Journal of Water and Soil Science
Year:2015 | Volume:19 | Issue:71|Papers Count:36

Achievement to sustainable development is dependent upon integrated watershed management. In other hand without detailed analysis of the rainfall - runoff observations, high risk of flood predictions will be translated into flood-induced capital losses. Considering the fact that not always hydrometric data are available, using synthetic unit hydrograph is one of the most popular methods of flood simulations for ungauged watersheds. This method has operational limitation for duration of runoff but in Instantaneous Unit Hydrograph (IUH) assumed to all take place at a discrete point in time therefore can be converted into and desired durations. According to literature few studies have been focused on Laplace transforms, H2U-Nash Unit Hydrograph in Iran, this work is an attempt to investigate model performance in Jooneghan catchment, located in northern part of Karoon great basin. Laplace synthetic hydrograph was derived base on effective rainfall while H2U-Nash model was simulated using moments technique and lag time. The mean absolute relative error of Laplace transforms, H2U-Nash was 0.42 and 0.25 respectively. Visual interpretation and statistical comparison of Nash-Sutcliffe efficiency coefficient of the models confirms that H2U-Nash model performs better than Laplace transforms model.

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.

In recent years, use of carbon-based adsorbents has increased in pollution reduction from aqueous solutions. Biochar is a carbon-rich porous material, with low costs, and environmentally friendly, which is prepared by pyrolysis of biomass. In this study, potential of rice husk biochar to desalinate irrigation water with EC of 5, 15 and 25 dS/m was investigated. The effect of pyrolysis temperatures of 400 (RHB4), 600 (RHB6) and 800 (RHB8) on selected physicochemical characteristics and their desalination power was considered. The results showed that pyrolysis temperature has a significant effect on biochar properties. RHB6 with 301.1 mg g-1 desalination capacity was more efficient than the other biochars. This adsorbent had maximum surface area (211 m2 g-1) and total pore volume (0.114 cm3 g-1). The results of this study could open new horizons to manage the agricultural wastes and simultaneously reduce the cost of irrigation water.

This study aimed to evaluate the performance of TM satellite data acquired in June 2009 to map soil salinity in southeast of Isfahan province. Ground salinity data (EC) was collected within 9 pixels, covering an area of approximately 8100 m2 using stratified random sampling technique at 53 sample sites. Spectral indices including TM bands, BI, SI1, SI2 and SI3, PC1, PC2, PC3 and also multiple linear regression modeling and maximum likelihood classification techniques were applied to the geometrically corrected image. Results of regression analysis showed that the TM band 4 had the strongest relationship with EC data (R2=0.48) and also the relationship of the modeling image using TM 3, TM 4, TM5 and PC3 was significant at the 99% confidence level. The accuracy assessment of the stratified TM4 and modeling image into five classes including 0-4, 4-20, 20-60, 60-100 and EC>100 ds/m indicated that there was more than 86% agreement with the field measurements of EC data. Therefore, it can be concluded that the discretely classified salinity maps have higher accuracy than regression methods for identifying broad areas of saline soils, and can be used as appropriate tools to manage and combat soil salinization.

Management of organic and inorganic treatments may have positive or negative effects on soil quality, plant growth and human nutrition. The objectives of this study were to determine the effects of organic and inorganic zinc fertilizer application on soil quality indicators and wheat yield. This research was conducted at Agricultural Research Station Roudasht, Isfahan, Iran. Sewage sludge and cow manure (5 and 10 t/ha), ash rubber (1 t/ha), powder rubber (200 kg/ha), ZnSO4 (40 kg/ha) were applied and wheat was cultivated. Soil samples were collected at tilling and harvest stages. After taking samples and measurements of the soil parameters, we determined the critical limits for each category and class rating for the each soil parameters, and the soil quality index was calculated. The results showed sewage sludge and rubber ash were significantly effective in increasing soil bioavailable Zn compared to other treatments. Application of sewage sludge and cow manure at 10 ton/ha improved soil quality. The expanded soil quality index can help better understand the effect of fertilizers on soil. A positive and significant relationship between soil quality indicators and Zn uptake and wheat yields was also observed. Our results indicate that addition of 10 t/ha sewage sludge as fertilizer can significantly improve soil quality, supplying the necessary amount of Zn for wheat growth.

Rill erosion is the detachment and transport of soil particles by concentrated flow of runoff. It is the most common form of water erosion in the hill slopes. Rill erodibility is the rate at which soil particle is detached and transported by shear force of the concentrated flow. The study was conducted to determine the rill erodibility in different soil textures in Zanjan province using a rainfall simulator. To this end, samples of eight soil textures consisting of clay, clay loam, silty loam, sandy clay loam, sandy loam, loamy sand, and sandy were collected from land surface and transported to small plots (120 cm - 100 cm) on a sloped uniform land (10%). The plots were exposed to five simulated rainfalls with a constant intensity of 60 mm h-1 for one hour. Based on the results, there was a significant difference among the soil textures in the rill erodibility (p< 0.01). Rill erodibility of the soils significantly correlated with mineral fraction (sand, clay, gravel) and exchangeable sodium percentage (ESP). With an increase in sand and gravel percentage, soil infiltration rate strongly increased and consequently production of the concentrated flow steadily decreased. Multiple regression analysis indicated that the rill erodibility in the soils was remarkably related to ESP (R2= 0.85, P< 0.01). Clay soil showed to have the highest rill erodibility among the soil textures due to higher exchangeable sodium percentage (ESP=13).

Since climate has a major impact on dust generation, it is essential to identify the climatic parameters affecting this phenomenon. In this study, climatic parameters including temperature, relative humidity, rainfall, maximum wind speed and direction were selected and their relationship with visibility data and also dust storm days (recorded at meteorological stations) was analyzed on monthly and yearly scales using multivariable linear regression. Results showed that the number of dust storm days has reached 366 days in the last five years. The minimum dust storm days occurred in autumn in all the stations of Khuzestan province including Abadan, Ahvaz, Omidiyeh, Dezful, and Masjed Soleiman and the maximum dust days for Abadan and Ahvaz stations and three remaining stations occurred in spring and summer, respectively. Results also showed that the highest frequency of dust storms in Abadan and Ahvaz stations did not coincide with summer season which has the lowest rainfall of the year. As a result, it seems that the main reason for this difference is the climatic characteristics of dust sources and deposition regions. The occurrence of dust events in the remaining stations in summer time indicated that the sources of dust storms might be local and within the study area. The regression analysis confirmed this issue as the number of climatic parameters which had significant correlations with visibility data increased from 8 to 16 from west to east in the region. Overall, the results showed that with the increasing distance from Arab countries such as Iraq and Saudi Arabia, dust sources were mostly local and provincial.

Plant parasitic nematodes, especially root knot nematodes, cause damage to most of agricultural products, and many efforts have been done to control them. In recent years, application of industrial waste and wastewater sludge as organic fertilizers in agriculture has been increased. To investigate the effects of sewage sludge on root knot nematode pathogenicity in tomato, different weights of sewage sludge (0, 4, 8, 15 and 25% of sludge in the soil) in soil were added as a completely randomized design with six replications. Analysis variance and mean comparison of growth indices of plants showed significant effects of treatments. For example, means of stem length of plants increased in soil with more amount of sewage sludge. This relationship was also observed in other indices and nutrients elements. So using sewage increased nitrogen, phosphorous, calcium and magnesium in tomato shoots inoculated with nematodes while the change of potassium was very small. Application of sewage sludge decreased the number of galls, egg-masses and eggs in egg-mass of root knot nematode.

In recent years, due to the overpopulation, serious water shortages, and need to consume more water, the use of wastewater treatment plant has attracted lots of attention. When the pollution load is not high, biofilm reactors are commonly used for the purpose. In this study, the porous concrete as a bed biofilm in reducing pollution load of wastewater was investigated. In order to evaluate porous concrete, basic mix designs were selected according to regulations ACI211.3R. To increase the specific surface area of concrete for biofilm growth, fine particles were added to the basic mix in three stages with each stage 10% by weight of coarse particles. Experimental design was a randomized complete block. A rectangular channel (with the cross section 20×30 cm2) and 8 meters in length was constructed near the wastewater treatment plant of Isfahan University of Technology. Then, the concrete blocks were made, put on the channel and biofilm processing operations were conducted on the pores of porous concrete cubes. Qualitative tests for BOD, COD, TSS and total coliform of samples from wastewater inflow and outflow were performed. Results showed that the removal of these parameters increased by adding fine particles. The average removal rates of BOD, COD, TSS and total coliform for the first mix design (1400 kg per cubic meter of coarse particle and without fine sand) were 25%, 33%, 45% and 37%, respectively. Similarly, the average removal rates of BOD, COD, TSS and total coliform for the fourth mix (1400 kg per cubic meter of coarse particle and 420 kg per cubic meter of fine sand) were 36%, 40%, 57% and 81%, respectively. It could be concluded that porous concrete can be used as a bed biofilm, and the third mix design (1400 kg per cubic meter of coarse particle and 280 kg per cubic meter of fine sand) was the best mix design.

Soil is one of the most important components in forests and distinguishing soil types and soil capability are first steps in forest management. The main aim of this study was to determine relationship between slope aspect and position, and chemical properties of the soil. Soil sampling was done in Tang-e-Dalab in Ilam province which is a part of southern Zagros. Samples were collected in both northern and southern slopes of oak stand (Quercus brantii). In each slope, three transects 50m apart were sampled. Overall number of samples was 60. After data normalization, the means were compared by Duncan test. Slope aspects influenced organic carbon and total nitrogen of soil. These parameters were higher in northern slope than southern one. Slope position showed a significant effect on C, N and P. Also, concentration of C, N and P were increased by moving down the position. Most amounts of C, N and P were 5.84%, 0.58% and 108.19 mg/kg in bottom, middle and bottom of northern aspect, respectively. The least amounts of C, N and P were 3.31%, 0.24% and 37.83 mg/kg in bottom, middle of southern aspect and top of northern aspect, respectively. The results of this study confirmed that nutrient concentration in northern slope was more than southern slope and nutrient concentration in soil was increased by moving downward.

Any change in the characteristics of air, soil, water and food that adversely affect the health of the ecosystem, activities of human and other organismsis called contamination. Heavy metal uptake by plants depends on the type and concentration of metalin soil, its bioavailability, and plant species. The use of new sciences such as geostatistics is useful for fast and simple determination of soil and leaf contamination risk. This study studied the amount of soil and leaves of Platanus orientalis contamination in order to map the lead (Pb) and cadmium (Cd) concentration in Rasht city using a geostatistic method. To achieve the goal, 126 samples of surface soil (0-30 cm) and 76 leaf samples (Platanus orientalis) were collected from city streets. Total concentrations of lead and cadmium in the soils and leaves were determined, and clay, silt and sand particle percentage, organic matters, and soil pH were measured. Average concentrations of elements in terms of mg/kg were as follows: soil’s Lead: 86.62, soil’s Cadmium: 0.6, leaf’s Lead: 8.99. For soil Pb and Cd and leaf Pb, spherical model yielded a better fit in the experimental variogram in GS+ program by using trial and error method. According to the spatial structure, Kriging and IDW estimators were used for interpolation. Kriging estimation was mapped using Arc GIS 9.2 software.

The effects of water quality, installation depth and space of subsurface drip irrigation (SDI) laterals on yield and visual quality of turfgrass were investigated. A field experiment was conducted at the experimental farm of Shahrekord University. The experimental design was a Split-Split Plot with experimental arrangement of completely randomized block design with 16 treatments and three replications. Treatments included two types of water quality: well water (W) and treated wastewater (WW), two installation spaces of SDI laterals (45 and 60 cm) and four depths of placement of SDI laterals (15, 20, 25 and 30 cm). Turfgrass indices recorded during the experiment included height, dry mass, color, visual density and growth uniformity. The ANOVA results showed that interaction of irrigation water quality × lateral spacing × installation depth of SDI laterals is significant on the height, dry mass and growth uniformity of turfgrass. Irrigation with wastewater as compared to well water produced grass with significantly higher height and more dry weight. Treatments irrigated with well water had a better growth uniformity than those treatments irrigated with wastewater. Results indicated that there was no significant effect of experimental factors on turfgrass color. The interactional effect of lateral spacing and installation depth on the turfgrass density was significant. Increasing installation depth and laterals spacing caused a decrease in turf’s yield and visual quality.

Nowadays, due to the effective role of nitrogen fertilizer in growth, yield and crop quality, farmers apply large amount of chemical fertilizers. High application of nitrogen fertilizers has caused soil and water pollution and environmental dangers, higher nitrate accumulation in plant, and different disease risks in human and livestock. In order to investigate the effects of nitrogen and cycocel application effects on soil nitrate pollution and agronomic traits of rice, an experiment was arranged in split plot based on a completely randomized block design with three replicates at Sari region (north of Iran) in 2010. The main factor was nitrogen in four levels and cycocel was considered as a sub factor in three levels. Results showed that maximum and minimum plant height and fourth internodes bending moment were obtained in 0 and 150 kg N ha-1, respectively. Higher filled spikelet percentage per panicle, grain yield and harvest index were obtained in 100 kg N ha-1 application. Application of N up to 150 kg N ha-1 increased soil nitrate by 44.7 percent. As cycocel application decreased, the plant height and panicle length were reduced, but tiller number per plant, filled spikelet percentage per panicle, and grain yield were increased.

In this research, the hydraulic behavior of two kinds of envelopes including synthetic envelope, PP450 and gravel envelope with USBR standard in two soil tank models with silty loam texture was investigated. Three water heads including 55, 75 and 105 cm (water logging) from drain level were used. The discharge of pipe drain in the steady state condition for gravel envelope and at 55, 75 and 105 cm water heads was 188.9, 172.0 and 897.0% more than those in PP450, respectively. Envelope hydraulic conductivity rates at gravel envelope for 55, 75 and 105 cm water heads were 24.6, 14.0 and 21.2 times higher than those in PP450, respectively, and gradient ratios in these water heads for gravel envelope were 14.5%, 2.8% and 14.2% lower than those for synthetic envelope. There were also different behaviors in the two kinds of envelopes for hydraulic conductivity and entrance resistance of pipe and envelope in 55 and 75 cm water heads relative to 105 cm. In general, according to the measured parameters in this research, gravel envelope showed a better performance.

Macrospore created by decaying plant root provides pathways for rapid transport of pollutants in soil profile. The main objective of this study was quantitative analysis of the effect of plant root (Zea mays L.) on bacterial and chloride transport through soil. Experiments were conducted in 9 soil columns packed uniformly with loamy sand. The treatments were bare soil, bare soil with corn (Zea mays L.) root and bare soil after decaying the corn root. The Breakthrough curves of Chloride were measured. Breakthrough curve (BTCs) of Escherichia coli and chloride were measured, too. The HYDRUS-1D one and two site kinetic attachment–detachment models were used to fit and forecast transport and retention of bacteria in soil columns experiment. The results indicated that the difference between soil hydraulic properties (saturated hydraulic conductivity and flow velocity) of the treatment was significant (p<0.05). The result also showed that the two-site kinetic model leads to better prediction of breakthrough curves and bacteria retention in the soil in comparison with one-site kinetic model. Interaction with kinetic site 1 was characterized by relatively fast attachment and slow detachment, whereas attachment to and detachment from kinetic site 2 was fast. Most of the cells showed retention close to the soil column inlet, and the rate of deposition decreased with depth. Low reduction rate of bacteria of the soil columns with plant root and with void root channel indicated the presence of macrospores in the soil created by deep corn root system.

In this work, the effect of raw and modified bentonite and zeolite with trivalent iron on the stabilization of water-soluble and adsorbed arsenic in a calcareous soil was studied. Raw and modified bentonite and zeolite were added to the soil in different weights in a completely randomized block design with three replications and kept to field capacity soil moisture content of 80% for 8 weeks. The concentrations of water-soluble and adsorbed arsenic, water-soluble and absorbed phosphorus in soil and soil pH were measured. Treatments significantly affected the mobility of arsenic and phosphorus in soil. Raw zeolite and bentonite in different levels increased arsenic mobility (about 107 to 325 % and 259 to 350% respectively). Despite the change in surface properties of zeolites modified with iron, this treatment at different levels increased arsenic mobility in soils by about 124 to 246%. Bentonite modified with iron had the greatest effect on reducing arsenic mobility in soil (about 91%). Phosphate mobility was similar to arsenic in different treatments.

Zinc deficiency is the most widespread micronutrient disorder in the production of wheat (Triticum aestivum L.) and other cereal crops. An experiment was conducted in greenhouse, in 2013, using the sterile sand-perlite (2:1 v/v), to study the effects of two beneficial microorganisms on growth and nutritional status of wheat (Nicknejad cultivar). The study was arranged as factorial in a completely randomized design with three replications. The experimental factors consisted of Piriformospora indica (E0: Uninoculated; E1: Inoculated), Pseudomonas putida (E0: Uninoculated; E1: Inoculated) and Zinc (Zn0: 0; Zn1: 2mM ZnSO4). The results showed that inoculation by P. putida increased shoot dry weight at both levels of zinc, but this increase was observed for root dry weight only without zinc application. The iron concentration of shoot was decreased as a result of inoculation by P. putida at both levels of zinc. However, P. indica inoculation increased iron concentration in zinc application, but had no significant effect without zinc application. At both levels of zinc, the highest P, Zn, chlorophyll a and b concentrations were achieved by inoculation with P. indica. Inoculation by P. putida reduced P concentration at both levels of zinc but it reduced Zn, chlorophyll a and b concentrations only with zinc application. The results of this research showed that despite negative effect of P. putida on nutrient uptake, inoculation by P. putida and/or P. indica plays an important role in the promotion of wheat growth in zinc deficiency conditions.

As there are some health and environmental concerns about wastewater, dewatered sludge, increase in green waste, and restricted legislation about burning them outdoors, environmental health engineers are investigating to find a simple, cost effective and efficient method. This is aimed to have healthy, safe and sustainable disposal of such materials. Co-composting of sludge and green waste is a newly developed process which can help us to achieve this goal. This study was to investigate the most suitable ratio of dewatered sludge to green waste from Chonibieh wastewater treatment plant in Ahvaz, Iran, and assess the feasibility of co-composting of this waste. So, dewatered sludge was composted with green waste as a bulking agent in three different ratios (1:1, 2:1, 3:1: green waste: dewatered sludge W:W). Then composting proceeded in pilot vessels (M1, M2, M3) for 23 days. The C/N ratio, the percentage of total nitrogen, phosphorus, total organic carbon, humidity and pH were tested in certain periods and compared with the national standards. This study showed that in M1, M2, M3 pilots, all parameters (except for total phosphorus) including C/N ratio, percentage of total nitrogen and total organic carbon, humidity, pH could meet class 1 national standard in Iran. Moreover, this compost product could meet the EPA microbial standards, class A. So, the product of this compost process is completely stabilized and could be used in agricultural lands.

With the advent of advanced geographical informational systems (GIS) and remote sensing technologies in recent years, topographic (elevation, slope, and aspect) and vegetation attributes are routinely available from digital elevation models (DEMs) and normalized difference vegetation index (NDVI) at different spatial (watershed, regional) scales. This study explores the use of topographic and vegetation attributes in addition to soil attributes to develop pedotransfer functions (PTFs) for estimating soil saturated hydraulic conductivity in the rangeland of central Zagros. We investigated the use of artificial neural networks (ANNs) in estimating soil saturated hydraulic conductivity from measured particle size distribution, bulk density, topographic attributes, normalized difference vegetation index (NDVI), soil organic carbon (SOC), and CaCo3 in topsoil and subsoil horizon. Three neural networks structures were used and compared with conventional multiple linear regression analysis. The performances of the models were evaluated using spearman’s correlation coefficient (r) based on the observed and the estimated values and normalized mean square error (NMSE). Topographic and vegetation attributes were found to be the most sensitive variables to estimate soil saturated hydraulic conductivity in the rangeland of central Zagros. Improvements were achieved with neural network (r=0.87) models compared with the conventional multiple linear regression (MLR) model (r=0.69).

Quantitative measurement of aeolian dust may help properly monitor and control the wind erosion. The aim of this study was to evaluate the efficiencies of four aeolian dust samplers including the modified Wilson and Cooke sampler (MWAC), cyclone dust sampler with cone (CDSC), cyclone dust sampler (CDS), and marble dust collector (MDCO) in comparison with the big spring number eight sampler (BSNE) in different velocity rates and particles sizes. For this purpose, MWAC, MDCO, BSNE were simulated and CDSC and CDS were designed and constructed. The relative efficiencies of the CDSC, CDS, MWAC, and MDCO were evaluated for the 80, 137, 260 micron diameter particle sizes (D50) in 2-7 ms-1 velocity by wind tunnel. The results showed that relative efficiency of CDSC is higher than CDS, MWAC, and MDCO as a consequence of the wind speed. CDSC and CDS relative efficiencies varied in relation to wind velocity, but MWAC, MDCO relative efficiencies remained constant. Also, CDSC, CDS, MWAC, MDCO relative efficiencies varied from 0.8, 0.48, 2.18, 0.58 times by increasing the particle size diameters from 80 to 260 micrometers, respectively.

Because of limiting water resources and increasing demand for food, it is necessary to investigate the effect of irrigation systems on water productivity. This research was conducted to evaluate yield and yield characteristics of two potato varieties under sprinkler and trickle irrigation systems. The treatments were two irrigation systems (sprinkler and trickle irrigation) and two potato varieties (Burren and Satina) in a randomized complete block design with three replications. Full irrigation was done based on moisture depletion from depth of root development in both irrigation methods.. Potato yield and water productivity (WP) in drip and sprinkler irrigation systems showed significant differences (P<0.01). The highest potato yield (24.08 ton ha-1) and water productivity (3.83 kg m-3) were obtained in drip-tape irrigation and Satina potato variety treatment. Also, the lowest potato yield (12.97 ton ha-1) and water productivity (1.73 kg m-3) were obtained in sprinkler irrigation systems and Burren potato variety. The potato yield in sprinkler irrigation system was obtained 42 percent lower than trickle irrigation system. In sprinkle system, dried top weight and height of stem were respectively higher and lower than those in trickle (Tape) irrigation system for both potato varieties. Overall, trickle irrigation is suggested for cool and dry climate to increase potato yield and water productivity.

Current study conducted to evaluate the effects of vermicompost and zeolite on the kinetics of nickel (Ni) fixation. Treatments consisted of a factorial combination of two vermicompost levels (zero and 2 w/w percent), three zeolite levels (zero and 4 w/w percent of zeolite of Firoozkoh, and Semnan) and two soil textures (clay and sandy loam) in three replications. All treatments were spiked with 50 or 100 mg Ni kg-1. DTPA extractable Ni was determined after 5, 10, 20, 30, 60 and 90 days. Ni availability was higher in sandy loam texture. Vermicompost application increased Ni availability in sandy loam texture in all the designated times. Zeolite application had no significant effect on Ni availability. The trend of Ni availability decrease was composed of two distinct stages with high and low Ni fixation rates. In the first step which continued up to 30 d, the available Ni fixation rate was high and then decreased sharply. Ni fixation data was suitably prescribed using simple Elovich and exponential equations. It seems that vermicompost has a greater effect to prevents Ni fixation and to retain it in available form in light texture soils. On the other hand, it seems that zeolite does not have any considerable effect on Ni fixation in calcareous soils.

The ability of different soil tests in predicting soil phosphorus (P) is important in soils amended with municipal sewage sludge. The objective of the present study was to evaluate several chemical extractants to estimate available P for bean growing in 10 calcareous soils amended with municipal sewage sludge from Chaharmahal-Va-Bakhtiari province under the greenhouse conditions. For this purpose, the soil samples were incubated with sludge at a rate of 39-ton sludge ha–1. The amount of available P of the soil samples was determined by Olsen, Colwell, ammonium bicarbonate-DTPA, 0.01 M calcium chloride, BrayІ, ІІ, Mehlich І and ІІ methods. A pot experiment in a completely randomized design was conducted to evaluate the bean plant indices. The results showed that the amount of extractable P with the above methods decreased in the following order: Colwell> Bray ІІ> Mehlich ІІ> Olsen> Ammonium bicarbonate DTPA> Mehlich І> Bray І> 0.01M chloride calcium. The extractable P with 0.01M chloride calcium, Mehlich І, ІІ Colwell and Olsen methods correlated significantly with plant indices (P concentration and P uptake). Thus, mentioned methods could be used to estimate plant-available P in the soils amended with sewage sludge.

Some recent research has indicated that certain alkaline contaminations may adversely affect mechanical properties of clayey soils. To examine the potential impact of alkaline divalent barium on the swelling characteristics of KAHRIZAK clay, the major solid-waste landfill at south of Tehran, a systematic set of experiments was conducted. Observations indicated that the swelling in the studied soil that belonged to the CH-MH group with a PI of 28.44, was reduced by about 17, 37, 48 and 54 percent, and swelling pressure by about 41, 55, 65 and 67 percent, respectively, after addition of barium chloride solutions to concentrations of 0.25, 0.5, 0.75 and 1.25 molal. It was also found that addition of barium chloride solutions to concentrations of higher than 1 molal had a little effect on reduction of swelling and swelling pressure.

The objectives of this study were to investigate the effect of dripper discharge and irrigation time on the wetted width in the sandy loam soil with high percentage of gravel and to evaluate previously developed models of estimation of the wetted width in the previous researches. The treatments included three irrigation times (T) of 4, 8 and 12 h and three dripper discharge rates (q) of 2, 4 and 8 l/h, with three replications. The wetted width of each dripper was measured 24 hours after irrigation application. The maximum and minimum wetted widths were 159.8 and 63.5 cm for T12q8 and T4q2, respectively. A linear model was developed as a function of two variables of irrigation time and dripper discharge rate was developed to predict the wetted width in sandy loam soil with high percentage of gravel. The evaluation of recommended models of wetted width for the studied soil showed that only one of six models was accurate enough to estimate wetted width. It can be concluded that the presence of gravels in the soil has a complex effect on width and depth of wetted zone. Thus, it is necessary to measure the wetted width and wetted depth in the field.

Desertification is known as a major crisis in arid regions of Isfahan province. This study aimed to assess the performance of three main desertification models including MEDALUS, MICD and FAO-UNEP for mapping desertification severity in the hotspot of Jarghuyeh region, eastern Isfahan. Different desertification indicators and their related indices were chosen based on the characteristics of the region and fieldwork, and spatially mapped in 27 geomorphologic facies. The desertification severity maps were classified based on the classification scheme for each model in ArcGIS 10 environment, and then comparison of the models and selection of the best one were achieved using IDRISI Tiga 16.03 software. The results of all three models showed that more than 95% of the region can be classified as severe desertification but due to the differences in the number of desertification classes and also indicators and indices only 45% of desertification severity was observed to be similar across the models. Results indicated that the MEDALUS model due to its flexibility to accept new indicators and indices, GIS-based characteristics, and use of geometric mean of indicators in desertification mapping seems to be a suitable model for studying desertification severity in the region. According to this model, 85% and 15% of the area are classified as very severe and severe class of desertification, respectively, which indicates that the rate of desertification is very high and immediate management programs are needed to slow down the desertification process in the region.

By modifying plants at genetical, physiological and ecological levels, entophytic fungi as the most important soil microorganisms have a pronounced growth-promoting activity and also increase plant resistance to biotic and abiotic stresses. This research was undertaken to evaluate the potential of P. indica to increase barley (Hordeumvulgare L.) resistance to lead (pb). Therefore, a greenhouse experiment with two fungus treatments (non-inoculated and P. indica inoculated) and five levels of pb (0, 25, 50, 100 and 500 mg/kg) with three replications was conducted based on a factorial design. Measurement of shoot and root dry weight showed that the growth of P. indica-colonized plants at all levels of pb treatments was higher (P<0.05) than that of the corresponding controls. Also, chlorophyll concentration of inoculated plants with P. indica was superior to non-inoculated plants. In addition, the results showed that in contrast to the plant shoot, lead concentration in the root of P. indica-colonized plants was higher than the non-inoculated controls.

Information on suspended sediment variation in times of flood is important in management of water resources, particularly management of basins, and in investigation of the causes of erosion. The relationship between discharge and suspended sediment concentration during floods is not similar and homogeneous for different reasons such as precipitation variety, discharge rate and sources of sediment and production of hysteretic loops. In this study, the instantaneous values of suspended load were simulated using genetic programming and regression methods. By comparing the two models, Genetic programming model was selected as the better one with the mean square error and determination coefficient of 0.8 and 0.5, respectively. Then based on this model, loops of suspended hysteretic load were drawn for the six events recorded in the period of 1387-1383. This resulted in 4 linear and 2 clockwise hysteretic loops for the river suspended sediment. Identifying various hysteretic loops is effective in determination of relative contributions of processes to production and transfer of sediment including amount and intensity of precipitation, flow rate and previous moisture conditions of watershed. The results showed that the clockwise hysteretic loops occurred usually in high precipitation and discharge, and linear hysteretic loops in spring because of low intensity precipitation.

One of the most essential and appropriate groundwater model components is accurate information of the recharge values among input data often introduced to the model as the percentage of rainfall of aquifers. The recharge values are influenced by many temporal and spatial factors. Firoozabad plain is one of the suitable plains for agriculture in the Fars province in which utilization of groundwater resources has been banned since 23 September 2002, due to the declining water level and negative balance. The main purpose of this study was to estimate the recharge values of groundwater aquifer by using SWAT in the MODFLOW model. Firstly, surface water was simulated via SWAT model, and sensitivity analysis, calibration, validation and uncertainty analysis of results were performed by SWAT-CUP software. After extraction of aquifer recharge values from the calibrated model, the groundwater of basin was simulated via MODFLOW model in both steady and unsteady conditions. Following the model calibration, the hydrodynamic coefficients of plain were determined and sensitivity of model was checked in terms of hydraulic conductivity and discharge rate of pumping wells. As for the confidence, the model was revalidated, which proved in simulating the behavior of the aquifer very well.

The aim of this study was to evaluate phytoavailability of cadmium to lentils after the application of composted animal manures. In a greenhouse experiment, two lentil (Lens culinaris) cultivars were grown in the soils applied with different levels of Cd from animal manure compost, and compared with Cd applied as cadmium chloride or their combination. Phytotoxicity of Cd was determined as plant growth, Cd accumulation, and the uptake of macronutrients. Addition of Cd significantly reduced plant growth and plant weight as well as plant water content. Phytotoxicity of Cd applied through manure composts was significantly less than the same rate of Cd amended with soluble CdCl2, suggesting the lower potential hazard of composted manure-applied Cd. Plants accumulated substantial amount of Cd in different plant parts. Most of the Cd taken up was retained in roots, and lentil roots had higher concentrations of Cd than the stem. Phytotoxicity of applied Cd in Ziba was significantly greater than that in Zabol cultivar. Cadmium addition especially as metal salt reduced nutrient concentrations in the shoot, and caused more nutrient accumulation in roots, probably due to the inhibition of their translocation to plant shoots. The results of this experiment point to the fact that the Cd source and loading rate are important factors in evaluation of Cd phytoavailability.