seeds were sown; young plants at 4 to 5 leaf stage were harvested and made ready for chemical analyses. Results of the soil analysis showed that in sewage sludge treatment (50 Mg ha-1) the CEC, and the DTPA extractable (Zn and Fe) increased significantly compared to control and other treatments in soils. Cow manure treatment (50 Mg ha-1) had a significant effect on OM, and EC. Result of the plant analysis showed that in the sewage sludge treatment the concentration of Zn in the roots, and the concentrations of Zn, Fe in the shoots increased significantly. In general, corn yields increased significantly in the sewage sludge treatment compared to the other treatments in clay loam soils. Generally, the results of this study showed that biosolid application including sewage sludge increased concentration of micronutrients (Zn and Fe) in soil and corn plant.
Research Article
R. Jenabi Haghparast; A. Golchin; E. Kahneh
Abstract
Heavy metals are entered to the environment by mining and by applying sewage sludge and agricultural inputs to soils. These metals have detrimental effects on environment and soil organisms. An experiment was conducted to determine the cadmium affects on earthworms (Eisenia fetida) in a calcareous soil ...
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Heavy metals are entered to the environment by mining and by applying sewage sludge and agricultural inputs to soils. These metals have detrimental effects on environment and soil organisms. An experiment was conducted to determine the cadmium affects on earthworms (Eisenia fetida) in a calcareous soil amended with 0 and 5% organic matter. The concentrations of Cd in soils were 0,10,20,40, 60 and 80 mg kg-1 and growth parameters of the earthworms were measured with 15 day intervals over 75 days. Survival, growth and cocoon production of earthworms were determined. The results showed that addition of organic matter to soils reduced the toxic effects of cadmium to earthworms. In soils contaminated with Cd the weights of the earthworms decreased with increasing the concentrations of this metal and cadmium had the highest negative effects on cocoon production. The highest earthworm’s mortality was recorded in soils contaminated with cadmium.
Research Article
J. Givi; A. Abedi
Abstract
Economical profit is one of the important factors, persuading farmers to plant a specific crop. So, in addition to qualitative and quantitative land suitability evaluation, economical one can be carried out as well, based on net or gross profit per surface area unit. The present research was done to ...
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Economical profit is one of the important factors, persuading farmers to plant a specific crop. So, in addition to qualitative and quantitative land suitability evaluation, economical one can be carried out as well, based on net or gross profit per surface area unit. The present research was done to evaluate land suitability, economically, by different methods for maize around Shahrekord city. In this regards, economical land suitability evaluation was carried out, using "internal rate of return", "gross profit", "net present value" and "benefit/cost ratio" methods. These methods are included in the ALES program. For model making in this program, a data base, including soil units, land characteristics, maize growth requirements, yield, discount rate, constant and variable costs and return of one weight unit of maize was established and then economical land suitability classes were determined. The results showed that as the "net present value" method is used, most of the land units are classified as S2. As the other three methods are used, all of the land units are classified as S1. Economical suitability class, determined based on "gross profit" method, without using ALES program, in 40% of the land units is S2 and in 60% of them is S1. The results of the economical land suitability classification, based on "net present value" method, using ALES program, is more in agreement with the results of qualitative land suitability classification of the study area that in a previous research, was done based on just physical land characteristics.
Research Article
Z. Lotfi Arpachaei; Abazar Esmali; kazem hashemimajd; n n
Abstract
In modern agriculture, the preparation of soil fertility map seems to be necessary to plan for appropriate using of fertilizers for crops. This study was conducted to prepare a distinct map for evaluating soil fertility according to soil chemical properties in 136 soil samples of Ardabil plain in Ardabil ...
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In modern agriculture, the preparation of soil fertility map seems to be necessary to plan for appropriate using of fertilizers for crops. This study was conducted to prepare a distinct map for evaluating soil fertility according to soil chemical properties in 136 soil samples of Ardabil plain in Ardabil province. To achieve this purpose, the available K and P, total N, EC, pH and organic matter of soil were mapped using geostatistical Kriging estimator into Geographic Information System (GIS) by ArcGIS9.3 software. The Analytical Hierarchy Process (AHP) was used for weighting soil fertility factors as the input data. Then a membership functions was defined for each factor by factorial scoring and the map of soil fertility was prepared and classified for wheat and potato by using AHP technique into GIS program. The results showed that 74.84, 3.59, 19.3 and 2.32 percentage of lands for wheat cropping were classified based on soil fertility into groups of weak, moderate and suitable, respectively while for potato it was 24.88, 27.57, 7.19 and 40.34 percentage, respectively. As a final result, this type of distinct soil fertility map for different crops could assist us to manage the appropriate using of lands and fertilizers.
Research Article
M.A. Khalaj; F. Moshiri; Hadi Asadi Rahmani
Abstract
This study was conducted to evaluate N2-fixing ability of rhizobia strains inoculated with common bean. The experiment was carried out in a randomized complete block design (RCBD) with 13 treatments including 10 Rhizobium isolates, two nitrogen fertilizer levels (200 and 400 kg urea per ha) and one control ...
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This study was conducted to evaluate N2-fixing ability of rhizobia strains inoculated with common bean. The experiment was carried out in a randomized complete block design (RCBD) with 13 treatments including 10 Rhizobium isolates, two nitrogen fertilizer levels (200 and 400 kg urea per ha) and one control (without Nitrogen and rhizobium) in four replications at Esmaeel Abad research station of Qazvin. Plant sampling was done in two growth stages and nodule number and dry weight, shoot dry weight and total N-uptake and seed yield were evaluated. Results of two years field experiment showed that isolate L-75 showed the superior N2-fixing performance and had the highest positive effect on growth factors and could be recommended to use as inoculants strain in Qazvin region. This isolate, produced highest nodule number and dry weight in both years of study. Seed yield production was promoted by 26 and 40% more than control by application of isolate L-75 in the first and second year, respectively. This study showed that inoculation of common bean with effective rhizobia strains resulted in promoting of plant growth and seed yield production and have the benefit to reduce nitrogen fertilizer application in bean cropping.
Research Article
M.A. Mousavi Shalmani; A. Khorasani; N. Pirvali Bieranvand; M. Noori Mohammadiye; A. Eskandari; S.M. Mohati
Abstract
Nitrogen (N) is the most usually used crop nutrient which represent importance of the efficient use of nitrogen fertilizers. At this study, the optimum fertilizer application pattern by using of 15N isotope technique in different irrigation systems and the influence of the fertilizer application time ...
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Nitrogen (N) is the most usually used crop nutrient which represent importance of the efficient use of nitrogen fertilizers. At this study, the optimum fertilizer application pattern by using of 15N isotope technique in different irrigation systems and the influence of the fertilizer application time on amino-N accumulation in roots has been investigated. The experimental design was a randomized complete block (sampling method) design with four main treatments (irrigation methods) and three replications (unit area 144 m2). Irrigation treatments include: T1; surface drip fertigation, T2; sprinkler fertigation, T3; sprinkler irrigation T4; furrow irrigation. In the middle of the each plot an area about 1- 2 m2 (15 plants) was allocated as isotopic sub plot. Results indicated that the least tendency to utilize the fertilizer sources was related to the fertigation treatments. Despite the highest root weight, treatment T2 is not recommended to use. The method of application of fertilizers in treatment T3 lead on to the highest nitrogen uptake efficiency and pure sugar. The method of application of fertilizers in T1 and T2 increase the rate of α-amino acid N in the sugar beet roots and decrease their quality. Treatment T4 produced relatively high quality roots that confirm the method of application of fertilizer in treatment T3. In the weather condition of central Iran, during the sugar beet growing season, the application of fertilizer should be begun 45 days after sowing seeds and must be completed within one month. Occurrence of isotopic fractionation phenomenon cause that the average percentage of labeled nitrogen fertilizer (Ndff %) in underground and aerial parts of the plant considered to be 20.1 and 16.1% respectively.
Research Article
A. Hassanoghli
Abstract
Produced sludge from wastewater treatment plants is a source of macro and micro nutrients and organic matters which is needed for agriculture. On the other hand, application of sludge with no criterion may cause some health risks and also, soil and surface water and ground water resources pollution may ...
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Produced sludge from wastewater treatment plants is a source of macro and micro nutrients and organic matters which is needed for agriculture. On the other hand, application of sludge with no criterion may cause some health risks and also, soil and surface water and ground water resources pollution may be followed. In this regards, the effect of different amounts of sewage sludge used as organic fertilizer in compare with chemical fertilizers on transport of minerals below the root zone and yield and yield components in soybean cultivation were studied. Therefore, 15 cylindrical plastic soil culomns with a height of 100 cm and 60 cm diameter were constructed and drainage PVC pipes with geotextile filter were installed for all of them. The sludge of Ekbatan housing complex wastewater treatment plant after processing and digestion was taken place and used. The culomns were filled by a Clay Loam textured soil and Soybean (Williams variety) was planted. Treatments include three levels of wastewater sludge fertilizer (10, 25 and 50 ton/ha), chemical fertilizers (150 kg/ha ammonium phosphate and 50 kg/ha urea) and control without using fertilizer in three replications. According to the results, the highest mean amount of nitrate in drainage water of culomns (base on split plot through time as statistical completely randomized design) was 57.17 mg/lit in the early season and treatment related to the use of sludge was 50 ton/ha. The lowest mean value of nitrate obtained from the control in the end of cultivation season and was 3.51 mg/lit. The most yield of Soybean was 277.85 gr grains per culomn which obtained from use of 50 ton/ha of manure sludge. The greatest weight of 1000 grains and the number of pods with values of 127.42 gr and 856 in number, measured in this treatment too. Application of 25 ton/ha sludge, chemical fertilizers and 10 ton/ha sludge were after it, respectively. So, the highest use of sewage sludge on soybean cultivation (at the rate of 50 ton/ha), transfer the highest amount of nitrate below the root zone and led to the best yield indicators
Research Article
mehri shahedi; S.H. Sanaiinejad; B. Ghahreman
Abstract
The purpose of this study is regional frequency analysis of Annual Maximum 1-day Rainfall (AM1R) and Annual Maximum 2-day Rainfall (AM2R) using L-moments theory in Khorasan Razavi Province. For this purpose, the basic statistical tests include: homogeneity, independency and outlier data for AM1R and ...
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The purpose of this study is regional frequency analysis of Annual Maximum 1-day Rainfall (AM1R) and Annual Maximum 2-day Rainfall (AM2R) using L-moments theory in Khorasan Razavi Province. For this purpose, the basic statistical tests include: homogeneity, independency and outlier data for AM1R and AM2R were surveyed in 123 rainfall stations. The province was divided into four regions based on cluster analysis, topography and spatial pattern of precipitation. Hydrology homogeneity was also controlled by running heterogeneity test for each region. generalized extreme value (GEV), generalized logistic (GLO), Pearson type III (PE3) and Log Normal type III (LN3) probability distributions were estimated for every region. To select the appropriate distribution of AM1R and AM2R data, the fitness was judged using an L-moment ratio diagram and the Kolmogorov–Smirnov test and GEVdistribution select . The regionally quantile estimateions for GEV distribution were also calculated for AM1R and AM2R data. In all of the Homogeneous regions, the estimated values of AM1R and AM2R from the obtained relations are close enough to the real data of return periods less than 200 years (The largest MAE was 0.0386). The average absolute error between the estimated and the observation values in each region is favorable, showing a high accuracy of the estimation.
Research Article
H. Ghorbani; A. Roohani; N. Hafezi Moghaddas
Abstract
In this research, a learning vector quantization neural network (LVQ) model was developed to predict and classify the spatial distribution of cadmium in soil in Golestan province. The cadmium data were obtained from soils measuring total Cd contents in soil samples. Some statistical tests, such as means ...
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In this research, a learning vector quantization neural network (LVQ) model was developed to predict and classify the spatial distribution of cadmium in soil in Golestan province. The cadmium data were obtained from soils measuring total Cd contents in soil samples. Some statistical tests, such as means comparision, variance and statistical distribution were performed between the observed points samples data and the estimated cadmium values to evaluate the performance of the pattern recognition method. The Results showed that in training and test phase, there were no significant differences, with the confidence level of 95%, between the statsitcal parameters such as average, variance, statistical distribution and also coefficient of determination in the observed and the estimated cadmium concentrations. The results suggest that learning vector quantization (LVQ) neural network can learn cadmium cocentration model precisely. In addition the results also indicated that trained LVQ neural network had a high capability in predicting cadmium concentrations for non-sampled points. The technique showed that the LVQNN could predict and map the spatial cadmium concentrations variability. Our results indicated that it is possible to discriminate different cadmium levels in soil, using LVQNN.
Research Article
M. Alizadeh; F. Mirzaei; T. Sohrabi; M. Kavoosi; M.R. Yazdani
Abstract
Water management in cracked paddy soils is an important issue in rice cultivation. In order to investigate the effect of rice straw and zeolite and their interaction effect on the physical condition of soils of paddy fields and prevention of crack, rice straw factor at four levels (0, 0.5, 1 and 1.5 ...
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Water management in cracked paddy soils is an important issue in rice cultivation. In order to investigate the effect of rice straw and zeolite and their interaction effect on the physical condition of soils of paddy fields and prevention of crack, rice straw factor at four levels (0, 0.5, 1 and 1.5 percent) zeolite factor at four levels (0, 8, 16 and 24 tons per hectare) and also moisture stages of soil which are wet and dry stages at 5 levels which have been studied in three replication as factorial based on the complete randomized block design in Rice Research Institute of Iran. Soil distance from the wall of the container, the width of cracks, a few days to reach the crack with a certain width, bulk density and surface cracks were measured. Results showed that adding high levels of residue to delay the occurrence of cracks. However, the addition of zeolite has no significant effect in delaying the cracks. The relationship between bulk density and surface cracks that follow the linear equation, With increasing cracks surface, bulk density is increased. Finally, Can be concluded that the addition of plant residues, causing disappearance of existing cracks and returned to the soil to be the initial state.
Research Article
T. Raiesi; A. Hosseinpur; F. Raiesi
Abstract
The objective of the present study was to evaluate several chemical extractants to estimate available phosphorus (P) for bean growing in calcareous soils from Chaharmahal-Va-Bakhtiari province. The amount of available P was measured by Olsen, Colwell, ammonium bicarbonate-DTPA, 0.01 M calcium chloride, ...
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The objective of the present study was to evaluate several chemical extractants to estimate available phosphorus (P) for bean growing in calcareous soils from Chaharmahal-Va-Bakhtiari province. The amount of available P was measured by Olsen, Colwell, ammonium bicarbonate-DTPA, 0.01 M calcium chloride, BrayІ, ІІ, Mehlich І and ІІ extractants. In addition, soil organic P and total P were determined. A pot experiment consisting of a completely randomized design with three replications was conducted to evaluate the plant performance in association with chemical extractants. After the harvest, dry weight, P concentration and P uptake were determined. The results showed that the amount of extractable P decreased in the following order: Colwell> Mehlich ІІ> Bray ІІ> Olsen> Ammonium bicarbonate -DTPA> Mehlich І> Bray І> 0.01M Chloride calcium. Organic and total P and phosphorus extracted by Colwell, Olsen and Mehlich ІІ methods correlated significantly with plant indices. In addition, the results of stepwise regression analysis showed that the organic P, Colwell and Olsen extractants could explain more variation in the indices of bean plant. The results of this research showed that Colwell, Olsen and MehlichІІ extractants could be used to estimate plant-available P in the studied calcareous soils.
Research Article
A. Shahnazari; Mirkhaleg Ziatabar Ahmadi
Abstract
One of the important components of suitable operation of subsurface drainage systems is its envelope. Several researchers have evaluated the efficiency of dry land drainage, but the operation of these materials in subsurface drainage systems of paddy fields has not been investigated. In this research, ...
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One of the important components of suitable operation of subsurface drainage systems is its envelope. Several researchers have evaluated the efficiency of dry land drainage, but the operation of these materials in subsurface drainage systems of paddy fields has not been investigated. In this research, the effects of two mineral and artificial envelopes on flow rates of drainage system in paddy fields of Sari Agricultural Sciences and Natural Resources university lands have been investigated. For this purpose, a drainage system consisting of 4 drain lines at 0.65 m depth and 15 m spacing was installed. For two drain lines, mineral envelopes and for other two drains artificial envelopes were used. During one canola growing season, the drain discharges were measured daily. There was significant difference (p=1%) between the mean discharge of drains so that the average drain discharge of drain with artificial envelope was 88 percent higher than the corresponding value of drain with mineral envelope. Based on the drainage water depth-rainfall relationship, the average of daily discharges of drains with artificial and mineral envelopes was equivalent to 2.5 and 1.8 mm rainfall, respectively. Also, comparison of the total costs of the two drainage systems showed that the drainage system with artificial envelope was 30% less expensive than drainage system with mineral envelope.
Research Article
A.A. Sabziparvar; S. Tanian
Abstract
The main aim of this research is investigating the effect of ENSO phenomenon on reference evapotranspiration (ET0) on monthly, seasonal and annual time scales, using Southern Oscillation Index (SOI). For this purpose, 13 sites located in cold climate regions with 50 years (1957-2006) meteorological data ...
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The main aim of this research is investigating the effect of ENSO phenomenon on reference evapotranspiration (ET0) on monthly, seasonal and annual time scales, using Southern Oscillation Index (SOI). For this purpose, 13 sites located in cold climate regions with 50 years (1957-2006) meteorological data were selected. In the first step, the reference evapotranspiration rates were determined for the selected sites by using FAO recommended approach. In the second step, different phases (El Nino, La Nina and normal) were separated in terms of SOI and the mean deviation of ET0 values at each phase were compared by Mann-Whitney test. At statistical significant levels (p< 0.1), good correlation were found between the ET0 values and SOI. About 72% of correlations were positive and the rest (28%) were negative. In positive SOI-ET0 correlations, the monthly averages of ET0 values during El Nino phases were 14.8% and 10.8% lower than ET0 of La Nina and Normal phases, respectively. On the contrary, the average ET0 rates in La Nina phases were 13.1% higher than the corresponding values of normal pahses. The mean time lag to observe the highest impact of ENSO on ET0 was 3.2 months. The highest effective months in the study sites was found to be November, October and December, respectively. In seasonal time scale, 68% of the statistical significant affecting cases were occurred in autumn. It was found that the cold climates were more sensitive to the ENSO signals than warm climates. The results can be useful for policy makers in water resources management and agricultural sectors.
Research Article
A.A. Zolfaghari; Mehdi Shorafa; M.H. Mohammadi; A. Liaghat; A. Hoorfar; manoochehr gorji
Abstract
Quantitative knowledge of soil hydraulic properties such as the soil moisture characteristics curve (SMC) is crucial for flow and transport modeling supporting hydrologic and agricultural engineering. However, many laboratory and field methods are currently available for direct measurement of the soil ...
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Quantitative knowledge of soil hydraulic properties such as the soil moisture characteristics curve (SMC) is crucial for flow and transport modeling supporting hydrologic and agricultural engineering. However, many laboratory and field methods are currently available for direct measurement of the soil hydraulic properties but, most or all of direct methods are too time consuming and costly. Thus developing of physically-based methods for predicting SMC is essential. In this study, an analytical method was developed to estimate Brooks-Cory model parameters using horizontal infiltration data. The new method was compared with Wang et al (2002) method. Sixteen soils with wide range of hydraulic properties were used to test the new method. The results showed that the new method estimates n and hd parameters smaller than those experimental values. Although, results showed that the new method properly predicts the measured SMC data. High coefficient of determination (R2=0.93) and low root mean square error (RMSE =0.03) confirmed the accurate predictability of new method. Mean RMSE of Wang et al (2002) method was 0.049. Therefore, results indicated that the new method is more accurate than Wang et al (2002) method for predicting soil moisture characteristics curve. The sensitivity analysis indicated that, for a given soil, the accurately estimation of SMC depends mainly on sorptivity parameter.
Research Article
M. Erfanian; S. Babaei Hesar
Abstract
Short wavelength of solar radiation that reaches the ground used as one of the key parameters in most models those estimate the potential Evapotranspiration, such as FAO Penman-Monteith. Despite the importance of amount of radiation, its measurement is done only in small number of stations in the country. ...
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Short wavelength of solar radiation that reaches the ground used as one of the key parameters in most models those estimate the potential Evapotranspiration, such as FAO Penman-Monteith. Despite the importance of amount of radiation, its measurement is done only in small number of stations in the country. Empirical radiation models, such as Angstrom- Prescott, despite the simplicity, require calibration and their coefficients must be properly estimated. In the present study a relatively simple physical model that called hybrid model was used to estimate daily solar radiation in 10 synoptic stations, Esfahan, Bojnourd, Bandar Abbas, Tabriz, Tehran, Ramsar, Zahedan, Kerman, Kermanshah and Mashhad and the results were compared with modified Daneshyar & Sabagh models those were proposed for various climatic conditions in previous researches. using a relatively small number of meteorological parameters include temperature, relative humidity, pressure and sunshine hours, Hybrid model estimated amount of radiation with reasonable accuracy. To compare the three models, mean error (ME), mean absolute error (MAE), root mean square error (RMSE) and mean percentage error (MPE) statistical criteria were used. Average of each error criteria in Hybrid model, respectively are, -0.27, 1.27, 1.59 and 2.01 and in the modified Daneshyar model are, -0.19, 2.64, 3.15 and 3.42. Also in modified Sabagh model these criteria are achieved equal to 0.91, 2.87, 3.93 and 11.20. Small amount of error criteria for Hybrid model represents the relatively high performance of this model in the estimation of solar radiation in daily scale.
Research Article
F. Nourmandipour; Mohammad Hady Farpoor; M. Sarcheshmehpour
Abstract
Crop management and irrigation water quality play an important role on soil properties. The present research aimed to study physicochemical properties and micromorphology of soils under pistachio orchards compared to non-cultivated adjacent soils. Four water samples with different Mg/ca ratios were selected ...
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Crop management and irrigation water quality play an important role on soil properties. The present research aimed to study physicochemical properties and micromorphology of soils under pistachio orchards compared to non-cultivated adjacent soils. Four water samples with different Mg/ca ratios were selected according to analyses of 500 irrigation water samples. Five pedons in pistachio orchards and 4 pedons in non-cultivated adjacent soils were studied. Routine physicochemical analyses and micromorphology observations performed on soil samples. Results of the study showed that electrical conductivity in non-cultivated soils (256 dS/m) was remarkably higher than cultivated soils (8.9 dS/m). Mg/Ca ratio in cultivated soils compared to adjacent non-cultivated soils increased with increasing Mg/Ca ratio of irrigation water. On the other hand, using high quality irrigation water decreased this ratio in cultivated soils compared to blank samples. Lenticular and interlocked plates of gypsum observed in non-cultivated soils. Isolated and small size lenticular gypsum crystals were dominant in pistachio orchard soils.
Research Article
A. Lakzian; M. Fazeli Sangani; Alireza Astaraei; A. Fotovat
Abstract
This study was conducted to evaluate using terrain attributes derived from digital elevation model (DEM) as ancillary data to predict soil organic carbon (SOC) by implementing different statistical and geostatistical techniques. A linear regression model (LR), Artificial Neural Network model (ANN), ordinary ...
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This study was conducted to evaluate using terrain attributes derived from digital elevation model (DEM) as ancillary data to predict soil organic carbon (SOC) by implementing different statistical and geostatistical techniques. A linear regression model (LR), Artificial Neural Network model (ANN), ordinary kriging (OK), ordinary co-kriging (OCK), regression kriging (RK) and kriging with an external drift (KED) were performed to predict spatial distribution of SOC in an area of 2400 km2 in mashhad, iran. The SOC was measured for 200 soil samples of the study area and their corresponding Terrain attributes value was extracted from derived from 10-m resolution DEM. correlation between measured SOC and individual terrain attributes was determined, the number of 160 data were used for model development and 40 as validation data set. Resulting maps of different interpolation methods were compared to evaluate map quality using MAE and R2 criteria calculated from plotting measured versus estimated data. The results showed that there is a significant but not strong correlation between SOC and terrain attributes. The comparison of estimation techniques showed that the KED technique with wetness index as ancillary data has the best performance (MAE=0.18 %, R2=0.67) of all, but no significant difference with RK. There were modest differences between maps created with geostaistical technique but sensible difference with LR and ANN ones. The results of this study propose that although there is a significant correlation between SOC and terrain attributes therefore It can be use for enhancing the quality of map, but it is not able to express the spatial variability of SOC as it is necessary for detailed soil map. Because there is other factors controlling SOC spatial distribution
Research Article
M.R. Tabatabaei; K. Shahedi; karim solymani
Abstract
The estimation of suspended sediment load is very important for water resources quantity and quality studies. The suspended sediment load is generally calculated by direct measurement of suspended sediment concentration (SSC) of a river or by using sediment rating curve (SRC) method. Direct measurement ...
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The estimation of suspended sediment load is very important for water resources quantity and quality studies. The suspended sediment load is generally calculated by direct measurement of suspended sediment concentration (SSC) of a river or by using sediment rating curve (SRC) method. Direct measurement of the SSC is the most reliable but it is very expensive and time consuming. Also, the efficiency of the SRC method is low because it can substantially underpredict the high and overpredict the low loads. In this research, in order to consider the possibility of estimating the fluvial SSC, using reflectance of satellite images, the correlation between red and infrared bands of MODIS sensor and SSC of Karoun river at Molasani station for a period of 9 years (2003-2011) was considered. In this relation, two models (statistical simple linear regression and feed forward back propagation ANN) were used. The evaluation of models results showed that the efficiency of ANN model with having R2 =0.89 and RMSE=122mg/l was better than the regression relation with R2 =0.49 and RMSE=204mg/l. The research results showed that MODIS sensor images and ANN can be used together to estimate fluvial daily SSC in large rivers.
Research Article
Hossein Sharifan; P. Mokhtari; A. Hezarjaribi
Abstract
By considering the shortage of water resources in our country and dominant share of agriculture in making use of these resources, economizing and saving in this sector and using management practices for raising the efficiency of water consumption is necessary and essential. Super absorbent polymers, ...
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By considering the shortage of water resources in our country and dominant share of agriculture in making use of these resources, economizing and saving in this sector and using management practices for raising the efficiency of water consumption is necessary and essential. Super absorbent polymers, polymer gel, Are hydrophilic and are able to absorb a vast amount of water, Salt water, or physiological solutions and enhance the act of saving water in soil. Using super absorbent polymer is one of the methods that enhances the utilization of water that not only provide conditions which makes quality performance better, it also considerably increases the water use efficiency. In this research we examined the effect of super absorbent on the infiltration equation parameters (Kostiakov _ Lewis) through the advance time calculated and the effects of superabsorbent on these equations also were examined. The experiment were performed in the educational farm of the university of natural resources and agriculture in a no cultivation conditions.in this research four combinations of superabsorbent polymer A200 with soil which were composed of 0,7,11,16gr of polymers in square at a depth of 25cm and the electric current was 0.75 liter per second were considered. The experiment were performed four times. The results indicated that by adding polymers A200 to the soil, advance time and rollback time were increased. also therefore the Infiltration and the cumulative soil Infiltration were increased.
Research Article
J. Behmanesh; M. Montaseri
Abstract
Potential evapotranspiration is one of the most important and effective factors for optimizing agricultural water consumption and water resources management. One of methods for prediction of evapotranspiration is to use the time series models. In this research, application of different time series models, ...
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Potential evapotranspiration is one of the most important and effective factors for optimizing agricultural water consumption and water resources management. One of methods for prediction of evapotranspiration is to use the time series models. In this research, application of different time series models, such as AR and ARMA, in order to predicting monthly potential evapotranspiration in Urmia synoptic station were evaluated. In this process, monthly potential evapotranspiration since 1971 to 2010 was determined and the first 35 years and last 5 years were used for model calibration and validation respectively. After selecting the best model, the potential evapotranspiration were predicted for the next 5 years. The results showed that AR(11) time series model had the best results in comparing the other models and the trend of AR(11) time series model had least error. The values of R2 and RMSE in AR(11) model were 0.96 and 1.85 mm/month, respectively.
Research Article
M. Esmaeili Varak; M. Safarrazavi Zadeh
Abstract
Weirs are common structure to regulate water surface and flow control in water conveyance channel and hydraulic structure. One of effective and economical method to increase the efficiency of weirs is utilization of labyrinth weirs which length of weirs increase with modification of plan form and therefore ...
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Weirs are common structure to regulate water surface and flow control in water conveyance channel and hydraulic structure. One of effective and economical method to increase the efficiency of weirs is utilization of labyrinth weirs which length of weirs increase with modification of plan form and therefore flow discharge will be increase. In this research, the discharge coefficient and the unit length discharge of labyrinth weir with liner-semi circular and semi circular with radius of 11, 16 and 20 cm and cycle of 2 to 6 was experimentally investigated. Comparison of results showed that in all labyrinth flow discharge coefficient had increasing trend with increase of relative effective head ( ) then decrease for due to collision of nape and with increasing , weir coefficient tend to broad crest weir because of local submergence. Comparison of results showed that the labyrinth weirs with circular plan have a better performance in comparison with liner-circular plans.
Research Article
F. Sahebi Vayghan; Davoud Farsadi; M. Esmaeili Varaki; A. Abbaspour; Ali hosseinzadeh
Abstract
Stilling basins are one of the most common structures for energy dissipation of flow with high velocity and among different sections and types of these basins, diverging basins have better performance and lower constructional costs. In this research, the feasibility of 3D numerical simulation of diverging ...
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Stilling basins are one of the most common structures for energy dissipation of flow with high velocity and among different sections and types of these basins, diverging basins have better performance and lower constructional costs. In this research, the feasibility of 3D numerical simulation of diverging hydraulic jump in rectangular basins was investigated using standard and RNG turbulence models using Fluent software. The free surface was determined using the VOF method. The outputs of numerical model in comparison with the results of physical model of hydraulic jump in diverging rectangular basins with diverging angels of and showed that the standard turbulence model evaluated the free surface of water, jump length and maximum velocity in defined sections better than RNG turbulence model. this model show that the efficiency of diverging basins in decreasing length of jump is more better than the classic basins. So this model is recommended for simulating hydraulic jump in diverging sections. Results showed that the mean relative error of water surface obtained from numerical model and measured values is about 7 percent. Modeled Velocity profiles were in good agreement with measured data. Also the numerical model showed the vortices that were accrued because of diverging walls as well as experiment investigations. These vortices accrued near the right side of diverging wall in high Froude numbers and in lower values of Froude numbers, accrued in both two sides of walls. The intensity of vortices was increased by increasing the angle of diverging walls.
Research Article
M. Salehian Dastjerdi; A. Hemmat
Abstract
Wetting and drying induce stresses in soil which changes the physical structure of the soil. For this reason, the effect of this process on evaluating the methods for estimating the threshold of compactibility (load-bearing capacity, pre-compaction stress) of a coarse textured soil (sandy loam) collected ...
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Wetting and drying induce stresses in soil which changes the physical structure of the soil. For this reason, the effect of this process on evaluating the methods for estimating the threshold of compactibility (load-bearing capacity, pre-compaction stress) of a coarse textured soil (sandy loam) collected from the fields of the Sugarecane and By-product Development Co. in Ahvaz province was studied. In this research, the plate sinkage test (PST) and confined compression test (CCT) methods were evaluated. Large air-dry disturbed soil samples were prepared and some of them were exposed to five wetting and drying cycles. After that, the large soil samples with/without wetting and drying cycles were compressed under three loads (0, 100 or 200 kPa) and then the centre section of the preloaded soil samples was firstly submitted to PST. Then immediately one cylindrical sample was cored for CCT. The results showed that for the soil samples without wetting and drying process, there was no significant difference between the applied load and the estimated values using PST method. However, for the soil samples under wetting and drying process, the obtained values were significantly greater than the applied loads. Therefore, for tilled soil, PST can be used as a quick method to determine the compression parameters of the soil in laboratory or in the field.
