WATER AND SOIL SCIENCE (AGRICULTURAL SCIENCE)
Year:2018 | Volume:28 | Issue:1 |Papers Count:18

Effects of two organic amendments, cow manure and bagasse compost of sugarcane, on the chemical fractions of cadmium in soil were investigated at three incubation times in the present study. Soil sample was polluted with 50 mg kg-1 of cadmium by spraying the cadmium salt and after 90 days 25 and 50 tons’ ha-1 of the organic amendments were added to the soil. Some of the soil chemical properties and contents of chemical fractions of cadmium were determined by sequential extraction method of Tessier after 1, 30 and 60 days from the date of adding the organic amendments. The most fraction of cadmium in the all of the treatments was observed in the carbonate-fraction and the soluble and exchangeable-and organic matter-fractions of cadmium were significantly (p<0. 05) increased by use of the both amendments especially by cow manure, due to increase of the total (TOC) and dissolved (DOC) organic carbon, also the content of the carbonate-fraction of cadmium was decreased especially in the soil treated with 50 tons ha-1 manure, significantly (p<0. 05). On the other hand, the effect of incubation time was significant only on organic matter-and carbonate-fractions of cadmium. Adding the both amendments led to a significant (p<0. 05) decrease of cadmium mobility factor from 57. 6% in the control to 43. 9% and 40. 8% in the 25 and 50 tons ha-1of manure and also to 49. 6% and 46. 9% in the 25 and 50 tons ha-1of bagasse compost treatments, respectively. Finally, it was deducted that adding the decayed manure and plant residues to the soil led to decrease the cadmium fractions with higher bioavailability, specially carbonate fraction, related to the other chemical fractions of the metal and also decrease the cadmium mobility in soil.

The soil and water salinity are usually crucial factors in diminishing the growth and production of crops in arid and semiarid areas. Inoculation of plant with plant growth promoting rhizobacteria particularly Pseudomonas and mycorrhizal fungi are helpful ways to facilitate plant growth in saline soils. In this research, the effects of two strains of Pseudomonas fluorescens (P. fluorescens Tabriz (PFT) and P. fluorescens Cha0 (PFC)) and the mycorrhizal fungus, Rhizophagus irregularis on proline concentration in plant leaves as well as some growth indices of tomato (var. Super strain B) under 4 different levels of salinity (1. 56, 3, 6 and 9 dS m-1 S1, S2, S3 and S4, respectively) were studied, The results showed that plant fresh weight was significantly (17. 36%) higher in non mycorrhizal plant (-AM) than mycorrhizal plant (+AM) (p<0. 05). The bacteria had significant effect on measured parameters. The dry and fresh weight of the root and shoot and chlorophyll index of leaves at the presence of PFC were significantly (p<0. 05) higher than those at the presence of PFT and PF0 (non-bacterial control) and application of both bacteria increased root mycorrhizal colonization percentage compared to the PF0 (PFC 34. 88% and PFT 31. 22%). Root fresh weight and chlorophyll index of the plant increased with the increase of salinity levels up to S3 but at S4 level these two parameters decreased (p<0. 05). Also, the root mycorrhizal colonization percentage significantly decreased by increasing the salinity levels while the proline concentration of leaves significantly increased (p<0. 05) with enhancement of the salinity.

The purpose of this paper is the selection of the most suitable probability distribution function to calculate and compare the RDI and SPI drought indices. Accordingly, using the meteorological data of thirty synoptic stations in Iran, annual rainfall data series and the ratio of precipitation to potential evapotranspiration were obtained. At first, Normal or Gamma distributions and Log-normal or Gamma distributions were used to determine the SPI and RDI annual values, respectively. Then using Kolmogorov-Smirnov index, the best distribution function was obtained to fit with the data series in the studied stations. After determining the index values based on the superior distribution function and also the mentioned distribution functions, replacement of different drought classes was evaluated. The results showed that in the most stations, the mentioned distribution functions could not be selected as the most appropriate distribution function and using them in determination of the indices could change the drought classes. The results of the statistical indices (RMSE<0. 434 and R2>0. 819) showed that the annual time series of the SPI and RDI indices (calculated on the basis of the most suitable probability distribution function) were approximately similar and their difference was not significant in none of the stations. Also the results showed that the RDI index was more sensitive than the SPI index to the selection of the distribution function, so the selection of the most suitable distribution function for determination of this index was more important.

Determining the evapotranspiration of plants is possible mainly by two methods, namely direct measuring and indirect estimation using climatic parameters. Evapotranspiration determination using direct method is difficult, costly and time consuming. For this reason, some indirect methods have been proposed for determination of crop water requirement with acceptable accuracy. A lysimetric study was conducted to determine the reference evapotranspiration (ETo) in Tabriz plain in a loamy soil. Evapotranspiration was measured in ten days and monthly intervals by water balance equation method and then compared with ETo obtained using some empirical methods. Results indicated that the average seasonal ETo and pan evaporation (Ep) for 9 months were 1226. 9 and 1947. 3 mm respectively. Comparison between the measured and estimated ETo by various methods showed that the pan evaporation (class A) and Hargreaves methods had the highest and lowest correlation with lysimeteric data, respectively. Based on the statistical analysis, Penman-Monteith method had the closest estimates to lysimeteric measurement. In general, Penman-Monteith was introduced as a suitable method for estimating reference evapotranspiration in Tabriz plain. Also, the best regression equation for estimating ETo using meteorological parameter was introduced.

The soil management and optimum usage require a correct soil classification and detection of their main characteristics. So in this research work, the Soil Taxonomy and World Reference Base systems proficiency to qualify saline and gypsiferous soils properties and estimate of the relative amount of clay minerals with effect on soil characteristics are discussed. For this purpose, saline and gypsiferous soils of two regions from east Azerbaijan (Dasht-e-Tabriz and Khaje) were selected and after soil profiles description, sampling of all horizons and layers were carried out. Then samples were prepaired and different experiments were conducted for the study of ST and WRB proficiency. In the majority of soil profiles, the presence of heavy textured lower horizons has caused excessive accumulation of salts in the surface and middle horizons and salic and gypsic horizons formations. In general, according to WRB and ST, soils of these regions are classified in three reference soil groups of solonchaks, solonetz and gypsisols and two suborders of salids and gypsids, respectively. Based on mineralogical results, the most common and abundant clay mineral in this soils were illite which could be used as a mineralogy class in family level of ST system. As a result, in this kind of soils, the WRB system by high explanation of soil properties and adding dominant clay minerals name in qualifiers can be superior to ST.

Horizontal intakes are of the most common structures for water withdrawal from open channels such as rivers, lakes and dam reservoirs. One of the hydraulic phenomena that mainly occurs during the water withdrawal process of the channels is the formation of vortex and air bubbles that can cause many problems for hydro-mechanical facilities of intakes. Insufficient height of water above the intake pipes (submergence depth) is the major cause of the vortex formation on horizontal intakes. Due to the importance of this phenomenon, many models have been developed to estimate the critical submergence depth. However, due to the uncertainties of the vortex formation near the intake, the obtained results often do not show a desired accuracy. In this study, using three experimental data series, the performance of artificial intelligence techniques (adaptive neuro-fuzzy inference system (ANFIS), support vector machine (SVM), gene expression programming (GEP)) and classical models were investigated for predicting the critical submergence depth of horizontal intakes with different bottom clearances in open channel flows. The results indicated that in estimating the critical submergence depth, the artificial intelligence techniques are more accurate than the classical models and a good agreement could be seen between the observed and predicted values. The best result for the test series was obtained for C=di/2 state (di and C were intake diameter and bottom clearance, respectively) using SVM method with the values of R=0. 988, DC=0. 976 and RMSE=0. 191. According to the results of sensitivity analysis, it was observed that the relative velocity and Weber number in intake pipe were the most and the least significant parameters in the estimation of critical submergence depth, respectively.

In order to evaluate the effect of mycorrhizal fungi, different sources and levels of iron on growth and nutrients uptake in Mexican lime (Citrus aurantifolia L) (one of the important rootstock in citrus growing regions in south of Iran), greenhouse experiments were conducted with factorial arrangement in a completely randomized design with three factors and four replications. Treatments consisted of three levels of mycorhizal fungus (without fungal inoculation, inoculation with Rhizophagus intraradices, inoculation with Glomus versiforme), two sources of iron (iron chelate, iron solphate), and three iron levels (0, 7. 5, 15 mg kg-1 Fe). The results indicated that co-application of mycorrhizal fungal species and iron sources improved plant growth charactrices and the concentration of nitrogen, potassium, iron, zinc, copper, and manganese. In the treatments inoculated with mycorrhizal fungi, with an increase in iron levels, the nutrient concentrations of iron, zinc, copper and manganese in soil were increased, likely because of the balancing effect of mycorrhizal symbiosis on nutrient concentrations in plants. It seemed that co-application treatments of fungi with iron sulphate were effective on different growth indices of plant and could reduce iron chelate consumption or be used instead of it.

Seepage is one of the main reasons of slopes destructions. In slopes, due to fluctuations of groundwater depth or water level in an earth dam, a channel or river, gradient of seepage exceeds its critical value and the boiling phenomenon happens. In this study, the performance of geogrid plates in controlling the boiling of slope due to rising of groundwater level or drawdown of channel water surface was investigated using an experimental model. Geogrid plates with three lengths of 10, 15 and 20 cm and spacings of 1, 2, 3 and 4 cm were placed in the slope. The experiments were carried out at different depths of groundwater and channel water. Results showed that in the best model of geogrid (plates with 20 cm length and spacing of 1 cm) gradient of boiling increased 71. 5 and 236 percent due to ascending of groundwater and descending of channel water conditions, respectively as compared to the control model. By increasing the length of plates or reducing the spacing between the plates, gradient of boiling increased. In all plates with different spacings, the number of non-occurrence of boiling in the descending condition of the channel water was less than that in the ascending condition of the groundwater. This is due to the simultaneous effects of hydrostatic and pore water pressure of the saturated soil of upper layers. In the ascending condition of the groundwater, boiling occurred mostly in the relative water depths equal to 0. 167 and 0. 333. In the descending of channel water conditions, critical status happened when the groundwater level was high.

In this study, temporal and spatial model of salt transfer was investigated using a wind tunnel testing. In this model, four variables namely time, distance from the salty source, salinity and wind speed were used in which salinity was considered as a dependent variable and the others remained variables were considered as the independent variables. By use of this model, the amounts of measured and calculated EC were compared with the regression model output. The evaluation criteria used here were coefficient of determination (R2), root mean square error (RMSE) and mean absolute error (MAE). The values of these criteria were obtained as R2= 0. 96, RMSE= 79. 14 μ s/m and MAE= 46. 15 μ s/m. According to the mentioned criteria, it could be concluded that the precision of the proposed regression model in evaluating the salt dust transfer in different spaces and times as well as in different wind velocities was very good.

The circular channels with side weirs are widely used to regulate the flow and control the water depth in the urban sewage disposal systems. In this study, the turbulence of flow field and variation of the free surface of supercritical flow in a circular channel with a side weir are simulated using FLOW-3D software, the RNG k-ε turbulence model and VOF scheme. Comparison between the numerical simulation and laboratory measurements shows that the numerical model has simulated the free surface and flow field profile with reasonable accuracy. According to the numerical simulation, the flow depth is decreased along the side weir. In all simulations, a free surface drop has happened at the upstream beginning of the side weir. There is also a surface jump at the downstream end of the side weir. The change of specific energy along the side weir for the supercritical flow regime is almost constant and the energy loss is not significant but by increasing the side weir length the energy difference between the upstream and downstream of the side weir increases. The velocity field analysis indicates that the maximum longitudinal and lateral flow velocities happen at the end and middle of the side weir, respectively. Also in each cross-section, the maximum vertical velocity happens in vicinity of the side weir.

Natural phenomena such as bed scouring in the outer bank and deposition in the inner bank of meandering rivers cause lateral migration of the river bend in the downstream direction. So far, different measures have been developed to control this movement. In the present study, the influences of floating vanes application on bed scouring and deposition in river bend has been investigated experimentally. For this purpose, a physical model of Karoon river 180-degree bend at the south of Ahwaz city was constructed. Also flume bed topography measurement showed that the bend scour had been occurred from 130 degrees’ location to the end of the bend. Therefore, seven floating vanes were installed in series at this bend segment and tested under three different Froude numbers (=0. 18, 0. 20 and 0. 22). The flow depth was kept constant for these tests. The vanes dimensions were designed according the Odgaard’ s recommendations for submerged vanes. Bed topography maps were measured using a laser meter and contour lines were plotted using the Tecplot software. The results showed that with installing floating vanes, the maximum scour depth reduced as much as 50%, 50% and 40% for Froude numbers equal to 0. 18, 0. 20 and 0. 22, respectively. It was also found that generally the scour depth not only was shifted toward the inner bend, sediment deposition also was observed at the outer bank.

Nowadays, the maximum operation of groundwater resources has been achieved in Iran. Also, the majority of extractable water resources are utilized and the managing of water resources in the future is depended on more extracting of water resources. For better basin management, forecasting the groundwater depth fluctuations in particular in arid areas is more necessary. In this study, time series spectral analysis is used to forecast the groundwater depth fluctuations of Chamchamal plain. In this regard, the monthly groundwater depth time series during 1995 to 2009 years are used for calibration periods and the periodogram diagrams are depicted. Data periodicity is analyzed by using Fourier spectral analysis and the deterministic term of data periodicity is eliminated. In the next step, stationary and normality in the data are considered. After that, the different time series models are fitted for the prepared data and accuracy of them were assessed by Akaike (AIC) criterion. The results show that ARMA (2, 1), ARMA (1, 1), ARMA (1, 1) models are the best fitted models for the measured data in Bazanabad, Gheshlaghabad and Gavkol piezometers, respectively. Finally, the residuals stationarity assumption test is used to check for the correct diagnosis of the fitted pattern. In this study, the results represent the high performance and accuracy of the applied new approach to the time series spectral analysis for forecasting groundwater depth by application of the regression coefficient amount of 0. 78 and SI-Index of 4% to 14% of piezometers' data. Using spectral analysis, as has been provided in this study, is very useful for forecasting groundwater depth.

Bendway weirs are important multi-purpose structures for erosion control and are implemented to control erosion, restore streams, and improve habitat. Investigation of the effect of weirs’ s height on flow pattern and erosion and sedimentation by application Mike 3 Flow Model FM was the aim of this research. The used variables were three flow discharge rates of 120, 150 and 180 (l/s), three weir heights of 0. 5y, 0. 7y (submerge weirs) and 1. 2y (spur) (y is the mean water depth). The length ratio (L/B) was kept constant during experiments (equal to 3 times of water surface width) as well, weir crest slope (flat crest) and weirs angle (60 degree) were also constant. The results showed that the maximum difference between experimental and simulation data of the maximum scour depth at the tip of weirs was about 7. 6 %. So a good agreement was found between the model and experimental results. Furthermore, the results revealed that the bendway weirs were more efficient than groins in reducing the velocity magnitude, decreasing the scour at the outer bank side and in decreasing the sediment deposition at the inner bank side. On average, the velocity magnitude at the outer bank side decreased by 81, 85 and 70 % in weirs with heights of 0. 3y, 0. 7y and 1. 2y, respectively. Generally, the results of this research showed that the weirs with a height of 0. 7y had the most influence on protection of outer bank.

In this paper two models have been written and solved by two approaches: non-linear programming (GAMS/MINOS solver) and simulated annealing methods in order to optimize operational rules in Mahabad reservoir. Because of missing the required eco-system data, these required data were calculated using Tennant method. The objective function was defined to minimize the deference between the amounts of agriculture water demand and the released water from the reservoir during 23 years of flow data (1370-1393) and their performance were evaluated using the operational indexes. Obtained results of both optimization models showed that, the simulated annealing algorithm with objective function value of 22. 01, reliability value of 25%, resiliency velocity value of 22. 22%, vulnerability value of 41. 04% and sustainability value of 0. 032, gave relatively better results compared to the non-linear programming method with the objective function value of 88. 92, reliability value of 48. 18%, resiliency velocity value of 32. 86%, vulnerability value of 84. 27% and sustainability value of 0. 024. Also, it was found that, simulated annealing algorithm took longer running time to achieve the global optimal point in comparison to non-linear programming. However, using simulated annealing algorithm estimated a lower water shortage of 1632. 24 MCM compared to the non-linear programming which estimated water shortage of 3351. 4 MCM. Simulated annealing algorithm decreased the shortage by distributing shortages in different months and estimated a better performance.

Usually, the amount of water that is delivered to the downstream of a gate in irrigation network does not match with the actual need and in some cases it is significantly higher than the need and sometimes it is far less. This imbalance in delivery and distribution of water not only reduces the product performance and farmer’ s satisfactions, but also for those farms that have received too much water may cause yield reduction due to excessive irrigation. In this study, using Rootcanal hydrodynamic model that is one of the irrigation channel hydraulic simulation models, several options for water delivery and distribution in E1R1canal of Dez irrigation network are simulated. Then using the simulation results, the performance index and volume of water losses are calculated. Also appropriate operation guidelines are determined and accomplished, then after implementation of them the canal performance and volume of losses are recalculated. The results show that in all scenarioes, increasing the number of operations, improves the performance indices of intakes and canal and among the various simulated options, the maximum performance improvement is 49% which belongs to the intake 6 in Scenario number2.

Water spreading on the permeable areas is an appropriate strategy for flood control and efficiency. Determination of appropriate site for water spreading is one of the most important stages of such projects. In this paper, suitable areas for water spreading in Shabestar plain were determined based on four parameters including slope, permeability, transmissivity and unsaturated alluvium thickness. For this purpose, by using data of drilling logs from exploration and piezometric wells in the area, layer parameters information was prepared in geographical information system (Arc GIS 10 software) and then maps were combined together. The results showed that the maximum area of the aquifer with 192. 794 square kilometers (40. 1 percent), had suitable condition for water spreading and 146. 512 square kilometers (30. 5 %) of the aquifer, had moderate condition. As well as 79. 786 square kilometers (16. 6 percent), had unsuitable condition for water spreading and 61. 046 square kilometers (12. 7%) of the aquifer had quite suitable condition.

In order to investigate the effects of manganese and salicylic acid on chemical composition, osmotic regulators and water relations of pistachio seedlings (Pistacia vera L. cv. Badami Zarand) under saline conditions, a factorial experiment was carried out in a completely randomized design with three replications under greenhouse condition. Treatments consisted of manganese with concentrations of 0, 10 and 20 Mn2+ kg-1 soil as MnSO4, H2O, and foliar application of salicylic acid hormone at three times with concentrations 0f 0, 0/5 and 1 mM and three levels of salinity (0, 1200 and 2400 mg NaCl kg-1 soil) that at the end of the experiment created average salinity of 2. 9, 7. 8 and 16. 1 dSm-1, respectively. The results showed that the salinity decreased the leaf relative water content and increased the electrolyte leakage, but the combined application of the manganese and salicylic acid increased the leaf relative water content 46 percent and decreased the electrolyte leakage. Salinity stress decreased the shoot Fe, Zn and Mn concentrations, but the combined application of 20 mg Mn2+ and 1 mM salicylic acid increased the concentration of these elements by 26, 89 and 80 percent compared to control, respectively. The concentration of proline and soluble sugars increased with increasing the salinity and also the combined application of manganese and salicylic acid increased the concentration of these parameters by 100 and 88 percent, respectively. According to the results of this experiment, it was concluded that the combined application of manganese and salicylic acid in saline conditions through improving the physiological parameters and also increasing the micronutrients concentration, improved the pistachio plant ability against the salinity stress.

Magnetic susceptibility is an indicator of material magnetic properties that some of the mineral particles of the soil are not exceptional from this feature. The present study was conducted to determine the vertical distribution of magnetic susceptibility (X), frequency-dependent magnetic susceptibility (Xfd) and its correlation with total iron concentration in 15 soil profiles with igneous, sedimentary and alluvial parent materials located in the central of zanjan province. The results showed an obvious effect of the amount of parent material lithology on the magnetic susceptibility of the soils. The maximum and minimum magnetic susceptibility in the soils which formed from igneous rocks and sedimentary rocks were found between 200-400 x 10-8m3kg-1 and 42-158 x 10-8m3kg-1, respectively. Although, the soil formation process affected on increasing the magnetic susceptibility of it, but due to high levels of magnetic minerals in samples of igneous rock, the effect of parent material lithogenic on soil formation processes was high. Magnetic susceptibility in soils formed from sedimentary rocks was more than similar their parent materials that was the reason for pedogenic formation of ferromagnetic minerals. There was a considerable difference between magnetic susceptibility variation model in soils derived on igneous rocks with sedimentary rocks. In the profile of alluvial soils, vertical distribution of total equivalent iron concentration and amount of magnetic susceptibility (118 – 567 x 10-8m3kg-1) were related to adjacent land unit parent material, chronosequence and soil forming process. Total equivalent iron concentration was in a same trend of magnetic susceptibility distribution.