Journal of Water and Soil Conservation
Year:2020 | Volume:26 | Issue:5|Papers Count:15

Background and Objectives: The lack of available water resources and its optimal use in arid and semi-arid areas have forced experts and authorities in the agricultural sector to apply high-efficiency irrigation systems such as surface drip irrigation (DI) and subsurface drip irrigation (SDI). SDI can reduce evaporation losses and increase irrigation efficiency due to water movement in the soil and drying of soil surface. For designing of DI and SDI, in addition to the dimensions of moisture bulb, that are the main parameters in determining the installation depth and the spacing of the laterals and emitters, wetted area of emitter around is very important. Most studies have been conducted on the distribution of wetted dimensions in a continuous drip irrigation system and few studies have been done on wetted area in pulsed drip irrigation. Thus, in this research, we focused on wetted area of emitter around in pulsed drip irrigation and its effective factors. Materials and Methods: In this study, experiments were conducted in a transparent plexyglass tank (0. 5*1*3 m) using three different soil textures (fine, heavy and medium). The emitter discharges were considered 2. 4, 4 and 6 lit/hr. The emitters were installed at 3 different soil depths (surface, 15 cm and 30 cm). Also, these experiments were also carried out for both continuous and pulse irrigation systems. In pulse irrigation, the pulse cycles were considered 30-30, 20-40 and 40-20 min. The first number refers to the irrigation time (on) and the second number refers to the resting time (off) of the system in each cycle. Results: The results of this research showed that the largest area of wetted bulb in the DI and SDI with pulsed application (for the same water volume of at the end of irrigation), is related to emitters with higher discharge rate in the light texture and in Heavy texture is related to lesser outflow rate. The results of the effect of soil texture on the wetted area indicated that in continuous and pulsed drip irrigation systems, the highest and lowest wetted area of moisture bulb was related to light texture and heavy texture, respectively. Also, the results showed that for all treatments, the down wetted area of emitter in the DI would be higher than the SDI. Also, the results showed that in DI and SDI (for the different outflow and texture), the down wetted area of emitter in pulsed irrigation (30-30) is relatively more than two other pulses (40-20, 20-40) and continuous irrigation. This difference will be clearly seen in light texture and in SDI. Conclusion: The results of the research show that the wetted area of around the emitter is different for different outflows and soil textures, as well as for continuous and pulsed method. Considering these parameters in the design of drip irrigation system increases the water application efficiency and decrease deep percolation losses.

Background and Objectives: Sesame is an oilseed plant that is resistant to drought but it is sensitive to water stress at seedling stage and during flowering to seed filling. Irrigation and drought stresses increase and decreases the amount of oil, respectively. Environmental stresses have reverse effects on the amount of oil and protein. In addition, high soil moisture causes root rot disease and low moisture causes phyllody disease. To increase the yield and oil, the enhancement of soil fertility, planting bred cultivar and adequate supply of moisture are necessary through irrigation. This study was conducted to evaluate the effect of irrigation intervals at different phonological stages on quantitative and qualitative characteristics and water productivity of sesame. Materials and Methods: This research was conducted in randomized complete block design with four replications at Behbahan Agricultural Research Station for two years (2013-2014). Treatments included I0 (irrigation interval based on farmer 's custom, twice weeks interval), I1, I2 and I3 irrigation after 90, 130 and 170 evaporation from class A pan, respectively, I4 (130 mm to flowering and afterward 90 mm), I5 (170 mm to flowering and afterward 90 mm) and I6 (170 mm to flowering and afterward 130 mm). During experiment: branches number and capsules number per plant, 1000-seed weight, first capsule height, plant height at harvesting time, seed oil percentage, seed yield, seed oil yield, water productivity of sesame seed and seed oil, root rot and phyllody diseases were recorded. Varince analysis were done by MSTATC statistical software and means were compared using Duncan, s Multiple Range Test. Results: The highest number of branches per plant (10. 31), number of capsules per plant (154. 50), 1000-seed weight (3. 78 g), seed yield (1381. 50 kg ha-1), oil amount (55. 11%), were recorded in I1 treatment, so that the highest seed oil yield (795. 55 kg ha-1) belongs to this treatment. The differences of oil yield among I1 treatment and I4 and I5 treatments were not significant. Maximum seed water productivity (0. 233 kgm-3) and seed oil water productivity (0. 125 kgm-3) were observed in I3 treatment. However, the difference among this treatment and I0, I5 and I6 treatments was not significant. The lowest infection severity to root rot disease (7. 22%) was recorded in I5 treatment. The highest infection severity to root rot disease (20. 63%) was observed in I1 treatment while the lowest infection severity to phyllody disease was recorded in I1, I2 and I6 treatments. Conclusion: The highest seed yield, 1000-seed weight and seed oil percentage were obtained in I1, I4 and I5 treatments. The differences of these characters among I1, I4 and I5 and other treatments were not significant (except I0 treatment). The highest seed oil yield were recorded for I1 and I5 treatments. The most seed water productivity and seed oil water productivity and the lowest water consumption belong to I5 treatment. Irrigation frequencies in I5 treatment were lower than I1 and I4 treatments. According to the results, I5 treatment has the lowest water consumption and the effect of this treatment on seed yield and gross income of seasame was similar to I1 treatment. Therefore, I5 treatment is recommended for proper irrigation of sesame in Behbahan region.

Background and Objectives: Sustainable management of water resources to maintain environmental needs requires an economic approach to agriculture. Security and management of water in the agricultural sector is the most important strategy for sustainable development of the country. Considering the development process of the country and the transformation of the national economy, the agricultural sector has become the key to the security and economic life of the country. The growing demand of the population and the need to provide food and increase production make the agricultural sector one of the most important economic activities that plays a major role in managing this sector and providing the country's needs. Because of the high share of water use in the agricultural sector, the country faces a depression crisis. Because of the high share of water use in the agricultural sector, the country faces a depression crisis. At present, the country's water potential is not responsive to the growing demand for water in this sector, so resource management and water use optimization in the agricultural sector are the only countermeasures With a depression crisis. This research has been conducted to determine the production and demand function for sugar beet as one of the basic crops in Khorasan Razavi provinces (Quchan, Chenaran, and Neyshabur cities) in 2016-2017 year. Materials and Methods: In the present study, the SURE method has been utilized to determine the water demand function. In this regard, the intrinsic and Alen-Uzawa Partial Elasticities of Substilution, intrinsic and Price Elasticity of Factor Demand parameters have been evaluated in the estimation of the production function and the cost of the transfer of water by the seemingly unrelated regression method. Also, the R2 and adjusted R2 indices have been analyzed for the evaluation of fitting of the model and the Statisticst for meaningful coefficients of the variables. Results: The results confirm the fitting of the used model for sugar beet production cost functions in the study area. The results of the coefficients in Quchan, Chenaran and Neyshabur County indicate that there is a positive relationship between water cost and labor costs, and a negative relation to the price of fertilizer, poison, seeds and production amount. Conclusion: Based on the results, water is a substitute for fertilizer and poison with partial elasticity greater than one and this point illustrates the impact of the consumption management and economic evaluation of water on improving the consumption of other fertilizer and poison inputs as well as the water in the production of sugar beet is in this area. Based on the results, it is suggested that policies such as optimal prices for inputs such as poison and fertilizer must be adopted to prevent environmental pollution.

Background and Objectives: Heavy metals enter the environment through the discharge of industrial wastewater and urban wastewater. Zinc (Zn) and copper (Cu) are considered as an essential element for life and act as micronutrients when present in trace amounts, but at high concentrations they cause environmental problems. There are several method to remove the heavy metals from aqueous solutions, one of which is adsorption using inexpensive inorganic sorbents. Materials and Methods: The raw diatomite as a sorbent for removal of Cu and Zn was supplied from Birjand mine. In this study, batch experiments were conducted for evaluation of the kinetic and thermodynamic adsorption of Cu and Zn from aqueous solutions by diatomite. The kinetic parameters of metal ions sorption by diatomite (0. 1g) were determined with 25mL solutions containing 100 mg L-1 Cu and Zn concentrations at 0, 10, 20, 30, 40, 50 sen 2, 5, 10, 20, 40, 60 min 2, 4, 6 hr at (at background solution 0. 03 mol L-1 NaNO3). For thermodynamic studies the solutions were stirred in a thermally controlled shaker at 10, 20, 30 and 40 º C. The adsorption behavior of heavy metals (Cu and Zn) in different time was conducted by pseudo-first-order, pseudo-second-order, Elovich and fractional power models. Also, Freundlich, Langmuir, Tempkin, Dubinin-Radushkevich isotherms models have also been used to the equilibrium adsorption at data 10, 20, 30 and 40 º C. Results: The results showed that the adsorption capacity of diatomite increased with increasing contact time. The time required creating equilibrium between the adsorbed metals on the solid surface and the fraction remaining in the solution for Cu and Zn were 40 and 120 minutes, respectively, and the amount sorption of Cu was more than Zn by diatomite. The maximum adsorption of Cu and Zn (qmax) by diatomite at 20 ° C was 56 and 27 mg g-1, respectively. Among adsorption kinetic models, pseudo-second-order model was better fitted for experimental data (R2=0. 99). The values of adsorption by diatomite, increased with increasing temperature, the adsorption data were well fitted with Langmuir (R2: 0. 96-0. 99). The thermodynamic parameters (Δ G, Δ H and Δ S) indicated that the adsorption of Cu and Zn ions were feasible, spontaneous and endothermic at 10-40 º C. The sorption energy parameter (E) of Dubinin-Radushkevich isotherm values indicated probably physical sorption reaction of the metals by the sorbent (E<8 kJ mol-1). Conclusion: Considering the presence of heavy metals in contaminated water and the importance of their removal, administration of diatomite as one of the cheap and accessible absorbents can be effective in the removal of heavy metals from contaminated industrial water sources, especially Cu and Zn.

Background and Objectives: The scouring of river bed around bridge is one of the most important issues in bridges destruction. It has been found that the occurrence of scouring on the bridges abutment is the most important cause of the destruction of bridges in all countries. Among the techniques of reducing scouring around the bridge abutment which are called “ indirect measures” is to modify the flow pattern and reduce the power of vortex vortices which are the main cause of scour. At the present study the performance of immerse vanes was investigated at a constant distance of 2 times of the abutment effective length and 4 different angles under four different flow conditions (Froude numbers = 0. 15, 0. 17, 0. 2 and 0. 22). The destruction of immerse vanes is impossible due to the installation of them above the bed and within the depth of the flow. Therefore, the main purpose of this study is to determine the most suitable angle of displacement of the vanes in the upstream of the bridge abutment, which will cause the least scouring. Materials and Methods: The experimental tests were conducted in a flume of 8 meters long and 1 meters wide. A rectangular abutment was installed at the middle of the test section (2 meters long) covered with bed of fine sand. Each test started by turning on the pump, which transfers the flow from the reservoir below the laboratory. The water flows through the flume after passing through a net that is filled with fibers in order to depreciate the flow fluctuations. At the end of the flume, after passing through the sliding valve, the flow into the pool was collected. At the end of the pond, a 53-degree triangular overflow was placed in order to measure the flow rate, which then flows into the underground reservoir. At the beginning of each experiment, after the leveling of the bed by opening the opening at the beginning of the flume, the flow gradually entered the flume so that the sediment would not be destroyed. After increasing the water level in the flume, the flow rate slowly increases to reach the desired flow rate. After adjusting the flow rate, the water level was set at the desired level of 15 cm and then the experiment lasted for four hours at a specified time. At the end of each experiment, the water was slowly drained from the flume. the purpose of this study was to compare the erosion and sedimentation pattern around the bridge abutment by changing the angles of the vanes, Therefore, the time of each test was considered to be 4 hours. At the end, the maximum scour depth and topography of the scour hole created around the ridge were taken by a laser meter with a precision of one millimeter and the data was saved in Excel files. Results: In this study, bed topography was taken for all experiments using laser meter and then plotted using Surfer software. The results showed that in all experiments, maximum scour depth was observed in the upper nose of the abutment and with increasing flow conditions, due to increased bed shear stress and the power of vortices around the structure, the maximum scour depth and scour hole volume increased. Also in this study, it was found that the angle of installation of the immerse vans has a great effect on the performance of the vanes in reducing the depth, surface and volume of the scouring hole. Conclusion: Generally, the results show that the use of immerse vanes significantly reduced the scouring compared to the case of no vanes. The most effective angle of installation was found to be equal to 65 degrees, which, on average, reduced the maximum depth of scouring, lenght and width by 66, 71 and 69 percent, respectively.

Background and Objectives: The accurate prediction of soil hydraulic parameters is essential to simulate the transport of water, solutes and contaminants in soil, management of the agricultural water, management of production and conservation of soil and water. The least squares regression is the most common method applied for fitting the soil-water retention curve (SWRC) function to the observed data-points to optimize its parameters. However, the variance of SWRC data varies in different moisture content and therefore, unlike the wet-end of SWRC, the conventional unweighted regression method may not be sufficiently effective in estimating its dry-end (higher suctions). While, selected soil processes, such as soil moisture redistribution or transport of contaminants in soil occur in low soil moisture contents which correspond to the dry-end of the curve. Consequently, in fitting different hydraulic functions to SWRC, the accuracy of SWRC parameters would be improved in the low-moisture range content by determining the appropriate weights for data points. Accordingly, the objective of this study was to investigate the effect of properly weighting the SWRC data points on increasing the accuracy of the estimated soil hydraulic parameters. Materials and Methods: In this study, undistributed soil samples were collected from 20 cm soil depth with six replications. The SWRC of the samples were measured at suctions of 0 to 15000 cm. In order to fit the van Genuchten equation of SWRC on measured values of h(θ ) and to estimate its hydraulic parameters through RETC code, the weighted least squares regression method was also used along with the conventional standard least squares regression method. For this purpose, some weights were assigned to the data points as the inverse of the variance of the measured volumetric soil water content in six replications, so that, the effect of the curve estimation error in low moisture contents were considered by assigning larger weights in the regression fitting. Finally, the accuracy of unweighted and weighted regression in the fitting of the SWRC model on the measured data was compared using statistical criteria and a suitable method for the averaging of hydraulic parameters was introduced. Results: Comparison of the fitted hydraulic parameters by unweighted and weighted regression showed that the mean values of the residual water content (Ɵ r), saturated water content (Ɵ s) and α parameter (reciprocal of air-entry suction) in the weighted method were lower than the unweighted method, however the n parameter values obtained by the weighted method were higher than unweighted method. The extraction of SWRC based on hydraulic parameters estimated by both unweighted and weighted methods showed that the weighted method increases the accuracy of the estimation and reduces the percentage of point error in lower moisture contents (higher suctions) compared to the unweighted method. Although, the weighting method generally increased the error of SWRC estimation and decreased the correlation between estimated and observed moisture content. Comparison of two methods of averaging of soil hydraulic parameters in the replicates showed that in both unweighted and weighted regression, the method II (averaging of volumetric water contents at different suctions and estimating hydraulic parameters) had a lower error in compression to method I (averaging of hydraulic parameters). However, in estimation of SWRC in lower moisture contents, the method I had lower point error than that of method II. The method I reduced the error percentage in the weighting method. Conclusion: Assigning proper weight to SWRC data points improves curve fitting in lower moisture range, which is very important in simulating redistribution of moisture or transfer of contaminants transport in the soil processes, particularly in arid and semi-arid conditions.

Background and Objectives: Discharging of pollutants produced by municipal developments, agricultural and industrial activities and climate change are among the issues affecting the quality of groundwater resources. Groundwater is one of the valuable resources that lack of proper management can transfer chemical pollutants through industrial and agricultural effluents. In relation to the influence of these factors, we can mention the changes in the groundwater level of Hashtgerd Plain which has fallen by about 15 meters over the past three decades. The innovation of this research is to use Satellite Images and monitor the quality of water resources status by identifying the factors affecting the quality of groundwater resources and studying soil and water resources conservation strategies. Materials and Methods: In this research, 24 samples (from 24 wells) obtained from different parts of Hashtgerd plain were prepared. The concentration of effective parameters on the quality of groundwater resources, including Nitrate, Sulfate, Calcium, Sodium, Magnesium, Potassium and total dissolved solids was self-measured using the standard reference method. Then the interpolation (Error estimation of interpolation methods) and quality analysis of ground water resources were investigated by Arc Map and AquaChem software’ s. Land-use changes were also investigated using Landsat 8 satellite imagery (OLI sensor) and ENVI software’ s. Then the obtained results were used to study the spatial variation of the quality parameters and identify the factors affecting the quality of groundwater quality changes. Results: The results obtained from the analysis semivariogram and the error estimation of the interpolation methods in this study for the nitrate parameter (1391-1394) show that the nugget effect ratio with sill from 0. 12 to 0. 17, indicating spatial continuity Strong is this parameter. In addition, the interpolation methods, the Empirical Bayesian Kriging method, had the lowest root mean square error (2. 99 mg/l). The results of the study of spatial variations of nitrate values in Hashtgerd plain groundwater resources indicate that the highest amounts of this pollutant (more than 50 mg/l) were located in the urban and industrial users (Arab Abad kouh, Qaleh Soleimani) Which can be linked first with municipal wastewater and then with the application of nitrogen fertilizers in agriculture. In addition to the above, the study of spatial variations of sulfate and groundwater ion ratios in the years 1391-1394 show that the values of this parameter in parts of the gardens and agriculture of the plain (central parts) more it is about the standard (more than 400 mg/l). The main cause of this increase is known as Hydrochemical reactions and factors. Conclusion: In general, the results of this study showed that the number of effective parameters in determining the quality of groundwater resources of Hashtgerd plain exceeds the standard limits. In addition, the groundwater level has dropped (9. 71 m) during the study period (1391-1394). In addition, due to the intensive impact of human factors on reducing the quality of groundwater resources in the Hashtgerd plain and reducing groundwater levels during the study period (1391-1394), consideration the groundwater protection area and management of groundwater pumping wells is essential.

Background and Objectives: Potassium occurs in soils in various forms. The behavior of potassium in soil can be difficult due to its interaction with the intrinsic properties of the soil. Although most soils contain large quantities of potassium, but most soils are not able to provide proper amounts for plant nutrition, so that the equilibrium reactions occurring between different forms of potassium have a profound effect on potassium nutrition. This research was carried out with the aim of investigating the relationship between different forms of potassium (soluble, exchangeable, non-exchangeable and construction) with physical and chemical properties of soils in citrus areas of Iranshahr and Khash towns in Sistan and Baluchestan province. Materials and Methods: First, according to previous studies, 30 samples of soils in Iranshahr and Khash towns with different characteristics. Then samplings were taken from depths of 0 to 30 cm. Physical and chemical properties of soil and various forms of potassium (soluble, exchangeable, non-exchangeable and construction) with total potassium were measured and relationship between different forms of potassium with each other and physical and chemical properties of soil were investigated. Results: Soils were in general light in texture, non-saline and calcareous. Organic carbon values in soils ranged from 0. 6 to 1. 6 percent, cation exchange capacity ranged from 7. 0 to 10. 5 centimoles per kilogram, and the pH ranged from 7. 0 to 7. 4. The amounts of different forms of potassium in the city of Iranshahr, potassium soluble ranged from 1. 4 to 20. 4, exchangeable from 122 to 315, non-exchangeable from 177 to 388, construction from 5709 to 13987 and a total 8420 to 14200 mg kg-1 soil. In Khash city, potassium soluble ranged from 5. 7 to 14. 3, exchangeable from 129 to 273, non-exchangeable from 293 to 493, construction from 5412 to 14085 and a total 9892 to 13850 mg kg-1 soil. Correlation test showed that there was a significant positive correlation between soluble potassium and sand (r=0. 5*) and negative correlation with silt (r=-0. 5*). There was a significant positive correlation between exchangeable potassium and organic matter (r=0. 7*), significant positive correlation with clay (r=0. 5*) and significant positive correlation with cation exchange capacity (r=0. 7*). Between non-exchangeable potassium and calcium carbonate there was a significant negative correlation (r=-0. 8*). Significant positive relationships among various fractions of soil K indicated existence of a dynamic equilibrium between different forms of K. Conclusion: The amount of potassium available in the plant (soluble, exchangeable, nonexchangeable potassium) is good in citrus growing areas in Sistan and Balouchestan province of Iranshahr and Khash, and therefore does not require potassium fertilizers in these two regions.

Background and Objectives: Selection of appropriate irrigation water price could be one of the primary economic measures in demand management of Iran's water resources management conditions. However, imposing any policies in the section would result in inter-sectoral (economic, social, and environmental) consequences. Identification of these consequences helps the water managers and authorities to find the optimum irrigation water price value. To investigate the results of implementing different policies and farmers' reaction to these scenarios, models are required that can help authorities achieve these goals with high confidence. Also, water resources planners believe that simulation of potential responses of farmers to the implementation of different policies can have an active contribution to making more correct decisions. Determination of the supplied water cost and the weighted average value of the economic value of water, to implement the scientific range of appropriate pricing scenarios to assess its inter-sectoral effects, is the main contribution of this study. Materials and Methods: The present study attempts to simulate the agricultural conditions of Roodasht Irrigation District using the economic model for the base year of 2014-2015. Inter-sectoral effects of irrigation water pricing and probable reactions of the farmers are also investigated. Finally, the degree of importance and ranking of the effects of economic, social and environmental indicators (by the AHP and SAW hierarchical hybrid approach) were used to achieve a reasonable and efficient water price in the irrigation network. Results: According to the results, employing the pricing scenarios led to alter the existing cropping pattern of the Roodasht irrigation district, located in Varzaneh city in Esfahan province, by the farmers. In other words, with increasing the irrigation water price, the positive reaction of the farmers (in the form of cropping pattern) has been detected. The analysis is conducted using the Positive Mathematical Programming economic model in Gamz software. However, employing the pricing scenario has been lead to negative impacts on the economic and social indicators, while positive impacts on the environmental index. In another words, under the conditions that the local water authorities impose the increasing water scenario, the farmers' income has decreased from 19. 9 to 14. 33 M IRR per hectare. Also, the effect of the first and fifth scenarios on the employment index was 60. 5% and 38. 37%, respectively. From the environmental point of view, these scenarios will also reduce water consumption and increase the energy balance. Conclusion: Summing up the obtained results, considering the importance degree of the intersectorial consequences of the pricing scenario; including economic, social, and environmental; the weighted average value of the entire crops of the existing cropping pattern (1540 Rial per a cubic meter) is selected as the irrigation water price.

Background and Objectives: As a crucial issue in aqua sciences, optimizing dam reservoirs exploitation has been studied with a variety of optimization techniques. In recent years, a large number of multi-objective Meta-Heuristic algorithms have been introduced. One of these algorithms is the second version of the multi-objective genetic algorithm with nun-dominated sorting, which was introduced in 2002 by Deb and et. al. Materials and Methods: In this research, the innovation and aim are to use the particle swarm algorithm with nun-dominated sorting approach and evaluate the efficiency of this algorithm in the optimization of operation of the reservoir performance. Finally, the results are compared with the NSGA-II algorithm, which ultimately leads to a sustainable management policy for water resource systems, and in particular the exploitation of the reservoir. In this research, the multi-objective version of the genetic algorithm and particle swarm optimization were investigated using concepts such as Non-dominated sorting and crowding distance and used to solve the optimization problem of the Mulla-Sadra reservoir in Fars province. The problem of optimization defined with two goals. One of them was minimizing difference between agriculture demand end releases. The second of objective function was maximizing flood storage volume. The two algorithms compared with criteria such as the run time, the number of solutions placed on the Pareto front, standard deviation and performance criteria (dispersion criteria). Results: The results of the research indicated that both algorithms have the ability to solve this optimization problem. Also, the results indicated that the algorithms have somewhat more performance than some other criteria. The results of the investigation of the runtime of each of the algorithms showed that the performance of the multi-objective particle swarm algorithm (NSPSO-II) is far more than the NSGA-II algorithm, so that the average runtime of the NSGA-II algorithm in the population of 50 The value of 21. 3879 seconds is approximately three times the average runtime in the NSPSO-II algorithm with a value of 6. 3169 seconds. Regarding the performance criterion, the NSPSO-II algorithm has a better performance than the NSGA-II algorithm. On the other hand, according to the number of solutions on the Pareto front, the NSGA-II algorithm found a lot more solutions on the Pareto front, for this reason, the standard deviation in the NSGA-II algorithm was less than NSPSO-II. Conclusions: The NSGA-II algorithm found a lot more solutions on the Pareto optimal front, and the solutions on the Pareto optimal fronted properly covered the Pareto front, unlike the NSPSO algorithm. Also, comparing the solutions in the Pareto optimal front showed that the NSPSO-II algorithm was stepped up to maximize the second target function, while the NSGA-II algorithm moved in the direction of minimizing the objective function.

Background and Objectives: Tamarix shrub is one of the most important plants in the arid and semi-arid regions which can more effect on soil microbial activities and community and it increases soil fertility through efficient nutrient cycling. In addition, this plant as a natural and adapted vegetation cover in the study area has important role in soil conservation and wind erosion control. The aim of this study was investigation of the natural tamarix shrub effect on soil microbial biomass and activities of desert soils in Pharokhabad plain of Dehloran, Ilam province. Materials and Methods: In order to study of soil biological properties, soil sampling carried out from soil surface (0-5 cm) under canopy of tamarix shrub and open area by using systematic randomized method. Total soil samples were 62 samples including 31 samples under canopy and 31 samples out of canopy. After collecting soil samples, it transfer to the laboratory and soil biological analyses including microbial biomass carbon and nitrogen, basal respiration, substrate induced respiration, metabolic quotient, microbial quotient and soil organic carbon were carried out on soil samples. Statistical analyses such as one-way analysis of variance (ANOVA) and correlation coefficient were performed by SAS 9. 1 software. The t-test was used to compare mean of soil biological properties. Results: The results of this study showed that there was significant differences (P<0. 05) between under canopy and open area in terms of soil biological properties. The highest soil organic carbon amount (2. 16%) observed under canopy of tamatrix comparison with open area. Soil microbial biomass carbon (654 mg C kg-1) and nitrogen (79 mg N kg-1) were higher significantly under canopy of tamarix than out of canopy. In addition, basal and induced respiration was higher statistically (P<0. 01) under canopy than open area. Basal respiration under canopy found positively correlated with metabolic quotient (qCO2), while there was a significant negative correlation between basal respiration and soil organic carbon. Conclusion: To sum up, according to results, soil biological activities and microbial biomass increased under canopy which indicates tamarix shrub is important plant in the study area. For example, the highest microbial biomass carbon found under canopy compared to open area. Therefore, in order to increase soil quality and health as well as combating soil erosion, reclamation and protection of tamarix shrub is essential in the study area. In this regards, department of natural resources and watershed of Ilam province and Non-Governmental Organization (NGO) can contribute for plantation and reclamation of this plant and other native vegetation cover.

Background and Objectives: Examination of rock resistance to erosion is of great importance in erosion and sediment studies. This is due to that information on rock resistance and rating rocks in terms of resistance to erosion and erosive factors provide useful guidelines to manage and control erosion and sediment in the watersheds. Therefore, this study was conducted to examine the resistance of 84 rock samples collected from different geologic formations of Fars group including marl limestone (Mishan formation), calcareous sandstone (Aghajari formaton), anhydrite (Gachsaran formation) and limestone (Asmari formation). The rate of rock resistance to erosion was measured by Los Angeles abrasion method. Materials and Methods: In the present study the resistance of four rock types was investigated using Los Angeles abrasion method. Geology map and Google earth image of the study area were used to select the sampling locations. Thereafter in field survey, roadsides that were appropriate for sampling were selected. For each rock type, stone samples were collected from seven back slopes with three replications (a total of 21 rock samples from each rock types). The resistance of rock samples to erosion was then examined using Los Angeles abrasion test. Statistical analysis was conducted using descriptive statistics including mean, variance, standard deviation, minimum and maximum. Moreover ANOVA and Tukey test were employed to compare means of rock resistances. Finally the results were described and discussed and rocks were rated in terms of their resistance to erosion. Results: ANOVA results indicated that there was a significant difference between rock types in terms of resistance to erosion at the 0. 05 level. Tukey test showed that Asmari limestone and marl limestone (Mishan formation) were not significantly different at the 0. 05 level in terms of resistance to erosion. Similar result was found for calcareous sandstone (Aghajari formation) and anhydrite (Gachsaran formation). Further, results revealed that the resistance of Asmari limestone and marl limestone (Mishan formation) to erosion were significantly different from calcareous sandstone (Aghajari formation) and anhydrite (Gachsaran formation). Conclusion: Generally, results indicated that Asmari limestone was the most resistant rock to erosion (with a 95% confidence interval) followed by marl limestone (Mishan formation), calcareous sandstone (Aghajari formation), and anhydrite (Gachsaran formation).

Background and Objectives: Continuous grazing and treading of animal in non-forage plant species habitats e. g. Astragalus gossypinus and Ferula assa-foetida can considerably affect plant growth and non-forage products (by-products) such as gum tragacanth yield through alteration of soil characteristics. Most studies in rangelands have addressed the relationship between different soil characteristics and forage production, and there is little information on the relationship between changes in soil properties and the amount of non-forage products (such as gum, essential oil, tangerine, assa-foetida, etc. ) in rangelands. Knowing the effect of grazing on soil properties in these habitats and the relationship between soil changes and the amount of by-products is important in determining the optimal grazing intensity for soil and plant conservation and the production of maximum products. This study aimed to investigate the relationship between soil physico-chemical characteristics and gum tragacanth production in Astragalus gossypinus habitats. Materials and Methods: This study was carried out in A. gossypinus habitats at the rangelands of Golpayegan, Isfahan Province, Iran. Treatments included lenient, moderate and heavy grazing intensities in A. gossypinus habitats. Soil and plant (gum tragacanth) sampling were carried out on transect with 100 m length and 100m space from each other in summer 2013. The quantity of gum tragacanth was measured on five randomly selected individual plants on transect lines. Soil physico-chemical variables, i. e., bulk density, porosity, infiltration rate, pH, EC, OC, available P and N were measured with standard methods. Relationship between soil variables and gum tragacanth production was investigated with the Pearson correlation coefficient. Results: The highest and lowest amount of gum production was observed in habitat with light and heavy grazing, respectively. Soil infiltration rate in moderate and lenient grazing intensities was 40. 15 and 32. 17 percent, respectively, lower than that in the habitats under heavy grazing intensity (P<0. 05). Mean value of soil EC in habitat with light grazing was lower than that in the habitats with moderate and heavy grazing intensities (P<0. 05). Mean value of soil organic carbon in moderately grazed habitat was 38 percent greater than that in lightly and heavily grazed habitats (P<0. 05). The highest and the lowest values of P were in heavily and moderately grazed habitats, respectively. Available N in moderately grazed habitat was greater that in lightly and heavily grazed habitats (P<0. 05). In different grazing intensities, there was a negative correlation between soil bulk density and gum production, but there was a positive correlation between soil porosity and infiltration rate with gum production (P>0. 05). All soil chemical variables, except EC, had a direct relation to gum production. Among soil chemical variables, the strongest positive correlation was found between the amount of organic carbon and soil available nitrogen with gum production in moderate grazing (P<0. 05) and the lowest correlation between the amount of available phosphorus and gum production in the light grazing (P>0. 05). In moderately grazed habitats, soil chemical properties had the strongest correlation with the gum production in comparison with light and heavy grazing intensities. In moderately grazed habitats, the amount of soil organic carbon and available nitrogen were significantly and positively correlated with gum production (r = 0. 74; P<0. 05). Conclusion: The correlation between soil chemical properties and gum production was stronger than the correlation between soil physical properties and gum production in A. gossypinus habitats. This study reports that if the livestock grazing is inevitable in A. gossypinus habitats, the stocking rate should not be higher than moderate intensity to obtain more gum as well as maintain soil and plant health.

Background and Objectives: Due to lack of water resources and per capita consumption in Iran, conservation of water resources is one of the most important and basic priorities. Drinking water in Sari city and its dependent villages are provided with groundwater resource. The poor quality of the outlet water especially the high amount of iron after the pressurized sand filters in the refinery of Moallemkola led to investigate the effective factors on the efficiency of the above filters. The purpose of this study is to investigate groundwater resource by changing the bed and surface load of pressurized sand filters to improve the removal of physical and chemical parameters of the water refinery. Materials and Methods: In this study, changes in filter grading were made using pressure filter sand model and using different substrates (silica, silica-anthracite and leca-anthracite) as well as changing their surface charge the physical and chemical parameters of pressurized sand filters were investigated. Samples were taken after treatment at three points in the refinery (at the beginning of the filter operation, at the end of the filter operation and after chlorination) after 4 months. The measured parameters included determination of suspended solids, turbidity, total soluble solids, hardness, calcium, magnesium and iron. The experiments were carried out in factorial and completely randomized design with three replications. Statistical analysis of data was done using SAS software and comparison of means was done by Duncan method at 5% probability level. Results: The results showed that the effect of substrates materials on TSS, Tu, TDS, Ca and Fe parameters was significant at 1% probability level. The effect of sampling point on all parameters was significant at 1% probability level. The silica-anthracite bed had the greatest effect on the reduction of all parameters, especially the reduction of turbidity and iron content. So that the reduction of turbidity and iron content in the silica-anthracite bed was close to 70% relative to the silica bed. The leca-anthracite bed was better than the silica substrate. The best reduction in chemical parameters of water was related to silica-anthracite in pressurized sand filters with a surface load of 54 cubic meters per hour. The interaction effect of different materials inside the filter and sampling point on TSS, TDS and Fe parameters was also significant at 1% probability level. The results of the comparison of the average of the physical and chemical parameters of the water studied at different points of sampling showed that the output water at the end of the disinfection had the lowest values relative to the water outflow from the filter at the beginning of the operation and the outlet water from the filter at the end of the operation. Conclusion: Administration of silica-anthracite in pressurized sand filters in addition to improving the water quality, will reduce the cost of operating (maintenance and repair) of the filters.

Background and Objectives: By regard to climate condition and low irrigation efficiency in our country, encouraging the farmers to use this technology and extending modern irrigation system is inevitable. In this study we attempt that modern irrigation methods has been how effective on productivity agricultural between farmers in province Kerman. And also difference productivity agricultural between modern irrigation and traditional irrigation methods have affected by which factors. Materials and Methods: In this study, consideration productivity agricultural in two modern irrigation and traditional irrigation systems by use Oaxaca-Blinder decomposition method and Recentered influence function model. Then data was analyzed by software Stata. Results: The result of decomposition method showed that ratio of Factors explaining was-17 and factors unexplained was-19 percent that signification. Recentered influence function method showed that in unexplained sector, type seed, amount of seed and use of machine in high decile and labor family in low decile were case gap in productivity. Conclusion: The result showed that share of unexplained factors more than explaining factors. And traditional systems less accesses to resource high yield and use of modern irrigation system, could increase productivity agricultural. Therefore can be increased level of production by improve irrigation system.