JWSS - Journal of Water and Soil Science

To assess the effects of different levels of soil lead on mineralization of organic carbon and nitrogen, a factorial pot experiment was conducted using litter bag method. The factors examined were different levels of soil lead (0, 25, 50, 100, and 200 mg kg^-1soil) and incubation periods (1, 2, 3 and 4 months) in three replications. At the end of incubation periods, the litter bags were pulled out of the pots and the weights of plant residues remained in bags were measured. The plant residues were also analyzed for organic carbon and nitrogen. Organic carbon and nitrogen losses were calculated by subtracting the remaining amounts of organic carbon and nitrogen in one incubation time interval from those of former one later incubation time interval. The results showed that the losses of organic carbon from wheat residues and carbon decomposition rate constant decreased as the levels of soil lead increased over than 25 and 50 mg/kg of soil respectively. The losses of organic nitrogen was more affected by lead pollution and decreased as the levels of soil lead increased, but nitrogen decomposition rate constant decreased as the levels of soil lead increased over than 25 mg/kg. The losses of organic carbon and nitrogen in 200 mg Pb/ kg of soil were 3.2 and 11.7 % lower than control treatment. The results of this research indicate that contamination of soil by lead increases residence time of organic carbon and nitrogen in soils and slows down the cycling of these elements.

Groundwater is a major source of drought. Karstic aquifers are important sources of groundwater in the West and Kermanshah province. This study was performed to investigate the effects of the meteorological drought on the karstic aquifer with different conditions of development. The studied areas in this research included two karstic aquifers, Bistoon-Parau and Patagh mountain in Kermanshah province. In this study, we used monthly precipitation and springs discharge during a period of 20 years.  Accordingly, the SPI and SDI indices were used to investigate the different states of meteorological and hydrological droughts, respectively. To determine the relationship between meteorological droughts and groundwater, Pearson correlation was used; aalso, to determine the time delay, the correlation between the different time conditions (no delay and delay 1 to 6 months) of the SDI index and the SPI index was investigated. The results of the relationship between the meteorological drought and groundwater showed that both had a significant correlation (p-value: 0.01). Also,  based on the results of the correlation between different time conditions (no delay and delay 1 to 6 months) ,the SDI index was compared to the SPI index, showing that the time delay between the occurrence of meteorological drought and groundwater in the studied areas without time delay or a maximum one-month delay had happened. Based on the results, Pearson correlation coefficients between the SPI and SDI indices in the Bistoon-Parav region were more than those of the Patagh mountain region indicating the development of the Bistoon-Parav karst region, as compared with the Patagh Mountain.

The study of the kinetics of non-exchangeable potassium (NEK) release is very important for a better understanding of K availability for plants in different soils. Moreover, aggregates with different sizes have different effects on the release of nutrients. Therefore, the aim of this study was to examine the release of NEK in 5 calcareous soils of chaharmahal-va- bakhtiari province, and small and large aggregates (<250 μm and >250 μm) using CaCl₂ 0.01 M at 25±1ºc for 2-2017 h. The results showed that cumulative released NEK in soils, and small and large aggregates was 173.5-372.7, 215.1-426.1 and 178.9-381.5 mg kg^-1, respectively. The results revealed that coefficients of the cumulative released NEK in small aggregates was lower than those of the soils and large aggregates. Based on the coefficient of determination (R²) and standard error (SE), the released NEK was well described by the first order, the power function, parabolic diffusion, and simplified Elovich equations. The rate coefficients of the release of K were different in different soils. The cumulative released amount of K and its rate of release in a solution of calcium chloride in small aggregates was more than those of large aggregates.

This study was done to evaluate the effect of topography, water table, and irrigation on gypsc soil development and clay mineral diversity in Ram-Hormuz Plain, Khuzestan Province. To localize, 10 profiles in this region that covered all purpose irrigation and topography situation were described. The results showed that the soils could be classified in Entisols, Inceptisols and Aridisols orders. All soil epipedons were ochric and subsurface horizons were cambic, gypsic, and salic. The salic horizons were formed under a low water table. The XRD results showed that smectite, kaolinite, illite, chlorite, palygorskite, vermiculite and sepiolite were the dominant minerals, respectively. Kaolinite and illite were inherited from the parent material, but chlorite was the result of both inheritance and transformation of other clay minerals except uncultivated or non-irrigated soils. Sepiolite was decreased in gypsic horizons, but palygorskite was increased in these horizons. Sepiolite was raised with increasing the depth under the good drainage class; this could be related to neoformation, but it was decreased with depth under the weak drainage class. These results could be due to the instability of this mineral in high moisture and its low Mg activity. There was also a negative correlation correlation between Palygorskite and smectite; this was such that most palygorskite was observed in the surface horizons, but smectite was in the subsurface. Smectite was the dominant clay mineral in the studied soils; it was formed from the weathering of other minerals as well as from neoformed ones in the lowlands. Vermiculite was formed in these soils due to k depletion by leaching or plant absorption. This happened in the illite to smectite transformation process. Therefore, topography and irrigation could be regarded as the main factors putting these soils in high category; also, clay mineral assemblage was different under this situation in these soils.

Exploitation of dam reservoirs is one of the major problems in the management of water resources. In this research, Crow Search Algorithm (CSA) was used for the first time to manage the operation of reservoirs. Also, the results related to the exploitation of the single-reservoir system of Shahid-Rajaei dam, located in Mazandaran province, northern Iran, which meets the downstream water demands, were compared to those obtained by applying the Particle Swarm and Genetic algorithms. Time reliability, volume reliability, vulnerability and reversibility indices, and a multi-criteria decision-making model were used to select the best algorithm. The results showed that the CSA obtained results close to the problem’s absolute optimal response, such that the average responses in the Crow, Particle Swarm and Genetic Algorithms were 99, 75 and 61 percent of the absolute optimal response, respectively. Besides, except for the time reliability index, the CSA had a better performance in the rest of the indices, as compared to Particle Swarm and Genetic Algorithms. The coefficient of variation of the obtained responses by CSA was 14 and 16 times smaller than the Genetic and Particle Swarm Algorithms, respectively. The multi-criteria decision-making model revealed that the CSA was ranked first, as compared to the other two algorithms, in the Shahid-Rajaei Reservoir's operation problem.

The goal of this study was to evaluate tannic acid as a coagulant in turbidity removal. Tests were designed using Taguchi method and carried out on the synthetic and natural turbid samples. In order to optimize turbidity removal by tannic acid, seven factors including pH, coagulant dosage, rapid mixing rate, slow mixing rate, slow mixing time, sedimentation time and initial turbidity were investigated. The results revealed that in optimum conditions,  tannic acid could n remove up to 71 percent of synthetic turbidity and 66 percent of natural turbidity; also, tannic acid showed more coagulation activity in the lower initial turbidities. ANOVA analysis showed that initial turbidity and slow mixing time were the most important parameters in the turbidity removal by tannic acid. In general, this study showed that tannic acid was capable of removing turbidity and could be used instead of common coagulants in the preliminary treatment.

This study covers a large agricultural and industrial area of Isfahan province, including three types of land use, i.e., agricultural, uncultivated, industrial and urban types. A total of 275 samples from surface soil (0-20 cm) were collected and water soluble fluoride concentrations of them were measured. The spatial structure of water soluble fluoride in the soils was determined by omnidirectional variogram in the GS⁺ software. The spatial distribution of water soluble fluoride in the soil was mapped by employing the point kriging method in the SURFER software. The results showed that the mean of the water soluble fluoride concentration in Isfahan soils (0.85 mg L^-1) was higher than the mean world soils (0.53 mg L^-1). The water soluble fluoride showed moderate spatial dependence, indicating that the spatial variability of water soluble fluoride was mainly controlled by intrinsic and extrinsic factors. The mean water soluble fluoride concentration was significantly higher in agricultural and urban areas, as compared with the uncultivated land. This could be due to application of phosphate fertilizer in agricultural areas and the atmospheric fallout of fluoride from the industrial sources such as steel factories. According to the generated kriging map, the higher concentration of fluoride was mainly recorded around the Zayande Rood River and in the central and western parts of the study area.

In this study, the distribution of heavy metals pollution including arsenic, antimony, nickel, copper, cadmium, cobalt, bismuth, lead and zinc in the stream sediments of Zarshuran- Aghdarreh area was investigated by using statistical techniques and the geometric integration of each sample basin. For this purpose, the degree of pollution in 154 stream sediment samples was analyzed and the distribution maps for enrichment factors were prepared by using a combination technique, pixel estimation, and statistical and geostatistical methods. The results of calculating the enrichment factors indicated that the higher enrichment was related to arsenic, antimony, bismuth, cadmium and lead. Furthermore, the concentration of zinc, copper, lead, arsenic, antimony, cadmium and bismuth in the stream sediment samples was higher than the global average. Application of the principal component analysis on the data led to the recognition of 9 main components for the dataset; the first 5 were components with eigen values greater than 1 and a cumulative percentage more than 85%. Arsenic, antimony, cadmium, lead and zinc in the first component, cobalt in the second component, bismuth in the third component, copper in the fourth component and nickel in the fifth component had the highest values.

In order to investigate the flow formation on dunes, the experimental data from a flume 12 meters long, located in Hydraulic Lab at Technical University of Graz (Austria), were collected. In this study, dunes (particle sizes of 13 and 6 mm) in a 2-D plan were developed with the wavelength of 1 meter, the lee angle of 8 degree, and the crest heights of 4 and 6 cm; these were uniformly installed across the width of flume. The analysis of the experimental flow velocity profiles measured by ADV and PIV technology and the numerical profiles modeled by SSIMM showed that in the same hydraulic conditions, there was no significant relation between drag coefficients of particles on dunes and flow discharge variation, while the water depth reduction caused a sudden increase in the drag coefficient up to 66%. Also, reducing particle size of the dune increased the drag coefficient and there was a significant relation between particle size (diameter) and dune formation, so that in smooth crested conditions, as compared with the sharp crested dune, the drag coefficient was increased up to 32%.

Trees crown can be regarded as main factor contributing to the conservation and support of soil in many ecosystems including semiarid forests in Zagross. The aim of this study was to find out the effect of tree crown of pictachio (Pistacia atlantica Desf) on N, OC, P, pH, EC and the texture of the soil. Soil samples were collected in and outside the crown of 5 single pistachio trees on four directions of each tree in a northern slope from the 0-5 cm depth of soil in the Sarvabad region, Kurdistan. The results of this study showed that the amount of the soil organic carbon was decreased from 6.71% in the soil inside tree crowns to 4.73% in the soils outside the tree canopies. The soil inside trees had a higher concentration of soil nitrogen (0.406%) than the one outside (0.224%) the tree crown; the concentration of phosphorus was measured to be 32.7 mg/kg in the soil inside canopy, while it was 21.1 mg/kg in the soil of outside the tree canopy. EC under the tree crowns was more than that outside the canopy. The results, therefore, showed that soil texture was lighter inside the canopy, as compared to outside; however, the acidity of the soil was not affected by tree crowns and no significant differences were observed in different areas of the crown. Therefore, Persian turpentine trees have positive impacts on the soil properties in Zagros forests and eliminating them will lead to the significant loss of soil fertility and greater soil erosion.

Emitter clogging for using agricultural wastewater increases the operating costs and reduces the motivation of farmers. The new method to reduce the emitters clogging is the use of a Merus ring that does not have the problems of chlorination and pickling methods, such as pollution and high cost. Due to the importance of agricultural wastewater use, this study investigated the emitters clogging and the effect of Merus ring on the emitter's efficiency in a trickle irrigation system. The treatments including irrigation water (well water and wastewater) and modified water (irrigation with Merus ring and irrigation without Merus ring), as the main factor and the emitters type treatment including Irritec (D₁), Corona (D₂), Axios (D₃), Netafim (D₄), Polirood (D₅), and Paya (D₆) as the sub treatments were performed in three replications. The results showed that the agricultural wastewater caused the emitters clogging in irrigation water and modified water treatments, but over time, the Merus ring had a positive effect on the evaluation parameters of the emitters. For agricultural wastewater, in the first and last irrigation periods, the average discharge of emitters with the Merus ring was 0.05 and 0.33 Liter per hours, respectively, more than the treatment without the Merus ring. The uniformity coefficient of emitters in the first and last irrigation periods, in well water with the Merus ring, was 0.31%and 6.67%, respectively, more than that in the well water without the Merus ring. Also, the uniformity coefficient of emitters in the first and last irrigation periods in agricultural wastewater with the Merus ring was 0.85% and 12.10%, respectively, more than that in agricultural wastewater without the Merus ring. At the end of irrigation period, the results showed that Netafim and Axios had the best and weakest efficiency, respectively. In general, the emitters used in the treatment of well water with the Merus ring had the highest discharge and the emitters used in the treatment of wastewater without the Merus ring had the lowest discharge.

The growth of world population and the demand for agricultural products can be regarded as one of the important issues that humanity has ever faced. There are serious concerns regarding surface and ground water pollution by nitrates because of using nitrogen fertilizers in the agriculture. Improving agricultural water management systems can reduce nitrate in drainage outflow and therefore, reduce the environmental pollution. This research was conducted to evaluate the effect of the controlled drainage and nitrogen fertilizer on nitrate leaching and environment pollution as a factorial randomized complete block design in Shiraz College of Agriculture. The treatments consisted of three fertilizer levels; 0, 200 and 300 kgN/ha, and three water table depths: free drainage, control water table at 60cm (CD60) and 90 cm (CD90) depths, respectively. According to the results, the value of drainage water and nitrate losses in the controlled drainage toward free drainage were significantly increased. The mean reduction of drainage water in CD60 and CD90, as compared to free drainage, was 59.3 and 35.7%, respectively. The decrease nitrate losses, as compared to free drainage, was 72 and 44%, respectively. The total value of nitrate leaching in 200 and 300 kgN/ha fertilizer treatments was 1.86 and 2.48 times of 0 kgN/ ha.

Understanding the distribution of different P forms in soil aggregate fractions is important in evaluating the risk of P run-off and leaching in the agricultural soils. The objective of the present research was to determine the effect of aggregate size on soil phosphorus availability and fractionation in 10 calcareous soils. Micro aggregate (< 0.25 mm), macro aggregate (> 0.25 mm) and whole soil were separated by dry sieving. Olsen P, total P, organic P, and inorganic P fractions in micro aggregate, macro aggregate, and whole soil were determined. Soil inorganic P fraction was  determined by a sequential extraction procedure including: dicalcium phosphate (Ca₂-P), octa calcium phosphate (Ca₈-P), apatite (Ca₁₀-P), P absorbed by Al oxide (Al-P), P absorbed by Fe oxide (Fe-P) and P incorporated in to Fe oxide (O-P). The results showed that the amounts of (Olsen P), (Ca2-P), (Ca8-P), (Ca10-P), (Organic P), (Al-P), (Fe-P), (O-P) and (Total P) in 70, 60, 40, 40, 60, 70, 60, 50 and 70 percent of soils, respectively, in the micro aggregates were significantly higher than those of the macro ones. Finally, by increasing the P content, particularly the smaller sized aggregates, it was likely that the eroded material would favor greater P loss.

Over the years, since the beginning of the national and infrastructural project of Development and Renovation of Paddy Fields of Iranian Northern provinces, it has been essential to evaluate water distribution and delivery Performance of the project to get its feedback in the pursuit of the desired goals. However, the results of the evaluation of a system can reliable when they are based on quantitative indicators, not on personal opinions and empirical judgment. So, in this study, Total Error (TE) of performance of water delivery system, a statistical indicator, and its component including adequacy, water management capability and equity errors were calculated and compared for two concrete and earthen irrigation canals. This analysis was done based on calculating water demand and measuring the volume of delivered water between outlets during the irrigation season in the paddy fields of Esmaelkola of Joybar city, in 2015. According to the results, although the concrete channel (0.28) had less error than the earthen channel (0.43) and in the concrete channel, as compared to the earthen channel, the share of the components of adequacy and water management capability from the total error was dropped from 47% to less than 10%, but the error in the water delivery of the concrete channel was still high due to the error in the equity of distribution, whose value was 0.25 (90% of the total error). Therefore, in order to reduce the performance error, after channel lining, it would be necessary to make fundamental changes in the intake and flow control structure in addition to the training of irrigators regarding water delivery based on water demand.

In this study, the WEAP model was used for the simulation and the Gravitational Search Algorithm (GSA) was applied as the optimization model. Due to the necessity of multiple simulations in the optimization process to achieve the optimal solution, the linkage of simulation and optimization models was done in the MATLAB software environment. To evaluate the performance, hedging policies achieved in the base period were investigated for the near future period under climate change. The results showed the poor state of aquifers under the baseline scenario; also, the continuation of the current management caused the Zayandehrood river basin to experience significant problems. So management of water resources using conjunctive hedging policies could improve the situation. The use of conjunctive hedging rules showed 11 percent increase in the group sustainability index for demands, in comparison with the baseline scenario. Also, according to the group sustainability index for the resources, applying the conjunctive hedging policies could increase the sustainability of surface water and groundwater resources as much as 5.2 and 6 percent, respectively, relative to the baseline scenario. The results also indicated the better performance of conjunctive hedging policies in comparison to the baseline scenario policies.

Soil erosion by water is a serious environmental problem, particularly in semi-arid regions. In these areas, water loss strongly affects soil loss as well as soil productivity in the rainfed lands. Determination of appropriate seed density for each tillage direction is vital to achieve high crop yield and to prevent soil and water losses. This study was conducted to investigate the combined effects of tillage direction and plant density on the soil and water losses in a rainfed land. Twelve crop plots with the dimensions of 1.5 m × 5 m were installed to investigate the effect of two tillage directions (up to the down slope and on the contour line), two seed densities (90 and 120 kg h^-1), a three replications in a rainfed land with 10% slope steepness. Soil and water losses were measured in each plot during the wheat growth period (from October 2015 to June 2016). Significant differences were found between both tillage direction and plant density in the runoff (P<0.05) and soil loss (P< 0.001). Runoff and soil loss in the up to down slope tillage was 4.16 and 4.08 times bigger than the contour line tillage, respectively. Runoff and soil loss with the seed density of 120 kg h^-1­ ­­were 11.25 and 26.32% lower than those with 120 kg h^-1­, respectively. This result was associated with the increased cover crop and its control on water flow and the enhancement of water retention in the soil. There was no significant interaction between tillage direction and plant density in the runoff and soil loss. The importance of tillage direction in the soil and water loss was very larger than that of the plant density. The application of 120 kg ha^-1 seed density on the contour line could, therefore,   considerably prevent soil and water losses in the rainfed lands.

Preferential flow is of great importance in the environment and the human health. So, rapid water transportation and consequently, pollutants and pesticides leak out and get into the groundwater, making it very difficult to measure and quantify. To quantify and describe the preferential flow, two gravity-driven models were used: 1) kinematic wave model (KW) introduced by Germann in 1985), and 2) kinematic dispersive wave (KDW) model developed by applying a second-order correction to the Germann’s model by Di Pietro et al. in 2003. So, the experimental data was obtained using the laboratory mini-rainfall-simulator over cylindrical soil samples at the laboratory. Their parameters were obtained using Solver add-ins in the Excel software. Then, the results were compared using the root-mean-square error (RMSE). The results showed that the KDW model could better predict the preferential flow (with lower RMSE). Also, the regression results showed 1) there was no significant relation between the preferential flow and the total porosity, and 2) there is a significant relation between the preferential flow and the macrospores.

With regard to the crisis of water resources in the country, overdraft of groundwater resources has caused undesirable situation for most of the plains. On the one hand it is necessary for the stability of the resources are constantly using these resources, future generations need to be considered. In this regard, in this study make a cropping pattern with aims to develop a sustainable supply of groundwater resources in the Baghmalek plain has been considered. In this study, time series variables technique are used for predicting future values of variables. Also, the dynamic programming model, is used to determine the cultural pattern. Information needed for this research in two ways questionnaire and the use of statistics resource of agri-jahad and Khuzestan province`s water and power organization in 2013, has been collected. The results show that water input is considering as a limited production factor in the agricultural sector of the region. In addition, using of above pattern, will make fundamental changes in the region`s cropping pattern. The use of modern irrigation methods can increase the agricultural production capacity to double size. The main proposed of study is choosing the patterns that consider intergenerational sustainability about scares inputs such as water.

The effects of climate change can be released from the surface to the soil depth, thereby affecting soil thermal regime. Thermal energy in the soil plays a very important role in causing climate changes. In this study, for the assessment and detection of  the climate changes, soil depths temperature, the measured data related to the  daily air temperature at a height of 2 meters (screen) during the years (1951-2014), and the soil depths daily temperature (5-10-20-30-50 to 100 cm), for 3, 9 and 15 hours, were obtained during a period (1992-2014) in Shahrud station. The climate change detection was employed to compare the treatment mean. As well, for detection of trends related to the annual, seasonal and monthly time series and their relation to the soil depths temperature, parametric methods (regression analysis and Pearson) and nonparametric (Mann-Kendall, Spearman) were applied. The results showed that the soil temperature was increased in all months except January, February and March. Also, in the seasonal time series, the soil depths temperature was increased in all seasons except winter. In fact, based on the results, the soil temperature in spring, summer and autumn was increased. Detection trends of the annual soil depths temperature showed that, except for the Pearson correlation coefficient method, soil temperature was increased at all soil depths.

Evaluating the possible relationships between vegetation and environmental characteristics can assist managers to identify effective factors influencing plants establishment and to characterize various vegetation communities. This study was aimed to evaluate the effects of long term grazing exclusion ( more than 33 years) and the controlled grazing system (resting – rotation grazing system) on the vegetation distribution and some soil properties in the Hamzavi research station in Hanna area-Semirom, Isfahan. Six transects (three parallel transects and three transects perpendicular to the general slope of the area) were established in each area and 10 square plots with the size of 2m² were placed along each transect; then, the cover percentage, production and list of all plant species were recorded. In each area, eighteen plots were collected randomly and in each plot, five soil samples were collected from 0-30 cm of the soil and then the samples were mixed and one sample of the compound was selected as an evidence plot. Soil properties such as pH, EC, CaCO₃, organic carbon, absorbable phosphor, total nitrogen, K, Ca, Mg, soil saturated percentage, cation exchange capacity, soil clay, silt, sand and fine sand contents were measured in the soil laboratory. The independent t test was used to compare the vegetation characteristics in two areas. Cation exchange capacity, CaCO₃, gravel percentage, soil phosphor content and grazing management were identified as the most discriminative factors in separating vegetation communities based on Canonical correspondence analysis (CCA) and cluster analysis. Controlled grazing management significantly modified some soil characteristics and increased the production (352 versus 184.2 kg/ha) and vegetation cover percentage (25.46 versus 18.37), as compared to the exclusion area (α= 5%). The vegetation density was increased significantly in the exclusion rather than controlled grazing area (3.03 versus 2.02 plant/m²). This study, therefore, revealed that controlled grazing management was more effective on improving some soil quality and vegetation characteristics rather than p long term grazing exclusion in the semi-arid ecosystems. So, avoiding long term grazing exclusion in semi-arid rangelands is suggested.