Journal of Soil Management and Sustainable Production
Year:2013 | Volume:3 | Issue:2|Papers Count:16

In order to investigate the sources of arsenic contamination and assessing the role of geomorphic properties on its distribution in Bijar area, 83 profiles were selected based on the prepared geopedology map and 227 soil and 20 water samples were collected. Routine physical and chemical characteristics, iron oxides and soil arsenic contents were measured in 227 samples. Arsenic probability risk was computed using indicator Kriging (IK) to assess the arsenic (As) contamination potential. Topsoil arsenic concentration showed significant correlations at the level 0.01 with clay (r=0.77), sand (r=-0.45), silt (r=-0.48), CEC (r=0.65), and Fe oxides (r=0.65) statistically. Subsoil arsenic concentrations showed similar correlations with soil properties. Significant differences in clay, silt, sand, Fe2O3 percentages and CEC in arsenic source landforms with Fe- rich rock and mud stone have led to their higher arsenic concentration compared to the other landforms. Arsenic content of water resources located at higher altitudes were lower than EPA and WHO guideline level, while the opposite was true (2-130 times) about the landforms located at lower altitudes. The distribution of high arsenic areas rasterized by IK confirmed that, from the arsenic sources (arsenic source landforms with Fe- rich rock and mud stone), the arsenic is spread to lower positions by erosion-deposition processes or soluble form. Soils with such concentrations of arsenic may be hazardous for human being and ecosystems.

The effects of physicochemical properties of soil and land uses were studied on aggregate stability in some part of Khuzestan province. Therefore, 56 samples were collected from 0-20 cm depth under different land uses including noncultivation, rotation cropping and sugarcane. Mean weight diameter (MWD) and physicochemical properties of soil such as organic carbon, sodium absorption ratio, electrical conductivity, CEC, texture, gypsum, bulk density and pH were determined. Multiple linear regressions (step by step method) were applied to determine the effect of soil properties on aggregate stability. The results showed that organic matter contents had maximum effect on MWD for all soils. Organic mater content were minimum in uncultivated lands due to high salinity, low rain, and weak drainage, therefore minimum aggregate stability were observed in uncultivated lands. The highest salinity was determined in uncultivated Abadan soils with minimum aggregate stability. Both artificial drainage and cultivation reduced soil salinity and increased organic matter and consequently increased aggregate stability. This changed 0.67, 1.2 and 1.4 MWD for uncultivated, rotation cropping, and sugarcane respectively in north region the Khuzestan province.

Information of P fractions in sewage sludge treated soils is necessary for better management of land application of organic amendments. The purpose of this study was to evaluate the effect of sewage sludge on the forms and distribution of P in a calcareous soil using a sequential fractionation procedure. A greenhouse experiment with six levels of sewage sludge (0, 22.5, 45, 90, 180 and 360 ton ha-1) was conducted as a completely randomized design with four replications with wheat plant for 90 days. In comparison with the control, sewage sludge application significantly increased all P forms. Among various P fractions, labile P showed the largest increase. In the control soil, the various P fractions could be ranked in the following order: HCl-P>OAc-P>CBD-P>NaCl-NaOH-P>Labile-P. In contrast, the order in biosolid-treated soils follows: HCl-P>OAc-P>Labile-P>CBD-P> NaCl-NaOH-P. In general, the results demonstrated that the dominance of inorganic P forms in sewage sludge. Inorganic P forms represented 80% of total P in biosolid-treated soils and 57% in the control. In control soil and biosolid-treated soils, Ca-associated Pi was the dominant fraction. Application of sewage sludge significantly increased the concentration of P in shoots of wheat compared with the non-manured control.

Arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) affect plant growth and tolerance under environmental stresses such as soil contamination with metals. In this study the effect of inoculation with selected strains of AMF (a mixture of Glomus species including G. intraradices, G. mosseaeand G. fasciculatum) and PGPR (a mixture of Pseudomonas species includeing P. putida, P. fluorescens, and P. aeruginosa), on uptake and translocation of Pb, Fe and Zn, height, yield and some physiological properties of Centaurea (Centaurea cyanus) was evaluated in a Pb contaminated soil. This study was carried out in greenhouse condition as a factorial experiment based on a randomized complete block design with two factors including Pb concentration (in four levels) and microbial treatment (in two levels) and in three replications. Soil was contaminated with Pb concentrations of 0, 250, 500 and 1000 mg kg-1 and was then sterilized and inoculated with the AMF or PGPR. Results indicated that with increasing soil Pb concentration, plant growth, shoot Fe and Zn concentration, chlorophyll and carotenoeids contents and leaf relative water content decreased, while proline content and the plant Pb concentration increased. The microbial inoculation resulted in a significant increase (P≤0.05) in plant growth, uptake and translocation of Pb, Fe and Zn, an improvement of plant water uptake and conservation and increase in contents of the plan photosynthetic pigments and proline. Mean shoot dry biomass of AMF and PGPR inoculated treatments were, respectively, 2 and 1.2 order of magnitude higher compared to the corresponding blank treatments. It could be concluded that microbial inoculation results in improved plant growth and increased tolerance against Pb toxicity.

The objectives of the present study were to evaluate the effect of heating on various inorganic phosphorus (P) fractions and sorption characteristics of highly calcareous soils of Kohgyloyeh and Boier-Ahmad province. Treatments were consisted of 5 soils and 4 heating treatment (untreated, 200, 350 and 550oC) for two hour. P fractionation included successive extraction with NaHCO3 (NaHCO3-P); pedogenic Ca-P (NH4OAc-P+MgCl2-P); NH4F (NH4F-P); NaOHNa2CO3 (HC-P), citrate-dithionite-bicarbonate (CBD-P), and H2SO4 (H2SO4-P) carried on 1 g sample in duplicate. P sorption was studied by equilibrating 2 g of samples with 20 ml solution containing 5 to 400 mg P kg-1 soil with 0.01 M KCl as background solution in duplicate. Results indicated that generally high temperatures (350 and 550o C) significantly increased NaHCO3-P, pedogenic Ca-P and NH4F-P. H2SO4-P significantly decreased in 350oC but significantly increased by 550oC heating. These changes indicate the transformation of inorganic P fractions to each other in studied temperatures in addition to transformation of organic P to inorganic P. Quantity of P sorption in the unity of P concentration (KF) decreased by 550oC in soils with lower CCE and higher Fe oxides, while it increased in soils with higher CCE and lower Fe oxides content. This effect is probably due to the transformation of crystalline Fe oxides to forms with lower specific surface area, which regualte P retention in the low concentration of P.

The effects of two different organic matters including compost and sewage sludge on the distribution of Cd, Pb and Ni in different fractions of two calcareous soils were investigated. The soil samples were treated with two levels of each organic material (0 and 2%). Heavy metals were added to soils at the rate of 10 mg kg-1 of Cd, 200 mg kg-1 of Ni and 400 mg kg-1 of Pb as nitrate salt. The samples were incubated for 12h, 20 and 40 days. After each incubation time, metals were fractionated by sequential extraction and analyzed for DTPA extractable form.Results showed that Pb and Ni were rapidly transformed from exchangeable to more stable fractions during the incubation intervals. In contrast, the amount of Cd in exchangeable fraction changed slightly and the considerable portion of Cd remained in this fraction. At the end of the experiment, the distribution percentage of Cd, Ni and Pb followed the order of carbonate>Fe-Mn oxide>exchangeable, Fe-Mn oxide>carbonate>organic matter, carbonate>Fe-Mn oxide>organic matter, respectively. There were almost no changes for the metals in the residual fraction.The effects of compost and sewage sludge on the distribution of studied metals in two soils were different. However, application of organic matter mainly resulted in the increased organic matter fraction and DTPA extractable forms of metals.

Soil is a vital component of environment which its quality and health maintenance should be considered as an important factor. Land use changes mainly affect soil quality and health. Soil microorganisms respond to these changes and have special capability to assay these criteria. This research was carried out as factorial on the basis of randomized complete block design with two factors in 200 ha of Mirabad region, Suldoz plain in West Azerbaijan of Iran. Three types of land uses (pasture, crops and apple orchards) and two soil depths including 0-30 and 30-60 cm were considered in this experiment as main factors. Soil enzyme activity including dehydrogenase (DHA), cellulase (CA), urease (UA), acid and alkaline phosphatases (ACP and ALP) activities were measured as biological indices. Some important soil physical and chemical properties such as organic carbon, pH, EC, calcium carbonate equivalent (CCE), soil texture and water aggregate stability (WAS) were also determined. Results showed that soil quality and health indices were significantly decreased in apple orchard and crop production fields compared to the intact grassland. Decline of urease activity in orchards and crop fields at 0-30 cm depth were 65.5 and 72.7% and in grassland with increasing soil depth (30-60 cm) were 77.5, respectively. Soil enzyme activities were significantly decreased in apple orchard and crop production fields compared to the intact grassland.

Study on the different media for production of foliage plants seems to be necessary. Media used in this research contains different rates of peat, vermicompost, municipal wastes compost and palm peat in combination with perlite and zeolite.Physical and chemical characteristics of media and growth indexes of plant with amount of nutritional compounds in plant were evaluated. Results showed that highest rate of nitrogen absorption was observed in treatment containing 50% peat and 50% perlite and combination of 50% peat and 50% zeolite showed better results in absorption of phosphorus, pottasium, iron and zinc and also better results in number of leaves and dry weight than previous treatments. Treatments with media containing 50% vermicompost, 25% perlite and 25% zeolite; 50% peat combination with 25% perlite and 25% zeolite or 50% municipal garbage compost, 50% perlite showed the best results in different growth indexes of plant. Results showed that according to best characteristics of zeolite, this mineral could be substituted with perlite, in combination with peat or other organic materials or as single media used.Also because of its availability, lower cost of vermicompost and municipal garbage compost than peat, treatments containing 50% vermicompost, 25% perlite and 25% zeolite or 50% municipal garbage compost, 50% perlite could be a good substitution of commercial media containing, 50% peat and 50% perlite, for production of Dracaena and other foliage potted plant.

Mineral weathering is a major source of most essential nutrients including potassium. The micaceous minerals, as the major source of potassium, are abundant in Iranian soils. The aim of this study was to investigate the effect of silicate dissolving bacteria and rhizosphere zone on using the structural potassium from glauconite. A pot experiment was carried out in a completely randomized design with factorial arrangment and three replicates under greenhouse condition.The factors of treatment were nutrient solution (complete or K-free nutrient solution) and silicate dissolving bacteria (with and without bacteria). The growth media was mixture of quartz sand (as the filling material) and glauconitic shale.During a period of 100 days, Pots were irrigated with distilled water and stegner nutrients solution. At the end of experiment, shoots were harvested and plant samples were prepared with dry ashing method and the concentration of potassium was determined with flame photometer. In K-free treatment, plant uptake was significantly affected by silicate dissolving bacteria at 1% level. In such a way the maximum uptake of potassium was belong to the complete nutrient solution and with silicate dissolving bacteria. No significant difference was found between complete nutrient solutions and without bacteria treatment and K-free nutrient solution and with bacteria treatment. In general, this indicates the effect of silicate dissolving bacteria on providing potassium for plant.

Crude oil is one of the most important soil pollutant in the south of Iran. Soil pollution takes place at the time of extraction, transferring and refining. Pollution can cause damage to the environment and zoological and plant population of the soil. Using microorganisms can be a suitable way to decrease oil products pollution. In this study effect of 4 strains of bacteria isolated from the soils of Bushehr province with different concentrations of salinity and also nutrients (nitrogen and phosphorous in 0, 48, 72, 144 hours durations in the biodegradation of Phenanthrene and toluene and gas oil was studied. The mentioned strains were named: Pseudomonas Stutzeri, Chryseobacterium, Acinetobacter Johnsonnii, Pseudomonas aeroginosa. The salinity levels were (1%, 3%, 5%) and nitrogen and phosphorous levels were (0.5, 1, 2 mgL-1). The results showed that the best salinity level is 1%. Every four isolated bacteria outstandingly were able to grow and degrade petroleum in 1% salinity in 144 hours after inoculation. Also P. aeroginosabacteria was more effective in the degradation process of phenanthrene and toluene and gas oil than the other bacteria. The best nitrogen concentration in biodegradation of gas oil was 2 mgL-1 in which the best performance is related to bacteria acinetobacter johnsonii and pseudomonas aeruginosa. The best time in biodegradation of gas oil is 144 hours. The best P concentration in biodegradation of gas oil was 2 mgL-1 in which the best performance is related to bacteria pseudomonas stutzeri.

In this research the effect of three Azotobacter inoculums in solid and liquid carrier were evaluated on growth and yield of rainfed wheat in Maragheh (Iran).The project was randomized complete block design with four replications which included control, solid A and B inoculants, liquid inoculum, farmyard manure, nitrogen fertilizer, a mixture of inoculums and manure. The results showed that the inoculants had not significant effects on growth indices, but inoculants+manure especially in liquid inoculums had the highest effect on growth and yield of wheat.Inoculation increased by 36.2% the seed yield, 37.8% the yield of shoot+root, 73% the N-uptake, 79% the P-uptake, 45% the Zn uptake, 27.6% the protein of seed over control. Manure without inoculum increased by 13.7% in seed yield, 42.5% in N-uptake, 57.5% in P-uptake and 25.8% in seed protein over control. The solid inoculants (A and B) +manure had significant effects on Zinc uptake. The seed protein content increased by 22.1 % due to the solid B inoculum.

Genistein is an important isoflavonoide in bean root exudates. It is as a molecular signal in the symbiosis to induce nod genes of Rizobium, exudation of nod factor with bacteri and finally making physiological responses in root and formation of nitrogen fixator nodule. Salt stress cause a disturbance in exudation of this compounds by plant root. The objective of this study was investigating the effect of Rhizobium leguminosarumb.v.phaseoli pre-induced with genistein (G) on nodulation, nitrogen fixation and growth of the common bean in salinity stress. The experiment was planned in three levels of genistein (G0=0, G5=5, G20=20 mM) and irrigation with three levels of salinity (S0=0, S1=2, S2=4 ds/m) and were combined in a factorial fashion in complete randomized design with three replicates in agriculture college greenhouse of Ferdowsi University. Plants were harvested after 30 days and wet and dry weight of root and shoot, number and weight of root nodule and plant nitrogen were measured. The results showed that weight and number of nodule were more sensitive to salinity rather than dry weight of plant.Genistein application with 5 and 20 m M concentration increased number, weight of nodule and bean nitrogen uptake in non saline soil. Adding 20 m M genistein increased average weight of each nodule in S1 level of salinity. Nodules number and weight decreased with increasing salinity from S1 to S2. Despite decreasing nodulation, by increasing salinity, plant nitrogen uptake and concentration was not decreased by using genistein.

Phosphorus (P) is the second limiting nutrient in soils for crop production after nitrogen. Information about the chemical forms of P in the soil and their relationships with corn growth and P uptake is important for the evaluation of P status and soil fertility and plant nutrition. To obtain such information 20 composite soil samples from depth of 0-30 cm were collected and P fractions were determined by sequential fractionation method. Results showed that shoot dry matter of corn had a significant relationships with chemical forms of phosphorus including dicalcium phosphate (Ca2-P), iron phosphate (Fe-P), apatite (Ca10-P), non labile organic P (NLOP) and available-P (Olsen-P). Ca2-P had a strong significant relationship with all growth parameters of corn (including dry matter, P concentration and shoot P uptake) and was presented in all regression equations.Root dry matter had a negative and significant correlation with Ca10-P. Ca2-P, Fe-P and Olsen-P had positive and significant relationship with shoot and root P concentration. Ca10-P had a negative and significant relationship with root P uptake. Finally, it was concluded that Ca2-P is probably the major source of available P for corn plant in studied soils.

The aim of this study was to investigate the promoting characteristics of plant growth, Pseudomonas fluorescens in the soils of Golestan province. Thirty Pseudomonas fluorescensspecies were isolated from 45 rhizospheric soils of soybean plants and their growth promoting potentials were studied as a function of sidrophore and hydrogen cyanide production rate, auxin and also mineral phosphate dissolution potential. The ability of production of isolates siderophore evaluated semiquantitively by CAS-Agar medium and the best isolate was P1/15 with the average ratio of halo diameter to 3.10 colone and isolates P11/1 with the zone diameter to colony 1.29 had the lowest production. The ability of HCN production of isolates evaluated by TSA medium riched by glycine and the best isolate was P1/4 with the extreme HCN production. The ability of isolates in auxin production also performed under condition of 0 and 50 tryptophane concentrations and P1/4 isolate with 92.01 mg/ml auxin production in the present of tryptophane had the highest rate of production of this hormone and isolates P5/2 to produce 2.62mg/ml had the lowest production. The isolates ability of dissolution of mineral phosphate by liquid PKV medium and P2/7 isolate with the 44.28 mg/l had the most solubility and isolates P11/1 with a solubility of 12.07 mg/l had the lowest solubility.

Experiment was carried in a split plot based on randomized complete block design with three replications in two years. Main plots were consisted of conventional tillage (CT), minimum tillage (MT) and no tillage (NT). Six methods of fertilization including (N1): farmyard manure; (N2): compost; (N3): chemical fertilizers; (N4): farmyard manure+compost; (N5): farmyard manure+compost+ chemical fertilizers and (N6): control were arranged in sub plots. Results showed that the highest soil bacteria number was obtained in N4 (194.4 × 106) and NT (135.4 × 106) treatments. The activities of urease (49.6 mg urea g-1 h-1), catalase (73.6 mg o2 g-1 h-1) and cellulase (17.8 mg glucose g1 h-1) were generally higher in the N2 and N4 treatments. The activity of acid and alkaline phosphatase and urease tended to be higher in the NT treatment compared to the MT and CT treatments.The maximum amount of grain yield was obtained from MT and N5 treatments.

Sulfur has an important role in plant nutrition, aciditification of rizosphere zone and finaly in increasing zinc availability of calcareous soils. In order to study the effects of sulfur and zinc on corn production, a three years experiments were conducted in Kermanshah, Qazvin and Behbahan reseaech fields. In these studies, by using a factorial test in randomized completely block design, main and combined effects of four levels of zinc (0, 10, 20 and 30 kg.ha-1 Zn as zinc sulphate) and three levels of sulfur (0, 200 and 400 kg.ha-1) were compared. The results indicated that main effects of sulfur and zinc on the most of studied parameters such as grain yield, 1000 grains weight, zinc content and zinc uptake by shoots were significant. Although the combination of sulfur and zinc improved parameters were studied, but only had a significant effect on the shoot Zn concentration and grains protein content.