Journal of Soil Biology
Year:2018 | Volume:6 | Issue:2|Papers Count:8

The aim of this study was to assess the impact of SDBS on some biological indices including microbial respiration, microbial biomass carbon, nitrogen and phosphorus, microbial quotient and metabolic quotient in a soil from Osku area. The experiment was conducted as repeated measures with between-subjects factor of SDBS at four levels of 0, 0. 01, 0. 05 and 0. 25% and within-subjects variable of time intervals at six levels of 2, 7, 15, 30, 60 and 90 days with three replications. Based on results, all biological indices declined (except for metabolic quotient which increased) in comparison with the control after application of SDBS. Soil microbial respiration decreased over time in each level of SDBS and the corresponding values were significantly lower at 0. 01 and 0. 05% of SDBS than those at zero and 0. 25% of SDBS. This trend was also observed for soil microbial biomass carbon. Being soil microbial community under stress at 0. 01 and 0. 05% of SDBS and induction of tolerance at 0. 25% of SDBS could explain these results. Soil microbial biomass nitrogen on the second day of incubation increased with increasing the SDBS level and decreased over time in all levels of SDBS (expect for control). Increasing microbial nitrogen biomass in the SDBS treated soils might be due to increasing the activity of Azotobacters or other nitrogen-fixing bacteria which are less sensitive to SDBS and are able to feed through it. The highest values of microbial biomass phosphorus were recorded in SDBS treated soils on the second day of incubation, but the values severely decreased after one week and thereafter the changes were negligible.

There are many scientific reports about the detrimental effect of environmental stresses on Rhizobium-legume symbiosis. Selection of some strains with high efficiency and tolerance to environmental stresses is the most commonly acceptable solution for that problem. In order to investigate the effects of inoculation of stress tolerant bean-nodulating Rhizobium strains on growth characteristics of bean and symbiotic efficiency, a greenhouse experiment was conducted with 29 strains of Rhizobium, one level of nitrogen (N=200 kg/ha) and a control treatment in a completely randomized design with three replications. Selected strains provided by the microbial collection of Soil and Water Research Institute. Plants were maintained up to 50% flowering and then harvested. Dry and wet weight of shoot, root and symbiosis efficiency were measured. The results showed that there was a significant difference in shoot dry weight and based on the results of this part, 4 strains (CCSM-B01171, CCSM-B01172, CCSM-B01186 and CCSM-B01210) were selected as strains with high efficiency in nitrogen fixation. Two more strains were also selected CSM-B01232 and CCSM-B01233 strains (type International strains) for next experiments. Tolerance of Selected Stains (totally 6 strains) to four environmental stress including pH in three levels (5, 7, 9), salinity in four levels (0. 97, 4, 8 and 12 dS/m), drought in five levels (0,-0. 05,-0. 25,-0. 9 and-3. 4 MPa) and temperature in three levels (29, 37 and 42 ° C) were assessed in the culture medium. Based on the results, CCSM-B01172, CCSM-B01171 and CCSM_B01232 strains had the highest tolerance to pH. CCSM-B01210 strain was resistant to drought. CCSM-B01186 strain had the highest tolerance to temperature and salinity environmental stress and recommended for further research.

Sulfur is mainly used to reduce soil pH and increasing nutrients availability in the calcareous soils. However, this process strongly depends on oxidation rate and its affecting factors (e. g. soil moisture content). In this research, the impacts of two soil moisture regimes (40 and 60 % of saturation) and four Sulfur levels (0, 500, 1000 and 10000 kg ha-1) inoculated with Thiobacillus bacteria on sulfur oxidation rates and some chemical soil characteristics were assessed in a complete randomized blocks design with three replications and two soil types (Kharghani and Khaldar) during one year and under constant 25 Co temperature. In this research, soil pH, electrical conductivity (EC), Phosphorus (P), Iron (Fe), Zinc (Zn) and sulfate concentration (SO42-) were measured. The results revealed that the pH adversely significantly (P<0. 01) decreased with increasing sulfur amount, while EC, Fe, Zn and SO4increased. The highest amount of pH reduction, increasing of EC, Fe, Zn and SO42-observed with application of 10, 000 kg Sulfur ha-1. Finally, the respective difference for pH, EC and SO42-compared withcontrol treatment in the Khargani soil were 0. 38 units, 1. 72 dS m-1, 2588 mg kg-1 and 60 days’ incubation; and in khaldar soil 2. 1 units, 3. 2 dS m-1and 4984 mg kg-1 in 360 days’ incubation. The amount of Fe and Zn available were found 3. 53 and 0. 87 mg kg-1, respectively indicating significant increasing compared with control plot in Khaldar soil. The highest P content was observed 0. 5 and 4. 1 mg kg-1 in Khargani and khaldar soils, respectively followed by 1000 kg Sulfur ha-1 application. It is concluded that the amount of sulur oxidation decreased followed by increasing in both sulfur content and incubation period. The highest increment was observed by applying 500 kg Sulfur ha-1. According to the results, Sulfur application up to 1000 kg ha-1 is suggested.

Plant root system has an important role in crop production. It is well known that roots assist as an anchor to the plant and water and nutrients absorption which are necessary for plant survival and growth. In order to evaluate the effect of phosphate solubilizing bacteria and mycorrhizal fungi under different levels of phosphorous chemical fertilizer application, an experiment was carried out in factorial arrangement using a completely randomized design with three replications at Agricultural Research Station of Ilam University in 2015. Experimental factors consisted of two dry land wheat cultivars (Keras Sablan and (Saji) and chemical and biological fertilizers (1-without application of phosphorous, 2-100% phosphorous chemical fertilizer, 3-pseudomonas putida(strain 168), 4-Funeliformis mosseae, 5-P. putida + F. mosseae, 6-P. putida + F. mosseae + 50% of phosphorous chemical fertilizer, 7-P. putida + 50% of phosphorous chemical fertilizer and 8-F. mosseae + 50% of phosphorous chemical fertilizer). Results showed that fertilizer sources had significant and positive effect on root system in wheat cultivars and seminal roots number, nodal roots number, sub-nodal number, seminal roots length, nodal roots length and sub-nodal roots length, root length density, root specific density, root volume density and root area density increased significantly. Maximum root number and root length (13. 3 and 397. 2 cm), root length density (0. 75 cm root/cm-3soil), root area (150. 3 cm-2), root volume density (0. 010 g root fresh weight) and root area density (166. 7 cm-2/g) observed in Saji cultivar ×F. mosseae +50 % of phosphorous fertilizer treatment but the minimum root system characteristics detected in Keras Sablan cultivar× control treatment.

In this study, the abundance and biodiversity of the soil macrofauna under two different plants coverages (Rosaceae shrubs and conifers) were investigated using pitfall trap in Choqasabz Forest Park (Ilam province). This research was carried out from April to September 2015 with two treatments (different plants coverages) and five replications. Every 20 days, trapped specimens were collected in pitfall traps and then counted and identified. During this study, a total of 4, 613 specimens were collected belonging to eight orders and 13 families of insects, and a single family of spiders. Results showed that the families Formicidae and Carabidae and orders Collembola and Diptera were the most abundant arthropods in pitfall trapps. Between Rosaceae and conifer plants, there was a significant difference in the number of insects belongs to Collembola (t(138)=2. 97, P=0. 004), Carabidae (t(138)=2. 93, P=0. 004), and Noctuidae (t(138)=2. 91, P=0. 004), while there was not a significant difference in the number of arthropods belongs to Formicidae (t (138)=0. 83, P=0. 406), Chrysopidae (t (138)=0. 103, P=0. 918), Diptera (t (138)=1. 15, P=0. 253), Orthoptera (t (138)=1. 543, P=0. 125), Heteroptera (t (138)=1. 11, P=0. 267), insect larva (t (138)=0. 816, P=0. 416) and spiders (t (138)=0. 420, P=0. 675). The most number of Collebmbola individuals were collected only in spring months and after that their density reduced considerably. Collembola and Noctuidae had significantly more density under Rosaceae than conifers while Carabidae had more densities under conifers. Arthropods have a valueble role in soil fertilization, nutrient cycling, plant production, decomposing matters in nature and regulation of other animal population. The results of this study could be useful in conservation and sustainable management of biodiversity in Choqasabz Forest Park.

Salinity is among the most important stresses worldwide that affect the absorption and transport of nutrients to plants due to its high sodium concentration. The objective of this study was investigate the possibility of using high adsorption capacity of biochar for increasing sodium adsorption, reducing sodium to potassium ratio of the plant and reducing the negative effect of salinity on plant growth, concentration and uptake of nitrogen and phosphorus with use of mycorrhizal as an bio-amendment. This research was conducted with factorial arrangement in completely randomized design with three replications. Treatments consisted of five levels of organic substances (control, poultry manure (PM)(1% and 2%), poultry manure biochar (PMB) (1% and 2%), four salinity levels (0. 5, 3. 6, 7. 9 and 12. 4 dS. m-1) and two fungus levels (control and inoculated with Funneliformis mosseae). Application of PM and its biochar significantly increased growth, greennessindex, concentration and uptake of macronutrients, but decreased percentage of root colonization. Application of PM significantly increased corn plant sodium concentration. Application of PMB had no significant effect on sodium concentration compared to the control treatment, but significantly reduced shoot sodium/potassium ratio (Na+: K+) by increasing potassium concentration. Biochar application at high levels of salinity (7. 9 and 12. 4 dS. m-1) significantly reduced shoots Na+: K+ ratio. AMF application did not affect plant growth due to the high amount of phosphorous at 2% PMB treatment. In general, results indicated that corn dry matter yield at co-application of fungus and 1% biochar treatment was similar to 2% PM treatment and also, did not inhibit the effectiveness of fungus in reducing the shoot sodium to potassium ratio at high salinity levels.

Wildfire is one of the most important destruction factors in forest and pastures. In forest and pasture ecosystems, soil mesofauna used as a bioindicator for environmental changes and management. The aim of this project was to address wildfire and land uses (forest and pasture) effects on soil mesofauna arthropods community in Badreh in Ilam province. For this purpose, soil sampling performed in two depths of soil surface (0-5 cm) and subsurface (5-20 cm) layers in wildfire occurrence and no occurrence of wildfire (control) conditions in 2015. In each land use, three plots (50 × 50 m) and five points from each plot was randomly taken from topsoil and subsoil depths (the total number of samples 60). Both forest and pasture land use found 3360 samples of different kinds of Phylum Arthropoda. The maximum soil mesofauna community belonged to pasture land use (control) by 30. 67% while the minimum soil mesofauna community belonged to this land use (wildfire occurrence) by 14. 35% as well as soil mites community abundance compared to insects community in forest was more than in pasture. According to results, Wildfire and soil depth affected significantly (α = 0. 01) on Mesostigmata, Collembola, Oribatida and Staphylinidae abundance. Forest and pasture land use had no effect on Mesostigmata significantly, while this factor showed significantly (p < 0. 01) on all mesofauna community. Generally, wildfire had negative effect on soil mesofauna abundance in different land uses.

Utilization of damask rose in sanitary and medicinal industries change it to valuable and economic goods. In order to investigate the effects of mycorrhizal fungi, plant growth-promoting bacteria and animal manure on yield and growth characteristics of damask rose, a factorial experiment in a randomized complete block design with four replications was performed in 2014 in Layzgan region of Darab city. The first factor was two levels of animal manure (0 and Two kg of per plant. The second factors was two levels of mycorrhizal fungi (without and with a mixture of three species of mycorrhizal fungi) and the third factor was four levels of plant growth-promoting bacteria (three strains of plant growth-promoting bacteria and no bacteria). The results showed that the effects of animal manure, inoculation with mycorrhizal fungi and inoculation with promoting bacteria had a significant (P < 0. 01)) effect on growth characteristics and root colonization of damask rose. Pseudomonas fluorescens had a significant effect on all measured characteristics. Interaction effects of each three factors had the greatest influence on wet and dry weight of flower, height and width of plant, number of flowers pre plant and root colonization which respectively caused the increments of 91, 78. 3, 57. 3, 34. 1, 77. 2 and 32. 7 percent to control. It was concluded that the simultaneous use of all factors had more positive effects on the improvement of measured characteristics.