JWSS - Journal of Water and Soil Science

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Zeolites are substances that have been renowned for their remarkable nitrogen adsorption capacity resulting of decrease in leaching rate of soil nitrogen. This research was conducted to study the effect of the zeolite dosage, zeolite particle size and the method of application on the nitrate leaching of the soil irrigated by treated wastewater (TWW). All of the adsorption tests were carried out in a 27 PVC columns with 11 cm diameter and 60 cm length. The experiments were consisted of 9 treatments and 3 replications including 2 zeolite application method (mixed and layered), 2 zeolite’s grain size (63-125 and <63 micrometer) and 2 zeolite dosage (2 and 4 percent). Zeolite powders were added to the soil in mixed or layered fashion. The soil columns were irrigated 13 times with TWW in a weekly period. In the 4th, 9th and 13th irrigation event, three samples were taken from input and output TWW introduced to columns to measure the change in nitrate concentration. The results were shown that nitrate absorption rate was increased by average of 164.3% and 350.7% in mixed and layered treatments, respectively compared to the control. The result showed that zeolite application method, irrigation event, zeolite’s grain size and dosage were statistically significant on nitrate absorption efficiency (P<0.01). It shows that as the zeolite size decrease the soil nitrate adsorption increases significantly. It increases when the zeolite percentage increases. The result show that the soil nitrate adsorption decreases as the irrigation event increase and soil adsorption potential degraded with irrigation events.

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The aim of this study was to investigate the effect of parent materials and pedogenic processes on distribution of Pb, Zn, Cu, and Ni in the residual soils derived from different parent materials in the Binaloud zone, western Mashhad. Two soil profiles on the summit of granitic, ultrabasic and metamorphic rocks were described and sampled from their genetic horizons. Pseudototal concentrations of selected heavy metals and fractions of these metals were determined using aqua-regia and sequential extraction methods, respectively. 178.1-419.7 mg kg-1of Ni in ultrabasic soil versus 0.7-27.5 mg kg-1 in the granitic soil make the Ni a distinctive element in the studied area. Cu with the average contents of 60 and 56.3 mg kg-1 in the ultrabasic and metamorphic soils respectively showed more concentration in comparison to granitic soils with 12.1 mg kg-1. The amount of Zn was not significantly different among the soils, although the average of this element in the granitic soil (55 mg kg-1) is slightly more than the other soils. Pb was only detectable in the surface layers of all pedons reaching up to 6 mg kg-1. Residual fraction except Ni and Cu in granitic soil was the main fraction for all of the studied heavy elements that was expectable according to the low weathering intensity of the soils. The eolain addition of gypsum and carbonates have influenced heavy metals concentration, especially in surface horizons. In conclusion, the amount of heavy metals was significantly affected by parent materials and the eolian deposition must be considered as the secondary influencing factor.

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Phosphorus behavior in waterlogged soils is significantly different from non-waterlogged soils. Changes in available phosphorus and inorganic phosphorus fractions after waterlogging in the paddy soils of north of Iran were studied in a laboratory research. A factorial experiment in a completely randomized design with two replications was performed with factors of soil at 14 levels (10 alkaline-calcareous and 4 non-calcareous or acid soils) and duration of waterlogging period at three levels (0, 30, 90 days). At the end of waterlogging period, phosphorus fractions in calcareous soils by Jiang and Gu method and in non-calcareous soils by Kuo method and available-P by Olsen method were determined. The results showed that the level of available-P in all soils was increased 90 days after waterlogging (on the average 2.3 times). In general, all P fractions were changed significantly after waterlogging and the amount of change was different depending on P fraction, soil type, and duration of waterlogging period. These results indicated the complex behavior of P in soils. The Al-phosphates were increased in 12 out of 14 calcareous and non-calcareous soils 90 days after waterlogging compared with air-dry soil. The Fe-phosphates were decreased in 9 out of 10 calcareous soils 90 days after waterlogging compared with air-dry soil while the effect of duration of waterlogging period on the Fe-phosphates in non-calcareous soils was not significant. The readily soluble-P in non-calcareous soils increased 30 and 90 days after waterlogging. The results indicated that some inorganic P fractions transformed into other fractions and probably organic P transformed into inorganic P during soil waterlogging period.

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One of the main objectives of soil classification systems is to identify the differences of soil properties for management purposes. In this study, the efficiency of American and WRB soil classification systems were compared in order to describe some of soil physical, chemical and mineralogical properties in arid and semiarid regions of central Iran. Khatoon-Abad and Mobarekeh plains as arid regions and Koohrang and Shahrekord plains as semiarid regions were selected. Then, representative pedons of each plain were chosen from 16 excavated pedons and soil samples were taken from the genetic horizons to determine soil classification. Results showed that soil orders of both Koohrang and Khatoon-Abad plains are vertisols according to American soil classification system whereas based on WRB system, these soils are classified as cambisols and calcisols, respectively. On the other hand, both Mobarekeh and Shahrekord soils are classified as calcisols in WRB system whereas these soils are classified as aridisols and inceptisols, respectively, according to American soil taxonomy. None of soil classification systems could show the existence of gypsum in horizons lower than 100 cm of the soil surface for Mobarekeh soil. Clay mineralogy indicates that smectite is the dominant clay mineral in Koohrang soil as explains well at the family level of American soil classification system. Results suggest that WRB has somewhat higher efficiency rather than American soil classification system for the studied soils.

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The purpose of this study was to measure daily and seasonal evapotranspiration and daily crop coefficient of two common varieties of sunflower (Sirna and Euroflor) via drip-tape irrigation system. For this purpose, the sunflower water use was determined by daily monitoring of soil moisture at the depths of 10, 20, 30, 40 and 60 cm, and the crop evapotranspiration (ETC) was measured using volume balance method. According to the equation recommended by FAO, the obtained value of KC for Euroflor and Sirna varieties at the initial stage was 0.32. According to volume balance method, the Euroflor KC value for development, middle, and late stages were found to be 0.75, 1.18 and 0.9 and for Sirna were found to be 0.72, 1.15 and 0.84 respectively. Seasonal amount of evapotranspiration for Euroflor and Sirna varieties was equal to 601 and 575 mm, which was 26 and 30 percent less than seasonal ET0 in Isfahan. The average value of during the sunflower growing season was 0.77, which was greater than that offered by Doorenbose and Pruitt (0.55). As the crop coefficients of two varieties were different during the growing season and they were also different from FAO KC, measuring the actual amount of KC as a function of growing degree days can increase the accuracy of the estimated ETc and help develop the crop models in order to improve the irrigation management.

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Comparison of the land suitability variations among the soil map units in viewpoint of pedodiversity indices may provide a good assessment of the soil mapping precision. The main objective of this study was to assess the significance of functional pedodiversity thorough two detailed map units for irrigated wheat and potato for class and subclass levels of suitability in the Faradonbeh plain, using Shannon and Simpson indices. First, soil samples at 35 and 47 sampling sites in the D and E map units, respectively, were collected from the depths of 0-25, 25-50, 50-75 and 75-100 cm. Then, the qualitative land suitability class and subclass of all sampling points for each studied land use, was evaluated based on simple limitation method. Although both indices showed higher values in the subclass level of suitability, but the average functional pedodiversity of the studied map units, indicate a significant difference (95% confidence level), just in this suitability level. It was observed that the significance of the pedodiversity indices is not influenced by the land use type or the analyzed diversity index. Hence, as a supplementary procedure to study the intra-unit variation of the soil maps, use of diversity indices may provide some worthwhile information

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Usually, dry soil readily absorbs water .However, not all soils display such characteristics. Some soils (hydrophobic soils) show resistance to wetting. Because of the importance of this subject and lack of research, we evaluated the effect of heating on water repellency and some of soil physical and chemical characteristics. So soil was combined with compost and heated at deferent temperatures, 100, 200, 300, 400 and 500 °C for 30 minutes in an oven or muffle furnace. The results showed that control treatment and heated soil at 300 °C had WDPT and MED 45 (s), 17% and 80 (s), 23% respectively. So, little water repellency was present prior to heating the soil. When soil was heated up to 300°C, intense water repellency resulted, but it was abruptly eliminated by increasing the heating. The soil texture was changed from loam to sandy loam at high temperatures (400 & 500 °C) and the sand percentage was increased. Organic matter decreased by increasing the temperature. Amount of pH decreased up to 200 °C and then increased at 500°C because of increasing ash in soils. Diminution of mineral and organic matter caused EC to decline in all the heated soils.

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Biocalcite infilling and bridging in a sandy soil was studied in the present research. Effects of 2 bacterial species (Sporosarcina pasteurii and Sporosarcina ureae), 3 reactant concentrations (0.5, 1.0, and 1.5 M of urea and CaCl₂ mixture), and 6 reaction times (12, 24, 48, 96, 192, and 288 hr) on saturated hydraulic conductivity and mechanical strength of a sandy soil were studied as a factorial experiment. Soil samples were selected from sand dunes of Joopar area, Kerman Province. Bacterial inoculums and reactant solutions were daily added to soil columns. Results of the study showed that S. pasteuriihad had a higher effect on decreasing hydraulic conductivity of the treated samples (11.57 cm/h) compared to the blank (41.61 cm/h) than S. ureae. Increasing reaction times (from 12 to 288 hrs) and reactant concentrations (from 0.5 to 1.5 M) decreased hydraulic conductivity by 49 and 16 %, respectively. S. pasteurii increased strength of treated samples up to 2.6 Mpa pressure compared to S. ureae. Reactant concentrations and reaction times increased soil strength significantly (2.13 and 4.1 Mpa, respectively). Micromorphological observation showed calcite crystals bridging soil particles and filling pore spaces.

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Phytoremediation models are important to understand the processes governing phytoremediation and the management of contaminated soils. Little effort has been made for evaluating the potential of the phytoremediation of metals based on the mathematical models. Therefore, the purpose of this study was modeling the phytoremediation of the nickel-contaminated soils. For this purpose, a model was recommended for estimating the rate of the phytoremediation of nickel from the soil by means of relative transpiration reduction and concentration of nickel in the plant functions. To evaluate the model, soil was contaminated with different levels of nickel by nickel nitrate. Then, the pots were filled with contaminated soil and Basil (ocimum tenuiflirum L.) seeds were planted. To avoid the dry tension, the pots were weighed and irrigated to the point of field capacity (FC) at short time intervals (48 hours). The plants were harvested in four times. At each harvesting stage, the relative transpiration values and nickel concentration in the soil and plant samples were measured. The performance of the model was evaluated by statistical methods such as Maximum Error, Root Mean Square Error, Coefficient of Determination, Efficiency of Model and Coefficient of Residual Mass. Results demonstrated that in the case of nickel contamination in soil, changes in the relative transpiration of Basil can be measured by the two proposed models and the linear model (R2=0.94) has a better performance compared to the nonlinear one (R2=0.84). Also the model obtained from the combination of linear function and nickel's concentration in soil has a relatively good (R=0.7) fit with the measured values of the remediation rate of nickel in soil.

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Soft computing techniques have been extensively studied and applied in the last three decades for scientific research and engineering computing. The purpose of this study was to investigate the abilities of multilayer perceptron neural network (MLP) and neuro-fuzzy (NF) techniques to estimate the soil-water retention curve (SWRC) from Khozestan sugarcane Agro-Industries data. Sensitivity analysis was used for determining the model inputs and appropriate data subset. Also, in this paper, the van Genuchten and Fredlund and xing models were used to predict SWRC. Measured soil variables included particle size distribution, organic matter, bulk density, calcium carbonate, sodium adsorption ratio, electrical conductivity, acidity, mean weight diameter, plastic and liquid limit, resistance of soil penetration, water saturation percentage and water content for matric potentials -33, -100, -500 and -1500 kPa. The results of this study in terms of various statistical indices indicated that both MLP and NF provide good predictions but the neural network provides better predictions than neuro-fuzzy model. For example, using MLP and NF models values of NMSE at prediction &theta;s, &theta;r, &alpha;, n and m in Fredlund and Xing equation corresponded to (0.059, 0.065), (0.154, 0.162), (0.109, 0.117), (0.129, 0.135) and (0.129, 0.145), respectively. Furthermore, &alpha; and n parameters at the first depth, and &theta;r and &alpha; parameters at the second depth in Fredlund and Xing equation were estimated with higher accuracy compared with equivalent parameters in van Genuchten equation

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The aim of this study was to evaluate soil properties changes in a soil toposequence series in Khuzestan province. Twelve soil profiles were dug in north to south direction in this province, according to the changes of the slope in Karoon’s alluvial deposits. The results showed that soil texture regularly changes to heavier form from north to south. It was slightly of redoxomorphic features in low land. Therefore, salic horizon was formed in this land. Despite high water table in this area, gray or mottle forms were few due to high soil salinity. The carbonates were eluviated from surface to subsurface horizon therefore, calsic horizon was formed due to illuviation. Secondary carbonate accumulation was maximum in the studied area. Both classic horizon and cambic horizon were formed in some pedons under long time cultivation in north regions. These developments were originated from organisms that grew under good drainage class. The smectite was seen in the south part of region. It may have been transported by river and deposited under high salinity and flocculated in contact to Persian Gulf’s saline water. The palygorskite was not seen in all patterns. This clay was removed in pedons under long time cultivation in the north area due to more leaching. High irrigation water can accelerate palygorskite transformation. Also, the XRD patterns showed that chlorite, illite, kaolinite and quartz were main clay minerals in the studied soils.

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Phytoremediation is one of the cleanup methods of polluted soil that is possible accumulation of heavy metals in plant tissues, exclusion of these elements from contaminated soil. Therefore, to achievement the objective, this research was done in pot culture using completely randomized design at the University of Birjand in 2011. Two species Spinacia oleracea and Lepidium sativum were used to remove or reduce the concentration of Cadmium (Cd) and Chromium (Cr). In this study, different levels of Cadmium (CdCl2) concentrations including 5, 50, 100 mg kg-1 and also chromium (CrCl3) concentrations 50, 100, 150 mg kg-1 were used respectively and control as well for each species with three replications. Results indicated that the Cd and Cr concentration in shoot of Spinacia oleracea and Lepidium sativum significantly affected by their concentration in soil (p<0/01). Results revealed that increasing of Cd and Cr concentrations in soil, showed an increase concentration of both metal in shoot of Spinacia oleracea. increasing of Cd concentrations in soil, showed an increase concentration of it in shoot of Lepidium sativum but the concentration of Cr was less. Also, comparison of cadmium and chromium concentrations in shoot of Spinacia oleracea and Lepidium sativum showed that two species showed same behavior of Cd and different behavior Cr concentration. So the analysis of data showed that both of species are appropriate for absorption of Cd and Cr and phytoremediation technology as well. It can be concluded that in high soil Cr concentration for phytoremediation Lepidium sativum is not appropriate.

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Reduction of quality and soil productivity due to organic carbon losses is one of the most important consequences of land use changes, that creates irreparable effects on the soil. To evaluate the land use effect on the amount of soil organic carbon in Vertisols, Sartip Abad series with extent of 1850 hectare in south of Bilehvar area in Kermanshah province was studied by using the completely randomized block design in factorial experiment with 10 repeats in farmland and grassland, some soil physical and chemical properties in two Lands compared with each other. The results showed that the soil organic carbon in surface horizons of grassland has been more than farmland and accordingly increase the amount of sequestrated carbon in grassland. No significant differences were found in the amount of soil organic carbon in lower horizons of two lands. Due to land use change from grassland to farmland, noticeably increase in Bulk density, Nitrogen, Acidity, soil Electrical Conductivity and decrease the organic carbon percent and the soil organic material. Pedutorbation, clay amount (higher of 50%), numerous small subsoil, and stable structure are the important factors in saving the organic carbon of vertisols that can reduce the effects of land use changes on organic carbon amount. Generally, it can be conclude that: the land use changes not only can create the severe damage on soil physical and chemical properties but with the carbon losses and more release of greenhouse gases exacerbate the pollution of environment which endangers the life in a earth planet.

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The aim of the study was to investigate the effects of land use on soil quality parameters using multivariate statistical analysis. Soil samples (0-25 and 25-50 cm depths) were taken from three land uses in forest area of Marivan including forest, rangeland, and cultivated land. Soil characteristics of pH, EC, sand, silt, clay and CaCO3 content, water-stable aggregates and their organic carbon content were measured. Principal component, cluster and discriminant analyses were used to evaluate the soil quality. Principal component analysis classified soil properties into five factors. The most important factors were soil aggregates organic carbon content and aggregate stability indices. Schematic distribution of factors and also cluster analysis showed the same pattern. Soil aggregates organic carbon content, water-stable aggregates and aggregate stability indices were the most sensitive factors to land use changes. These soil properties and factors had the same pattern in forest and rangeland, but significantly reduced in the cultivated land use. Land use change from forest to cultivated land resulted in significant decrease of aggregates organic carbon content, water-stable aggregates and also an increase of pH. The results showed the usefulness of multivariate statistical methods for integration of the soil properties and determination of different soil quality indices.

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Soil aggregate stability is considered as a key indicator of soil quality and health assessments in rangelands. Many factors and properties such as soil texture, organic carbon, calcium carbonate, sodium adsorption ratio, and electrical conductivity might affect soil aggregate stability. The effects of these factors on aggregate stability of 71 soil samples collected from 4 rangeland sites (2 in semi-arid and 2 in arid lands) in Isfahan province were investigated. Aggregate stability was measured using the wet-sieving method. To optimize the trial conditions for the investigated soils, three shaking times (5, 10 and 15 minutes) were used to impose different hydromechanical stresses on the aggregates of ten soils selected out of the studied soils. The structural stability was assessed using mean weight diameter (MWD) and geometric mean diameter (GMD) of the water-stable aggregates. Significant differences of MWD were observed between the shaking times. The 10-min shaking was selected as best for structural stability assessment in the studied regions because it resulted in better differentiation of soils on the basis of structural stability. Among the intrinsic properties, soil organic carbon content had the most important role in aggregate stability in all zones. However, electrical conductivity (in addition to organic carbon content) had an important role in aggregate stability in the arid rangelands. Log-normal distribution and GMD could represent better the aggregate size distribution when compared with normal distribution and MWD in the studied regions. Overall, wet-sieving method with shaking time of 10 min is suggested to assess the soil structural stability in rangelands of Isfahan province. Therefore, soil aggregate stability and the factors affecting this vital indicator can be used efficiently for assessing and monitoring management effectiveness and rangeland functionality trend.

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Topography and land use are among the most important factors affecting the soil formation. Chemical forms of Fe and magnetic susceptibility (&chi;) are widely used for the evaluation of soil development. This study was conducted in order to determine the effect of these factors on &chi;. A toposequence was selected in Madvan Plain, Northern Yasouj. Nine soil profiles (paddy and dryland soils) were dug and sampled from diagnostic horizons. Magnetic susceptibility was measured by Bartington Dual Frequency, MS2 Meter at frequencies of 0.46 and 4.6 KHz. Results indicated that less amounts of &chi;, frequency dependence of &chi; (&chi;fd%) and CBD extractable Fe (Fed) (3.1, 2.6 and 2.7 times, respectively), and more quantities of oxalate extractable Fe (Feo) and Feo/Fed ratio (5 and 7.2 times, respectively) were measured in paddy soils. The highest value of &chi; was observed in pedons located on plateau and piedmont plains, and the lowest belonged to those located on river terraces with aquic conditions. Compared to paddy soils, &chi; enhancement at soil surface was greater (17%) in dryland soils. A positive correlation existed between &chi; and some soil characteristics such as Fed, clay content and &chi;fd%.

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CEC of the soil is the exchange sites of organic and inorganic soil colloids. Modeling and Estimation of CEC is a useful indicator for fertility. The new alternative approaches for estimating CEC are indirect methods based on intelligent models. In this research in order to estimate CEC, 485 soil samples were prepared from two regions, chaparsar (Mazandaran in northern Iran) and Bostanabad (North of West Azarbaijan, Iran).In this paper introduces the application of genetic programming. Input parameters that are percent Clay, Organic Carbon and Silt, evaluate using genetic programming, neural network and Neural Inference Systems-Fuzzy models. The results indicate a good ability to intelligent models for CEC Estimation According to indices used in this study. Genetic programming model with a root mean square error of 1.78 and coefficient of determination 0.95 compared to other models have been more efficient and is able to provide satisfactory results, Also are the explicit solutions that reflect the relationship between input an output variable, was presented based on genetic programming. This preferred the genetic programming model adds the other models. Stepwise regression analysis to determine the contribution of each of the parameters indicated in the CEC that organic materials having Most coefficient of variation of 84% is justified CEC and clay and silt, respectively, with a correlation coefficient of 10% and 6% respectively.

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In the present research, the performances of six empirical models, i.e., simple threshold exceedance, fixed proportion exceedance, quadratic function of storage, power function of storage, cubic function of storage, and exponential function of storage were investigated for estimation of groundwater potential recharge in a semi-arid region. First, the FAO Dual Crop procedure was used to calibrate evaporation from bare soil during the occurrence of potential recharge period. Then, the empirical models were calibrated utilizing soil moisture and potential recharge data. For validation of empirical models, soil moisture and potential recharge were simultaneously estimated for an independent event. Results indicated that 5 of the six models (except for the simple threshold exceedance model) were able to estimate potential recharge with a reasonable accuracy, showing the maximum computed value of NRMSE (Normalized Root Mean Square Errors) of 24.4 percent. According to validation results, exponential, cubic, and power function models provided better estimation of potential recharge in comparison with the linear models. Also, all of the applied empirical models were able to simulate soil moisture during the recharge period with an acceptable accuracy. Finally, the exponential model with minimum NRMSE value for soil water simulation and also acceptable performance of potential recharge estimation was recommended for estimation of potential recharge in the study area.

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Texture fractal dimension is a physical index to describe soil particle size distribution having a variety of applications. Fractal dimension may be calculated from three relations of mass-time, mass-diameter and modified mass-diameter (Kravchenko-Zhang) with two linear and nonlinear options for fittings. The aim of the present study was to compare methods and select an appropriate one and fitting option for determining the fractal dimension using hydrometer data. Sixty soil samples were collected from four fields of Taqanak, near Shahrekord. After removal of organic matter and other initial treatments, hydrometer readings were obtained at 0.67, 1, 2, 5, 15, 30, 60, 120, 180, 1440 and 2880 minutes and were converted to mass-time or mass-diameter data. Nonlinear fitting of the Kravchenko-Zhang mass-diameter relation was selected as the most appropriate method of calculating the fractal dimension of solid particles, due to its highest coefficient of determination and smallest mean square error and lowest Akaike Information Criteria. Error analysis also confirmed this conclusion. There was a significant, though not very strong, relationship between the fractal dimension obtained by linear and nonlinear fitting of mass- diameter and Kravchenko-Zhang mass-diameter methods. These relationships can be used to correct the fractal dimension determined by other methods and fitting options.

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Evaluation of chemical and biological indicators of soil in different land uses could be helpful in sustainable range management, preventing degradation of soil quality trend. This study was conducted in Friedan in Isfahan province in 2010 to compare chemical and biological indicators in three land uses (rangeland, degraded dry land and dry land), during two growing seasons (May and September) in three slopes (0-10, 10-20, 20-30 %). Nitrogen, phosphorus, potassium, organic matter, cation exchange capacity and microbial soil respiration were measured. Results showed that all measured characteristics except potassium decreased over an increase in the slope. Maximum values of phosphorus, organic matters, cation exchange capacity and soil respiration were obtained in pasture (28.4 mg/kg, 0.62%, 20.38 cmol/kg, 33.2 mgC/day, respectively)but potassium maximum rate was seen in dry land form (406.8 mg/kg).The effect of season on all measured parameters was significant except for N, while the highest amounts of phosphorus, potassium, cation exchange capacity and soil respiration (28.7 mg/kg, 377.3 mg/kg, 19.6 cmol/kg and 25.9 mgC/day, respectively) were seen in May and the highest organic matter rate (0.68%)in September. The results of this study showed that an increase in the slope, poor range management, and the end of the growing season could be major factors degrading the soil quality indices and soil productivity.