فهرست مطالب m.r. mosaddeghi

This study was conducted in the summer of 2021 to evaluate and validate the gravimetric soil water content measurements using a field oven. Ten soil types with a salinity of saturated paste (ECe) less than 4 dS m-1 and three saline soils were studied around Urmia Lake. Plots with dimensions of 1 m × 2 m were prepared for the selected soils to measure gravimetric soil water content and soil physical and chemical properties. The gravimetric water content (θm) values measured using the field oven (i.e., θmFO), were compared with those measured by a standard lab oven (i.e., θmLO). The soil water content values measured in the lab, regarded as a benchmark, were measured at 105 °C for 24 h. Temperatures of 120, 140, and 160 °C with three durations of 10, 15, and 20 min were used to dry the soil samples in the field oven. There was very good compatibility between the values of θmFO and θmLO when the soil samples were dried in the field oven for 15 or 20 min at all three temperatures. Significant linear relations were obtained between the θmFO and θmLO values as the slopes of linear relations were close to 1, the intercepts of relations were negligible and the distributions of measured data around the line 1 to 1 were unbiased. The minimal effects of soil organic matter content, clay content, salinity, and bulk density on water content measurements by the field oven indicate an important advantage of this method. These results confirm the high efficiency of the field oven for fast and reliable measurements of water content in different soils.

Drought is one of the most important abiotic stresses limiting the survival, growth, and production of plants in many regions of the world including Iran. Genetically, different species adopt different strategies to confront with drought. One of the mechanisms that plants have evolved to adapt to the environmental changes is stress memory. In this study, different genotypes of smooth bromegrass were evaluated to investigate the drought stress memory and drought stress tolerance based on a greenhouse pot experiment. Thirty three genotypes of smooth bromegrass were evaluated in three moisture environments: control (C), once drought-stressed (D2), and twice drought-stressed (D1D2) in a factorial arrangement according to the randomized complete blocks design with two replications. The dry matter yield decreased by 45 and 36% in the one-stress and two-stress treatments compared to the control, respectively. These results indicated the role of drought stress memory in modulating drought stress through the influence on forage dry yield and root dry weight. The root dry weight reduced in the once stress and twice stress conditions by 32 and 19%, respectively, compared to the control environment. This finding shows the significant effect of stress memory on the root growth. Based on the principal component analysis, superior genotypes were identified for future researches. Overall, the results suggested that smooth bromegrass is capable to activate some drought stress memory mechanisms related to morphological and root traits.

Smooth bromegrass is particularly adapted to areas with medium and low annual precipitations and has a high drought tolerance when compared with the other grasses. Drought is one of the most important environmental factors with adverse effects on plant growth and development and affects all morphological, physiological, biochemical and metabolic aspects of plants (Farooq et al., 2009). Therefore, it is necessary to identify drought-tolerant genotypes (Saeidnia et al., 2017b). The term stress memory was first proposed by Trewavas (2003), as the plant's ability to access past experiences to better respond to future stresses. In open-pollinated species that are difficult to develop inbred lines, such as smooth bromegrass, the main breeding method is to create synthetic varieties that are obtained through the crossing of suitable parents. Besides, half-sib matting is one of the most common methods for obtaining genetic information such as estimating the additive effects and dominance of genes (Nguyen and Sleper, 1983). Saidnia et al. (2017a) in a study on the genotypes of orchardgrass species found superior genotypes for hay production. They also examined the genetic parameters and heritability of dry matter yield and introduced the superior genotypes for the further researches. Hence, this study was designed to investigate stress memory and its effect on improving drought tolerance in a smooth bromegrass germplasm.

This research was carried out from February 2017 to June 2018 in the research greenhouse located at the Isfahan University of Technology as a pot experiment. A sandy loam soil with bulk density, field capacity, and wilting point of 1.57 g cm-3, and 12.5 and 7.4 %w/w, respectively, was used for filling the pots. The genetic materials included 33 genotypes of smooth bromegrass that were collected from different regions of the country and some foreign gene banks. The genotypes were investigated in three moisture environments including control (C), once drought-stressed (D2) and twice drought-stressed (D1D2) as a factorial experiment in the form of a randomized complete blocks design with two replications.

The analysis of variance showed that drought treatments had a significant effect on most of the traits. A significant difference was observed between the genotypes regarding the measured traits indicating high genetic diversity among the genotypes. The secondary drought stress significantly reduced most of the traits. The dry matter yield decreased by 45 and 36% in the once-stress and twice-stress treatments compared to the control, respectively. These results indicated the role of drought stress memory through the effect on dry yield of forage and root dry weight. Also, the root dry weight was reduced by 32 and 19% in the conditions of one stress and two stress compared to the control environment, respectively, which shows the significant effect of stress memory on the root system. Multivariate analysis showed that under the twice stress condition compared to the other two moisture environments, the relationships of the traits have undergone severe changes, which is a confirmation of the effect of initial stress and stress memory.

This research indicated a high genetic diversity among the smooth bromegrass genotypes in terms of stress memory responses, which can be used in the selection methods. For example, the means of dry matter yield and root dry weight decreased to a lesser extent when grown in the presence of twice drought stress, than once drought stress. This finding shows that the mechanisms of the stress memory related to morphological and root traits in this plant are activated by applying preliminary mild drought stress and help the plant to have a smaller decrease in growth. Based on the principal component analysis, superior genotypes were identified for future research. The results of this research can be used in breeding programs and future genetic research. It is also suggested that suitable genotypes be studied more in field conditions over several years.

Monitoring the changes in physical and hydraulic properties and stability of growth media due to root growth effects and wetting and drying cycles is important. Wetting and drying cycles can probably change physical characteristics, availability of water, air and nutrients for the plant and, as a result, might affect the growth and yield of the greenhouse plants. The growth period greatly affects the physical characteristics of the growth substrates; therefore, the watering of growth substrates should be managed according to these changes to avoid improper irrigation.

In this study, 14 growth media were prepared from individual substrates with different volumetric ratios. In order to evaluate the changes of growth media over the time (i.e., during consecutive irrigation events) in the greenhouse, 10 wetting and drying cycles were applied on the growth media in the lab. Several physical indicators including easily available water (EAW), air after irrigation (AIR), water buffering capacity (WBC) and water holding capacity (WHC) of the growth media were determined before and after the wetting and drying cycles. Besides, the subsidence, decrease of mass and decomposition of the growth media were determined over the time. Total porosity (TP), bulk density (BD), particle density (PD), pH and electrical conductivity of the mixtures were measured as well.

The pH values in the growth media varied from 5.72 to 6.94. The maximum pH value was related to sawdust- sugarcane bagasse biochar produced at 300◦C vermiculite-zeolite, and wheat straw-vermiculite substrates, and the minimum value was related to the cocopeat-perlite substrate. The values of EC in the growth media varied from 0.21 to 1.43 dS m-1. The highest and lowest EC values among the growth substrates were related to date palm bunches-vermiculite-rockwool and rockwool (0.2)-perlite substrates, respectively. The bulk density (BD) values of the growth media varied in the range of 0.163-0.401 Mg m-3. The values ​​of total porosity (TP) of the growth media varied in the range of 64.8-82.8%v/v. The highest TP was related to the cocopeat-perlite substrate. The TP values ​​of most of the substrates were greater than 70%v/v. The average values of EAW in the growth substrates ranged from 0.123 to 0.272 cm3 cm-3. The highest EAW was related to the sawdust-sawdust biochar produced at 500 ◦C vermiculite-zeolite substrate. The application of wetting and drying cycles increased EAW in most of the growth media. Therefore, it can be stated that the time had a positive effect on the EAW in most of the growth media. The average values of AIR before and after the application of wetting and drying cycles for the growth media varied in the range of 0.063-0.240 cm-3 cm3. The highest value of this indicator was observed in the sawdust-date palm bunches biochar produced at 300◦C vermiculite substrate. In all substrates (with the exception of the sawdust-sawdust biochar produced at 500◦C vermiculite-zeolite), the AIR increased after wetting and drying cycles. The range of WHC values before and after applying wetting and drying cycles was 0.453-0.699 cm3 cm-3. The highest WHC belonged to the wheat straw-vermiculite substrate. The WHC values of five growth media, including cocopeat-perlite, decreased due to the application of wetting and drying cycles, and the WHC values of nine growth media decreased. The most stable substrate after the wetting and drying cycles was rockwool-sawdust-vermiculite. The effect of time on the quantity of WBC was positive, so that with the application of wetting and drying cycles, the WBC values of most of the substrates increased. In all substrates, subsidence and dry weight reduction were observed after the wetting and drying cycles. These changes were low for the substrates with a high volumetric ratio of inorganic materials. The least change among the growth substrates in terms of decomposition (dry weight reduction) was related to the completely inorganic substrate rockwool (0.1)-perlite (%0.17). The most stable substrate in terms of subsidence after wetting and drying cycles was the rockwool-sawdust-vermiculite, which has a large volumetric ratio of individual inorganic substrates. The highest subsidence was observed in the substrates containing wheat straw (wheat straw-vermiculite and date palm bunches biochar produced at 300◦C wheat straw-vermiculite). The organic matter content in all the growth substrates decreased over time (after wetting and drying cycles). The decrease of organic matter in the substrates can be related to the decomposition of organic materials as a result of wetting and drying cycles.

The BD, TP, EAW and WHC of the majority of growth media were in the optimal ranges and for some mixtures even better than cocopeat-perlite. Wetting and drying cycles could affect the growth media through several processes such as decomposition of organic compounds, displacement and rearrangement of particles, fragmentation of particles, shrinkage, hardening and subsidence. The growth media with a high percent of organic substrates were unstable as compared with those containing a high proportion of inorganic substrates. In general, the wetting and drying cycles increased the frequency of micropores in the growth media. The wetting and drying cycles positively affected EAW, WHC, AIR and WBC of most growth media. These findings imply that wetting and drying cycles may improve the growth media according to the studied extensive variables. However, it is necessary to study the intensive variables such as hydraulic conductivity, oxygen diffusion and pore tortuosity in the growth media for better evaluation of the impact of wetting and drying cycles as well.

According to the rapid population growth, the challenging issue of production of economic and suitable food sources has led to greater attention to soilless culture greenhouse production systems. Components of growth media in horticulture are usually selected based on physical and chemical properties and their abilities in providing enough water and oxygen for roots. This study was conducted to investigate the feasibility of using some agricultural wastes (i.e., sawdust and wheat straw) and three rockwool types (i.e., raw, ground, ground, and sieved) as substitutes for commercial greenhouse growing media such as cocopeat and perlite. Several hydraulic, aeration, and chemical properties including easily available water (EAW), air after irrigation (AIR), water holding capacity (WHC), water buffering capacity (WBC), saturated water content (θs), bulk density (BD), total porosity (TP), water drop penetration time (WDPT), pH, and electrical conductivity (EC) were measured and scored in the growth media. Raw rockwool had larger particles compared to ground rockwool, which resulted in its faster water release. Processing of the rockwool decreased the saturated water content and saturated hydraulic conductivity due to the decrease in particle size. Four growth media were scored as very good and one was scored as good. The highest and lowest scores belonged to sawdust (34) and ground rockwool (30), respectively. The studied growth media with high TP, EAW, and WHC and low BD, EC, and WDPT can be used individually or combined with other commercial substrates for greenhouse growth media.

One of the most significant environmental crises in arid, semi-arid, sub-humid, and even humid regions is the destructive phenomenon of desertification and in the arid and semi-arid regions is wind erosion. These problems exist in large areas of Iran and it is necessary to use an environmentally friendly and economic method to solve this problem. In this study, calcium bentonite clay was used for the first time in Iran and perhaps in the worlds in the critical region of Sajzi, which covers an area of 65 hectares. Experiments were performed on the crusts after one year of mulching with bentonite clay. The results showed that wind erosion has a negative and significant correlation with the mean weight diameter and geometric weight diameter of aggregate, aggregates with diameters greater than 0.25 mm, shear strength, and penetration resistance. On the other hand, the results of the permeability test using double-ring and by three models (Kostiakov, Horton, and Philip) showed that the lowest mean square error (SSE) and the highest coefficient of determination (R2) belonged to the Kostiakov model in the mulch-applied and control samples. This result indicated the superiority of the Kostiakov model compared to Horton and Philip's models. Wind erosion intensity was also measured in situ using a portable wind tunnel at 20 points in the Sajzi region. The findings showed that mulch application has controlled more than 95% of soil erosion.

Sewage sludge has positive effects on chemical and physical properties of soil. Biochar production from sewage sludge, while having positive effects on the soil, can lead to its effective management, especially in relation to the environment. The objective of this study was to investigate the effect of sewage sludge and its biochar on water repellency and structural stability of two calcareous soils with clay loam and loam texture under corn cultivation. Sewage sludge was mixed with soils in the rates of 10, 20 and 40 t ha–1 (S1, S2 and S3). The equivalent application rates of biochar were 7.3, 14.5 and 29 t ha–1 (B1, B2 and B3). At the end of corn growing period, soil water repellency was measured by the intrinsic sorptivity method. Water-dispersible clay (WDC) was also measured as an indicator of soil structural instability. Results showed that the water repellency index (RI), ethanol sorptivity (SE) and soil-water contact angle (β) were significantly higher in sewage sludge and biochar treatments than those of control. However, the WDC in the sewage sludge and biochar treatments was significantly lower than the control. The values of RI and β in the clay loam soil were significantly higher than the loam soil. In both sewage sludge and biochar treatments, an increment in the application rate increased the RI. In the clay loam soil, the highest RI and SE were observed in the sewage sludge and then in the biochar treatment; while in the loam soil, the RI had the trend of biochar > sewage sludge > control. Overall, the results indicated that the use of organic treatments such as sewage sludge and its biochar would increase sub-critical soil water repellency and structural stability.

This research was performed to determine the effect of inoculation of two species of arbuscular mycorrhizal fungi (AMF) on soil available water (SAW) and glomalin concentration under drought and salinity stresses according to a factorial based on completely randomized design with three replications. Treatments included two plant species Atriplex canescens and Haloxylon ammodendron with inoculation of two fungal species Glomus geosporum and Glomus mosseae plus two levels of salinity stress at 7 and 14 dS m-1, and two levels of drought stress including maximum allowable depletion (MAD) of 50 and 80%. After one year of treatments, plant available water (PAW), least limiting water range (LLWR), integral water capacity (IWC), total and easily extractable glomalin concentration and soil organic carbon (SOC) content were measured. Results indicated a significant increase in SOC, glomalin concentration, PAW, LLWR, and IWC by increasing the salinity level in treatments inoculated with G. mosseae and G. geosporum. The highest percentages of increase in PAW (147%), LLWR (140%) and IWC (85%) as compared with control were observed under combined salinity and low drought treatment (14 dS cm-1 + MAD of 50%) in A. canescens inoculated by G. geosporum. The highest concentrations of total glomalin and easily extractable glomalin were observed in both plant species under salinity of 14 dS m-1 and severe drought treatment (MAD of 80%) with the inoculation by G. geosporum and G. mosseae. Overall the results of this research indicated a reduction in negative consequences of drought and salinity stresses in the soil under cultivation of A. canescens and H. ammodendron, with application of mycorrhizal fungi.

Soil compactibility can be quantified using different indices such as maximum dry bulk density (BDmax) and critical water content (θcritical) in a compaction test. The objective of this study was to determine soil properties influencing soil compactibility by evaluate pedotranfer functions (PTFs) with respect to their accuracy and usefulness for the prediction of BDmax and θcritical using linear regression and ANN methods. 100 soil samples were collected from arable and virgin lands in southeast Iran. Primary particle size distribution, CaSO4, CaCO3, organic matter (OM) contents and natural bulk density were used as predictors. Two PTFs were developed using linear multiple stepwise regression: a PTF that estimates BDmax using clay and sand contents and natural bulk density as predictors (R2 = 0.45), the other one for the estimation of θcritical using clay and CaSO4 contents as predictors (R2 = 0.51). Furthermore, an attempt was made to construct PTFs for the prediction of the BDmax and θcritical using ANNs. High prediction efficiencies were achieved using the ANN models. Generally, when all of the easily-available soil properties were included as predictors, much more accurate estimates were obtained by the ANN models for the θcritical and BDmax as compared with the linear regression method. Sensitivity analysis showed that the most important variable in BDmax prediction using ANNs is the BDnatural followed by sand and clay, CaCO3 and CaSO4 contents. The θcritical had the highest sensitivity to clay content and the lowest sensitivity to OM content in the studied soils.

Shortage of water resources and deterioration of water quality have urged the need to develop new technologies for the removal of contaminants from water. Heavy metals produced by municipal and industrial activities are among the most toxic contaminants present in the natural and waste waters. Different methods have been developed for the elimination of heavy metals from water resources and industrial waste waters. Adsorption is an effective and economic method for the water purification purposes. Nowadays, clays and natural polymers have been widely used as the adsorbents for heavy metals, due to their eco-friendly nature, natural abundance, low cost and high specific surface area. If these adsorbents are used as a hybrid material, some of their physical and chemical restrictions would be alleviated. In this study, polyacrylic acid–bentonite hybrids and natural bentonite were compared in terms of Pb adsorption in the batch and fixed-bed column systems. Besides, the effect of pH on Pb retention was investigated in both systems. The results of the batch studies showed that Langmuir and Freundlich isotherm models were appropriate in ing quilibrium Pb sorption data. Pb sorption by the sorbents was increased with the rise in solution of pH from 4 to 6, showing the greatest Pb sorption capacity at pH values of 4 (83.29 mg g-1) and 6 (103.3 mg g-1). Different indices of filtration and adsorption, including average relative effluent concentration, relative adsorption index, relative transmitted index, and filtration coefficient, were calculated from the break-through curves, indicating that the polyacrylic acid-bentonite nanocomposite was superior in the Pb sorbtion, as compared to bentonite. Also, a higher pH value resulted in the greater Pb removal from the solutions.

An investigation was carried out for the journals in 13 branches of Agricultural Sciences and Natural Resources at the Department of Agricultural Sciences, IR Academy of Sciences. A total of 200 Iranian scientific journals were qualitatively evaluated. As part of that project, the results of 10 journals in the fields of soil science published in 2014 are reported. Ten indices for evaluating the format of the journals and five indices for the quality of the articles published in the journals were designed and used. The data were statistically analyzed to rank the journals. Results showed that none of the journals received the highest ranking (very good). Twenty percent were good, fifty percent were medium, twenty percent were weak and ten percent were placed in the very weak category. The journals were also compared by the following criteria in relation to published articles: innovativeness, applicability and up-to-datedness of articles and practical usefulness and necessity of publication of the journal. In this regard, Biology Journal scored highest. Journals of Soil and Water Conservation Researches, and Soil Management and Sustainable Production scored highest for the necessity of publication. None of the assessed journals showed any preference in view of practical usefulness.

A challenge of sustainable development is related to agriculture, food security, and conservation of water and soil resource, under the current crop production paradigm. Increasing crop yields often have negative environmental impacts. Soil salinization and sodication are major environmental hazards that limit agricultural potential and are closely related to agricultural unsuitable management and water resources overexploitation, especially in arid climates. In this study, we investigated the negative impacts of saline and sodic irrigation water on soil properties that it is necessary to study the factors affecting the degradation of soil structure to implement proper land management and we intended to help the farm producer or landowner to understand the fundamental differences between these two problems. Samples of clay loam and sandy loam soils were treated in 5 wetting and drying periods with different types of water quality (which combinate different levels of EC and SAR). Soil water content of samples was achieved at soil matric suctions of 0, 10, 20, 40, 60, 100, 300, 1000, 2000, 4000 and 15000 cm. Also, dispersible clay and saturated hydraulic conductivity were determined. Results showed that increasing of SAR caused dispersion of clay and saturated hydraulic conductivity was decreased with increasing of dispersed clay. Increasing SAR caused some macropores and mesopores changed to micropores and as result enhanced water retention especially at high matric suctions. Water retention capacity was enhanced by increasing in water EC as that flocculated soil particles and created new soil pores.

Water repellency is one of the major problems of oil-contaminated soils and influences water redistribution via reduced infiltration, enhanced surface runoff and soil erosion, and preferential flow. The objectives of this study were to examine the effects of petroleum on water repellency and soil water content. Undisturbed samples were collected from sandy loam and clay loam textured soils and three levels of petroleum including 0, 0.5% and 1% (w/w) were added to the samples. The water drop penetration time (WDPT) test was used to measure the water repellency of soils. The soil water characteristic curve (SWCC) of the soil cores was measured using sandbox and pressure plate apparatus. The van Genuchten-Mualem model was fitted to the SWCC data and soil physical quality index (S) as defined by Dexter. Increment of petroleum increased the soil water repellency and sandy soils were most susceptible to water repellency due to low specific surface area. Petroleum contamination also changed soil pore size distribution, as the soil field capacity and available water content (AW) was increased due to development of soil microporosity. Although greater water repellency increased AW in the polluted samples, reduction in soil macroporosity could result in unfavorable condition for plant growth. Petroleum contamination affected the shape and slope of SWCC. Water retention in petroleum-contaminated soil of the two textures of sandy loam and clay loam was lower at low suction values due to decrease in macroporosity, while in clay loam soil it was higher at high suction values due to increase in microporosity. Petroleum significantly decreased the S index of both soil textures;but it was more severe in sandy loam texture. According to Dexter classification and results, water repellency due to petroleum decreased soil quality by reducing macro pores and S index (ranged between 0.02 to 0.035), which have unfavorable result for plant growth. Also, coarse textured soils could develop water repellency more readily.

Almond (Prunus dulcis) is an important horticultural crop in Iran especially in East Azarbaijan province. Due to the scarcity of water resources and increase in their salinity during the recent years, also economic importance of this crop in the area, studying the salinity effect on almond water relations seems crucial for irrigation scheduling. This investigation aimed to evaluate the salinity effects on some water stress indicators that can be used for irrigation scheduling in almond orchards. The study was conducted during 2014 based on randomized complete block design with three replications on a loamy sand soil at horticultural station of the State Agricultural Research Center. Treatments comprised three irrigation salinity levels viz. 2 (T1), 4 (T2), and 5 (T3) dS m-1. Air temperature (Ta) and relative humidity were taken from the meteorological site. Canopy temperature (Tc) leaf water potential (LWP) and volumetric soil water content (WC) at three depths (0-20, 0-40, and 0-70 cm) were measured at midday (12-14) during the growing season using infrared thermometer, pressure chamber and TDR respectively. Results indicated that salinity has significant effect (p

This study was conducted to investigate the effect of water salinity and sodicity on pore size distribution and plant-available water of two clay and sandy clay loam calcareous soils. All combinations of water EC values of 0. 5، 2، 4 and 8 dS m-1 and SAR values of 1، 5، 13 and 18 (in total 16 solutions) were used to wet and dry the soil samples for five cycles. Then، water retention of the soil cores was measured at matric suctions of 0 (θs)، 10 (θ10) 100 or 300 cm (θFC) and 15000 cm (θPWP). The following quantities were calculated: the difference between θ100 or θ300 and θ15000 considered as available water contrent، the θs and θ10 as macrorosity، the θ10 and θ100 as mesoporosity، and the θ100 as microrosity. The initial porosity of both soils was similar، but the greater values of pore indices and θFC، θPWP and AWC were measured in the clay soil due to clay swelling. As water EC increased، mesopores were destructed and altered to macropores and micropores. Salinity altered the mesopores into macropores due to contraction of diffuse double layer and particle’s flocculation and consequently decreased the θFC، and created new micropores which were responsible for the higher value of θPWP. These trends ultimately diminished the AWC. As water SAR increased، mesopores were destructed and altered to micropores but it did not significantly affect the macropores. With increment of SAR، both θFC and θPWP increased due to structural distruption clay swelling and dispersion resulting in increased adsorptive and interlayer surfaces. The increasing effect of SAR on θPWP was greater and more distinct so that AWC was reduced. As a result، high values of SAR of irrigation water decreased the soil available water to plants besides its toxicity and hazardous effect on plants. With increment of irrigation water salinity، the destructive impacts of SAR diminished. The influence of water quality on water retention was pronounced for the clay soil. ‎

The aim of this study, was to evaluate the effect of winter cover crop residues on speed of seed potato emergence and percentage of organic carbon, soil specific weight and soil temperature. An experiment was carried out at the Research Farm of Agriculture Faculty, Bu-AliSinaUniversity, in 2008-2009. The experiment was a randomized complete block design with three replications. Winter cover crops consisted of rye, barley and oilseed rape, each one with common plant density (rye and barley at 190 kg.ha-1 and oilseed rape at 9 kg.ha-1) and triple plant densities(rye and barley 570 kg.ha-1 and oilseed rape, 27 kg.ha-1) and control (without cover crop). The results showed that rye and barley with triple plant densities produced higher biomass (1503.5 and 1392.2 g/m2, respectively) than other treatments.Soil physicochemical properties were affected significantly by using cover crops. Rye, barley, and oilseed rape with triple rate and rye with common rape of plant densities produced, the highest organic carbon. Green manure of rye and barley with triple and rye with common rate plant densities, reduced soil specific weights by 17.3, 18 and 18 percent as compared with the control treatment (without cover crop planting). Rye and barley with triple plant densities increased average soil temperature by 12 and 11 percent respectively in comparison with control treatment. These treatments increased speed of seed potato emergence by 20 and 12 percent respectively as compared with that of control treatment, respectively. Other treatments showed no significant difference as compared to control. Cover crop residues increased plants speed of seed potato emergence through improving soil conditions.

In this study، raw and treated wastewaters were used for potato cultivation in lysimeters. Five irrigation water treatments were included as: raw wastewater، treated wastewater، fresh water، a combination of 50% raw wastewater and 50% fresh water and a combination of 50% treated wastewater and 50% fresh water. The experiments were run within greenhouse during a period of four months. After construction and preparation of the lysimeters، they were filled with a two-layered soil. The textures of the upper and lower soil layers were sandy loam and sandy clay loam، respectively. In order to create the structure and conditions of the natural soil and develope macropores and preferential pathways، lysimeters were irrigated systematically each week during a period of five months before plantation. A total of eight irrigation programs with an interval of eleven-days were applied during the growth season. Unsaturated water infiltration into the soil was measured using a disk infiltrometer at the beginning and at the end of growth season. In order to evaluate the irrigation effects on soil physical properties، DISC Software (numerical) and Wooding (analytical) methods were employed to analyze the infiltration data. The results of saturated hydraulic conductivity were compared with direct measurements of the constant-head method، in which the numerical method (DISC software) was identified as the best method. The results showed that in all treatments، the saturated hydraulic conductivity and steady-state infiltration rate at matric suctions 5 and 10 cm increased after irrigations when compared with the initial values. Result also indicated that the unsaturated hydraulic conductivity and steady-state infiltration rate increased significantly in the wastewater treatments compared to the fresh water. Also، the maximum values of the steady-state infiltration rate and saturated hydraulic conductivity were observed in the raw wastewater and the combination of treated wastewater and fresh water treatments. The minimum value also belonged to fresh water treatment. Moreover، the highest changes in θs، αVG and nVG were recorded in the combined fresh water-treated wastewater treatment. The lowest variations of these parameters (except θs) were observed in fresh water treatment.

Soil quality, aggregate stability and erosion sensibility are affected by different range management practices. This research aimed to evaluate the relationships between soil organic carbon, mean weight diameter (MWD) and aggregate size distribution in the surface soil layer (0- 20 cm) of various range sites with different grazing intensities (non, slightly and heavily grazed) in Bardasiab rangeland, Feridounshahr, Isfahan province. Stratified random sampling method was used to collect soil samples along the established transects. Some physical and chemical properties of soil samples such as texture, electrical conductivity (EC), organic carbon (OC), MWD and sodium absorption ratio (SAR) were measured in the soil laboratory. Simple linear regression and One-way ANOVA followed by the Fisher’s LSD test were used to analyze the data. Results of regression analysis showed that MWD and OC of the soil samples were significantly correlated (α =1%, R 2 = 61.3 %). The soil MWD values of range sites with various grazing intensities were significantly different (α =5%). Organic carbon was increased and SAR was decreased in the sites located inside exclosures, which lead to higher soil MWD. Aggregate size distribution among various sites were significantly different (α =5%) only for the aggregate smaller than 0.25 mm. Soil aggregates sizes between non-grazed and heavily grazed sites were also significantly different only for the size ranges of 4- 8 mm) α =5%, (and less than 0.25 mm) α=1% (. In addition, macro aggregates increased and micro aggregates decreased in range sites with no or slight grazing intensity, respectively as these sites experienced low trampling and increased litter and organic carbons. Soil aggregate stability can therefore be used as an appropriate indicator for monitoring the impact of different management practices on rangeland soil quality and health.

Soil physical and chemical properties, and test conditions might affect soil structural stability. In this study, the effects of test conditions as well as intrinsic soil properties on structural stability were investigated for selected soils from Hamedan Province. Mean weight diameter (MWD) and tensile strength (Y) of aggregates were determined by wet sieving method and indirect Brazilian test, respectively. The soil samples were pre-wetted slowly to matric suction of 200 kPa before the wet sieving. The pre-wetted samples were wet-sieved for 5, 10 and 15 min in order to simulate different hydro-mechanical stresses imposed on soil structure. Tensile strength of soil aggregates were also measured at air-dry and 500 kPa matric suction conditions. Short duration shaking (i.e. 5 min) could effectively discriminate the Hamedan soils in terms of structural stability due to their fairly low aggregate stabilities. The soil organic matter content had the highest impact on MWD followed by both clay and CaCO3 content. The same was true for the Y values i.e. OM played the highest role in mechanical strength of soil aggregates. The highest coefficient of determination (R2) was obtained between Y and the intrinsic soil properties for matric suction of 500 kPa. The organic matter content had an important role in water and mechanically stable soil aggregates. The results indicated that short-duration wet sieving (i.e. 5 min) and measurements of tensile strength at matric suction of 500 kPa could be recommended for aggregate stability assessment in Hamedan soils

Transport and filtering of pathogenic bacteria through porous media and groundwater resources are important and، therefore the effect of various factors on bacteria transport and filtering has been given a great attention nowadays. In this study، effects of calcium sulfate and carbonate on Psedomonas fluorescens filtration and filtering parameters were investigated in saturated sand columns under steady-state flow. The calcium carbonate levels included 0، 5، 10 and 20 %w/w and calcium sulfate levels consisted of 0، 5 and 10 % w/w which were thoroughly mixed with sand (0.15-0.25 mm). The experiment was considered factorial in completely randomized design with three replicates. The treated sands were poured into pyrex cylinders with length of 20 cm and diameter of 7 cm. Then، steady-state saturated flow with constant flux was applied to the columns. When the steady-state flow was established، the bacteria suspension with concentration of 106 CFU cm-3 (C0) was injected as step input into the columns. The leaching then was continued up to 5 times of pore volume (PV). The effluent concentration of the bacteria (C) was measured at 0.25 PV intervals. Then، the sand columns were divided into 0-5، 5-10، 10-15 and 15-20 cm layers in order to measure the filtered bacteria in each layer. The results showed that the effects of calcium carbonate on retaining of the bacteria in the 5-10 and 10-15 cm layers were significant at 1% level. It was significant at 5% for the 15-20 cm layer. The effect of calcium sulfate was also significant at 5% for the 10-15 cm and 15-20 cm layers. The interactive effects of treatments on bacteria adsorption was significant for the 5-10، 10-15 and 15-20 cm layers. The retained concentration profile and the filtration coefficient were significantly affected by the treatments، showing higher bacteria adsorption at lower depths and predominance of physical filtering. The results showed the high filtering capacity of carbonate and sulfate minerals which could ultimately reduce bacteria transport in saturated porous media towards groundwater resources.

The increased potential for soil erosion and compaction due to continuous row crop production and intensive tillage is causing some concern and has led to the consideration of reduced tillage techniques as part of the solution. The objective of this study was to investigate the short-term (one-year) influences of different management practices on the physical properties of a sandy loam soil under corn crop. Treatments were the combinations of three tillage systems (no-till, NT chisel plow, CP and moldboard plow, MP) and three composted cattle manure rates [0, 30 and 60 ton (dry weight) ha-1]. The experiment was carried out in a split-plot design. Three replicates of the treatments were applied in a randomized block design. Saturated hydraulic conductivity (Ks), total porosity (TP), macro-porosity (Macro-P), micro-porosity (Micro-P) of soil and mean weight diameter (MWD) of aggregates, were measured to a depth of 22.5 cm when 100 percent of the tassels appeared. Tillage and manure combination had significant effects on Log[ Ks], TP, Macro-P and Micro-P. The MP system increased pore space and continuity due to complete inversion and loosening, and as a result Ks, TP, Macro-P and Micro-P were higher than NT system. Higher Macro-P observed for CP might have caused higher Ks versus MP. Reduced tillage systems increased MWD and the increment of manure caused an increase in MWD over all tillage treatments. The results indicate short-term positive effects of manure application on soil pore size characteristics and aggregate stability under moldboard and chisel plowings in the region.

Soil tilth is crucial to seedling emergence, plant growth, and crop yield. Soil tilth of unstable soil is very susceptible to change. Internal forces originating from matric suction can change soil physical properties. A laboratory study was conducted on pots of a surface silty clay loam soil of Khomeinishahr series (fine-loamy, mixed, thermic Typic Haplargids, USDA), located in Research Farm of Isfahan University of Technology. Soil surface subsidence, bulk density, cone index, and tensile strength were measured after first flood irrigation. Results showed that the seedbed (0-20 cm) with a bulk density of 1.2 Mg.m-3 will be changed to a massive soil with high values of bulk density, cone index, and tensile strength after soil wetting. Slaking, slumping and coalescence of the soil caused soil surface to subside about 1.5 cm in 20 cm soil layer. After irrigation, cone index and tensile strength increased abruptly with decreasing of moisture content. It is shown that the dominant source of strength (cone index and tensile strength) gain during drying is the effective stress due to matric suction. In the absence of external loads, physical state (tilth) of the soil returned back to the original state. Therefore, soil slaking and slumping and rearrangement of particles along with the internal forces are the factors leading to soil hardness.

Tillage system effect, Conventional (CT) vs. No-Till (NT), on soil physical properties and Br transport was studied at two locations in North Carolina. The soil types were a Typic Paleudults at Coastal Plain (site 1) and a Typic Kanhapludults at Piedmont (site 2). Bulk density (BD), total porosity (TP), macroporosity (MP), and saturated hydraulic conductivity (Ks) .were measured in plant row (R), and trafficked (T) and untrafficked (N) interrows. A rainfall simulator was used to apply two early season rainfalls to 1 m2 plots where KBr suspension was surface applied for Br leaching study. The first simulated rainfall event (30 min) consisted of a low (1.27 cm h-1) or a high (5.08 cm h-1) rate applied, 24 h after Br application. One week later, the high rainfall rate was repeated on all plots. Soil samples were taken two days after applying first and second simulated rainfall (a week between them) and the end of season from different depths for measuring Br concentrations. Soil physical properties were affected by both tillage system and position. Bulk density was higher in NT versus CT and in T position versus Rand N positions. Total porosity was lower in NT versus CT but MP was significantly higher in NT. Saturated hydraulic conductivity was about 90% lower at T position versus N and R positions. Coefficient of variation was quite large, making it difficult to obtain statistical differences between tillage systems. The surface l0-cm of soil contained the highest Br concentration for depth treatments with treatment differences occurring primarily in 0 to 25 cm depth. In first and second sampling dates, more Br leached under NT versus CT system. However, there was no significant difference between the two tillage systems in Br leaching at the end of the growing Season. In site 1, Br leached more due to the coarse texture and high Ks of the soil.

Soil structure maintenance and stability is an important index indicating sustainable soil management. In this regard, components such as soil moisture and organic matter affect soil compactibility during farm machinery trafficking. Soils in Central Iran are commonly very low in organic matter (OM) and thus susceptible to compaction. This study was conducted to measure the effects of soil moisture content and manure application on soil compactibility. A randomized complete block design with four blocks (replicates) with the treatments nested (split-block) into the blocks was used in the soil (Typic Haplargids), located in Isfahan University of Technology Research Farm (Lavark). One-year aged manure treatments 0, 50, and 100 t ha-1</sup> were incorporated into soil up to the tillage depth (20 cm) by a heavy disc. After five months (July-November), a two-wheel-drive tractor Universal Model U-650 was passed through the field at soil moisture contents of plastic limit (PL), 80% PL (0.8PL), and 60% PL (0.6L), either once (P1) or twice (P2). Bulk density (BD), cone index (CI), and soil sinkage (S) were measured as indices of soil compactibility and trafficability. Adding manure countered the effects of load and wetness on BD and CI, significantly. There was a significant difference between the effects of 50 and 100 t ha-1</sup> of manure on BD but not on CI. Manure application reduced soil sinkage at high moisture contents (PL) but increased it at low moisture contents (0.6PL). Adding manure also reduced the BD and CI of subsoil. Repeating the passage of tractor (P2) increased compaction significantly. The significant increase in BD and CI did no occur at 0.6PL. When no manure was applied even at 0.6PL, there were limitations for trafficability, whereas this limit for 50 t ha-1</sup> treatment was reached at 0.8PL. Results from this study indicate that the manure application at a rate of 50 t ha-1</sup> reduces soil compactibility and increases soil moisture trafficability range.