Journal of Water and Soil Conservation
Year:2020 | Volume:26 | Issue:6|Papers Count:16

Background and Objectives: One of the major concerns in the use of the Universal Soil Loss Equation (USLE) in different areas under sever soil erosion rate is the lack of precise data on the cover crop factor (C) for various agricultural crops. Despite in some countries especially the United States, quantitative information are available on the C-factor, there are substantial difference in climatic and pedological conditions with other areas especially semi-arid regions. Rainfed wheat is the major agricultural crops in these areas which would be planted with different density and row spacing in slope farms. There is no information on the effect of seed density and row spacing on the C-factor in rainfed wheat in semi-arid regions. Materials and Methods: The experiment was conducted whit two seed density (90 and 120 kg per hectare) and two row spacing (20 and 25 cm) along with their control plots (without planting seed). The experiment was performed with the blocky randomized design at three replications in a 10% slope land during 2015-2016. Wheat seeds were sown by drilling set whit nine and eleven rows for making 25 cm and 20 cm spacing between rows, respectively. Eighteen plots (1. 5m × 5m) were installed to measure soil loss under natural rainfalls. The C-factor for each planted plots was determined using the proportion of soil loss in that plot to the same row spacing plot without wheat cultivation. An independent t-test was used to analysis on the effect of seed density and row spacing on the C-factor in the rainfed wheat. Results: Results indicated that C-factor in 90 and 120 kg per hectare seed density was 0. 42 and 0. 43, respectively. The C-factor between the two seed densities wasn’ t statistically significant. Increasing seed density in the planting rows decreased wheat growth due to increasing repetition rate among plants. The C-factor in 9-row seeding with 25 cm row spacing was 0. 34, while its value in 11-row seeding was 0. 51, showing 33% significant increase in the C value (P<0. 05). Decreasing of soil loss and the C-factor in 9-row spacing plots was associated with increasing furrow cross section area on one hand, and a little plant repetition occurred between the rows, on the other hand. Thus, soil loss in the cultivated plots was less than the control plots. Significant difference wasn’ t found for interaction between seed density and row spacing. The lowest value of the C-factor was observed in 9-row seeding (25-cm row spacing) with 120 kg per hectare. Conclusion: The study indicated that the C-factor in rainfed wheat varies between 0. 33 and 0. 51. Seed density was not the major factor controlling the C-factor in rainfed wheat, while the row spacing significantly affected on the C-factor in the rainfed lands in the area. The C-factor of wheat can be considerably declined by changing row spacing from 11-row (20-cm row spacing) to 9-row (20-cm row spacing) with 120 kg per hectare seed density in rainfed lands.

Background and Objectives: To describe and evaluate all the complexities and to develop river ecosystem management plans, it is necessary to examine all the components at different spatial and temporal scales. In this regard, a hierarchical multiscale framework has been applied as a flexible, openended approach to conduct hydro-morphological assessment and also to support river basin managers through exploring the causes of hydro-morphological management problems and devising sustainable solutions. The framework has been suggested by REFORM Project (REstoringrivers FOR effective catchment Management). Generally, the hydro-morphological assessment framework and management plan cycle in river basins consists of four main steps as: 1) Delineation and characterization of spatial units; (2) Hydro-morphological assessment of past, current and future trends; 3) Identification and prioritization of pressures and 4) Developing management plan and implementing measures for restoration and rehabilitation The present paper introduces and applies the first stage of this framework in Tilabad watershed (Golestan province-North of Iran). The separating of the different spatial units of the study area allows the first to identify homogeneous spatial units from the region to the geomorphic units and then identify the spatial relationship and hydromorphological processes between them. It is also possible to detect the hydromorphological effects of any natural and human pressure on different scales. Materials and Methods: Remote sensing and GIS techniques along with several additional field surveys as well as some data and information on hydrology, climate, topography, geology and land cover, valley characteristics and channel and floodplain morphology were utilized to divide the river system into internally consistent spatial units including bio-geographical regions, catchments, landscapes, river segments, river reaches and geomorphic units. Results: Based on the above-mentioned methodological framework, the hierarchy of spatial units in the study area contains two units of bio-geographical region, one unit of catchment, four units of landscape, eight segments units and 26 Reach units. Conclusion: The results of this research has important contributions to systemic hydro-morphological assessment and development of management plans in the Til-abad Watershed by increasing process understanding and by providing descriptions on the characteristics and the relationship between different spatial units. This hierarchical multi-scale framework has the applicability and generalizability to other river basins in Iran formulating the integrated assessment and management practices.

Background and Objectives: Drought is one of the most important natural hazards that affect a significant number of people due to extensive damage. Drought is also a phenomenon that directly related to the issue of water scarcity and because of its reversibility, can affect the various aspects of human life and the environment. The drought affects almost all the determinants of the hydrological cycle from the onset of precipitation and then the surface water flow and eventually storage in groundwater. Therefore, in this research, due to the results of the stable process of precipitation and temperature in the Ardabil DareRood basin, SPI Index which relies on precipitation, with the RDI index which combines the parameters of potential evapotranspiration and precipitation, were compared and evaluated in different time intervals. Materials and Methods: In this study, in order to identify drought and wet periods, monthly precipitation data, Minimum and maximum monthly temperature for seven stations were used during the period of 30 years (1985-2014) in the Ardabil valley northwest of Iran. In order to identify the trend in the precipitation and temperature series in this research Man-Kendall (MK) and Sen's slope (Sen) models were used. Also, to assess the long-term stability of the trend in the time series LOWESS curve (at a significant level of 5%) was used. Also, using Aridity index, four stations in the arid area and three stations in the semi-arid region were established. In order to calculate the RDI index, potential evapotranspiration values were used. The PET value in the RDI index was obtained using monthly temperature data and Hargreaves method. Finally, SPI and RDI indices were compared in 3, 6, 9 and 12-month scales. Results: The results of the LOWESS curve showed that the annual temperature at all stations follows an incremental scenario. While the precipitation behaves differently and often is decreasing. The results also showed that SPI and RDI indices are very similar in different time scales, and R2 is in most cases greater than 0. 90. The most severe drought observed in the SPI and RDI models of the Ardabil station in 2010-2011 on a 3-month scale, whose values were respectively-3/11 and-3/09. Also, the results showed that the RDI index that extreme and severe wet values it’ s larger than SPI. Eventually, both indices are many similarities with each other but because of RDI's use of PET, it can be used more widely for arid and semi-arid regions of Iran Conclusion: This research, two SPI and RDI indices were used to compare the drought events in the DarehRood Ardabil basin of the northwest of Iran. Due to the dry and semi-arid climate of most regions of Iran, it is very probable that the amount of precipitation is zero in some seasons. Therefore, precipitation-based indices such as SPI may have less efficiency than RDI index, which, in addition to rainfall, uses potential evapotranspiration (PET) in their formulation. Considering the importance of PET parameter in agriculture and water resources management in Iran, it is necessary to examine the RDI index in other regions of Iran, such as the northwest and mountainous regions of Iran and its results can be compared with other indicators such as the important and highly applicable SPI indicator.

Background and Objectives: Soil organic carbon (SOC), as a great constitute of soil organic matter (SOM), has an important role in chemical, physical and biological processes of soil. SOM or SOC is a key parameter of soil quality and a soil fertility indicator. SOM has an essential role in formation of soil aggregate and its stability, water and nutrients adsorption, water holding capacity, infiltration of air and water, hydraulic conductivity, soil water repellency and carbon sequestration. Various studies have shown that the quantity and quality of SOM can be affected by anthropogenic activities such as farming practices and other economic development activities. It has also been reported a high rate of SOM loss on eroded lands. Hence, monitoring temporal and spatial variation of SOM is essential for evaluating long-term soil productivity management. However, conventional soil sampling and chemical measurement of SOC, especially in large geographic scale, is tedious, time consuming and expensive. Therefore, rapid and precise assessment of SOC content can be useful in long-term management of soil. The objective of this study was to investigate the ability of soil visible-near infrared (vis-NIR) spectroscopy for estimating SOC in Zrebar lake watershed of Marivan, Kurdistan province, Iran. Materials and Methods: A total of 100 soil samples were collected from the studied region, with an area about 10718 hectares. The spectral reflectance and physicochemical properties of all soil samples were measured under laboratory controlled conditions. After recording of the spectra, different pre-processing methods were applied and compared. Then, pedo-transfer functions (PTFs) and spectral transfer functions (STFs) were developed to estimate SOC content using stepwise multiple linear regression (SMLR). The accuracy and reliability of the derived PTFs and STFs were evaluated using coefficient of determination (R2), normalized root mean square error (NRMSE), mean error (ME), index of agreement (d), and ratio of performance to deviation (RPD) statistics. Results: Based on the results, soil organic carbon showed high and significant (significance level of 1%) correlations with spectral reflectance values at wavelengths 858 and 1916 nm. The results indicated that the derived PTFs had the higher accuracy (R2avg=0. 83, NRMSEavg = 24. 55%) to estimate SOC in comparison with the STFs (R2avg=0. 44, NRMSEavg= 44. 31%). However, SOC could be also fairly estimated by the derived spectral transfer functions (Ravg2=0. 52, RPDavg= 1. 44). The results also revealed that the Savitzky– Golay smoothing filter with 1st order derivative was the best spectral pre-processing method to reduce the effect of random noise and improve the calibration models. Conclusion: Overall, the results indicated that although the performance of STFs was not superior to the corresponding PTFs for estimating SOC, but this approach can be used as a reasonable indirect method in case of unavailability of PTFs.

Background and Objectives: In earth dams, due to different properties of materials core and shell, heterogeneous settlement occurs between different sections of the dam. This action leads to a phenomenon of arching which creates some transverse cracks in the impermeable section of the dam, especially near the dam connection to the lateral walls, which can be expanded during the first period of impounding and with the sudden application of reservoir water pressure to core. Ultimately, in more critical situations, it leads to hydraulic failure and causes the scouring phenomenon and jeopardizes the safety of the dam. In this research, the results of instrumental analysis of main stresses and arching coefficients of the Eyvashan earth Dam core during the first impounding period were compared with the results of Geostudio and Plaxis software. The results show that the highest arching rate after impounding has been applied at the upper levels, but the highest percentage of arching from the beginning of construction to the end of the impounding stage was equal to 46% and at 13 of the height of the core from the floor. In addition, due to the ratio of arching coefficient in the range of 0. 55-0. 66, the dam in terms of arching in the first impounding period is normal and there is no problem in terms of hydraulic deflection. Materials and Methods: The Eyvashan earth Dam is located 1. 5 km from the upstream of the village of Eyvashan and about 57 km from Khorramabad city on the Horoud River. The dam is rock fill type with a Vertical core, with a height of 62 m, a crest height of 1868 m and a normal elevation of 1864 m above sea level. The strain-strain analysis of the Eyvashan dam was performed based on Mohr-Columb behavioral models in terms of strain condition using Geostudio and Plaxis software. For analysis of stress-strain and consolidation settlement, the modeling has been done in eight layers. Results: By study and comparing the arching coefficient obtained from the Electrical Pressure Cell installed in the Eyvashan earth dam and Numerical analysis results, it was determined that the arching coefficient in the different levels of the core is in the conventional range and the risk of arching do not notice the dam. Α ccording to the graphs from the results of the observational data, the highest percentage of arc in the near-filter elements occurred. In addition, the comparison of instrumental results with the results of the numerical analysis of matching is about 90%. Conclusion: By comparing the results of measured and predicted total stresses with Geostudio and Plaxis software, it was found that the total stresses obtained from numerical analysis in the Total Pressure Cell installed at one level are approximately the same and are not significantly different, and the function of the software is appropriate. In addition, the difference in the total pressure values obtained from the instrumentation and the numerical analysis can be due to differences in the specific gravity of the materials in the design and the reality or due to errors and inappropriate performance of the instrument.

Background and Objectives: Optimal operation of the reservoirs of dams, as one of the most important water resource systems, has a high complexity. This complexity is due to the stochastic nature of the river discharge, the high dimensionality and conflicting objectives of reservoir operation problems. Increasing the number of dams, placing dams relative to each other and having different objectives will significantly increase the dimensions of the problem, which can complicate and non-linearize the structure of these problems. In this research, with respect to the unique nature of evolutionary algorithms (EAs) in the evaluation of objective functions and the probability of low localization in the local optimum solutions, a hybrid of differential evolution (DE) and particle swarm optimization (PSO) with multi-strategy (DEPSO) is used to optimize operation of a system with three reservoirs of Karoon1, Godar and Dez with the purpose of hydropower generation. Materials and Methods: In this research, by modifying the parameters and factors affecting both algorithms of DE and PSO, a new hybrid algorithm is presented. The proposed algorithm (DEPSO) promotes the local and global search capability of the basic DE algorithm to obtain optimal operating policies. Initially, the efficiency and accuracy of the proposed algorithm are evaluated using the Ackley and Griewank mathematical functions. Then, the results of the DEPSO were compared to the DE, PSO and ABC algorithms. Finally, the proposed algorithm is applied to optimally solve a three-reservoir system in Iran to generate hydropower energy. It should be noted that the results are presented in ten different runs for all problems to evaluate the reliability and accuracy of the contestant algorithms. Results: The obtained results by the proposed hybrid algorithm (DEPSO) indicated that the average of objective function value for 10 runs and during 15-year operation period was 14. 33, 10. 00 and 38. 50 percent better than those form the DE, ABC and PSO algorithms, respectively. Also, by increasing the number of operation period from 180 to 240 monthly periods, the average of objective function value calculated by the DEPSO for 10 runs was 14, 22 and 35 percent better than those from the DE, ABC and PSO, respectively. Conclusion: Considering the results obtained by the DEPSO, it can be clearly seen a significant improvement in the objective function value compared to the DE and PSO algorithms and especially with the increase of decision variables from 180 to 240 the performance of the method was more suitable than the other algorithms. This indicates the superior performance of this method compared to the other algorithm for optimizing the hydropower energy generated from multi-reservoir systems.

Background and Objectives: The floodplains are relatively flat lands in the vicinity of the rivers with the residential, industrial or agricultural usage. The sudden breakdown of large dams leads to the formation and propagation of devastating flood waves over the downstream. The flood propagation occurs over the floodplains due to the topographic variations and in-stream obstacles such as bridges. These waves are developed one and two dimensional over a small reach of the river and floodplains, respectively. In the hydrodynamic simulations, two-dimensional characteristics of the dam-break flow over the floodplains have been studied scarcely. Therefore, the combined effects of the floodplains obstacles, constriction and the bottom barriers are calculated over the dam-break flow characteristics. Materials and Methods: In the present study, the moving particle semi-implicit (MPS) method was used to the numerical study of the dam-break flow characteristics over the floodplain. From advantages of this method are including the incompressibility, the particle-based and using of powerful models of gradients and Laplacian in velocity-pressure corrections without any complex smoothing functions. Hence, the effects of the reservoir initial water level, the shapes of the obstacles-lateral transitions as well as the bottom barriers on the hydraulic parameters were studied in 15 various cases. The floodplain obstacles are cylindrical, cubic, rhomboidal and asymmetric, and the bottom barriers are cubic. At first, the sensitivity analysis was carried out on three particles diameters including the 0. 01, 0. 015 and 0. 20 m. Finally, the diameter of the particles equal to 0. 015m was adopted as the water particles size in the model. The simulations carried out through more than 280000 spherical particles, with the second order spatial and temporal accuracy. Results: The precision of the numerical results was calculated using the NRMSE normal error through the comparison with the previous experimental one. The results demonstrated that evacuation of the reservoir occurs in numerical solutions faster than the experimental. Therefore, the MPS model under and overestimates the values of the free-surface profile height and the flow propagation velocity, respectively. The impact of flow to the floodplain obstacles leads to the rising up and the formation of a three-dimensional flow at the obstacles place, the lateral constrictions and the bottom obstacles. Further, the shape of the obstacles represents a crucial factor in the free surface profile deformations, the horizontal component of the surface velocity and the drag resistance forces applied to the flow. Conclusion: Normal error values showed that the accuracy of the MPS method in the calculation of the free surface longitudinal profile deformations are variable between 88 and 91 percent.

Background and Objectives: The study of changes in the behavior of rivers is of particular importance in the protection of aquifers and the determination of the boundaries of the river bed, as well as the reduction of possible damages. Dams are among the structures that have the greatest impact on river morphology. Therefore, it is very important to study the morphology of rivers leading to large dams in planning and ease of strategic decision making on the construction of engineering structures along the river. In recent years, due to the unique characteristics of remote sensing and satellite images, many studies have been done to investigate the morphological changes of rivers. In this research, the study uses 26 Landsat satellite images to investigate the morphological changes of the Bazoft River between 1985 and 2015. Materials and Methods: In order to evaluate the morphology of a river, determination of the morphological parameters such as river boundary displacement, changes in the area caused by erosion and accretion of the banks in the long and short periods is essential. It should be noted that the short and long term periods were 1 and 10 years, respectively. To determine the required satellite image data, 26 frames of Landsat satellite images were selected and analyzed using ENVI and GIS softwares. Finally, the map of the studied river boundary was prepared and difference between the main channel of the river on the left and right bank on the cross section in two different years was considered as the main channel movement in that time interval. The negative and positive values of the main channel movement considered as accretion (land development) and erosion (land degradation), respectively. Results: The results showed that the most changes occurred in the 62 to 84 km range of Bazoft River, which is due to the presence (existence) of riffles near the Mavarz hydrometric station and numerous lateral branches in these two intervals. Investigating the area of erosion and accretion in long-term periods showed that in the years 1985-1994, 1994-2005 and 2005-2015, the river was associated with coastal accretion. For the 30-year period of 1985-2015, the average accretion and erosion of the river was estimated to be about 69. 43 and 42. 34 ha, respectively, in which 27. 99 hectares of land were created by sedimentation. In the short run, the results showed that there is no significant difference between the mean accretion and erosion of the left bank, and on this bank the accretion area is about 2% more than erosion, whereas on the right bank of accretion, there were about 8% of the erosion that this difference is meaningful at 95%. Conclusion: Investigation of the morphological changes of Bazoft River using satellite images in a thirty-year period showed that the most changes are in the range of 62 to 84 km of the river, which can be reduced by controlling the river and protecting the coasts in this area. The most accretion area was observed near the Mavarz hydrometric station and adjacent to Khuzestan-Chahar Mahal and Bakhtiari road so it can be proposed as a suitable place for sand and gravel harvesting as a nonstructural method for river protection. Generally, the left bank was more prone to erosion, while the amount of accretion in the right bank is greater than the erosion.

Background and Objectives: One of the main reasons for the failure of bridges in the United States and around the world is scouring. The flow characteristics, the base shape and the angle of its deposition relative to the flow and characteristics of the sediments are all factors that interfere with the complexity of the scouring problem of bridges. It should be noted that the final scour depth created near the bridge base is equal to the total erosion depth due to local, general and narrowing of the flow width. Since the propagation of the scour hole threatens the sustainability of the bridge structure, predicting the amount of dirt and adopting the necessary measures for its containment are considered as common engineering measures in river engineering. Materials and Methods: In this study, the effect of air foil lattice collars on aerodynamic bridge foundations was investigated. In order to investigate the research in this study, a flume was used at Azad University of Ahvaz with the following characteristics. The input and output channels of the flume are a rectangular weirs with a Plexiglas sheet, so that the length of the direct input channels at the beginning of the flume and the output at the end of the flume are 4. 5 and 2. 5 meters, respectively, the width and height of the flume are 0. 5 and 0. 6 meters and the body of the flume is at a height of 0. 7 meters from the ground. Results: By installing the collar at a relative depth of 0. 1, the length of the collars of the scouring net was reduced compared to the collarless base. By installing the collar at a relative depth of 0. 5, the lattice collars with relative lengths of 6, 8 and 10 were 35. 2, 37. 4 and 38. 4 percent, respectively, to reduce scouring compared to the collarless base. Also, by installing the collar at relative depth (Z/D)=1 with a length (L/D) of 6, 8 and 10, collars were 27. 7, 31. 6 and 31. 4 percent compared with a collarless bridge pier, respectively. By increasing relative velocity (V/Vc) from 0. 54 to 0. 95, on average, the scouring increased by 113. 8%. By installing the collar at a relative depth (Z/D) of 0. 1, 0. 5 and 1, 16. 6, 35. 2 and 27. 7 percent lower scouring were observed compared with the collarless base. Also, by increasing the depth of the lattice aerodynamic collars the scour reduction decreased by 22. 3 percent. Conclusion: It can be concluded that the best depth of the collar is about half the diameter of the base of the bridge. Also, simulation with the Flow-3D math model is close to the physical model and has an average of only 4. 5% error, which is acceptable.

Background and Objectives: Salinity is one of the most extensive processes of soil degradation, which limits the increase in the production of food products for more demand. Inoculation of plants with salt tolerant plant growth promoting bacteria with the ability to produce ACC-deaminase and indole-3-acetic acid often decreases the negative effects of high salt concentration and improves plant growth parameters. Therefore, the aim of this study was to determine the effect of rhizosphere and endophytic salt tolerant bacteria isolated from rhizosphere and roots of the halophyte Salicornia on wheat plant growth parameters in different salinity concentrations. Materials and Methods: This experiment was conducted in greenhouse conditions in a completely randomized design with four levels of salinity: 0, 4, 7 and 10 dS/m in saturation extract and four levels of bacteria: no bacterial strains (control), rhizosphere bacterial strain, endophytic bacterial strain, and combined use of rhizosphere and endophytic bacterial strains in 3 replications. After harvest, the morphological and physiological characteristics of the wheat plant were measured. Data analysis was performed using SAS software. Results: The results showed that plant yield was significantly affected by salinity. Increased concentration of NaCl from 0 to 4 dS/m did not have any effect on all growth parameters, and in some cases, it improved them. But with increasing salinity level from 4 to 7 and 10 dS/m, salinity had a negative effect on all growth parameters with the highest negative effect in the concentration of 10 dS/m. In the absence of salt stress, the presence of bacteria increased plant yield. In salt stress conditions, inoculation of bacterial strains had a significant effect on plant growth and increased the shoot dry weight (9. 49-26. 68%), root length (3. 94-27. 47%), root dry weight (10-47. 36%), root dry weight to shoot dry weight ratio (19. 41-20. 69%) and reduction of leaf relative water content (1. 2-11. 71%), superoxide dismutase activity (7. 63-15. 8%) and proline (12. 5-33. 33%) compared to control. Conclusion: In general, the inoculation of bacterial strains resulted in improving wheat plant growth parameters (7 out of 13 measured growth parameters). To be halophytic bacterial strains and salt tolerance of wheat cultivar used in this study can be some of the reasons for not being affected other 6 growth parameters by treatments. According to the results obtained from this study, to improve wheat plant growth parameters and reduce the effects of salinity stress by the salt tolerant growth promoting bacteria isolated from Salicornia plant as a bio-fertilizer, it is needed to perform more studies (i. e., use of higher salinity levels and different wheat cultivars) at the field and greenhouse level.

Background and Objectives: One of the major topics in river engineering is design and construction of the bridges. Beside their stability considerations, estimating the maximum depth of scour in the vicinity of the pier is also very important. Scour is one of the most important reasons for instability and ultimately the collapse of the bridges. While most of the previous researches on bridge piers scour are mainly focused on steady flow conditions, in rivers and especially during flood events, the flow is unsteady and the time variations of flow discharge could be rather fast and rapid. The results of studies have shown that taking into account the unsteady flow would cause more economic and realistic prediction for the maximum depth of scour around the bridge piers. So far, many different methods have been used to protect piers of the bridges. In this research, a non-structural and environmental friendly solution has been used to reduce the depth of the scour of bridge piers in unsteady flow conditions. Materials and Methods: So far, nanostructured materials have been used mainly for improving concrete resistance behavior and earthen rural roads. In order to achieve the research objectives, the combination of nanostructured materials, called Nano-clay was used in a flume bed around the bridge piers. Several experiments for both steady and unsteady flow conditions were conducted on a cylindrical pier with a diameter of 35 mm, in a channel with a 9. 5 m length, height and width of 40 cm and a slope of 0. 001. Experiments have been carried out in two different cases, with and without the Nano clay materials on the channel bed. For simulating unsteady flow conditions, some stepped triangular hydrographs with a time to peak of 7. 5 minutes and peak flows of 8, 12, 16 and 20 liters per seconds were used in two different modes of with and without Nanostructure materials. Results: The results of experiments in unsteady flow conditions indicated that with the presence of nano-materials and with increasing the flow discharges, the maximum scouring depth around the bridge piers reduces. It has been also shown that the maximum reduction of scour depth was nearly 62. 86% which was happened at maximum flow discharge of 20 lit/sec. In this particular flow discharge, the maximum scour depth has been reduced from 47. 4 mm to 18 mm. The minimum reduction of scour depth was about 56. 15% which was happened at the minimum flow discharge of 8 lit/sec. Conclusion: The time evolution of scour around bridge pier has been studied and compared in both cases, with and without presence of nano-materials. In the presence of nano-materials and for all maximum discharges, it has been observed that the scouring process at initial time steps was similar to the condition without nano-materials but with a sharper trend. The trend in later time steps has experienced with the lower changes and finally has reached to a constant value.

Background and Objectives: Cotton is a plant that responds to the amount of irrigation water and irrigation time and due to lack of water in Golestan province, the need for optimal use of water unit is more than ever before. This will not be achieved except by applying modern methods of surface irrigation or pressurized irrigation and appropriate management of irrigation and enhancing of water use efficiency. Materials and Methods: This experiment was conducted as a split plot design in a factorial with three replications at Hashemabad Cotton Research Station. Physical and chemical parameters of soil such as soil texture, bulk density, moisture content of field capacity and wilting point, soil salinity and soil acidity before cultivation were measured by sampling from two depths of 0 to 30 cm and 30 to 60 cm. fertilizer requirement was calculated according to soil test. Irrigation was done before planting due to soil moisture deficit. Planting of two cotton cultivars was done randomly. During the growing season and before the first irrigation, sprinkler irrigation system as line source was implemented. Irrigation was carried out based on the water requirement of Plot I5 to reach the field capacity. During the growth period, parameters of yield and yield components including plant height, time of the first flowering, and boll opening and finally the yield were measured. Different amounts of irrigation water treatments including rainfed to over irrigation as main plots and treatments of different amounts of nitrogen fertilizer including 0, 33, 66 and 100% fertilizer recommendation as well as cotton cultivars were considered as subplots. Results: The results showed that the highest yield (4362 kg / ha) was related to I4 treatment and the lowest yield was obtained from rainfed (without irrigation) with 3379 kg / ha. The yield of I2, I3, I4, I5 and I6 treatments was 2. 2, 16. 7, 29. 1, 8. 1 and 15. 7%, higher than rain fed (I1), respectively. Among fertilizer treatments, the highest yield was related to treatment of without fertilizer application, which was significantly different with treatments of 66% and 100% fertilizer requirement while the lowest yield was related to 66% fertilizer requirement. In a research year (2012) due to suitable rainfall in the growing season, cotton plants were well-grown and any excess water or nitrogen fertilizer accelerated vegetative growth which ultimately led to a decrease in reproductive growth and Subsequently, reduction in cotton yield. In terms of earliness percentage, rainfed and I4 treatments were the earliest and the latesttreatments. Different amounts of nitrogen fertilizer had no effect on earliness percentage. The highest number of bolls per plant was related to I5 and I6 treatments, which had significant difference with I1 and I2 treatments, but did not have significant difference with I3 and I4 treatments. The amount of nitrogen fertilizer application from 0% to 100% of fertilizer requirement did not have a significant effect on the number of bolls per plant. Conclusion: Regarding to results of yield, yield components and saving in water, the best irrigation treatment was I4 treatment. The yield of Golestan cultivar was 17. 9% higher than that of B-557. Water use efficiency in rainfed and full irrigation treatments was 1. 51 and 0. 81 kg /m3 /ha, respectively. The earliness of B557 was higher than Golestan cultivar. Cultivars of Golestan and B557 were the same in number of bolls per plant.

Background and Objectives: Nowadays, the use of zinc (Zn) fertilizers has been expanded to alleviate the deficiency of this element and improve the yield and quality of agricultural products. The knowledge about the availability and release of adsorbed Zn after application in soil is necessary to achieve the best fertilization management and soil and water conservation against Zn accumulation in soil. On the other hand, presence of anions in irrigation water, agricultural fertilizers and sewage sludge can affect adsorption, desorption and availability of nutrients such as Zn. Zinc adsorption characteristics was usually studied using isotherm coefficients; while availability of adsorbed Zn in soil is important in soil fertility. In this study, the effects of orthophosphate, nitrate and chloride anions on adsorption and desorption capacity were investigated in five calcareous soil of Chaharmahal-Va-Bakhtiari province. Materials and Methods: In this study, a solution containing concentrations of 25, 50, 75, 100, 150 and 200 mg l-1 of Zn as ZnSO4 source in the presence of KH2PO4, KNO3 and KCl electrolytes (50 mM) was used. After Zn adsorption in soils, availability and desorbed of Zn was measured by DTPA-TEA and 0. 01 M CaCl2, respectively. The amount of Zn desorbed in 0. 01M CaCl2 is adsorbed Zn as non-specific. The adsorbed Zn as specific was calculated from the difference between the amounts of adsorbed Zn and desorbed Zn by 0. 01 M CaCl2. Results: According to the results, the highest amount of Zn adsorbed in the presence of all three anions was specific. Percentages of adsorbed Zn in all soils in the presence of nitrate anion were more than two other anions (P<0. 05) and ranged from 99. 65 to 99. 80 in the chloride solution (more than other anions P<0. 05), 99. 84 to 99. 99 in the nitrate solution and 99. 55 to 99. 72 in the orthophosphate solution. Availability of adsorbed Zn ranged from 41 to 43% in orthophosphate solution, 49 to 54% in nitrate solution and 58 to 61% in chloride solution. Conclusion: The result showed that highest amount of available adsorbed Zn was extracted in the presence of chloride, nitrate and orthophosphate (P<0. 05). About 50% of the Zn adsorbed extracted by DTPA-TEA. In the presence of all studied anions, more than 99% Zn adsorbed as specific. Therefore, zinc at specific adsorption sites and 0. 01 M CaCl2 were not able to release this element. The results of this study showed the application of P and Zn as fertilizers in calcareous soils can lead to a reduction in extracted Zn by DTPA-TEA in treated soils with these nutrients.

Background and Objectives: Knowing the factors affecting the movement of water and salts in the soil profile and the use of new modifiers such as biodegradable can help to manage the proper management of nitrate leaching from the root zone and prevent the pollution of groundwater. Biochar is produced from pyrolysis of various biomasses under anaerobic conditions (or low oxygen conditions). The adsorption capacity depends on its physical and chemical properties, which is influenced by various factors such as raw material, particle size, pyrolysis temperature, temperature variation rate and temperature keeping time. Materials and Methods: In this research, the straw of the wheat and brassica napus have grinded and after its drying, by using a furnace for 4 hours at 600 ° C, wheat and napus biochar have prepared. The treatments test included the control (soil), soil + wheat biochar 2%, soil + wheat biochar 4%, soil + Brassica napus biochar 2%, soil + Brassica napus biochar 4%. Columns with the height of 10 and 20 cm and a diameter of 160 mm have prepared and a mixture of biochars (2%, 4%) and soil have poured into the soils columns. In order to leaching, before experiments, 10 pore volume of distilled water has poured into each of the columns. In the first day, one pore volume of water, distilled water has poured into each of the columns. The second and third days one pore volume of nitrate solution at concentrations of 20, 50 and 100 mg/L and on days 4, 5, 6 and 7 a distilled water pore volume have added to each columns. Then the solution was filtered using paper and the concentration of nitrate was measured with a spectrophotometer to determine the amount of leached and absorbed nitrate. Results: The results showed that the addition of biochar to soil on both levels, especially the combinational biochar, caused a significant decrease in nitrate leaching relative to the control in all days. In general, nitrate leaching in biochar 4% less than control and biochar 2%. Also, at a height of 20 cm, the nitrate leaching rate decreased from the soil column. Conclusion: Regarding the results, the use of untreated combination of brassica napus and wheat biochar resulted in lower nitrate leaching from the soil.

Background and Objectives: Cover crops are a strategy for enhancing the soil health and quality in agricultural systems. The relationship between cover crops and soil biological activity is an important component of soil health. Cover crops affect many of the physical, chemical and biological properties of the soil through soil organic carbon. Additionally, they prevent the loss of soil nutrients by quickly growth and creating a suitable plant canopy on the soil surface. The aim of this study was comparing the effect of mono and mixed cropping of cover crops on soil physical and biological properties improvement on short term condition. Materials and Methods: In order to investigate the effect of cover crops on some physical and biological properties of the soil an experiment was conducted based on randomized complete block design with three replications at research farm of the University of Mohaghegh Ardabili in 2017. Experimental treatments were monoculture of rye (Secale cereal), chickling pea (Lathyrus sativus L. ) and hairy vetch (Vicia villosa) (100%) and their dual and triple intercropping with 50% and 33. 3% seed proportions, respectively. The base of seed rate on rye, chickling pea and hairy vetch monoculture were 100, 25 and 25 Kgha-1 respectively. Results: The results showed that the highest biomass of cover crops (530 gm-2) obtained from rye monoculture and the lowest biomass from hairy vetch monoculture and hairy vetch+ chickling pea (85. 5 and 91. 6 gm-2 respectively) intercropping at the terminating time of the cover crops. Also, the comparison of the means showed that the highest organic matter (0. 53%) and soil microbial population (2600000 number per gram) were obtained from rye + chickling pea +hairy vetch intercropping. The soil organic matter (SOM) increased 11. 3% by rye + chickling pea +hairy vetch intercropping relative to control (no cover crop). The highest number of earth worms belonged to rye monoculture treatments. On average, earthworms in all of cover crops treatments increased by 80. 5% relative to control. Also, the intercropping of rye +hairy vetch caused the lowest bulk density (1. 01 gcm-3). The soil bulk density reduced 6. 17% by rye + chickling pea relative to control. Cover crops decreased the time of water infiltration in the soil. The minimum time required for water infiltration on growing (8. 39 Sec. ) and terminating time of cover crops (4. 99 Sec. ) obtained by hairy vetch monoculture and rye + chickling pea intercropping. Conclusion: Cover crops, whether mono cultured or mixed, improved soil physical and biological properties even in one growing season. Rye and hairy vetch were the most effective in dual and triple intercropping system.