Water and Soil

Abstract This study was conducted to evaluate using terrain attributes derived from digital elevation model (DEM) as ancillary data to predict soil organic carbon (SOC) by implementing different statistical and geostatistical techniques. A linear regression model (LR), Artificial Neural Network model (ANN), ordinary kriging (OK), ordinary co-kriging (OCK), regression kriging (RK) and kriging with an external drift (KED) were performed to predict spatial distribution of SOC in an area of 2400 km2 in mashhad, iran. The SOC was measured for 200 soil samples of the study area and their corresponding Terrain attributes value was extracted from derived from 10-m resolution DEM. correlation between measured SOC and individual terrain attributes was determined, the number of 160 data were used for model development and 40 as validation data set. Resulting maps of different interpolation methods were compared to evaluate map quality using MAE and R2 criteria calculated from plotting measured versus estimated data. The results showed that there is a significant but not strong correlation between SOC and terrain attributes. The comparison of estimation techniques showed that the KED technique with wetness index as ancillary data has the best performance (MAE=0.18 %, R2=0.67) of all, but no significant difference with RK. There were modest differences between maps created with geostaistical technique but sensible difference with LR and ANN ones. The results of this study propose that although there is a significant correlation between SOC and terrain attributes therefore It can be use for enhancing the quality of map, but it is not able to express the spatial variability of SOC as it is necessary for detailed soil map. Because there is other factors controlling SOC spatial distribution

Abstract Iron is an essential micronutrient for plant growth. The existence of lime, low content of organic matter and excess application of phosphate fertilizer in soils are the factors affecting its availability. In this study the effects of lime, phosphorus and organic matter on growth and iron uptake of maize were evaluated. A greenhouse experiment was conducted with two levels of lime (0, 2% calcium carbonate) two levels of organic matter (0 , 1% cattle manure),three levels of phosphorus (0, 200, 400 kg ha-1 triple super phosphate). The experimental design used, was completely randomized ,factorial, with 2 replications. Results showed that application of cattle manure significantly increased shoot dry weight, iron concentration and iron uptake of maize. The application of lime had no significant effect on shoot dry weight however it decreased iron concentration and iron uptake of maize. Application of phosphorus increased shoot dry weight but decreased iron concentration and iron uptake of plant. The study of organic matter interaction with one of the other treatments showed that application of organic manure can improve the negative effects of lime and phosphorus.

Abstract High concentration, of heavy metals and the presence of phosphorus in soils may cause a reduction in the growth and activity of arbuscular mycorrhizal (AM) fungi and consequently, the spore production of these fungi would decrease. In order to evaluate the effect of zinc and cadmium as heavy metals and phosphorus on arbuscular mycorrhizal fungi activity through measuring glomalin produced by these fungi a factorial experiment arranged as completely randomized design was carried out. Experimental factors included two fungal species G. mosseae and G. intraradices and non mycorrhiza (NM), six combinations of metals (400 mg of Zn, 25 mg of Cd, 400 mg of Zn + 25 mg of Cd, 50 mg P, 50 mg of P+ 400 mg of Zn + 25 mg of Cd, and no metal kg-1 soil sample) in three replications. The results showed that inoculated treatments produced more glomalin compared to non mycorrhizal treatments. The application of Cd, Zn and P caused a significant reduction in produced glomalin by both fungi species. The most reduction of glomalin in G. intraradices was detected in Cd treatment and in G. mosseae was in Zn treatment. The result also showed a positive correlation between the measured glomalin by Bradford assay and the percent of root colonization. According to the results of this study, glomalin in soil could be an indicator to monitor arbuscular mycorrhizal fungi activity and soil health.

Abstract Soil enzyme activities can be used as indicators of soil quality for assessing the sustainability of agricultural ecosystems. The objective of this study was to determine the effects of barley residue input rate, burning, urea fertilizer and tillage management on activities of alkaline phosphatase and urease under field conditions, after a period of 90 days. The experiment was carried out based on a completely randomized design with a factorial arrangement in two replications. The treatments included two levels of barley residue input rate (3 and 6 t ha-1), burning (without and with stubble burning), urea fertilizer (0 and 125 kg ha-1) and tillage systems (no-till, conventional tillage). Results showed that 6 t ha-1 crop residue treatment increased enzyme activities in comparison with 3 t ha-1treatment at 0-5 cm. Whereas stubble burning and tillage treatments significantly decreased urease and alkaline phosphatase activities. The urea fertilizer had no effect on alkaline phosphatase activity, whereas urease activity positively affected by urea application. Urease activity was affected more than alkaline phosphatase activity by management practices in soil. The results of this experiment showed that no-tillage system along with crop residue retention of 6 t.ha-1 and without stubble burning systems would be the most effective management to protect and promote soil alkalin phosphatase and urease activity.

Abstract Sewage sludge with having the organic matter is considered as a source of micro and macro elements. In order to investigate the effect of different levels and period of application of sewage sludge (SS) on organic matter, respiration, and acid and alkaline phosphatase activity, factorial design were studied, in 3 replications. Sewage sludge at five levels, (20 and 40 tons of sewage sludge, 20 and 40 tons of sewage sludge + 50 percent of chemical fertilizers (CF) per hectare, without taking sewage sludge) and period of application three levels (two, three and four years) was considered. The results showed that application of SS at all levels, increased soil organic carbon (O.C) and soil microbial respiration and enzyme activity were compared with the controls (p

Abstract Abstract Atrazine biodegradation by bacteria is one of the most important aspects of bioremediation. Atrazine can be degraded by various species of bacteria. Bacteria use atrazine as nitrogen and carbon sources. The aim of this study was to determine atrazine degradation by Pseudomonas fluorescence and Pseudomonas aeruginosa. The experiment consisted of two Pseudomonas bacteria, three levels of atrazine concentrations (100, 200 and 300 mg.l-1) and four types of MSM medium (complete, without nitrogen, without carbon and without nitrogen and carbon source). The results showed that both bacteria were able to degrad atrazine at all concentrations. However, increasing atrazine concentration led to more degradation of this herbicide. Biodegradation of atrazine by Pseudomonas fluorescence in concentrations of 100, 200 and 300 mg.l-1 was 18.5, 48.91 and 72.6% respectively and it was 19.08, 33.83 and 62.66% respectively for Pseudomonas aeruginosa in a period of 48 hr. The most degradation of herbicide was observed by Pseudomonas fluorescence in MSM medium without N treatment. In this study nitrogen source was a limiting factor in degradation of atrazine by Pseudomonas fluorescent. Nitrogen source had no significant effect on degradation of atrazine by Pseudomonas aeruginosa in comparison with other MSM medium. In addition, the carbon source in both conditions (with and without) had no significant effect on atrazine degradation by both bacteria. Keywords: Atrazine, Biodegradation, Pseudomonas aeruginosa, Pseudomonas fluorescence

Abstract Abstract With increasing population, Mine activities for metal proceeding are also increasing, so environment will be influenced by contaminant especially heavy metals. In situ immobilization of heavy metals using inexpensive amendments is considered as a simple and cost-effective approach for reducing heavy metal contamination. In this research we used sequential extraction for assessing reduction in availability of heavy metal in lead and zinc mine waste (bama mine around Isfahan). The effects of chemical amendments consist of 3 level of Zeolite 0 (Z1), 5% (Z2) and 10% (Z3) and 3 level of Triple Super Phosphate 0 (P1), 0.25% (P2) and 0.5% (P3) on speciation of Pb, Zn and Cd was investigated by sequential extraction based on tesier method. Total concentration of Pb, Zn and Cd were 2300, 16500 and 27.4 mgkg-1 d.m. Result showed that TSP transform heavy metal specially Pb from exchangeable and carbonate fractions to residual and organic, sulfides fractions. Zeolite also transformed Pb and Zn from carbonate fraction to residual fraction. But eth effect of phosphorous was superior to zeolite. There was no interaction between Zeolite and TSP. Keywords: Soil pollution, Heavy metals, Fractionation, In situ immobilization

Abstract Abstract Incorporation of plant residues in soils is an important agricultural practice for maintaining soil fertility under organic management systems. Plant residues quality, soil physical and chemical properties, and the microbial population diversity of soils are the most important factors influencing the decomposition of added organic matter to soils. Decomposition rate of municipal wastes compost, vermi compost, manure and pistaco compost was studied in two soil samples with contrasting texture, two herbicides and three salt concentrations under laboratory condition. Soil moisture was adjusted at 50% water holding capacity and soil samples were incubated at 28 oC. The CO2 production was used as an index for decomposition rate of organic matter. Result showed that decomposition rate of pistaco compost is higher than those municipal wastes compost of vermi compost and manure. The CO2 evolution concentration and the rate of organic matter decomposition followed , and equations, respectively. A positive correlation was found between the rate of organic matter decomposition and K value. The results also showed that high decomposition rate based on K value, belong to pistaco compost, manure, municipal wastes compost and vermi compost, respectively. Keywords: Organic matter, Decomposition rate, Soil texture, Soil salinity, Pistaco compost

Abstract Abstract Wenner direct contact method is a method of estimating apparent electrical conductivity (ECa) of agricultural soils in situ. This method can be affected by factors such as quality of electrodes in contact with soil, type of employed electric current, moisture content, clay content and compaction of soil. In this research, the effect of electrode type (rod and plate) and electric current type (direct and alternating) on accuracy of estimating soil ECa has been investigated to design a soil EC mapper. A prototype soil EC meter based on direct contact method has been made. The device assessed by a completely randomized experimental design with factorial layout. The independent variables were soil salinity (five levels), electrodes type (two levels) and current type (two levels). Four soil types with different clay contents from regions around Mashhad city (Khorasan Razavi, Iran) have been used with three replications. The results analyzed with SPSS17 software and validated with 1:1 soils water extract EC’s. Significant difference between electrodes types and electric current types was observed. The correlation coefficients of direct contact measured EC’s with soil water extract EC’s was between 0.94 and 0.99 for all treatments. Based on the results of this research, plate type electrodes and AC current were recommended for the design of tractor rear mounted soil EC mapper. Keywords: Electrical conductivity, Wenner method, Plate type electrode, Rod type electrode

Abstract Abstract Different definitions have been proposed for soil quality. Various soil properties have been suggetsted as soil quality indices by researchers. This research was conducted to study the relationship between slope of retention curve at its inflection point (S index) and other soil physical quality indices, because the reserches between S index and soil physical properties are little. Thirty five soil samples were collected and some physical and chemical properties measured . The moisture contents were measured at 0, 1.5, 2.5, 5.5, 10, 20, 30, 50, 100, 200, 300, 500, 1000 kpa pressure heads. The parameters of Van Genuchten equation (1980) were determined by using of RETC software. The slope of retention curve at the inflection point were determined and it was considered as soil physical quality index (S). Then the relationship between S index and soil physical properties was determined by SPSS software. According to the S index and penetration resistance (PR), It seems that the physical quality of studied soil samples was suitable for accesssing. Also there was a significant correlation between S index with mean weight diameter (MWD), clay percentage, sodium absorption ratio (SAR), organic matter percentage, electrical conductivity (EC), least limiting water range (LLWR), available water content (AWC), and penetration resistance (p

Abstract Abstract Osmoreguolation is a physiological processes that plant cell uses to maintain water balance and it is generally caused by metabolite accumulation inside the cell. Inoculated legumes by some drought tolerant Sinorhizobium isolates helps osmoreguolation by increasing biological nitrogen fixation. In order to find some drought tolerant sinorhizobium isolates, 80 isolates were isolated and purified from different parts of Kerman province. They were tested for drought tolerant in liquid Trypton Yeast medium with different water potential (0, -1, -2 and -3.5 MPa using PEG 6000) and then they were classified into tolerant and sensitive groups. Four out of eighty isolates of Sinorhizobium (two from each group) were selected for a greenhouse experiment. The experiment was carried out in a factorial arrangement with a completely randomized design. The results showed that in water stress condition, inoculated plant substantially increased the nitrogenase activity, shoot dry weight, proline content, root soluble sugars, soluble protein concentration, K/Na in shoot and root by 2, 3, 2.7, 1.7, 1.1, 3 and 2 times, respectively. Keywords: Sinorhizobium, Alfalfa, Water stress, Nitrogenase activity, Reducing sugars, Proline

Abstract Abstract Uranium is a natural heavy metal widely dispersed across the earth crust. In many cases due to anthropogenic disturbance, it has been found beyond its natural abundance which resulted in soil-water pollution. The objective of this study was to investigate the capability of Iranian natural zeolite clinoptilolite for removal of uranium (VI) from aqueous solutions. In order to optimize removal efficiency of uranium, bath techniques were used as a function of various parameters, i.e., initial uranium concentration, pH solution, shaking time and dose of zeolite. The sorption of uranium was investigated by using Langmuir and Freundlich model. Maximum uranium uptake by zeolite achieved at 200 mg U L-1, pH 5 and 20 h contact time. The results of the experiment also revealed that Langmuir model was able to predict uranium adsorption mechanisms by zeolite more accurate than Freundlich model. Considering low cost and great natural resource of zeolite in Iran, it is suitable for environmental applications. Keywords: Uranium, Zeolite, Langmuri, Freundlich

Abstract Abstract Soil drying and rewetting (DRW) cycles are considered as environmental stress that would affect the physical, chemical and biological properties of soil and nutrient cycles. The study of soil drying and rewetting effects on plant nutrition and soil fertility is very important and crucial specially their environmental effects. In this study, the effects of 1, 2, 3, 4 and 5 drying and rewetting cycles on dissolved organic carbon (DOC) and phosphorus (DOP) and available forms of nitrogen (nitrite, nitrate and ammonium) in two Alfisols in a completely randomized design with three replications were investigated. The results showed that with increasing DRW cycles dissolved organic carbon, organic and inorganic phosphorus and ammonium decreased significantly in soil solution compared to control (samples were kept in wet condition). Reduction in DOC and DOP could be due to the higher mineralization of organic carbon and phosphorus. Dissolved organic nitrogen decreased significantly after three and four drying and rewetting cycles in soil 1 and soil 2 respectively. The highest amount of dissolved organic nitrogen was obtained in five drying and wetting cycles treatment. Keywords: ِDrying and rewetting, Dissolved organic carbon, Phosphorus and nitrogen

Abstract Abstract A large number of studies have shown that direct application of rock phosphate dose do not have enough efficiency to release phosphorus compared to chemical fertilizers. The main purpose of this study was to increase the efficiency of direct application of rock phosphate. Incorporation of rock phosphate with sulfur, organic matter and inoculation with sulfur-oxidizing bacteria and phosphorous-solubilizing fungus, seems to be a suitable alternative for increasing the efficiency and applicability of rock phosphate. This experiment was carried out in laboratory condition, using completely randomized factorial design with 12 treatments and 3 replications. The treatments included sulfur at three rates, 0% (S0), 10% (S1), 20% (S2), vermicompost at two rates, 0% (V0), 15% (V15), and inoculation with Thiobacillus thiooxidanc, Aspergillus niger (BF) and without inoculation. Water soluble phosphorus and pH were measured during incubation time (15 and 60 days). The results of experiment showed that water soluble phosphorous increased over the time and the maximum level of water soluble P was observed using treatment of 20% sulfur, 15% vermicompost and inoculated with Thiobacillus and Aspergillus (BFS2V1). The amount of water soluble phosphorus in BFS20V15 was significantly higher than other treatments. Keywords: Rock phosphate, Organic matters, Water soluble phosphorus

Abstract Abstract Uranium as a natural radioactive heavy metal widely disperses throughout the earth's crust. In many cases, the natural abundance has been re-distributed due to anthropogenic activities, resulting in radionuclide contamination in groundwater and surface soil. Uranium through the plant uptake can enter the chain. The degree of speciation of radio nuclides in soils in areas with differing levels of uranium is of great interest in order to further the knowledge of the processes that determine the mobility and distribution of these contaminants from the installation, and consequently the potential short and long term risks. In the present work, we used a sequential extraction procedure based on Tessier’s method to determine the fractionation of uranium in a calcareous soil. The effects of two levels of uranium, 585 and 3240 Bq/kg 238U on the uranium distribution in soil fractions at 30 and 90 days of incubation were studied. The results indicated that U primarily associated with the carbonate fraction (62%) and increased by increasing the uranium level in soils. A comparison of extraction results from different incubation times showed that the pattern of uranium association with different fractions changed during the time of incubation. Keywords: Distribution of uranium, Sequential extraction, Calcareous soils

Abstract Dissolved Organic nitrogen (DON) is an important constituent of Dissolved Organic Matter (DOM). It has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. Dissolved inorganic nitrogen, which is another form of total soil dissolved nitrogen, includes NO3, NO2 and NH4, which is very important for plant nutrient. Soil managements such as fertilizer application affects the flux and concentration of DON and DIN in soils. The purpose of this study was to evaluate the effects of different N-fertilizers application on DON and DIN content of two Alfisols located in near the Caspian Sea in the north of Iran. An experiment carried out using complete randomized design with factorial arrangements. Four level of N-fertilizers (Urea, Ammonium nitrate, Ammonium sulfate with Control)) and six different times (0, 7, 14, 28, 42, 60 day) with three replications in two different soils. Changes in DON, DIN, pH and soil respiration were monitored during the period of 60 days. The results showed that dissolved organic nitrogen decreased significantly by N- fertilizer application in both soil samples however, NO3, NO2 and NH4 increased. Ammonium sulfate showed the maximum effect on DON reduction and it can be due to the pH reduction. Changes in DON during the experiment varied from 11 to 75 % in both soil. At the end of experiment, NO3 + NO2 formed a major part of total Dissolved nitrogen in soils.

Abstract Elevated atmospheric carbon dioxide and other green house gases have increased the Earth temperature in recent century, which it affects all biochemistry cycles in soils. To examine the effect of atmospheric CO2 concentration and temperature on N forms in soil solution in a calcareous soil, an experiment was conducted in a completely randomized design with factorial arrangement in the laboratory conditions. Initially, soil was treated with one percentage of cattle manure compost and 200 kg ha-1 of urea, then changes in forms of soil nitrogen (total dissolved nitrogen, dissolved inorganic nitrogen, dissolved organic nitrogen, sum of nitrate and nitrite and ammonium) were evaluated in two levels of temperature (25 and 35 oC) and two different carbon dioxide concentrations (350 and 700 ppm) during 60 days of incubation with three replications. The results showed that the effect of carbon dioxide on nitrogen forms was different at 25 and 35 oC. Carbon dioxide increased dissolved organic nitrogen but dissolved inorganic nitrogen and nitrate and nitrite decreased at 25oC treatment. While total dissolved nitrogen, dissolved inorganic nitrogen and NO2 + NO3 increased at 750 ppm of carbon dioxide treatment, it had no effect on dissolved organic nitrogen. Changes in dissolved organic nitrogen were higher than other forms of nitrogen during the experiment. The maximum and minimum dissolved organic nitrogen were occurred faster than other nitrogen forms at 35 oC treatment. The results of this experiment showed that elevated carbon dioxide with increasing temperature increased the rate of nitrogen biochemical reactions in soil.

Abstract Abstract Arsenic (As) contamination of soils is a global problem. Legumes are often used in remediation of contaminated sites because of their capacity to fix nitrogen. In the present study, the effects of inoculation of bean (by Rhizobium leguminosarum bv. phaseoli) on plant uptake and tolerance to arsenic were investigated. An experiment with a factorial arrangement, two levels of inoculation (with and without inoculation) and five levels of arsenic concentrations (0, 2.5, 5, 7.5 and 10 μM) in completely randomized design with three replications was carried out in a sand culture system in a green house condition. The results showed that the dried shoot weight was increased significantly by inoculation treatments. However, dried root weight and plant height were not affected by inoculation. Dried shoot weight was significantly decreased by increasing arsenic concentrations. The least dried shoot weight was observed in 5, 7.5 and 10 μM of arsenic. The response of dry root weight and plant height to arsenic concentrations was similar to dried shoot weight. The least nodule number was observed in 5 μM arsenic treatment and nodule number in other treatments was not affected by arsenic concentration. Arsenic concentration in shoot increased by Rhizobium leguminosarum bv. phaseoli inoculation. The concentration of arsenic in bean shoot increased by increasing arsenic concentrations in medium. However the highest concentration of arsenic in root and the least nodule number were observed in 5 μM arsenic. Key words: Arsenic, Sand culture, Nodulation Inoculation

Abstract Abstract Heavy metals enter to human food chain through the plant and soil contamination. It is very important to evaluate the affecting factors on plant uptake of heavy metals. In this study the effects of copper and zinc availability on cadmium uptake of root and shoot of corn and sunflower was investigated. The experiment was carried out with a factorial arrangement, two species of plants (sunflower and corn), two cadmium concentrations (0.02 and 0.05 mg /l) and three concentrations of zinc and copper ( 0, 0.025 and 0.05 mg/l for Zinc and 0, 0.01 and 0.02 mg/l for copper) based on a completely randomized design with three replications. The results showed that copper and zinc availability had no effect on cadmium uptake of corn plant. The highest concentration of cadmium in root corn was observed in 0.05 mg/l of cadmium concentration without copper application. In sunflower, the addition of 0.05 mg/l zinc to medium decreased cadmium uptake in 0.02 and 0.05 mg/l cadmium treatments. The synergistic effect of cadmium and zinc was observed in 0.05 mg/l cadmium and 0.025 mg/l zinc treatments. Zinc concentration had a positive effect on cadmium uptake in root and shoot of sunflower in this treatment. Key words: Zinc, Copper, Cadmium, Corn, Sunflower

Abstract Abstract Heavy metals uptake and their distribution in plants are different. In addition to the genetic factors, environmental factors such as interactions of heavy metals with essential elements are very important on the amount of heavy metals uptake. In this study, the effects of iron and manganese on accumulation of cadmium in shoot and root of sunflower and corn in different concentration of those elements in a hydroponic condition was investigated. The results showed that cadmium uptake in root and shoot of sunflower were higher significantly compared to corn. The concentration of cadmium decreased in the shoot of sunflower and corn with increasing the iron availability. Cadmium concentration of corn root was not affected by iron availability but cadmium concentration in sunflower root was reduced dramatically. Manganese availability had less effect on cadmium accumulation of root and shoot of both plants. Cadmium concentration of root and shoot of sunflower increased by manganese availability but it was different in corn plant. Key words: Cadmium, Corn, Sunflower, Iron, Manganese

Abstract Abstract Soil contamination with heavy metals is a serious problem in all over the world. Soils are contaminated by many different sources of heavy metals. Currently different methods are used by researchers for identifying heavy metal contamination. Assessing soil metal toxicity with bacterial bioluminescence is one of the new techniques. In this study, different concentrations of zinc and copper (0, 5, 20, 120 300,755, 2000 mg/kg for Cu, 0, 10, 30, 70, 160 400, 1000, 3000 mg/kg for Zn in sulphate form) were applied to Lincoln soils, New Zealand, in two different sites. After one year, the total concentrations of copper and zinc were measured in soil samples. Bacterial bioluminescence technique (Bioluminator) was used for determination of toxicity threshold of Cu and Zn for E.coli.. The results showed that the bacterial bioluminescence decreased by increasing copper and zinc concentrations. We also found that the bacterial bioluminescence decreased, 50% compared to control plot at 450 and 65 mg/kg Cu and Zn concentrations respectively. The correlation between bioluminescence and total metal concentration showed that zinc was more toxic to E. coli than copper. Keywords: Bioluminescence, Heavy metals, Zinc, Copper. E. coli

Abstract Abstract Uranium is a radioactive heavy metal. Development of nuclear industries and application of phosphate fertilizers contain uranium impurity resulted in soil contamination with uranium. A Pot experiment had been conducted under controlled condition. The experiment carried out in completely randomized design with two factors, including two plants (soybean and sunflower) and six levels of uranium (0, 50,100,250,500 and 1000 mg/kg). Plants harvested after 40 days of experiment and before the generative stages. Soil samples were extracted by DTPA and AAAcEDTA. Uranium concentration in plant tissue increased by increasing the uranium in soil. The ratio of uranium in root:shoot was between 20-100 in sunflower and soy bean. Extraction efficiency of DTPA and AAAcEDTA increased by increasing of uranium in soil. The results of the experiment showed that AAAcEDTA extracts more uranium in all applied uranium concentrations. Both extractants had a good correlation with uranium in plants; however, extraction efficiency of AAAcEDTA was well correlated by uranium concentration in plant tissues. The results of the experiment suggest that AAAcEDTA is suitable extractant for uranium as phytoavailability indicator. Key word: Uranium, phytoavailability, laser fluorometry, sunflower and soybean

Abstract Abstract Genetic evidences have shown that the rhizobium bacteria nodulate the legume plants because of nod, sym and fix genes. Almost all members of rhizobaceae family harbor large plasmids, which are highly variable in number and size. Representative of nif, fix and nod genes have been located on the symbiotic plasmids of different rhizobium species. Therefore, the size and numbers of plasmids of bacterial isolates (by the plasmid profile technique) could be used as a diversity index in ecological studies. In this investigation, the diversity of 196 isolates of sinorhizobium sp isolated from Hamada soils was evaluated by using Plasmid profile technique. The results showed that the number of plasmids among all isolates varied from 1 to 4 and totally 13 different plasmids were identified. The size of plasmids varied from 50 to 200 kb. Isolates with 1, 2, 3 and 4 plasmids formed 63, 21, 13 and 2 percentage of the population. Isolates of sinorhizobium with 2 and 3 plasmids were clustered into 8 and 15 groups, respectively, based on plasmid patterns. Four isolates which contained 4 plasmids were grouped in four different clusters and finally all isolates of Sinorhizobium (196) were grouped in 28 different groups. Key words: Plasmid profiles, Sinorhizobium

Abstract Abstract Some species of earthworms have great ability to breakdown the organic wastes and transform them to vermicompost. It is very important to optimize the growth conditions and earthworms reproduction to achieve high efficiency in vermicompost production. In this study the effect of aeration, soil and sugar beet molasses on the number of adult and juvenile worms, cocoons and earthworm biomass were studied in a completely randomized design with 8 treatments. Sugar beet molass had the highest influence on the number of adult and juvenile earthworms, cocoon and biomass. Aeration had a significant effect on the number of juvenile worms, cocoons, and earthworm biomass, although it had negative effect on adult worms. Treatments with soil increased the number of cocoons and biomass significantly, however, had no significant effect on the number of adult and juvenile earthworms. The highest amount of earthworm biomass was obtained during the seventh and eighth weeks of experiment and decreased afterwards. The earthworm growth rate in treatments with sugar beet molass was much higher than control. Key words: Earthworm, biomass, growth rate, sugar beet, molass, vermicompost

Abstract Abstract Blood meal contains large amount of nitrogen and iron that can be supplied to plants instead of chemical fertilizers. Nitrogen is the most important nutrient for corn plant. The main objective of this study was to determine the capability of blood meal to release nitrogen and iron and its consequence effect on corn growth. An experiment under laboratory and greenhouse conditions was conducted in the form of a completely randomized design with 6 treatments and 3 replications. The treatments included 3 levels of blood meal (1.5, 3 and 6 ton/h), urea fertilizer (200 kg/h), Fe EDDHA (5 kg/h), and the control. The results of soil incubation demonstrated that release of iron from blood meal was similar to Fe EDDHA and the amount of iron reached to its highest level after 30 days of adding to the soil. Nitrogen was released from all levels of blood meal slower than urea, and the amount of inorganic nitrogen in blood meal was less than urea. The results of corn growth showed that the application of blood meal one month before planting could provide the needed nitrogen and iron and have a positive effect on its growth. Key words: Blood meal, Nitrogen, Iron, Corn