WATER AND SOIL SCIENCE (AGRICULTURAL SCIENCE)
Year:2013 | Volume:23 | Issue:1|Papers Count:20

Stepped spillways have significant importance for their indisputable effect on energy dissipation and for compatibility with roller compact concrete method in construction. In order to design these spillways, physical models are commonly used in spite of spending great time and cost. Progress of high speed computers, however, permits to utilize computational fluid dynamic (CFD) method and therefore diminishing time and cost. In this research, some physical results are used for simulation of flow on stepped spillways, by applying FLUENT CFD package. Skimming and transitional regimes are investigated for the spillway. The simulated parameters were characteristic depth (Y90), characteristic velocity (V90), clear water velocity and mean air concentration. Multiphase models consisting of volume of fluid (VOF), mixture and Eulerian and also turbulence models of k- e, also coupling pressure-velocity algorithms of PISO and Simple were used both two and three dimensionally. Mixture and RNG k-e for multiphase and turbulence models totally produced satisfactory results. The results were good for evaluation of the hydraulic parameters considering air bubble entrainment in skimming regime and relatively poor for transitional regime.

To evaluate the effects of nitrogen sources and rates on yield and yield components of cucumber a factorial pot experiment with completely randomized design and twenty treatments and three replications were conducted at the green house of agricultural education center in Tabriz, Iran, in 2009. Treatments of the study consisted of factorial combinations of four nitrogen sources (urea, sulfur coated urea, ammonium nitrate and ammonium sulfate) and five rates of nitrogen (0, 150, 300, 450 and 600 kg nitrogen per hectare). Traits measured in the study were fruit yield, number of fruit per plant, fruit length and diameter. Results of the variance analysis of data showed that the main and interactive effects of nitrogen source and rate were significant on fruit yield and  length at 1% probability. The highest fruit yield (640.2 g/plant) was obtained from the application of 600 kg nitrogen per hectare as sulfur coated urea. The highest fruit length and number of fruit per plant were also obtained from this treatment. Comparison of the  means values showed that the lowest fruit yield was in the treatment with ammonium nitrate.

Density of deposits is bounded on different variables e.g. physical properties of sediment particles, rate of deposits' layer compaction and type of reservoir operation. These criteria have uncertainty and so the specific weight of deposits has the same problem. In this paper, the effective factors that influence the density of deposits in the reservoirs had been classified and then the basic concept of Delta method was stated as one of the popular techniques for analysis of uncertainties. Further, the case of Kenny reservoir in the White River basin at northern Colorado was selected to determine the specific weight of deposits in the reservoir and the coefficient of variation. The results of this investigation indicate that in the case of Kenny Reservoir the density of deposits is 1267±125.6 (Mean± SD) kg/m3, and the coefficient of variation of specific weight for accumulated deposits equals  9.9% for the period of 15 years of reservoir operation.

Prediction of crop yield is one of the managerial and planning tools in agriculture. Meteorological variables and drought indices play an essential role in yield prediction. In this study, the yield of four crops, namely wheat, barley, chickpea and watermelon was predicted in Mashhad and Birjand regions based on meteorological variables and drought indices using three regression models of Ridge, Enter and Step Wise. For this purpose, ten meteorological parameters and seven drought indices were used in three structures as input multivariate regression models. Results showed that among the meteorological variables, the two variables: number of rainy days and maximum air temperature had higher correlation with crops under study. Similarly, among drought indices, Nguyen index showed such higher correlation. It was found that Ridge multivariate model including weather parameters and meteorological drought indices could be recommended instead of two structures of meteorological variables and drought indices for yield prediction. This recommendation was based on multiple regression analysis and higher determination coefficient (R2) and a lower normal root mean squared error (NRMSE). Also, determination coefficients for all four products in both regions were from 0.91 to 0.99 and NRMSE from 0.09 to 0.48. Results also showed that the most prediction accuracy was for wheat with R2 of 0.996 and NRMSE of 0.09 in Mashhad and for chickpea with R2 of 0.999 and NRMSE of 0.09 in Birjand. Similarly, the least accurate prediction belonged to watermelon having R2 of 0.92 and NRMSE of 0.48 in Birjand and R2 of 0.96 and NRMSE of 0.27 in Mashhad. Overally, due to high R2 and low NRMSE, Ridge regression model is recommended for both regions.

Today the hydro–electric power plants are important sources of energy production. Among the elements of the hydro-electric power plants, penstock is a high pressure pipe and high important that conveys water from dam reservoir or any high head water to power plant turbines. The important of penstock is due to its expensive design and maintenance; so a considerable percent of the construction cost of power plants is allocated to penstocks structure. So optimization of penstock has a great effect on a hydro-electric project cost reduction. Using Heuristic methods to optimum design of different structures has been an important object being studied in recent years. Among Heuristic algorithms, Ant Colony Optimization method is a powerful optimization tool which has been considered by researchers in many fields. In this study, the dimensions of penstock were optimized using Ant Colony method. For this purpose on the basis of the selected Ant Colony Algorithm, Shahryar dam (in Miyaneh) was investigated. The results indicated that ACS algorithm has high capability in optimization and can considerably reduce the weight of penstock.

Amount of micronutrition elements in agricultural soils is one of the most important  properties in crops production.  Most Better management of these elements in broad sense requires that their maps be produced in the study area. One of the most important tools for providing these kinds of maps is geostatistics. In the study, the efficiencies of four methods including weighted moving average, spline, ordinary kriging, and co-kriging in interpolating four elements of iron, zinc, boron, and cobalt were investigated. After investigating variograms and running these methods results showed that for interpolating iron, zinc, boron, and cobalt the co-kriging  method was the best. Also results of interpolations revealed that iron had the lowest interpolation error (MAE=0.353 and RMSE=0.661). Then, based on the co-kriging method zoning maps of these elements were prepared for Hamadan province. Based on the created maps shortage of micro-nutrition elements was observed in Northern parts of the province. Therefore, in order to obviate this shortage and attain sustainable agriculture in this region, using micro complete fertilizers is offered.

Vegetation is one of the soil forming factors that  its influences on soil micromorphological properties have been less attentioned. In this research to assess the effects of vegetation and its associated processes, five profiles with different covers including rapeseed, corn, alfalfa, apple and pine with a control profile were dug, described and sampled from all horizons in the countryside of Tabriz. Soil samples were physicochemically and micromorphologically analyzed after preparation. The results revealed the good pedality and structure improvement of surface horizons were in comparison with underlying ones. The order of soil pedality rate and degree of structure improvement for different covers were observed under apple, pine, corn, alfalfa, rapeseed and control profile (bare). Soil voids of surface horizons were found to be in packing void forms because of environmental effects. This is more obvious in farming vegetation than trees and bare because of application of several tillage instruments. Observation of excrement pedofeatures in the  surface horizons and high abundance of them in the garden covers rather than forest and farming covers and bare land show the high biological activity in this vegetation. Presence of lime coatings refers to the role of plants and organisms through the production of CO2 and dissolution and sedimentary of carbonate in these soils. Presence of iron coating, nodules and iron-manganese oxides in some of the horizons is the evidence of oxidation and reduction processes in some horizons that according to the low water table and climatic condition, the reason can be found in the irrigation management.

In recent years, nitrogen fertilizer consumption in agriculture, accumulation and movement of salts in soils and modeling their movement have  received extensive attention, But in using these substances, there should be a balance between the production increase and the quality of agricultural products, otherwise, undesirable effects, such as environmental pollution and soil and ground water contamination will occur. The objectives of this study were to investigate the effect of potassium zeolite on nitrate ion sorption and retention in a saturated sandy loam soil under laboratory condition with four treatments of 0, 2, 4 and 8 g zeolite per kg soil and to simulate nitrate ion leaching using Hydrus-1D model. The study was conducted as a completely randomized block design. Ammonium nitrate fertilizer with concentration of 10g per liter was added to soil columns and then leaching was performed. Results of the study showed that by increasing the amount of potassium zeolite to soil, the mobility of nitrate ion reduced and the nitrate retention in soil increased. Also, the Convection- Dispersion (CDE) and Mobile- Immobile (MIM) models were used to simulate the nitrate ion mobility in soil. Absorption isotherms and diffusion and dispersion coefficients were determined through the inverse modeling. Because the soil was disturbed, CDE model estimation was closer to observed values in all four treatments. Both the CDE and MIM models showed that as the amount of zeolite applied to the soil increases, the diffusion coefficient and dispersion coefficient of nitrate ion in the soil decreases and increases, respectively.

Oil contamination in Iran due to high application of oil compounds, is one of the most dangerous pollution factors. Bioremediation is a prime strategy for remediation, by which the pollutants can be removed by making use of microorganism or any biological process that employes microorganisms or their enzymes to rehabilitate the environment altered by the contaminants. With regards to the importance of this method, screening and isolation of oil-degrading bacteria from contaminated site of Bushehr province were done in Carbon Free Minimal Medium enriched by gas oil. In this study 19 isolates of bacteria (PDB 1-19) were isolated, and the molecular and kit identifications showed different genus and species such as Stenotrophomonas maltophilia, Ralstonia sp., Vibrio sp., Sphingobacterium sp., Zymomonas sp., Pseudomonas aeruginosa, Paracoccus sp., Pantoea sp., Achromobacter xylosoxidans, Acinetobacter johnsonii, Serattia odorifera, Pseudomonas alcaligenes, Entrobacter cloacae, Pseudomonas stutzeri and Chryseobacterium sp. In order to determine the efficiency of these bacteria in hydrocarbon-degradation an inoculum of pure culture of bacteria containing 108 cfu/ml was used in liquid assay, which was performed in factorial experiment based on completely randomized design with 2 replications. Utilization of hydrocarbon sources was again detected in CFMM broth supplemented with 2% gas oil where the growth turbidity (OD600nm) as an indicator for utilization of hydrocarbon and bacterial growth was measured at different times of 0, 48, 168, 216 and 312hr. Results showed that in CFMM broth assay all main factors including bacteria and time as well as their interaction were significant (p<0.01). These bacteria were effectively able to mineralize gas oil and among bacteria, best results was achieved by Chryseobacterium sp. The ability of bacterial isolates for degradation of oil-compounds increased by increasing time of incubation.

Measurement of the critical level of phosphorus due to several economical and biological reasons is of great importance in paddy fields. The present research was done for determining the critical level of phosphorus in the paddy fields cultivated by rice cv. Hashemi using 6 extraction methods including Olsen, Morgan, Soltanpoor, Colwell, Bray and Mehlich 3. In this project, among 100 paddy fields evaluated for their soils, 27 fields were chosen based on the maximum range of variation in their pH, organic matters and extractable phosphorus. In the selected fields we did two fertilizer treatments of 0 and 120 kg of triple super phosphate per hectare, and then the critical level of phosphorus in the extraction having the best correlation with the rice yield was measured via the visual method of Cate-Nelson. By this approach the critical level of phosphorus for Colwell, Olsen, Soltanpoor and Morgan extraction methods were 35, 16, 3 and 4.5 mg/kg, respectively. With respect to the presence of a good relationship between Olsen extraction method and relative rice yield, also owing to the cost- effectiveness and time- saving feature of this technique we strongly recommend this approach as a suitable way to extract the absorbable phosphorus, and the use of the phosphate fertilizers is suggested  in the paddy fields of Guilan province.

Urmia Lake is the largest inland lake of the country and the second largest saline lake in the world. Due to climate change, decrease of precipitation, overuse of surface water resources and low agricultural efficiency in the Urmia Lake Basin water level of the lake decreased and its water salinity increased. The average surface water amount of this basin is 7.2 billion cubic meters per year that this amount should provide the minimum environmental requirement of Urmia Lake (about 3.1 billion cubic meters per year). Thus, control and optimal allocation of surface water resources (4.1 billion cubic meters per year) to three stakeholder provinces (West Azerbaijan, East Azerbaijan and Kurdistan) is an important issue that must be considered. This paper introduces a multi-criteria decision making model as a possible approach to the problem of allocating the water resources of the Urmia Lake basin to all neighboring provinces. In this paper by using of simple additive weighting, compromise programming and TOPSIS methods and by considering the social, economical and environmental criteria the share of each stakeholder is obtained and then abilities of these methods are compared. According to the results of the compromise programming method, the shares of West Azerbaijan, East Azerbaijan and Kurdistan  provinces respectively are 1.804, 1.312 and 0.984 billion cubic meters per year.

Precise estimate of evapotranspiration (ET) or crop water requirements crucial for improving water resources management and eventually increasing water use efficiency. Considering the vast varieties of crops cultivated on large scales, calculating precisely the crop water requirement from ordinary methods of estimating reference evapotranspiration is difficult and in some cases even impossible. Therefore, it is necessary to develop methods to compute crop water requirement in large areas with sufficient accuracy. One of such methods is to use remote sensing data which covers a much larger areas as compared with methods depending on field weather data. One of the most well known methods to compute actual ET from remote sensing data is SEBAL method (Surface Energy Balance Algorithm on Land). In SEBAL method, all fluxes of the energy balance at the earth's surface including net radiation, soil heat flux, and sensible heat flux are calculated from satellite images and finally actual ET is computed based on the energy balance at the earth's surface. It is intended to evaluate spatio-temporal variation of daily ET in Mirza Kochakkhan sugarcane Agro-Industry farms located in southern part of the Khosetan province using MODIS images for 10-day periods during a growing season in 2006-2007. The results obtained indicated that the SEBAL method was an efficient method to estimate actual ET during the growing season. Maps of actual ET generated by ERDAS and GIS software showed that fields which were well irrigated or had a good crop cover had the highest values of ET. However, actual ET decreased for areas with less crop cover or dry fields. The data obtained from the generated maps of actual ET were closer to the data obtained from the field with a coefficient of determination of R2=0.77.

In recent years, some specialized software has been developed for land evaluation goals that  the common aspect of them is the generation of an environment for patterning and modeling of evaluation methods. The purpose of the present study is the assessment of susceptible land for irrigated maize, sunflower and barely crops in Jaldyan and Pasveh regions with an area of 9680 ha lain between 36o30' to 36o5' N latitude and 45o05' to 45o25' E longitude in West Azerbaijan province by GIS technique. After determination of climate, soil and landscape characteristics of the region, crop requirements of land utilization types were determined using the tables developed by Sys and Givi, and finally land suitability was recognized by ArcGIS software. Results show that in the surveyed region, the climatic classes are highly suitable (S1) for irrigated barely and moderate suitable (S2) for maize and sunflower due to the limitation of relative humidity of the growing cycle. Also, the most important soil limiting factors for crops production are pH, CaCO3, texture, coarse fragments and topography in areas. It is suggested that, this method of overlaying two or more map layers to produce a new map, to be used more in land evaluation, because it is very difficult and time-consuming by traditional methods. In other words, using GIS in land suitability surveys increases the accuracy and progress of research.

Abutments are widely used structures for protecting outer banks of river bends and its stabilization projects. Temporal variation of scour hole around an abutment, and the determination of equilibrium scour depth in designing and applying abutments are very important. Nowadays, several empirical relationships for predicting temporal variation of scour hole depth at abutment are presented. In the recent decade, due to ability of complex phenomena modeling, the artificial intelligent methods have very wide applications in many fields of water engineering. Gene-expression programming, a branch of evolutionary algorithms, is able to optimize the model structure and its components. In this study, using gene-expression programming, temporal development of scour hole around a wing-wall abutment has been simulated and compared with experimental data. By considering effective parameters in temporal development of scour around the abutment using dimensional analysis, the dimensionless parameters of t/te and v/vc have been selected as independent variables a/L, b/L, c/L  and ds/dse parameters as dependent variables. Comparison of results of gene-expression programming with experimental data show that gene-expression programming is able to simulate the process of temporal development of scour hole and depth, very well.

most important agricultural crops in Iran that needs much water and mainly cultivated in waterlogged conditions. In order to increase water use efficiency and yield of rice, reduce environmental pollution with chemical fertilizers and increase organic matter of paddy soils application of organic fertilizers is recommended. This investigation was conducted to study the effects of soil water conditions, sewage sludge, poultry manure and chemical fertilizers on the growth characteristics and water use efficiency of rice plant (Oryza sativa L. cv. Ali Kazemi) in a calcareous clay loam soil under greenhouse conditions. The study was performed as a factorial experiment in a randomized complete blocks design including soil water conditions at three levels (continuous submergence, alternate submergence and alternate saturation) and source and amount of organic and chemical fertilizers in 10 levels (control, 100% chemical fertilizers (456.5 mg urea, 66.4 mg Ca(H2PO4)2.H2O and 22 mg ZnSO4.7H2O /kg of soil), 6g sewage sludge per kg of soil with and without 50% chemical fertilizers, 20g sewage sludge per kg of soil with and without 50% chemical fertilizers, 3g poultry manure per kg of soil with and without 50% chemical fertilizers and 6g poultry manure per kg of soil with and without 50% chemical fertilizers) with three replications. Results showed that the tiller and leaf number per plant, leaf area index and shoot and root dry matter in continuous submergence and alternate submergence were greater than alternate saturation. The effect of soil water conditions on water use efficiency of rice plant was not significant. Application of organic and chemical fertilizers increased the above mentioned characteristics and water use efficiency as compared to the control treatment. With increasing the level of sewage sludge, tiller and leaf number per plant, stem length, shoot and root dry matter, the ratio of shoot dry matter to that of root, leaf area index, leaves chlorophyll index and water use efficiency increased but by increasing amount of poultry manure from 3 to 6 g per kg of soil the above mentioned plant characteristics decreased. In general, alternative submergence with application of 20 g sewage sludge per kg of soil to achieve the optimum growth of rice and increase water use efficiency in greenhouse conditions is recommended.

Intensive livestock grazing may change soil properties and ecosystem functioning through reductions in soil quality and fertility. The objective of the current study was to establish the influence of three different rangeland grazing regimes (i.e., free grazing, controlled grazing and short-term ungrazing regimes for 8 years) on carbon (C), nitrogen (N) and C mineralization associated with different primary particle-size fractions in Shayda natural rangelands with cropping history in Chaharmahal VA Bakhtiari province. Results indicated that organic C and total N concentrations were higher in grazed than ungrazed rangelands, but the C/N ratio did not show any difference between grazing regimes. Controlled grazing regime had a higher amount of particulate organic matter (POM) while ungrazed regime had a higher amount of hot-water extractable carbohydrate (HWC). The amount of C and N increased with decreasing particle size from sand to clay fractions in all grazing regimes. Rangeland grazing regimes altered organic C and total N associated with primary particle-size fractions. Free grazing regime increased C contents in the silt-size fraction but had no influence on C contents in the other fractions. Additionally, although grazing regime had no influence on the sand-size fraction N, free grazing increased the amount of N in the silt and clay-size fractions. Bulk soil C mineralization was higher in the grazed regime compared to the ungrazed regime most likely because of higher organic C and POM under these conditions. Results revealed that C mineralization was higher in the sand and silt fractions with higher weight proportion in the bulk soil and a low degree of humification in all grazing regimes.

An experiment to study the effect of advection on energy balance in process of canola field evapotranspiration was designed and conducted at the Agricultural Research Station of Tabriz University in spring of 2010. For this research canola was planted in a lysimeter located in the middle of a 1.6 hectare experimental field. Evapotranspiration rate, leaf area index and plant height were determined inside the lysimeter. The advection phenomenon was investigated using the energy balance in the field surface, Priestley-Taylor coefficient (a) and the ratio of evapotranspiration obtained from advection energy to vegetation surface evapotranspiration (Rad ). Bowen’s ratio (b), and ratio of lysimetric evapotranspiration to received net radiation in the fields (ET/Rn ) on different days after planting in the canola field were also determined. Negative values of sensible heat flux confirmed the  advection occurrence from 39 days after planting and values of  a and ET/Rn  showed that advection affected evapotranspiration process as significantly in this region. The values of  Rad reached more than 60 percent in some days of the growing season. This issue clearly proved the influence of advection energy on canola field evapotranspiration. In the study region except regional advection, local advection could occur across large fields due to the existance of small farms, different timings and amounts of irrigation and fallow duration of some farms. Results showed that, when leaf area index and plant height reached to 1 and 15 cm respectively, temperature gradient between the farm and the surrounding area were increased due to increment of LAI and plant height which increased the transpiration in turn. In this stage the resulted negative values of b and H confirmed the occurance of advection phenomenon.

The aim of tillage practice is the improvement of seed germination condition, facility of root development and improvement of plant growth. For this reason we study the effect of different tillage practices on safflower yield in rotation with wheat in dry lands. This experiment was conducted in RCBD with 4 replications and 4 treatments for 3 years in a rotation with wheat-safflower system. The tillage treatment was carried out after wheat harvesting and included T1: moldboard plow to depth of 20 cm in soil in autumn, handle seedling and fertilizer and the disk harrow in spring,(control), T2: direct sowing with grain drills in spring, T3: using rotavator in autumn and spring planting with grain drills, T4: chisel plow, disk harrow in autumn and grain drills planting was done in spring. Our data showed that among the treatments the highest value of grain yield , 0.929 ton/ha, belonged to T4 and  the lowest value, 0.564 ton/ha, belonged to T1. According to the results of simple correlations, plant height and number of capitula in plant had more effects on yield in respect to other yield components. The highest soil moisture content in stem elongation stage, 23.76%, and blooming stage, 20.56, of safflower belonged to T4. At 0 to 30 cm of soil depth the minimum value of bulk density 1.158 g cm-3, and the maximum gravimetric soil moisture in T4 were observed, while the greatest bulk density 1.259 g cm-3, and the least amount of moisture content in soil belonged to T1 treatment.

Side weir is used as a regulator structure to control discharge and water level in rivers and channels. A labyrinth side weir is a kind of weirs which does not  have a direct and smooth edge in the plan view. When the opening length is limited, these side weirs can divert more water out of the channel by increasing the effective length. To evaluate performance of the side weir and estimate the rate of flow passing through it, the discharge coefficient should be determined. In this research, hydraulic behavior of a labyrinth side weir with a trapezoidal plan in the single-cycle has been studied experimentally. Upstream Froude number of the side weir was modified in each test and the effects of opening length, height and side angels on the discharge coefficient were investigated. The results of the tests were analyzed to find out the effect of defined dimensionless parameters such as length, height and angle on the discharge coefficient in subcritical flow. The results obtained showed that in comparison with the normal side weirs the discharge coefficient of the trapezoidal labyrinth side weir increased about 15-30 percent. Also, the discharge coefficient decreased with increasing the Froude number and side angles and increased with increasing the opening length and height of the weir. In the range of experiments, the angle of 30 degrees gives the highest discharge coefficient that is approximately 1.5 times the other angles.

The bacteria of genus Azospirillum is one of the plant growth-promoting bacteria with N2 fixation ability that has been observed in the rhizosphere and the intercellular of the cereals and other plant roots. In this research the effect of some indigenous isolates was surveyed on some of the growth parameters and nutrients uptake. In this research 58 Azospirillum isolates were isolated from 38 samples of soils and canola roots from the different regions of Golestan province, Iran. Then they were compared to select the superior growth promoting isolates. The effect of inoculation of superior isolates on canola (the variety of Hayola 401) was carried out under growth chamber conditions, at fertilizer level (50% and 100%, based on soil test), in randomized complete block design (RCBD) with 3 replications and 2 harvest stages. The inoculation of 4 Azospirillum isolates on some of the growth parameters of canola showed that the bacterial treatments significantly increased shoot dry weight, potassium and nitrogen uptake compared with the control in the  first harvest, but they did not have any significant effect on all parameters in the second harvest. The maximum amounts of potassium and nitrogen uptake and the maximum amount of shoot dry weight were observed in inoculated plant by auxin-producing isolate with the amounts of 34.01, 31.43, and 0.627, respectively, in the first harvest. Also the effect of fertilizer treatments was significant on amounts of plant nutrients uptake and shoot dry weight in  the first harvest , and on shoot dry weight, root dry weight, plant potassium, and nitrogen uptake in the second harvest. The highest amounts of nutrients uptake, shoot dry weight, and root dry weight in the  both harvest stages were observed in 100% fertilizer treatment.