Journal of Water and Soil Science

Assessing the Efficiency of Sorghum (Sorghum Bicolor) and Common Lambsquarter (Chenopodium Album) in Phytoremediation of Zn From Soil

H. Hadi

Heavy metals contamination of soil and plants has very important and vital role in relation to health and life of human and other organisms. The aim of this study was to assess the efficiency of sorghum (Sorghum bicolor) and sommon lambsquarter (Chenopodium album) in phytoremediation of Zn from soil. Efficiency of 0.01M CaCl2, 0.1M NaNO3, and 1M NH4NO3 for extraction of “bioavailable fraction of soil Zn was also compared. Correlation between the Zn concentrations extracted by these methods and plants response (relative yield and shoot Zn concentration) to soil Zn contamination was then evaluated. For this purpose, a calcareous soil sample was contaminated with different concentrations of Zn. Sorghum and common lambsquarter, were grown in pots containing the contaminated soil and were analysed for their Zn concentrations after harvest. Results of this study showed that, common lambsquarter was more tolerant to low and medium concentrations (≤900 mg/kg), but sorghum tolerated high concentration of Zn. Also sorghum was more capable in removal of Zn from soil in comparison to common lambsquarter, so that soils contaminated with low Zn levels (≤900 mg/kg) can be remediated by sorghum. In addition, there was a significant correlation between 1 M NH4NO3-extractable soil Zn and the plants response (relative yield and shoot Zn concentration) to soil Zn contamination.

Comparison of Soil Taxonomy and WRB for Description of Soil Properties in Some Arid and Semiarid Regions of Central Iran

M. Bahmani

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.

Influence of Moisture and Pests Stresses on Corn Yield

J. Abedi Koupai

As increasing of disaster such as drought and pest invasion in recent decades, it is essential to find out practical approaches in optimizing water use and water management for reduce the adverse effects of this disaster in agriculture. In order to study the effects of water stress and pest stress on corn yield, an experiment was conducted in the research farm of Isfahan University of Technology. In sprayed and non sprayed of the field, a factorial design, based on the completely randomized block, was carried out with three treatments of irrigation regimes including intensive stress (50% water requirement), moderate stress (75% water requirement) and no water stress in four stages of corn growth from seed germination until tasseling, from tasseling until milky, from milky until harvest and the whole period of corn growth, in four replications for one year (2005). The results showed that applying water stress on corn reduced seed yield between 6-62% and also decreased other agronomic characters except protein percentage. Water stress in non sprayed condition, reduced significantly more physiological characteristics of corn compared to the sprayed condition. Intensive water stress and pests stresses increasd 3 and 13% of percentage protein, respectively. In sprayed condition applying moderate stress in first stages of corn until the first of third stage is suggested in drought condition.

The Effect of Inter-Row Tillage on Potato Yield Quality and Quantity and Water Use Efficiency in A Fine-Textured Soil

A. Heidari

efficiency was investigated during a 2-year period (2009-2010) in a silty clay loam soil in Tajarak Research Station (Kaboudarahang Township), Hamedan. The experimental design was a strip-plot within a randomized complete blocks design. The horizontal band, the irrigation water rate after flowering, included full and deficit irrigation (100% and 75% potato water requirement) and the vertical band, kind of inter-planting row tillage including 1- subsoiling to 30-35 cm soil depth, 2- chiseling to 20-25 cm soil depth, 3- sweeping to 5 cm soil depth and 4- no-till. During the growing season, soil mechanical resistance (cone index) in two stages and water infiltration into the soil were measured. At the end of the growth season (harvesting time), potato yield quantity and quality were measured. Result showed that the effect of inter-row tillage on soil mechanical resistance was significant. Subsoiling and chiseling had lower soil mechanical resistance and higher water permeability between treatments, respectively. The effect of inter-row tillage on potato yield was significant so subsoiling and chiseling had a higher potato yield between treatments, respectively. The effect of irrigation water rate on potato yield was not significant. The effect of inter-row tillage on water use efficiency wasn’t significant.

Influence of Natural Zeolite on the Soil Nitrates Irrigated with Wastewater: Study on Application Method, Particle Size and Dosage of Zeolite

S.H. Tabatabaei

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.

Changes Trend of Some Chemical Characteristics of Groundwater in Segzi Plain from 1995 To 2008

A. Khanamani

Underground water resources considered as a major source of fresh water. Increasing need to water in Iran, causing to immensely utilization and ground water balance disorder, so that state of ground water in many of area is negative.The purpose of this study is to investigate the trend of changes in some of the characteristics of groundwater during the period 1374 to 1387 is Segzi plain. For this purpose, data gathered from the Organization of regional water and homogenous test with Tom test (Run-test) at 95% confidence level was performed on the data. The independence of data evaluated by time series auto correlated functions (ACF), to do this, the amount of auto correlated data computed in different time delays and finally Mann- Kendall test used to evaluate the trend of time series properties in groundwater. The results of Run-Test showed that all of used series in this study were homogenous (P value< 0.05). The result of trend analysis test for region’s wells showed a significant increase in chlorine in underground water resources (P value< 0.05). Calcium has an increasing Trend too about 3 units. Results also showed that all used series in this study are random and Mann- Kendall trend analysis test can be an appropriate for trend evaluating in data series. As regard to irregular utilization of underground water resources by increasing depth of water level, amount of different salts such as chlorine and sodium increased, that causing to surface source degradation like soil and plant cover in agricultural area.

The Potential Risk Assessment of Heavy Metals on Human Health in Some Agricultural Products in Isfahan Province

M.Afyuni

Regards to the importance of using safe vegetables, controlling the concentrations of heavy metals is necessary for consumer's health. Therefore, this study was aimed to evaluate the potential risk of heavy metals on human health for non-cancerous and cancerous diseases through consumption of agricultural products in Isfahan province. The samples were included wheat, rice, carrots, onions, leafy vegetables and potatoes which were collected randomly from the studied area. In order to assess the risk of non-cancerous diseases, Target Hazard Quotient (THQ) and Hazard Index (HI) were calculated for a specific element as well as combinations of different elements. The results showed that the THQ for arsenic was more than one in wheat and was less than one for other heavy metals if one product is consumed. This indicates that the likely effects of arsenic for noncancerous diseases of wheat are not alone, rather they are for other elements in various products. Risk indicators for men and women are 2.6 and 2.9 respectively, which indicates the effects of noncancerous diseases resulting from consumption of products. Cancer risk due to arsenic in samples of wheat consumption is higher than the Onion and potential cancer risk for this disease for this element is in the middle. The parameters for the lead element in both cases is low.

The Spatial Variability and Mapping of Scaling and Corrosion Potential and Related Water Quality Parameters in the Shahrekord Aquifer

H. Beigi Harchegani

Shahrekord groundwater is the main source of water for drinking, and the agricultural and industrial activities of its inhabitants. Water quality measures of scaling and corrosion can deteriorate steel-based systems used for storage or supplying water for drinking and to industry and irrigation. The main aim of this study was to assess the spatial variability and mapping of scaling and corrosion using Langelier index (LI) and Ryznar index (RI) and that of the related parameters of pH, total dissolved solids (TDS), total hardness (TH), and total alkalinity (TA) in Shahrekord groundwater. For this purpose, water samples from 97 wells were analyzed for pH, TDS, TH, and TA and LI and RI indices were calculated. The Gaussian model best described the spatial variability of TDS while the Spherical model was best for all other parameters. Based on LI and RI averages of, -0.13 and 7.9 respectively, Shahrekord groundwater has a slight potential for corrosion. The values of all parameters, except RI, were lowest in the northwest and highest in the southeast of the aquifer. In most parts and in the center of the aquifer, the values of LI ranged from -0.5 to zero indicating negligible scaling potential. Spatial distribution of the RI index was almost inversely symmetrical to that of LI index. LI showed strong positive correlations with its components (varying from 0.61 to 0.90) while RI had strong negative correlations with its components (ranging from -0.66 to -0.98). LI and RI had the strongest correlations, respectively, with pH (r=0.90) and total alkalinity (r=-0.90).

Determination of Evapotranspiration and Crop Coefficient of Two Rice Cultivars in Mordab Plain (Guilan Province)

M. Mirlatifi

Since more than 75% of the rice fields in Iran are located in the Northern provinces i.e. Mazandaran, Guilan, and Golestan identifying the crop water requirement of rice fields is essential for water resources planning in the Northern provinces. The objective of this research was to ascertain the crop water requirement of two rice cultivars namely Hashemi and Khazar in Guilan province during 1389 growing season. Four iron barrels with diameter of 56 cm were used as lysimeters to grow the cultivars mentioned. According to a simple volume balance approach the crop water use of the four lysimeters were determined during the growing season. The elements of volume balance approach such as the depths of drainage, precipitation, and irrigation were recorded daily and the average of 5-day and 10-day periods were reported. The daily rice crop water use during the growing season was found to range from 2.4 to 6.3 mm/day with a seasonal crop water use ranging from 430 to 470 mm for Hashemi and Khazar cultivars, respectively. Daily reference evapotranspiration was computed by the FAO-Penman-Montith equation and accordingly rice crop coefficients were computed. The crop coefficient of Hashemi variety was found to be 1.1, 1.3, and 1.1 during the initial, mid, and end growth stages, respectively. In addition, the aforementioned parameters for Khazar variety were 1.2, 1.3, and 1.1.

Evaluation of SCS Method in Derivation of Initial Abstraction of Precipitation in Watershed Scale

R. Mohammadi Motlagh

The main scope of this research is evaluation of Soil Conservation Service Procedure in derivation of initial abstraction of precipitation in watershed scale. For this purpose Dalaki watershed which is located in south east of Iran was selected then by using hec-hms and GIS models and a number of observed rainfall runoff events some parameters like CN of watershed ,K and X of Muskingam method and initial abstraction of precipitation were calibrated through two different search algorithm of univariate and Nelder & Mead methods. The early results of this research indicated the superiority of Univariate search algorithm over the Nelder&Mead method both in calibration and also validation processes. Then using calibrated CN and Initial abstraction parameters which were derived through Univariate search algorithm, the factor between initial abstraction and potential retention of surface runoff (S) in each of sub basins were estimated. 0.13, 0.43 and 0.19 were derived as the above mentioned factor respectively for Minimum, Maximum and mean of the above mentioned factor in this step of the research which showed an acceptable compatibility to the offered factor of 0.2 by SCS. Then in rainfall runoff modeling process of this watershed SCS offers a reliable method of initial abstraction estimation.

Effect of Parent Materials and Pedogenic Processes on Distribution of Pb, Zn, Cu, and Ni in the Residual Soils of Binaloud Zone, Western Mashhad

A. Karimi

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.

Effect of the wheat (Triticum aestivum L.) rhizosphere on the bioavailability and fractions of zinc in some calcareous soils

H. R. Motaghian

Rhizosphere is a small zone and has quite different chemical, physical, and biological properties from bulk soil. This research was performed to study the available Zn and its fractions in the wheat rhizosphere and bulk soils by using rhizobox at greenhouse conditions. Total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and available Zn using 7 chemical procedures and Zn-fractions were determined in the rhizosphere and bulk soils. The results indicated that TOC, DOC and MBC in the rhizosphere were increased significantly (P<0.01). Zn extracted using several chemical extractants (except 0.01 M CaCl2) in the rhizosphere were significantly (p<0.05) higher than in the bulk soils. Also, concentrations of Zn-fractions (except carbonate-associated) in the rhizosphere were significantly (p<0.05) different from concentrations of Zn-fractions in the bulk soils. Results indicated that correlation between uptake index and extracted Zn using DTPA-TEA and Mehlich 3 were significant (p<0.05). Moreover, significant correlation (p<0.05) between uptake index and exchangeable Zn and Zn associated with iron-manganese in the wheat rhizosphere and bulk soils were found. The results of this research illustrated that available Zn and its fractions in the rhizosphere soils are different from the bulk soils. Therefore, application of the rhizosphere soil would be recommended in the study on these properties after planting.

Changes in Available Phosphorus and Inorganic Native Phosphorus Fractions after Waterlogging in the Paddy Soils of North of Iran

N. Najafi

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.

The Influence of Roughness in Adverse Bed Slopes on Conjugate Depth and Energy Losses of Hydraulic Jump

N. Pourabdollah

Most of researches related to hydraulic jump have been done on horizontal and rough beds, and little attempt has been made on rough beds with adverse slopes. The aim of this study was to investigate the influence of rough beds with adverse slope on hydraulic jump characteristics. The variations of energy loss in stilling basins with three adverse slopes and three different roughnesses were studied. Results showed that increase of roughness caused that relative depth of jump in stilling basins with rough bed and adverse slope decreased as compared to horizontal smooth beds. The experiments were performed on rough beds in different conditions where Froude number ranging between 4.9 and 7.8. Result showed that reduction of relative depth was about 31.15%. Results also showed that in such cases the relative energy losses are more than that for classic conditions.

Potential of Natural Clay Deposits to Prevent Cadmium Uptake by Canola

T. S. Taleghani

Stabilizing heavy metals in polluted soils is a method to prevent them from entering plants. Clay minerals are considered good sorbents for heavy metals due to their low cost, high abundance, easy manipulation and harmlessness to the environment. The objective of this study was to investigate the potential of clay deposits containing smectites and palygorskite to sorb cadmium and to reduce its movement into canola. Two selected deposits are located in the Isfahan Province. Physical and chemical characteristics of clay deposits were determined. The clay fraction was then separated from each deposit sample. This study showed that palygorskite was the dominant clay mineral in deposit sample 1 and smectites in deposit sample 2. These clays were then used as an amendment to plant growth medium. Pot experiment was carried out with canola (Brassica napus) as a test plant with 3 replicates. Treatments included three growth media: smectite + quartz sand, palygorskite + quartz sand and pure quartz sand (control treatment) under 3 Cd concentrations: 0, 2.5 and 7.5 ppm. Results obtained from the pot experiment indicated that deposits containing smectite and palygorskite were very useful in stabilizing cadmium in polluted soils and could prevent Cd from entering plant. Smectite clay mineral could retain a higher quantity of cadmium as compared to palygorskite. Plants in pots amended with smectite had a higher growth rate as compared to those in control and palygorskite amended pots. Cadmium accumulation in plant roots was much higher than that in shoot. Furthermore, the higher Cd concentration in growth media resulted in the higher amount of Cd uptake by the plant.

The Effects of Land Use Change on Chemical and Physical Soil Properties (Case Study: Ghoshe Spread Flow and Contiguous Agriculture Land)

H. Kashi

Change in land use and tillage practices has great influence on soil physical and chemical properties. The present study has focused on the effects of converting undisturbed soil to agricultural lands. Chemical and physical soil properties, infiltration, cation exchange capacity (CEC), electrical conductivity, pH, bulk density, porosity, sodium, potassium, total Ca + Mg, organic matter percentage, sodium adsorption ratio (SAR) and lime percentage were measured using standard frequently used methods. Fifty soil samples from agriculture land and other 50 soil samples from undisturbed land were collected from 0 – 30 cm depth and different statistical analysis were performed. Agriculture land is Cultivated for more than 20 years. The results showed that change in land use from undisturbed to disturbed soil did not significantly changed soil organic matter content. Also, soil electrical conductivity showed a huge increase whereas pH showed non-significant changes due to land use change. Unlike pH, SAR, organic matter percentage and lime percentage, some other soil parameters showed significant decrease in quality through land use change. Correlation coefficients of the effective factors were calculated to explain the main reason for lowering soil quality. The results showed that sodium in EC bulk density in porosity and CEC sodium and Ca+Mg in SAR EC in soil infiltration and Ca+Mg in organic matter showed the most correlation.

Evaluation of Watershed Management Practices (WMPs) Effect on Flood Characteristics

M. Vafakhah

The occurrence trend of floods in recent years shows that the most of Iran regions located in attacks of destructive floods and loss of life and property of flood damages is increasing. Watershed management practices (WMPs) are one of the superior and appropriate solutions for flood hazards mitigation. The impact of WMPs can be investigated using different approaches. In this study, the direct impact of WMPs was investigated using quantitative evaluation of flood characteristics for two periods, pre and post periods of measures implementation. Therefore, daily hydrograph of investigated periods and the results of flood analyses including number of floods occurrence, flood frequency percent in the different months and seasons were determined in Hajighoshan and Tamar hydrometery stations. Also, the mean continuing, rise and subsidence time of floods and maximum peak discharge of observed floods were investigated. The research results showed that the occurrence trend of floods had relatively increased. The number of floods has increased in post periods of measures implementation in two hydrometery stations, while WMPs effect on all flood characteristics were positive, as the continuing time of floods has increased with 0.5%, rise and subsidence time of floods and maximum peak discharge of floods have decreased with 7.9%, 21.98% and 70%, respectively. Totally, if WMPs volume pre watershed area isn't low, WMPs effect on flood characteristics will be positive.

Effect of Vermicompost and Nitrogen on Growth, Concentration, and Uptake of Nutrients in Sunflower

M. B. Heyderianpour

A study was conducted to evaluate the effect of vermicompost and nitrogen (N) on growth, nutrient concentration and uptake of N, phosphorus (P), potassium (K), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) in sunflower shoots as a factorial experiment arranged in completely randomized design (CRD) with three replications under greenhouse conditions. Treatments included three levels of vermicompost (0, 2.5, and 5 % by w/w) and three N levels (0, 90, and 180 mg kg-1) as urea. Application of 2.5% vermicompost significantly increased the average fresh and dry weights, and uptake of K, Fe, Zn, Mn, and Cu of shoots as compared when no vermicompost was applied, but decreased Zn and Cu concentrations. Application of 90 mg N, increased fresh and dry weights, and concentration of N, Zn, and Mn, total uptake of N, P, K, Fe, Zn, Mn, and Cu in sunflower shoots, but decreased P concentration. Application of 180 mg N increased total N uptake than that of 90 mg N kg-1 treatment. Combination of 2.5% vermicompost with 90 mg N, significantly (p<0.05) increased dry matter yield of sunflower as compared to 2.5% vermicompost without N treatment

Potassium Release Kinetics from K-Feldspar in Comparison with Muscovite as Influenced by Different Extractants

H. Khademi

In Iran, no research has yet been performed on potassium release from feldspar in comparison with that from muscovite. The objective of this research was to compare potassium release kinetics of these minerals as influenced by organic and inorganic extractants using successive extraction method. The experiment was carried out in a completely randomized design with a factorial combination. Treatments consisted of three kinds of K-bearing minerals (Muscovite, and Yazd and Ward feldspars), three extractants including CaCl2, oxalic and citric acids of 0.01 M concentration and 6 times of extraction (1, 2, 8, 24 and 48 hours). The results indicated that the potassium release from muscovite was 6-8 times higher than that from feldspars. The type of extractant significantly affected potassium release. Potassium release by organic extractants was 2.5-3 times higher than that by CaCl2 as an inorganic extractant. Different kinetic equations showed that power function, parabolic diffusion and first order equations adequately described K release whereas Elovich equation did not. Among the three equations, power function equation was selected as the best model describing K release from the minerals. Based on the selected kinetic equations, it seems that potassium release from K-bearing minerals is controlled by diffusion process.

Concentration of Selected Heavy Metals in Atmospheric Dust of Isfahan and Neighboring Metropolitan Areas

H. Khademi

Atmospheric dust is an important source of heavy metals, particularly in urban environments. Heavy metals can easily attach to dust particles and be distributed in large areas. The objective of this study was to evaluate the status of major heavy metals in the atmospheric dust of Isfahan and adjacent cities. A total of 144 dust samples were taken during a period from August to December 2010 from Isfahan, Khomeynishahr, Falavarjan, Mobarake and Zarinshahr cities. Dust samples were extracted with HNO3 65% and the total concentration of metals including Pb, Zn, Cd, Cu, Ni, Co, Cr and Mn in the samples was measured by an atomic absorption spectrometer. The mean concentration of these metals was 223.5, 470.3, 3.5, 71.0, 82.0, 26.5, 24.4 and 426.3 mg kg-1, respectively. Results indicated that heavy metals concentration in any area was different depending on the source of pollution and it was much higher than the mean concentration of the corresponding heavy metal in soils. Besides, the highest deposition rate of all the heavy metals in this study was found in November-December period. This could be attributed to an increase in the use of heating systems and also to a temperature inversion event prevailed in the area. Atmospheric deposition seems to be an important pathway of heavy metals addition to soils. For example, it is responsible for 35-91% and 12-47% of Pb and Cd entering the soil in the area, respectively.

Effect of Cultivation on Soil Available Water Using Parametric Pedotransfer Functions

H. Aryanpour

Soil tillage changes chemical and physical properties which can change the soil available water capacity. For understanding the effect of soil disturbance in cultivated soil on available water, parameter pedotransfer functions of these soils created and their results were compared with measured available water by moisture release curves. For this purpose 54 soil samples were taken from cultivated and non cultivated soils of Abyek-Qazvin area northwesthern Iran. Selected properties of these soils such as particle size distribution, bulk density, organic carbon, calcium carbonate, cation exchange capacity and pH were determined. Soil moisture curve of samples were obtained by pressure plates. Parameter pedotransfer functions were created by Mualem-van Genucten model for non cultivated soil and their available water were predicted. The predicted available water was compared with measured available water. The results illustrated that the predicted results had higher correlation coefficient for moisture of permanent wilting point compared to of field capacity moisture, As the correlation coefficient was inccreased from 0.67 to 0.83 and also the root mean square error (RMSE) reduced from 2.59 to 1.06. So the predicted available water was overestimated.

Comparison of Functional Pedodiversity in Two Detailed Soil Map Units (A Case Study: Faradonbeh Plain, Chaharmahal-Va-Bakhtiari Province)

I. Esfandiarpour Boroujeni

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

Sensitivity Analysis of SWAT Mode in Chehelchai Watershed, Golestan Province

H. Akbari Mejdar

Over-parameterization is a well-known and often described problem in hydrological models, especially in distributed models. Therefore, using special methods to reduce the number of parameters via sensitivity analysis is important to achieve efficiency. This paper describes a sensitivity analysis strategy that graphically assigns for each parameter a relative sensitivity index and relationship of the parameter and the outputs of the model. The method is illustrated with an application of SWAT model in the Chehelchai catchment, Golestan province. In this study, total water yield, along with four major parts of water budget including surface runoff, lateral flow, groundwater and evapotranspiration was selected as objective function. SWAT is a river basin model that can be used to predict the impact of land management practices on water, sediment and agricultural chemical yield in watersheds. A relative sensitivity index was used for ranking the sensitivity of parameters. The results showed that soil evaporation compensation facto (ESCO), CN, soil available water capacity (SOL-AWC), deep aquifer percolation fraction (RCHRG-DP) and soil bulk density (SOL-BD) have the most influence on river flow. These parameters are generally stated as the most sensitive parameters of SWAT model in most of the same researches worldwide

Determination of Crop Water Use and Crop Coefficient of Two Hybrids of Sunflower (Euroflor and Sirna) under Drip-Tape Irrigation System

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.

Laboratory Study of Channel Slope and Rod Diameter Effect on Intake Discharge Coefficient under Rack Floor Condition

A. Masjedi

Floor intake is one of the best options for diverting mountain rivers' flow. Determination of discharge diverted in different conditions of flow in main channel is one of the main objectives for intake under rack floor condition. Gradient and shape of grid rod floor can affect the discharge deviated. In this experiment, placement and gradient of grid rods and also their effects on the discharge coefficient and hydraulic parameters were investigated. For this purpose, a physical model made of glass with variable gradient was used for the main channel. To conduct and measure the discharge diverted, a sub-channel 8 meters away from the entrance of main channel was installed below the main channel. Length and width of intake entrance were 10 and 50 cm, respectively. At the entrance of intake a longitudinal grid with four different rod diameters, constant-space passing, and four different gradients were used. Meanwhile, for the investigation of flow rate four discharges were used. The results showed that intake discharge coefficient was increased with an increase in diameter of grid rod floor, reduction in floor gradient, and increasing of depth in the upstream network. In all cases, increasing the Froude number resulted in an increase in the intake discharge coefficient in the upstream network

Derivation, Validation and Comparison of Class and Continuous Pedotransfer Functions for Predicting Soil Cation Exchange Capacity in Several Textural Classes

H. Khodaverdiloo

Cation exchange capacity (CEC) is one of the important indices in soil fertility. Direct measurement of CEC is time consuming and expensive, especially in aridisols containing high amounts of carbonates and gypsum. Alternatively, CEC could be indirectly predicted through pedotransfer functions (PTF). The objective of this study was to predict CEC using class and continuous PTFs.A data set (n = 977) was classified according to the soil textural class and was used to derive the PTFs. Another independent set (n = 173) was used to test the reliability of the PTFs. The root mean of square error (RMSE), mean error (ME) and index of agreement (d) were applied to evaluate the PTFs. Within every textural class, we furthermore evaluated the relative improvement (RI) of the continuous PTFs over the corresponding class PTF. The continuous PTFs were more accurate than class PTFs for finer textural classes while the former showed higher reliability in coarser textural classes. With an increase in relative particle size, prediction bias of class PTFs decreased RMSE was 8.55 and 3.88 in clay and sandy loam textural classes, respectively. Consequently, according to the results obtained in this study, for the prediction of soil CEC, continuous PTFs are suggested to be used for silty loam and finer textural classes while for loam and coarser classes application of class PTFs is preferred.

Effect of Topographic Threshold Conditions on Gully Erosion )Case Study: Alla Marvdasht -Lamerd & Fadagh –Larestan)

M. Zare

Gully erosion and sedimentation have high priority in Fars Province due to the losses from destruction of lands, roads and civil structures. In the present study, in order to evaluate the threshold for the development and initiation of gully topography in Fars province, two regions were selected including Allamarvdasht, Lamerd and Fedagh, Larestan. 30 gullies were selected in each mentioned area. Morphometric parameters were measured and topography threshold was drawn. To evaluate the effect of measured parameters on topography threshold, each gully was clustered based on parameters and cluster analysis. To determine the effect of dominant hydrologycal processes on gully initiation and development, the multivariate analysis was employed using SPSS (version 14) software. Using the power relationship between watershed area and slope of each gully, the dominant hydrological processes in gully initiation and development were determined by means of Excel software and were compared with coefficients of foreign regional studies. The results showed that in the two studied regions, the most effective hydrologycal process was surface runoff. Results also demonstrated that in these regions changing the shape of upstream basin topography to circle and their expansion have increased the threshold of watershed topography of gully erosion. Increasing the sodium absorbtion ratio and removing the ground cover reduce the threshold of gully erosion topography. Increasing the depth of gullies and soil organic matters resulted in greater relative threshold of topography.

Effect of Phosphorus and Water Stress on Growth, some Water Relations and Plant Nutrient Concentration of Pistachio Seedlings in Greenhouse Conditions

A. Tajabadi Pour

To study the effects of soil phosphorus (P) application on growth and water relations and nutrient concentration of pistachio seedlings (Badami-e-Zarand) under water stress, a greenhouse experiment was conducted. Treatments were arranged in a factorial manner as a completely randomized design with three replications. Treatments consisted of six P levels (0, 30, 60, 90, 120 and 150 mg P Kg-1 soil as H3PO4) and three irrigation intervals (2, 4 and 8 days). Results showed that as water stress increased, growth parameters significantly decreased. As irrigation interval was increased to 8 days, shoot and root dry weights, shoot/root ratio, leaf area and leaf number and stem height decreased. Photosynthesis parameters were significantly decreased by increasing water stress. Also, P and Zn concentrations decreased as irrigation interval increased. Analysis of variance indicated that P application had no significant effect on growth parameters, transpiration rate and photosynthesis. It seems that Olsen extractable P (5.35 mg kg-1 soil) was sufficient for optimum growth of pistachio seedlings and thus, no growth responses were observed from P application in this experiment. Application of phosphorus significantly increased P and decreased Zn concentrations.

Short-Term Impacts of Minimum Tillage on Soil Structure Stability in Northern Khuzestan

B. Khalil Mogaddam

Extensive tillage leads to the degradation of soil structure and aggregate stability. The effects of three different tillage implements including (combination tillage, chisel packer and disk), three levels of soil water content including (0.5, 0.7 and 0.9 plastic limit), three working speeds including (6, 8 and 10 km/hr) and two soil textures including (loam and silty clay loam soils) were studied. The study was carried out in Khuzestan Ramin Agriculture and Natural Resources University, in 2011. Soil aggregate mean weight diameter (MWD), geometric mean diameter (GMD) as determined by wet sieving method and soil surface roughness (SSR) were measured. Results showed that chisel packer with 0.744 mm MWD produced largest soil aggregates in both soils because of using narrow blade and shanks and small rake angles compared to other tillage treatments. Soil aggregate size was shown larger than other tillage treatments where chisel packer was employed but it was not suitable because of deep furrow shapes. Combination tillage was able to make a better soil condition to be used for seeding where the experiment was conducted.

Analysing Drought Past Trend and Forecasting its Future in Isfahan Province

M. Khodagholi

The geographical location of Isfahan province has led the province to be at risk of drought. One of the ways to mitigate drought is evaluation and monitoring of drought based on indices that can determine its intensity and permanence in each region. In this research, for drought and trend analysis standard precipitation index and Mann-Kendall test were used, respectively. Also, monthly precipitation time series of Isfahan province was applied to forecast drought from 1970 to 2009. For this purpose, Box and Jenkins modeling approach (1976) was used which has three main steps, namely model identification, parameter estimation, goodness of fit test or time independency and normal test of residual. The results showed that most of the stations in Isfahan province were faced with severe drought in the year 2000 and this situation was repeated one more time in 2008. Also, the results brought forth multiplicative models in all the stations. ARIMA (1,0,0) (0,1,1) showed the highest correlations between control and forecast data in Isfahan, Meime and Ardestan stations, and the model ARIMA (0,0,1) (0,1,1) displayed the highest correlation between control and forecasted data in Naein, Freydoonshahr, Khansar and Natanz. These models were selected as the best models through which the amount of precipitation was predicted till 2015. The trend of forecast data across Isfahan province showed that in most months the trend is not significant.