Journal of Water and Soil Conservation
Year:2018 | Volume:25 | Issue:4 |Papers Count:22

Background and Objectives: Conservation and optimal use of soil and water resources are considered as the principles of sustainable development. Excessive use of natural resources caused by increasing agricultural lands area has led to some adverse consequences such as soil and water pollution. The use of vegetative buffer strips is considered as an effective strategy to reduce surface water pollutions and soil erosion. The present study was carried out to investigate the effect of runoff rate, plant species and type of contaminants on the efficiency of vegetative buffer strips in qualitative and quantitative conservation of soil and water in Mazandaran, Iran. Materials and Methods: The field of this research is a part of agricultural lands of Sari city. The width and length of the experimental plots were 1 m and 10 m respectively. The present study was carried out using 12 experimental plots with dimensions of 1 m × 10 m in randomized complete block design, in Mazandaran province, Northern Iran. The treatments were included vetiver grass, turf-grass with coverage area of 3 m2 and control (bare) treatment with four replications. The experimental plots were installed with a slope of 15% those which were isolated from the surrounding environment. Also, a runoff collecting tank drainage was placed at downslope end of each plot. Vetiver grass and turf grass were the plant species used in the buffer strips planted in the early February of 2015; so that, three meters of each plot contained the studied plant species and seven meters of the plot length was left as bare to produce runoff. Artificial runoff was produced with runoff rate equal to the runoff generated by 25 and 100 return period precipitation. Runoff sampling was annually carried out from the collected water at downslope of each plot since a month after planting the species; so that, it was conducted since February 2015 until January 2016. In order to evaluate the efficiency of vegetative buffer strips in water and soil conservation, the performance of these buffers was studied for runoff, sediment removal as well as the pollutants such as nitrate (NO3-) and phosphate (PO4 3-). Means of achieved data were compared and statistically analyzed using Duncan test by SPSS software. Also, variations of the efficiency of vegetative buffer strips over time affected by two runoff rates was studied using the related graphs. Results: According to the results, the maximum efficiency of vetiver buffer strips was obtained under the runoff generated by 25-year return period precipitation; so that, the mentioned treatment reduced the runoff volume, sediment, nitrate (NO3-) and phosphate (PO4 3-) contration by 85%, 88%, 83% and 87%, respectively. Also, there was a relatively good correlation between phosphate and sediment (R2=0. 66) as well as nitrate and runoff volume (R2=0. 67). The growth stage and age of the plant also played a significant role in the efficiency of the vegetative buffer strips for sediment control, so that over time, by increasing the height and coverage percentage, vetiver grass gave a more appropriate performance in pollutants control and specially suspended sediment compared to the other studied vegetative buffer strips in the present study. Conclusion: The efficiency of vegetative buffer strips in runoff quantity and quality control is is less affected by the characteristics of the strip and the stage of plant growth and its species and the intensity of flow plays an important role because the efficiency of vegetative buffer strips affected by 100-year return period runoff showed a more irregular trend compared to 25-year return period runoff. The two buffer plants also showed different performances to reduce runoff volume and its pollutants. The vegetative buffer strips played a role as nutrients and sediment source that caused soil and surface water pollution over time. So, periodic harvesting can be considered as an effective strategy to deal with this issue.

Background and Objectives: Soil Water Repellency (SWR) is one of the dynamic soil characteristics that either reduce water penetration in the soil or prevent it. In the northern forest areas of Iran, fire is one of the most important environmental concerns and is one of the main causes of the change in soil water repellency phenomenon. Therefore, this study aims to investigate prescribed fire effect on the soil of forest areas of Toshen's watershed, temporal variability and its interaction with physical and chemical properties of soil in Golestan Province. Materials and Methods: Soil of forest areas in the slope class of 15-30% and depth of 0-5 cm of soil surface was studied in 30 replications in laboratory. Physical and chemical properties of soil, including percent of clay, silt and sand, soil organic matter, pH, EC and aggregate stability (MWD) were investigated before and after fire. In order to study the effects of fire on soil water repellency in laboratory conditions, prescribed fire was applied. SWR was determined with Water Drop Penetration Time and Molarity of an Ethanol Droplet tests, before and after fire. Results: According to the WDPT test, before the fire, 100% of plots were wettable (class 1), but one day after the fire, 100% of the plots were showed slightly water repellent (class 2 and 3). The MED test showed that all plots were wettable (class 0) before the fire. One day after the fire, the intensity of SWR increased, so that 30, 50 and 20% of the plots were slightly water repellent (class 1), moderately water repellent (class 2) and less strongly water repellent (class 3), respectively. Investigating the process of temporal variability of both SWR indices showed that the SWR class after the fire is temporary and up to one month after that, the SWR classes is greatly reduced. The results showed that there are good correlations between two post-fire hydrophobic tests. (R2=0. 85). There was a moderate correlation between two WDPT and MED SWR tests with pH, EC, MWD and soil organic matter, but as for soil texture components, there was poor correlation. Relatively poor SWR correlations with soil physical and chemical characteristics indicate that these changes are not likely to be the main cause of SWR changes. Some of these changes can be explained by the variability of aggregate stability after the fire. These changes in the mechanical stability of the soil structure can be caused by two main mechanisms: (1) Changes in the composition of the solid components in the soil that increase the cohesion forces between the particles in the aggregates. Consequently, the stability of the soil structure against the physically destructive forces increases. (2) Changes in the physicochemical properties of the soil solution (an increase in the EC) that prevent clay dispersion and microaggregate destruction (physicochemical mechanism). Conclusion: Finally, the results of this study showed that despite the high wettability in loess soils, fire can be an external factor that causes a weak and immediate increase in SWR. The slightly soil water repellent may be due to the following: (i) SWR often occur in coarse soils with high organic matter. (ii) The samples were taken from the soil surface layer (0-5 cm), while the fire can cause some organic matter to accumulate in the subsurface layers and cause SWR on lower horizons.

Background and Objectives: The reduction of atmospheric precipitation, limited water resources and the increase to withdraw from groundwater have led to a decline in the water table of the plains and therefore the modeling of groundwaters is an effective tool for managing and protecting these resources. Most studies carried out on groundwater prediction are related to the prediction of the water level and less attention has been paid to hydrographs of the aquifer. Therefore, the purpose of this study was to first introduce hydrograph modeling of the aquifer using a neuro-fuzzy metamorphic model and then compare the result with modeling by the trans-model of gene expression simulator, which both models for the first time in this study for this The purpose of the study was to address the fundamental question of whether fuzzyfunction models, which are fairly acceptable in most of the studies that lack data and information, can also be better in this case study than the simulation model The gene expression, which has shown good performance in most recent studies. Materials and Methods: The study area, Laur-Andimeshk Plain, is part of the Dezful-Andimashk Plain. In the area of the Laura-Andimashk Plain, the 8 piezometer loops, which have relatively good distribution in the region, form the plain piezometric network. To do this study, using the geometric coordinates of each pysometer and the monthly statistical information of the 8th pizometer of the Laura-Andimashk plain, for 5 years (89-88-93-92) and using the Tesine method in the GIS environment, weighted average Peü someter was obtained and the time series of the groundwater level of the plain, which represents the hydrograph of the representative aquifer of the study area, was calculated. Results: By comparing the transmutation of the neuro-fuzzy simulator and the transmutation of the gene expression simulator, it is observed that in the training stage, the coefficient of nonfuzzy-simulation of the transcoding explanation is more than the transcoding explanatory factor of the gene expression simulator. However, in the test stage, the transdermal expression coefficient of the gene expression simulator is greater than the fuzzy-fuzzy simulator. On the other hand, according to the mean square error of the error, it is observed that the transcendental-neural-fuzzy simulator has a lower mean square root mean square error in the test phase. Based on the OI criterion, the closer the values are to one, the better the model performs, it is observed that the transmutation of the gene expression simulator has, by difference, a more OI benchmark than that of the neuro-fuzzy simulator and can be seen by observing the table values It is concluded that the performance of the trans-model of the gene expression simulator is better than the framed-neural-fuzzy simulator and, in the absence of data and information for the modeling of the hydrograph representing the aquifer, using conceptual models such as the Modflow, the Transmodel gene expression simulator can be a good alternative. Conclusion: The results showed that Transformer gene expression simulator with coefficient of explanation of 74 percent at test stage compared to non-fuzzy-simulation model with coefficient of explanation of 64 percent has better performance and it can be concluded that models based on fuzzy function, which in most of the studies that lack data and information, we have relatively acceptable results. In this case study, we did not have a better performance than the conventional model of gene expression simulation. In the absence of data and information for modeling hydrographs, representing the aquifer using conceptual models such as Modflow, Gene expression simulator can be a good alternative.

Background and Objectives: The drought is considered to be one of the most important natural phenomenon affecting various aspects of human life. Therefore, understanding how this phenomenon behaves is an important part of the water resources management which is directly related to the concept of drought. Knowledge of frequency of drought events with specified magnitudes can be of great importance in water resources planning and management. This knowledge is provided by using the drought frequency analysis methods. However, because of the multivariable nature of the drought, studying its aspects or variables individually probably cannot result in an efficient and comprehensive knowledge about this phenomenon. Therefore, in recent years, several multivariate methods and techniques have been developed for multivariate drought frequency analysis. The application of copulas in multivariate drought frequency analysis is one of the approaches that has shown a considerable efficiency in this field because of the multivariate nature of drought and the noticeable correlation between its variables. The objective of current research is to study the meteorological and hydrological drought events in Gharesoo-Gorganrud basin and to perform bivariate drought frequency analysis in this basin by copulas based on the drought severity and duration. Materials and Methods: In the current study, the copulas are utilized to perform bivariate drought frequency analysis in Gharesoo-Gorganrud basin. The drought severity and duration were calculated based on the meteorological and hydrological drought indices for 23 watersheds in the study area and are used in the drought frequency analysis. In addition, the efficiency of different copulas are assessed in each watershed and the return periods corresponding to average values of drought severity and duration are calculated in each watershed. Finally, the maps of return periods of the meteorological and hydrological droughts are plotted for the study area. Results: There are clear inverse correlations between the meteorological drought frequency and the variables severity and duration in the studied watersheds. In addition, a high correlation is observed between the mean statistics of the two meteorological drought variables severity and duration. Furthermore, there is a clear inverse correlation between the hydrological drought frequency and severity. However, it is observed that the correlation between the hydrological drought severity and duration is much lower than the corresponding value between the meteorological drought severity and duration. This issue can be caused by the effect of the magnitude of the recorded discharge in the watersheds on the value of hydrological drought severity variable. In general, Gumbel-Hougaard copula shows the highest efficiency for meteorological and hydrological drought frequency analysis in the study area. In addition, the highest values of the joint return period corresponding to the mean values of the drought severity and duration based on most of the assessed indices in this study are observed in the subbasins 18 and 22. Conclusion: According to the results, in the study area, the cumulative increase of meteorological drought severity is due to increase in the duration of drought events. Also, in general, Gumbel-Hougaard copula can be considered as the most efficient option among the studied copulas for drought frequency analysis in the study area.

Background and Objectives: Basil (Ocimum basilicum L. ) is one of the most important plants belonging to the genus Lamiaceae, which is used as herbs, spices and as well as fresh vegetables. Today with increasing population, lowering of water resources, as well as rising prices for agricultural land, mechanized agriculture is of particular importance, at this time, with the introduction of nanotechnology into the production of fertilizers, on the one hand, the ability to absorb them by plant is dramatically increased, because of lowering the pH of products as well as degradation of fertilizer particles as much as an iodine particles. On the other hand, economic justification and production cost per unit area has been very suitable for farmers due to lower fertilizer requirements. Materials and Methods: The present study was investigate the interaction of deficit irrigation, soil texture and nano-fertilization on yield components of Keshkeni luvelou basil varieties. Therefore, in order to compare the interaction of deficit irrigation, nano-fertilization and the effects of soil texture in the amount of irrigation water in light soil texture (W1) and medium (W2) on of Keshkeni luvelou basil varieties, factorial experiment was done based on randomized complete block design (RCBD) with 18 treatments and 3 replications. Deficit irrigation treatments consisted of three levels of irrigation (I1=100% ET), (I2=75% ET), (I3=50% ET) and done on the plant, 3 level of fertilizer contains nano-fertilizer with full concentration (F1), 70% (F2) and No nano-fertilizer (F3). Results: The results of ANOVA (Analysis of Variance) showed that irrigation has a significant effect on the mucilage, swelling index, essential oil content, seed weight in plant, number of seed in plant, number of branches, number of the inflorescence height, number of nodes in plant and seed yield. The results an interaction of soil, fertilizer and irrigation on the parameters showed that the significant at 0. 01 level, so that the maximum amount of mucilage (0. 40 mg) in the treatment F2I2W1, swelling index (67. 67 mL) treated F1I1W2, Essential oil content (0. 833) in the treatment F1I3W1, number of nodes in plant (125), the inflorescence height (10. 66 cm), number of seeds per plant (2712), seed weight in plant (3. 36 g) in the treatment F1I1W2 and was lowest in the treatment W2I3F3. Also, the maximum seed yield (61. 26 gr/m2) was obtained in the sandy loam soils treatment, full irrigation and nano-fertilizer with concentration of %100 (W1I1F1) which is represents of Nano fertilization on yield improvement of basil. Conclusion: The results showed that irrigation treatment had a significant effect on the growth characteristics of Ocimum basilicum and with increasing stress on basil plant due to lack of moisture necessary for optimum plant growth has led to a decrease in traits and getting undesirable growth indices. While the percentage of essential oil of Basil plant increases with increasing water stress, so that the highest percentage of essential oil was obtained in F1I3W1 and F1I3W2 treatments and it illustrates that nano-fertilizer has a positive effect on essential oil content of basil plant. The results showed that irrigation, soil texture and nano-fertilizer have a significant effect on mucilage and swelling index, so that it was significant at 99% probability level.

Background and Objectives: Vulnerability of surface water resources to contamination in comparison with groundwater is often higher and thus, their quality buffers determination is more important than groundwater. On the other hand, according to the intended purpose and the importance of rivers, the different values of quality buffers can be considered around the river. The aims of rivers quality buffers determination are mainly the reduction of water pollution, erosion control and sometimes the creation of wildlife sanctuaries. Materials and Methods: The United States Agriculture Organization (USDA) considers various physiography factors of rivers such as topography, soil holding capacity and vegetation as effective factors for finding out rivers quality buffers. Considering in USDA method only physical factors and aim to improve it, the USDA method was combined with rivers quality vulnerability for the first time. The case of this study was the Ab-Shirin river in Kohgiluyeh and Boyer Ahmad province, where its branches have been qualitatively analyzed. In order to determine the qualitative vulnerability of the river, sampling of the river was carried out at 9 stations in March 2015. Results: This study presents a new method to determine the quality buffers of rivers by combining the USDA method with qualitative vulnerability based on sampling. The USDA method proposes an initial quality buffer for the Ab-Shirin river by integrating slope, soil type and vegetation layers of river banks. In the next step, sampling was done along the river to determine its qualitative vulnerability. Sampling analysis showed that the amount of Nitrate Concentration, BOD and Ec were higher than other qualitative parameters, especially at the upstream intersections of the river branches. Moreover, some studies were already conducted by other researchers to propose quality buffers. In other words, where the concentration of contamination exceeds their limitations, they could be reduced or eliminated by increasing the quality buffers of the river. These buffers should also be added to USDA suggested buffers. For instance, where the slope and the soil permeability of the river bank are low and also the vegetation is thick, USDA suggested a quality buffer about 21 m, but regarding the sampling and the other studies result, it considers increasing to 26 m. In other words, by increasing the buffer around 5 meters, according to other researchers’ studies, the concentration of contamination will be moderated due to increased distance and transport time. Conclusion: The results of the qualitative classification of Ab-Shirin showed that the biggest change in vulnerability belongs to branches come from the Dehdasht study area, at the intersection of branches in the Tilkeh-Kuh zone. Also, the quality buffers of the Yasouj River vary from 10 m to 55 m and the parameters of Ec, Nitrate and BOD have the greatest effect on the increase in buffers.

Background and Objectives: Today, it is necessary to develop biological soil remediation methods that are cost-effective and eliminate pollution without degrading soil fertility. So, studies have been done to reduce the mobility and bioavailability of heavy metals. Recently, biochar is widely used to reduce the toxicity of heavy metals. Biochar is a carbon-rich organic matter, which is produced from pyrolysis of residues under limited oxygen conditions. It is made up of polycyclic aromatic hydrocarbons in which carbon atoms are annularly bounded. Aromatic structure makes it resistant to biological and chemical changes. This carbon-rich material has many functional groups such as, hydroxyl, ketone, ester, aldehyde, amine and carboxyl and significant amounts of humic and fulvic organic acids, which their composition and heterogeneous surface can exhibit different hydrophilic or hydrophobic properties and acidic and basic features. Therefore, biochar has the capacity to stabilize organic and inorganic materials. Furthermore, this material can reduce the risk of entering heavy metals contamination into food chain due to its surface area, porous structure, high pH and CEC. The aim of this study was to investigate the application of Walnut leaves and biochars produced from which at three temperatures of 200, 400 and 600 ° C on the availability and uptake of lead by maize (Zea mays L. Cv. Single cross 704). Materials and Methods: In this study, a pot experiment was conducted, consisting of soils treated with 0, 0. 5, 1 and 2 percent (w/w) of Walnut leaves and its derived biochars produced at 200, 400 and 600 ° C. Walnut leaves and biochars were mixed with 3 kg of soil in 3 replicates and were incubated for 45 days in greenhouse conditions. After incubation, 3 seeds of maize were planted in each pot while adding fertilizers needed. Shoots and roots were harvested after 8 weeks of planting. The maize indices (shoot and root dry weights, Pb and Zn concentration in shoots and roots, bioaccumulation factor and translocation factor) and DTPA-extractable of pb in soils were determined. Results: The results showed that DTPA-extractable of pb and its bioaccumulation reduced by increasing the producing temperature and the application rate of biochars in calcareous soils. Treating soil with 0. 5, 1 and 2% of biochar produced at 600 ° C, significantly reduced pb concentration in shoots by 31. 3%, 33. 5%, 36. 1%, respectively and pb concentration in roots by 32. 0%, 35. 6% and 36. 2%, respectively (P<0. 05). Physiological responses showed that modifiers were effective for increasing the ratio of shoot to root of maize throughout its growth. Treating soil with 2% of biochar produced at 600 ° C, increased significantly the dry weight of shoot and root by 131. 4% and 116. 7%, respectively compared to the control. Also, results showed that the DTPA-extractable of pb decreased by increasing the producing temperature and the application rate of amendments in soils. Treating soil with 0. 5, 1 and 2% biochar produced at 600 ° C, reduced the Bioavailable soil Pb concentrations (DTPA extraction) by 35. 3, 40. 1 and 49. 1%, respectively (P<0. 05). Therefore, biochars were able to reduce the contamination of Pb in treatments and increase maize dry weight. Conclusion: Biochar decreased the concentration of Pb in plant tissues and increased maize growth by reducing the bioavailable soil Pb concentrations (DTPA extraction). Therefore, biochar can be assisted to maize for phytostabilizing Pb in soil and improving phytoremediation.

Background and Objectives: One of the general categories for discretization of equations and creation of computational geometry in the numerical methods is mesh-based and mesh-free methods. Previously, mesh-based methods have been a useful tool for flow modeling. However, these methods have some limitations for modeling free surface flows, changeable boundaries and complicated geometry. In recent years, new generation of computational fluid dynamics methods named meshfree methods has been introduced which one of them is smoothed particle hydrodynamics method. Smoothed particle hydrodynamics method is a fully Lagrangian method which solves the computational domain without using meshes. In this method, the integral expression is used for the approximation of functions and smoothed functions have a key role in integral approximations. Materials and Methods: In the present study, the Incompressible Smoothed Particle Hydrodynamics method has been used for dam break waves modeling. In order to validate the computational results, the reports of two experiments of dam break problem have been used. For the numerical modeling, the cubic spline function and initial distance between particles of 0. 003 m, 0. 004 m, 0. 006 m and 0. 008 m have been used and the sensitivity analysis has been done on the effect of the initial distance between particles. Also, the effects of quantic spline smoothed function and beta smoothed function on results of modeling for two experimental data with the initial distance between particles of 0. 006 m have been performed to reduce the computational costs. Results: After reviewing the results of the modeling and comparison of the mean relative error related to each of smoothed functions were found that the most accurate results are related to the cubic spline smoothing function. In order to investigate the influence of the initial distance between particles in the modeling, a comparison was made between the results of the numerical model for various distances of 0. 003 m, 0. 004 m, 0. 006 m and 0. 008 m for two experimental dam break tests for the superior cubic spline smoothed function. Conclusion: The results demonstrated that the ability of the numerical model has been enhanced by reducing the initial distance between the particles (increase the number of particles) in which applying the initial distance of 0. 003 m would improve the results of the wave front by 43. 5% and water level oscillation by 93. 7% compared to the initial distance of 0. 008 m.

Background and Objectives: Rhizosphere processes have an important role in zinc (Zn) fractions in soils. Plant roots have the ability to transform metal fractions for easy uptake by root exudation in the rhizosphere. In the peresent study, the effects of EDTA, citric acid and poultry manure extract (PME) on fractionation of Zn in the rhizosphere of corn (hybrid (KSC. 704)) were investigated in two contaminated soils with different texture. Materials and Methods: This research was conducted as factoriel in a completely randomized pattern with three replicates in greenhouse condition and citric acid and EDTA were used at concentrations of 0, 0. 5 and 1 mmol kg-1 soil and poultry manure extract at concentrations of 0, 0. 5 and 1 g kg-1 soil. Three seeds of corn were planted in the rhizobox. After 10 weeks, the plants were harvested and rhizosphere and bulk soils were separated. Dissolved organic carbon (DOC), microbial biomass carbon (MBC) and Zn fractions were determined in the rhizosphere and bulk soils. Results: The results showed that there is a difference between rhizosphere soils properties and bulk soils. In both soils, DOC and MBC in the rhizosphere were significantly (P≤ 0. 05) increased, while, pH in the rhizosphere was significantly (P≤ 0. 05) decreased comared with bulk soils. In sandy loam and clay loam soils, the average of exchangeable Zn and Zn associated with organic matter in the rhizosphere were significantly (P≤ 0. 05) lower than those in the bulk soils, while, the average of Zn associated with iron-manganese oxides, Zn associated with carbonate and residual Zn in the rhizosphere were significantly (P≤ 0. 05) higher than those in the bulk soils. In the rhizosphere and bulk soils of both soils, the maximum amounts of Zn fractions in different fractions were respectively, in the order of associated with iron-manganese oxides, residuals, associated with organic matter, associated with carbonates and exchangeable fractions. A significant correlation was found between Zn uptake by shoots with Zn associated with iron-manganese oxides in both soils (r = 0. 71, P<0. 05). In sandy loam soil, the highest Zn uptake by shoots was observed in the 1 g kg-1 PME treatment. In clay loam soil, the highest Zn uptake by shoots was observed in the 0. 5 g kg-1 PME treatment. In sandy loam soil, 1 mmol kg-1 EDTA and in clay loam soil 1 mmol kg-1 citric acid treatments resulted in the release of the highest Zn concentrations in the iron-manganese oxides fraction. The results of average comparison showed that the average of the exchangeable Zn and Zn associated with iron-manganese oxides in the sandy loam soil were significantly (P≤ 0. 05) higher than those in clay loam soil, while the average of the Zn associated with organic matter and residual Zn in clay loam soil were significantly (P≤ 0. 05) higher than those in sandy loam soil, which can be attributed to different soil characteristics. Conclusion: The results of the present study showed that soil physical, chemical and biological changes due to the corn roots caused not only Zn depletion in mobile soil Zn fractions, but also lead to change soil’ s stable Zn fractions. Since the excessive use of chelators can lead to increase more availability of soil’ s zinc without increasing the plant’ s absorption, so administration of higher concentration levels is not recommended.

Background and Objectives: Zinc (Zn) is among the micro elements which is, essential for humans, animals and plants growth at low concentration. High concentrations of heavy metals in soils may pose long-term health risks to ecosystems and humans. Clay minerals play an important role in accumulation, adsorption/desorption, as well as exchange processes of metal ions. The bioavaibility of these trace elements by plants decreases with the clay mineral content in soils. The aim of this study is to evaluate Zn sorption by soil fractions in puddling and non-puddling conditions with respect to their mineralogy. Materials and Methods: According to previous studies, eight profiles (Four in paddy and four in non-paddy condition) were sampled and described and all soil profiles were classified in Inceptisols order. For this purpose, eight surface soil samples (0-30 cm) were collected. Soil samples were air-dried and crushed to pass through a 2-mm sieve and physico-chemical experiments were performed. All size fractions were separated and content of minerals in sand, silt and clay fraction were determined. Zinc sorption analysis was performed by adding eight levels of Zn from 100 to 3000 μ mol in 0. 01 M NaNO3 solution as background to sand, silt and clay particles and were shaken for 24 h. The data obtained for Zn sorption on different samples was analyzed for Freundilch, Langmuir and Temkin equations. Results: The results of study showed that the amount of zinc sorbed increased with increasing in the concentration of Zn in the contact solutions. The zinc absorption in the clay and silt fraction was much higher than the sand fraction. The results showed that freundlich equation (R2=0. 95) was more fitted to other equations, in puddling and non-puddling condition. KF of Freundilch, indicating sorption value in equilibrium concentration of Zn that in clay fraction of puddling soils it’ s mean (9668. 5) more than silt (4682. 7) and sand (2666) fractions. KF Mean of Freundilch in clay, sand and silt particles of no puddling soils was equal to 8313, 5982. 7 and 2991. 7 respectively. The results indicated sorbed Zn value was significantly correlated with clay content in all sample (n=8, r=0. 73*). The presence of vermiculite mineral in puddling soils is the reason for high Zn sorption (n=8, r2=0. 768*), whereas semectite and palygorskite minerals in no puddling soils affected Zn sorption (n=8, r=0. 85*). In silt fraction mixed minerals such as illite-vermiculite and illite-smectite (n= 8, r=0. 77*) and low content of calcite are main factors to Zn sorption. The presence of quartz and feldespare in sand fraction decreased Zn sorption. While, the presence of small amount of calcite and dolomite (n= 8, r=0. 96*) in this fraction, increased zinc sorption value. Conclusion: Generally, it can be concluded that the type and amount of minerals in soil components are one of the factors that influence the absorption of zinc. The presence of vermiculite and smectite minerals in paddy soils and non-paddy soils are important clay minerals in Zn sorption.

Background and Objectives: Nowadays, human societies spend a lot of money to maximize profits and minimize their costs. The issue of selecting the best arrangement for the pipe diameters and the optimal pumping head of pressurized irrigating network so that minimize total cost while meeting all restriction of network, has received considerable attention by the engineers during past years and is an important issue of hydraulic research. To date, many researches have been done in the field of optimization of pressurized irrigation system to reduce the cost of this infrastructure. In this research optimization of pressurized irrigation system is often done by using available commercial codes or toolbox's of conventional evolutionary algorithms integrated with hydraulic models. In this research, a Visual Basic language optimization code has been developed based on genetic search for integer numbers, in which the optimal design of pressurized irrigation systems with branching layout is done by taking into account the velocity and pressure constrains. Materials and Methods: In developed code that is based on genetic algorithm optimization method an integer numeric is assigned to each available diameter. Then, to determine the optimal diameter of network pipes, by applying the cross-over, mutation and reinsertion with elitism approach on set of chromosomes an integer numeric for each pipe is selected. The output of the model contains the optimal diameter and minimum cost of the irrigation network. Calibration and verification of the model was accomplished by comparing the model result with analytical solutions of several nonlinear problems included different constrains. Finally, we have used of the proposed model for optimal design of Ismail Abad irrigation network in Lorestan province. Results: The results showed that in comparison with existing conditions, optimized design by the present model could reduce cost of implementation of pipelines of Ismail Abad irrigation network from 825935. 28$ to 730958. 37$. In addition, in manual design, the pressure head at the beginning of the system was 140 meters and in optimization mode was 13. 08 meters, which is approximately the same, in other words, the cost of the pumping station in both methods is almost equal. Also, by comparing the network in existing conditions and the optimized network using a genetic search of integers, there is a significant difference between the obtained diameters. In such a way that of the 16 pipes in the network, there were 10 pipes with decreasing in diameter and 3 pipes with increasing in diameter. Conclusion: The present model has the ability to solve various optimizations linear and nonlinear problems included different constraints and the results of the model are completely equal to analytical solution results. The results were shown that the use of developed optimization model could reduce 11. 5% cost of implementation of Ismail Abad pipelines.

Background and Objectives: The use of medicinal plants for remediation of heavy metals from contaminated soils is an economical, cheap and effective strategy. The widespread transfer of natural materials and pollutants to different parts of the environment (soil, water and atmosphere) has imposed great pressure on the self-purification ability of the soil. Accumulation of pollutants is a concern regarding both humans and ecosystems. Among pollutants, heavy metals are particularly important because they are not degradable and also have harmful physiological effects on organisms even at low concentrations. Soil pollution with heavy metals in human societies is one of the major environmental problems and the transfer of these elements via crop production affecting human population health. One of the modern and low cost methods for remediation of contaminated soils is the use of plants. Phytoremediation is an emerging technology which utilizes plants and microorganisms in the rhizosphere to delete, modify or limit the toxic chemicals in soil, sediment, groundwater, surface water and even atmosphere. The aim of this study was to evaluate the phytoremediation ability of Thymus daenensis Celak. with mycorrhizal fungi in polluted soils with lead and cadmium. Materials and Methods: This study was conducted as a factorial exam in the greenhouse conditions. The first factor was four levels of heavy metals: lead (100 mg. kg-1 soil), cadmium (15 mg. Kg-1 soil), concurrent use of lead and cadmium and control (zero) and the second factor was fungal treatments (at five levels: G. intraradices, G. Mosseae, G. fasciculatum, the simultaneous use of all three species and control-non inoculated) in a randomized complete block design in three replications. Results: Analysis of variance showed a significant effect of mycorrhizal fungi on Pb and Cd concentration in shoots and roots of thymus. The highest cadmium concentration in polluted soil was observed in Shoot (62. 1 mg. Kg-1 DW) inoculated with G. mosseae and root (56. 1 mg. kg-1 dry weight) inoculated with G. fassiculatum respectively. Conclusion: The results showed a high ability of Thymus daenensis Celak. to absorb heavy metals from contaminated soils. Other findings of this study were more accumulation of lead in root than shoot of Thymus daenensis. Based on the results, Mycorrhizal fungi can improve the phytoremediation of contaminated soils with Cd and Pb.

Background and Objectives: Achieving to sustainable development is not possible without conservation of soil and water resources and reducing land degradation. On the other hand, in the low density-vegetation lands, biological soil crusts induced by the activity of soil microorganisms play an important role in conserving and improving of soil stability. However, in degraded lands, biological soil crusts are less developed. Thus, recently, biological soil crusts restoration by providing the appropriate conditions for increasing soil micro-organisms activities have been considered through the new biotechnologies applying such as soil microorganisms stimulants. However, the quick and lasting effects of soil conservation strategies is the most important criteria in the selection of management measures. Hence, this study was planned to assess performance of a soil bacterial stimulant nutrient (named B4) as completely bio-amendment in reducing soil loss and runoff at laboratory and small plots conditions. Materials and Methods: In the study, the experimental plots were filled by collected soil of degraded and erosion-prone area of Marzanabad-Kandelus region based on the layering, grain size and bulk density of the native soil area. The solution with 15 g calcium acetate l-1 distilled water (dw), four g yeast extract l-1 dw and five g dextrose l-1 dw was prepared as B4 stimulant nutrient. Then the B4 was spraied on plots. To this end, two treatments of B4 injection and control with three replications were considered. After 15 days, in the Rain and Erosion Simulation Laboratory of Tarbiat Modares University, the simulated rainfall was carried out with during of 100 min and intensity of 50 mm h-1 according to high-erosive rainfall of the native area. Then, the soil loss and runoff components were measured. Results: Statistical comparison of results indicated that injection of B4 stimulated the proliferation of soil bacteria and, as a result of the effect of bacteria on some soil characteristics, improved the soil loss and runoff components, which was more effective in reducing soil losses than surface runoff. The start time and time to peak of runoff at the control plots (without injection) were increased significantly (P<0. 05) from 24. 83 to 49. 22 min and from 78. 66 to 92. 66 min at the stimulant nutrient plots, respectively. Also, the volume and peak of runoff, soil loss and sediment concentration at the stimulant nutrient plots were decreased significantly (P<0. 05) at rate of 88, 92, 95 and 35%, respectively compared to control and measured as 275. 66 and 18. 66 mm, 0. 49 g and 1. 79 g l-1, respectively. Conclusion: According to the present results, the restoration and enhancement of biological soil crusts in low density-vegetation and degraded lands through stimulating and increasing population of soil micro-organisms using micronutrient stimuli such as B4 as has been considered as a biological, efficient and quick strategy to conserve soil and water resources. However, further researches are required to achieve reliable strategies by using other microbial stimulants and evaluating their durability during successive and long-term precipitation.

Background and Objectives: Plants such as rice need to provide their nutrient elements by using fertilizers to have more production per unit area. For this purpose, it is essential to recognize macro-elements amount in soils and prepare their ideal maps. Soil CEC is a vital indicator of soil fertility quality and pollutant sequestration capacity and the properties of nitrogen, phosphorus and potassium as macro-elements for plants. This research was conducted with the aim of estimating and mapping the desired properties in order to obtain the results and maps that could be used in optimum management of fertilizer use and control of groundwater contaminants. Materials and Methods: The study area with an area of about 40, 000 hectares is one of the central areas of Guilan province. 247 soil samples were collected from depth 0-30 cm. The values of CEC, total nitrogen, phosphorus and potassium in soil samples and their descriptive statistics were determined. The normal distribution of data was analyzed using Kolmogrov-Smirnov test. Data that did not have normal distribution was normalized with appropriate transformations. Before the use of interpolation method, trend and anisotropy analysis were performed. Semi-variograms were calculated using ordinary Kriging and maps were plotted. Results: The amount of K and P varied from 78 to 269. 5 mgkg-1 and from 2. 3 to 56 mgkg-1, respectively. The average contents of K and P were 192. 03 and 16. 51 mgkg-1, respectively. The amount of total N changed from 0. 02% to 0. 8%, which its average was 0. 26%. Also, the content of CEC varied from 10. 6 to 47. 1 cmolckg-1 and its average was 26. 72 cmolckg-1. The fitted model was based on semi-variograms of total nitrogen was exponential and those of phosphorus, potassium and CEC were spherical. Determination coefficient (R2) of models had high value and the nugget effect/threshold is less than 25%. These characteristics showed that semi-variograms of properties had strong spatial structure. After specifying the semivariograms, a map of their values was prepared using ordinary Kriging. Evaluation criteria values R2, RMSE and MAE derived for K 0. 79, 27. 84 and 0. 106, P 0. 73, 8. 17 and 4. 63, total nitrogen 0. 72, 0. 059 and 0. 025 and CEC 0. 76, 4. 06 and 3. 09. Criteria values R2, RMSE and MAE showed that accuracy of prepared maps was ideal. With attention to interpolation maps, spatial distribution of K was good in western, north-western and central area of studied region. K deficiency was concentrated in southern and north-eastern areas. The phosphorus and nitrogen content are suitable in the central area to the north and in the south of the region are deficient. According to the nitrogen and phosphorus map of soil, excessive consumption of nitrate and phosphorus fertilizers can lead to groundwater contamination. Also, the use of potassium fertilizers results its fixation, too. Precise attention to CEC map and on-time fertilizer application can solve this problem. Therefore, paying close attention to the values of these parameters in the maps and their critical and optimal limits can optimize the consumption of fertilizers considerably, prevents additional costs to farmer and pollution of ground water resources. Conclusion: Since the investigation of N, P, K and CEC is important for determination of soil fertility quality, so, the maps of spatial distribution of mentioned parameters were prepared via determination of experimental semi-variogram with strong spatial structure using kriging. The criteria of R2, RMSE and MAE showed that maps accuracy was acceptable. Spatial distribution of K was good in western, north-western and central area of studied region. K deficiency was almost concentrated in southern and north-eastern areas. The contents of P and total N were suitable in central and northern areas which their deficiencies were observed in southern area.

Background and Objectives: Numerous benefits that people obtain from ecosystems are called ecosystem services. This services have a wide range and one of the most valuable of them is water yield. Water yield means long-term average of annual rivers flow and recharge of aquifers by precipitation. Due to different land use types and their potential in water yield, the evaluation of water yield at each land use type is important. The objective of this study is to assess and map the water yield at different land uses such as rangeland, agriculture, residential areas, bare ground and Juniperus ecological niche to decide which management decisions are appropriate for the area and how much water is provided by each land use. Materials and Methods: This study is done in Delichai watershed, one of the northern sub watersheds of Hableroud river basin that located in Tehran province. The water yield model is based on the Budyko curve that determines the amount of water running off each pixel of land as the total precipitation less the fraction of the water that undergoes evapo-transpiration. The required data include maps of land use and land cover, annual precipitation, average annual potential evapotranspiration, soil depth, plant available water content, boundary of watersheds and sub-watersheds as well as a biophysical table reflecting the biophysical attributes that entered in InVEST 3. 3. 2 tool to map and estimate water yield ecosystem service. Results: After entering the required data model as well as comparing the initial results obtained with the actual data in the outlet, the model was calibrated with hydrogeological parameters Z and the final results were obtained after calibration. According to the results, the amount of water runoff in whole Delichaee watershed is about 42 million cubic meters. The results of different land uses indicated that the maximum amount of runoff in land uses is in bare grounds with 2923. 992 cubic meter per hectare and then, Rangeland and agriculture land uses with 1264. 109 and 1062. 725 cubic meter per hectare runoff respectively have the highest values. Also, the lowest amount of runoff is 511. 287 cubic meter per hectare in Juniperus ecological niche. Conclusion: The results of this study showed that Although InVEST model needs available and relatively simple data but it has high efficiency and we can use it for mapping ecosystem services and decision making. Physiographic and climatic factors have a great impact on the amount of water in watershed and among these factors, elevation and precipitation are the most effective ones. However, the effect of vegetation on runoff should not be overlooked. Therefore, according to the importance of water provision and problems in water supply for people who live in the region, a relative estimation of runoff rate and the role of vegetation in reducing it can be made by using this model or other models.

Background and Objectives: Salinity is one of the major environmental stresses which negatively influence the agricultural production. The saline soils usually have poor soil structure due to lack of organic matter. Therefore, application of organic matter improves soil aggregate stability, increases soil porosity and enhances soil water holding capacity. Biochar is a carbon rich product, which is produced by burning crop residues and animal manure, under high temperature and limited oxygen conditions. Biochar, when used as a soil amendment, increases soil fertility and improve soil quality. Therefore, the aim of this study was to investigate the effect of different levels of irrigation water salinity and wheat straw biochar on some of soil chemical properties after wheat harvest. Materials and Methods: A greenhouse experiment was conducted based on completely randomized design with four saline irrigation levels (0. 5, 5, 7 and 9 dS m-1) and four levels of biochar (0, 25, 50 and 75 Mg ha-1) with three replications. The soil texture used in experiment was sandy loam with a bulk density of 1. 53 g cm-3, the saturated paste extract electrical conductivity of 0. 66 dS m-1 and the volumetric soil water content of 21 and 8% at field capacity and permanent wilting point, respectively. The biochar was produced from wheat straw at 500 oC and under non-oxygen conditions. After harvesting of wheat, soil chemical properties (such as sodium, calcium and potassium concentration, soil electrical conductivity in the saturation paste extract and sodium absorption ratio) were measured in two layers of 0-10 and 10-20 cm. Statistical analysis was performed using SAS software. The comparison between the effects of treatments on studied characteristics was performed with Duncan's test at 95% probability level. Results: In general, the results showed that the concentration of sodium, potassium and calcium, electrical conductivity and sodium absorption ratio in the 0-10 cm layer with the application of the highest level of biochar (75 Mg ha-1) increased by 1. 1 and 143. 8, 2. 2, 2. 1 and 0. 8 times in comparison with no biochar application. In the same soil depth (0-10 cm), the latter parameters with the application of the maximum level of water salinity (9 dS m-1) were enhanced by 14. 8 and 1. 6, 8. 6, 2. 1 and 5. 4 times in comparison with 0. 5 dS m-1 salinity. The concentration of measured ions, soil electrical conductivity and sodium absorption ratio were higher at 0-10 cm compared with those in 10-20 cm due to evaporation from soil surface and higher water holding capacity in top layer of soil due to biochar application. On the other hand, the increase in soil electrical conductivity in both layers by application of biochar was due to high saturated paste extract electrical conductivity of the used biochar (7. 5 dS m-1) in comparison with the electrical conductivity of the soil (0. 7 dS m-1) and also accumulation of ions in the soil (as water was not drained out of the pots). Conclusion: Although, biochar increased soil salinity and other soil chemical properties due to its salinity, the increase in biochar application to the levels higher than 25 Mg ha-1 to some extent reduced the negative effects caused by elevation of salinity. On the other hand, considering the increase of potassium along with presence of biochar, it can be used as modifier in soils with potassium deficiency. Therefore, according to biochar ability as soil amendment, biochar (with low salinity) can be proposed at levels of less than 25 Mg ha-1, so that its use is economical.

Background and Objectives: Measurement of evapotranspiration using weighing lysimeter is the most accurate method. However, due to the gravitational fabrication of the weighing laser, simple empirical methods are widely used for calculating potential transpiration evapotranspiration and their results were compared with reference (FAO-Penman-Monteith) method. Therefore, the main objective of this study is to compare the accuracy of 20 experimental models of reference evapotranspiration estimation and providing the best experimental method in the cities of Rasht, Sari and Gorgan in northern Iran and in the coastal strip of the Caspian Sea. Materials and Methods: In this study a cross comparison of FAO-Penman-Monteith method and 20 empirical equations was done for calculating potential evapotranspiration in a period of 10 years from 2007 to 2016, in Rasht, Sari and Gorgan synoptic stations in coastal zone of Caspian Sea. These stations were selected for climatic variation from humid climates to Mediterranean climates. The Root mean squared error (RMSE), Mean Absolute Error (MAE) and Percent error (PE) were used to measure accuracy of these methods. Results: The results showed that daily evapotranspiration values obtained from Ravazzani method were closer to FAO-Penman-Monteith method than those of the other models. So that for the model, the measured errors involve RMSE, MAE and PE, were obtained 0. 77, 0. 54 (mm/day) and 21. 6% for Rasht, 0. 8,-0. 39. (mm/day) and 9. 4% for Sari and 0. 99,-0. 42 (mm/day) and 9. 88% for Gorgan. Also, the results indicate a low performance of the Romanenko model. Overall, in all of the studied climates, the Ravazzani et al., Berti et al., Hargreaves-Sammani, Irmak et al. and Valiantzas models had better performance than other models in the estimation of reference evapotranspiration Conclusion: The results of this study showed decrease in the accuracy of ET models compared to reference model of FAO-Penman-Monteith for moving from humid to Mediterranean climate. The mass transfer based models like Mahringer and Tabari showed relative undesirable efficiency in coastal zone. Therefore, it can be noticed that empirical equation can lead to variable efficiency in different climate.

Background and Objectives: Estimation of sediment values in sub-basins is an important issue in watershed water management. Determination of the monthly and annual river flow volume and sediment from upstream are very important in the design and operation of dams. The possibility of using mathematic models has been provided by expansion of computer software technologies and knowledge about factors affecting erosion and sedimentation. The use of erosion and sedimentation models in the watershed studies has increased due to good fitness between the results of some models and the observed values. In order to evaluate the SWAT capabilities in runoff and sediment simulation, this research was carried out in Geraty sub basin. The SWAT model is a comprehensive model for predicting the effects of different management methods on runoff, sediment, chemical and nutrient material transport in the basins with different soil, land use and management condition for long periods of time. Materials and Methods: Different data and maps were used for preparation of required basic files for delineating the basin into sub-basins and HRUs. These basic file include: Digital Elevation Model (DEM), soil map and Land Use/Land Cover (LULC) map. The weather input data was including maximum and minimum daily air temperature, solar radiation, wind speed and relative humidity. SWAT-CUP software was used to calibration and validation of the model parameters. The SUFI-2 algorithm was used for parameter optimization. In this study, the SWAT model was calibrated with the monthly observed discharge and sediment rates and physical parameters. Then, the model was assessed. The model was calibrated using monthly discharge data from Bidouaz Esfaraien station for the period 1986-2001 (16 years) and GhaleSefid station for the period 2004-2009 (6 years). Also, the model was validated using monthly discharge data from Bidouaz Esfaraien station for the period 2002-2005 (4 years) and GhaleSefid station for the period 2010-2011 (2 years). The sediment load data for the years 2011-2009 (3 years) were measured in GhaleSefid station. Results: Calibrated model showed an acceptable precision in simulation of monthly discharge in Bidouaz Esfaraien and GhaleSefid stations. MSE, R2 and NS parameters for monthly discharge in Bidouaz Esfaraien station was obtained 0. 516, 0. 87 and 0. 64, respectively. In simulation of discharge in GhaleSefid station these statistic parameters were 0. 55, 0. 89 and 0. 71, respectively. These statistic parameters in sediment simulation 0. 42, 0. 72 and 0. 59, respectively. The results showed that the total annual runoff depth at Geraty basin is about 22. 39 mm and total annual sediment is about 773 ton/year/km2. Considering the area of 747. 109 km2 for this basin, the total volume of long-term annual runoff is estimated to 16. 71 million cubic meters and also about 576983. 31 tons of sediment will be drained out from the Geraty basin. The maximum sediment load and runoff occurs in April and May. Conclusion: Analysis of the SWAT model results in sediment simulation shows that the model capability in sediment simulation is good. Regarding to high uncertainty in sediment prediction, the model was able to simulate the maximum amount of sediment in the calibration and validation phases successfully.

Background and Objectives: Water shortage in the Sistan region has become a water crisis in the region due to its full dependence on the Hirmand River and the droughts of the last two decades. On the other hand, the vast majority of people in the region have been affected by the agricultural sector, and the limited availability of water has pushed this sector into food supply with a production challenge. Due to the fluctuation and high risk of water supply in this region, because water resources in the Sistan area are limited and scarce, water demand management is of particular importance to address this problem. On the other hand, wheat production in Sistan region is one of the most important and strategic products that plays a major role in the agricultural economy of the region. Materials and Methods: Therefore, in the present study, the cost function of the Sistan wheat demand function has been estimated from the translog cost function. The data needed to estimate the translog cost function, including quantities and input prices, and the production of 150 wheat labor, were collected using cross-sectional data of 2016-2017. The method used in this study is a seemingly unrelated duplicate regression (SURE). Results: The results of the model estimation show that the price of labor and family and land use and land use have a positive effect on the share of water costs, while the price of water and the amount of production have a negative effect on the share of water costs and the intersection stretches It shows that the input of water has a strong succession with other inputs. The water has a substitute relationship with the inputs of the leased and family labor force, fertilizer, and sub-cultivation area, and it has the highest degree of succession with fertilizer. Conclusion: All coefficients of the variables in the water cost share model, with the exception of the leased labor force, are meaningful. Due to the low coefficient of determination in the cross-sectional data, the coefficient of determination in the estimated model for wheat yield is %0. 61 represents the good fit of the model, which explains independent variables as well as dependent variables (total cost change). The Watson camera statistics show that there is no self-correlation phenomenon in the model. The absolute magnitude of the self-priced stretch of water demand for wheat is greater than one, which indicates that it is possible to control water demand by adopting pricing policies through influencing production inputs other than water.