نشریه تحقیقات کاربردی خاک
سال نهم شماره 3 (پاییز 1400)

The combined use of chemical chelates along with the planting of hyperaccumulator plants has been suggested as an effective method to increasing the extraction efficiency of heavy metals and helping to improve contaminated soils. Vetiver is known as a resistant plant to salinity, drought and high concentrations of heavy metals. Recently, the use of biodegradable chelates in soil refining from heavy metals has been considered by researchers. This study was designed to investigate the effect of different levels of biodegradable chelates Ethylenediamine-N,N'-disuccinic acid (EDDS) and methylglycinediacetic acid (MGDA) on increasing the adsorption of Cr(IV) by Vetiver grass. Chelates concentration were defined at four levels (0, 1, 2, 4 mmol/Kg soil) and soil chromium contamination at four levels of potassium dichromate (0, 100, 200, 400 ppm). The results showed that the vegetative growth characteristic decreased with increasing soil chromium and chelates concentration. The use of 4 Mmol of MGDA on soil chromium concentrations (0, 100, 200 and 400 ppm) increased the chromium ratio in root by 1.26, 2.0, 1.48 and 2.5 times and this ratio in treatments of EDDS were 1.5, 2.7, 2.25 and 2.9 times more than the control treatment, respectively. Also, the use of 4 Mmol of MGDA in shoots increased the chromium ratio by 2.8, 3.7, 4.1 and 4.2 times and in EDDS were 1.5, 3.8, 4.1 and 6.7 times more than the control. Increasing chelates concentration from 1 to 4 Mmol in all soil chromium levels increased the ratio of shoo/root chromium and showed higher performance of EDDS than MGDA. The effect of soil chromium levels and chelate concentrations on biomass and vegetative characteristics of roots and shoots was decreasing, but EDDS increased plant diameter. The results of bioconcetration factor (BCF) and translocation factor (TF) showed that Vetiver have a special ability in phytoextraction of soils contaminated with hexavalent chromium. The treatment of EDDS at 4 Mmol intensifies the absorption of chromium, especially in the roots and to some extent increases its transfer to the shoot of vetiver grass. Therefore, this compound is introduced as a suitable biodegradable chelate to increase phytoremediation efficiency by vetiver in chromate-contaminated soils.

Soil physicochemical properties are important variables in runoff production and soil loss. This research was conducted to find the most important soil properties affecting runoff and soil loss in rainfed wheat furrows under fallow condition. To this end, three rainfed landswith 15% slope gradient were selected in south west of Kermanshah province. In each land, furrows with 5 m in length and 30 cm in width were created using sowing set. Runoff and sediment were measured using simulated flows with a discharge of 0.5 and 1.5 lit.min-1 for 60 minutes in three replications. The results showed that in the two flow discharges (0.5 and 1.5 lit.min-1) runoff and soil loss are negatively correlated with clay, sand, soil permeability (If), organic matter and clay to silt ratio (p<0.01), while positive correlations were found between them and silt (p< 0.01) and bulk density (p< 0.05). The results of multiple linear regression analysis showed that runoff production and soil loss by a 0.5 lit.min-1 flow discharge can be estimated using using the clay to silt ratio, organic matter and soil permeability (If) with a R2 of 0.94 and 0.81, respectively. Runoff production and soil loss by a 1.5 lit.min-1 flow discharge can be estimated using soil organic matter and soil permeability (If) with a R2 of 0.90 and 0.94, respectively.

In the current study, the effect of organic (vermicompost and biochar) and chemical (gypsum and elemental sulfur) amendments and combination of vermicompost and chemical treatments on the possibility of improving a saline-sodic soil was investigated. The experiment was conducted using a completely randomized design with three replications in a greenhouse condition. After mixing with different treatments, soil samples were kept in the field capacity for 120 days and then some of the most important chemical and nutritional properties of the soils were determined. The results showed that vermicompost caused a significant decrease in soil pH compared to the control treatment and its combination with elemental sulfur was the most effective treatment in improving pH (a drop of 0.75 to 0.95 unit in soil pH). All treatments significantly increased soil EC and SAR compared to the control treatment by increasing the concentration of soluble salts (such as Ca+2 and Mg+2) and replacing some of these ions with soil exchangeable Na. Among the treatments, vermicompost and gypsum had the greatest impact on EC and SAR by an increase of 2.8 to 3.8 dS m-1 in EC and 8.6 to 9.3 units in SAR. While available P, Fe, and Zn significantly increased by the direct release of nutrients from organic compounds and the improvement of soil chemical conditions following using the combination of organic (vermicompost) and chemical treatments, the individual chemical treatments had little effect on the improvement of elements. Overall, the combined application of chemical and organic treatments (vermicompost) more effectively than individual treatments has improved the unfavorable chemical conditions of saline-sodic soil and increased its fertility.

Spatial distribution of erosion phenomena and susceptibility analysis of different parts of watersheds to their types, plays an important role in environmental planning, so that the preparation of susceptibility maps to types of erosion and identification of factors affecting it, can Reducing the risk of various erosive phenomena will lead to providing the necessary management measures for the relevant areas. In this research, a bivariate statistical method was investigated for analyzing the susceptibility of Surface, Rill, Channel and Riverbank erosion phenomena using eight factors of rock resistance, land use and land cover, slope percentage, slope aspect, plan curvature, slope length, stream power index and soil hydrologic group in Omarabad watershed of Urmia. The results showed that regarding the effect of various factors predisposing to the occurrence of Surface, Rill, Channel and Streambank erosion, acceptable results with a clear trend in surface and rill erosion were not obtained, However, in the case of channel and streambank erosion, each of the factors, according to the relevant classes, has a positive or negative effect on the occurrence of this type of erosion and the effect of one factor cannot be considered as complete, positive or negative. factors such as lithology, slope length, slope percentage, slope aspect and SPI have the most positive effect on the occurrence of Channel and Streambank erosion. On the other hand, according to the calibration of the susceptibility map to Channel and Streambank erosion, only 20% of the area with Channel and Streambank erosion related to calibration were in the range of areas with very high to severe sensitivity in the susceptibility map. This indicates the inefficiency of the susceptibility map produced using the above eight predisposing factors and emphasizes the research on other more important and effective factors in creating the desired erosion phenomena in the study area.

Available water is the main limiting factor in crop growth and production in arid lands. In order to investigate the effect of silicon application on yield and yield components of sunflower under different moisture levels, an experiment was conducted in the form of split plots in a randomized complete block design with three replications in Gonabad. The main factor of irrigation with different moisture levels based on water requirement includes 100% water requirement, 80% water requirement, 60% water requirement and 40% water requirement, and the secondary factor of silicon consumption time in four levels No application (control), application in vegetative stage, application in reproductive stage, application in both vegetative and reproductive stage. The experimental results showed that reducing the moisture level from 100% to 40% water requirement reduced head diameter, head dry weight, chlorophyll index, relative water content, number of seed per head, 1000-seed weight, seed yield, biological yield, harvest index, oil percentage, oil yield and seed yield; So that the lowest amount of seed yield (1730.8 kg / ha) and biological yield (10458.21 kg / ha) were obtained in the treatment of moisture level of 40% water requirement. Also, the application of silicon under low irrigation levels based on water requirement improved the effects of reducing moisture levels in all evaluated traits and seed yield. The highest seed yield (7572.96 kg / ha) was obtained in the treatment of 80% water requirement and application silicon in the vegetative and reproductive stages and the lowest seed yield (1193.54 kg / ha) was obtained in the treatment of 40% water requirement and without the use of silicon. The application of silicon in the vegetative and reproductive stages compared to the control treatment increased 2.5, 1.5 and 2.5 times the oil yield at different levels of irrigation, including 80, 60 and 40% water requirement. In general, the results showed that the use of silicon in the vegetative and reproductive stages at a moisture level 80% the water requirement compensated for the adverse effects of reducing the moisture level in the studied traits.

To control soil erosion, several measures can be conducted which information on their effects is very important in managing soil erosion. Therefore, this study was conducted to assess and model soil erodibility in two adjacent sites in Behbahan region (Khuzestan province). At one site afforestation and contour furrowing were conducted to control soil erosion and the other site without any controlling measures was considered as control. Totally 150 soil samples were collected from the surface layer (0-5 cm) and K was estimated using the methods introduced by Wischmeier and Smith (method A) and Vaezi et al. (method B). For spatial modelling of K, based on digital soil mapping (DSM) techniques, several environmental covariates were derived from a Landsat 8 image and a digital elevation model (DEM) and two models including random forests (RF) and artificial neural networks (ANN) were employed. The values of K for methods A and B varied from 0.025 to 0.087 and 0.002 to 0.008 t.ha.h/ha.Mj.mm with means of 0.067 and 0.006 t.ha.h/ha.Mj.mm, respectively. Results revealed good correlation between K and remotely sensed covariates. Although K (method B) had significant correlation with some of the covariates derived from DEM, but there was no significant correlation between K (method A) with all covariates derived from DEM. Results indicated a significant difference between two sites it terms of K estimated by method A, while there was no significant difference in case of K estimated by method B. Model validation showed that both RF and ANN models resulted in good and unbiased estimates of K (methods A and B). In general, the findings indicated, although the performance of DSM techniques in modeling K were high, performances of the models and the results of means compassion may significantly differ in terms of the method through which K is estimated.

Soil and plant pollution is a serious problem that has received more attention in recent years due to its impact on human and ecosystem health. Daily consumption of agricultural products is the most important route for human exposure to various pollutants and diseases. In this study, the effect of different types and levels of amendments on the absorption of lead in peppermint plant in greenhouse conditions was investigated. The experiment was performed as a factorial in a completely randomized design. Experimental treatments included 10 types of amendments: nanosilica, microsilica, ferrosilica, magnesium ferrosilicon (with and without chitosan coating), chitosan and bentonite, at five levels (zero, 0.125, 0.25, 5, 1%). The results showed that all the amendments tested had a decreasing effect on the concentration of plant Pb, transfer factors and biological aggregation. Among the amendments, microsilica modifier had the greatest effect on reducing leaf and root Pb and bioaccumulatio factor. On the other hand, chitosan had a greater impact on reducing the transloction factor than other amendments. Also the most effective amendments on vegetative traits were ferrosilicon amendments coated with chitosan, bentonite, chitosan, and microsilica. According to the results, ferrosilica with chitosan coating and microsilica had more effective role in reducing the destructive effects of lead on peppermint.

To evaluate the effect of Piriformospora indica and Pseudomonas fluorescens inoculation on some growth and physiological parameters and nutrient acquisition of sage (Salvia officinalis) under salt stress conditions, a pot experiment was conducted in factorial based on randomized complete blocks design with three replications. The treatments included inoculation with microorganisms at three levels (non-inoculation and inoculation with P. indica and P. fluorescens) and salinity stress at four levels (0, 25, 50 and 100 mM of NaCl). The results showed that salinity stress and inoculation with microorganisms had significant effect on the measured parameters, so that by increasing salinity concentration, percentage of root colonization by P. indica,growth paramaters, leaf relative water content (RWC), chlorophyll index (SPAD), essential oil conten and yield, N, P and K content and K/Na ratio decreased while Na and Cl content increased. The amounts of all evaluated parameters in fungi and rhizobacteria inoculation were more than non-inoculation treatments except for Na and Cl content. The highest and lowest of dry herb yield (29.61 and 13.51 g pot-1), RWC (82.45 and 54.83%), chlorophyll content (35.36 and 26.1), essential oil content (2.02 and 1.37%), essential oil yield (0.049 and 0.017 ml plant-1) and P content (0.41 and 0.10%) were observed in non-stress conditions+ P. indica inoculated plants and 100 mM salinity+ non-inoculated plants, respectively. Overall, the findings of this study showed that plant growth-promoting microorganisms inoculation can ameliorate the adverse effects of salinity stress on growth, yield and essential oil production in sage by maintaining chlorophyll content and improving water and nutrient uptake.

Siderophores are low molecular weight organic chelators which mostly expressed under iron deficiency to chelate Fe (III) metal ions in order to regulate iron based activities. Cyanobacteria, which are Gram-negative photoautotrophic prokaryotic organisms, hydroxamate type of siderophore predominates. The objective of this investigation was to determine the potentials of some indigenous cyanobacteria for siderophore production in Tabarestan Biotechnology Institute in 2014. For this purpose, 30 strains of cyanobacteria were isolated from Guilan paddy field. Potentials of these strains for siderophore production were evaluated by chrome azorel-S assay (CAS-agar) through color change. Pot experiment was performed to evaluate the application of selected top strains of cyanobacteria on growth and yield of rice plant (cv. Tarom Hashemi). Cyanobacter inoculation treatment was selected with the top seven strains and control treatment without inoculation with three replications was performed in a randomized complete block design in the greenhouse. The results of this study showed that the highest rate of siderophore production in CAS- agar Chroococcus sp. GGuCy-34 and Anabaena sp. GGuCy-49, 4.19 and 4.08 respectively and in spectrophotometer method strains of Anabaena sp. GGuCy-21 and Nostoc sp. GGuCy-47, 6.69 and 5.75 (µmol/L.day) respectively. Anabaena sp. GGuCy-42 highest grain yield (8.27 g pot-1) Chroococcus sp. GGuCy-34 showed the highest iron uptake (2.31 mg pot-1) and Cylendrospermum sp. GGuCy-25 the highest N (81.3 mg pot-1) and P (11.7 mg pot-1) uptake in pot experiment in rice plant. The results of the evaluation of siderophore production of cyanobacteria in CAS- agar with the results of the pot experiment were more consistent. Increased iron uptake can be attributed to the effect of siderophore strains on plant iron availability. Due to the fact that cyanobacteria capable of producing siderophore can also be used as stimulants of plant growth.

Heavy land preparation and leveling in sugarcane cultivation in Khuzestan damages soil structure. It makes the soil prone to compaction during harvesting. To reduce the effects of soil compaction and root improvement, rotation operations are common in ratoon field. Since subsoil (ratooning) plowing directly affects the development of sugarcane roots, therefore, this study was conducted to investigate the depth of ratooning operations of fields of ratoon cane on soil bulk density and its effect on plant root development and subsequent quantitative and qualitative yield of sugarcane. Ratooning operations were conducted at two depths of 30 and 50 cm and compared with no ratooning control. Quantitative yield including height, diameter, number of cane and shoot fresh weight per unit area were determined at the end of growth and before harvest. After harvest, cane root distribution was investigated in different depths. The results of analysis of variance showed that the ratooning depth operations were significantly affected cane height, stalk number per m-2, stalk weight, millable cane yield, sugar yield, and soil bulk density. But the cane stalk diameter, syrup brix, recoverable sugar, and soil bulk density at a depth of 30 (BD30) cm were not affected by the depth of ratooning. R-50 treatment increased cane height (28.2%), stem number (5.7%), stalk weight (42%), millable cane yield (55%) and sugar (53%) compared to control, and reduced soil bulk density in depth of 50 cm (3.6%). However, R-30 treatment resulted in increased soil bulk density (3.6%) and reduced yield of sugarcane (12.8%) compared to control. Also, root weight was higher in R-50 treatment compared to control and especially R-30. In addition, more than 50% of root distribution was observed in R-30 treatment in the first 10 cm layer of soil. In general, the results of this study showed that reducing the depth of ratooning to 30 cm, not only did not have a positive effect on the above factors, but also increased the soil bulk density, more root extending near the soil surface and eventually, reduced sugarcane yield. In other words, limiting root development to soil depth causes more root density on the soil surface and thus leads to the absorption of nutrients in a more limited volume of soil, which ultimately reduces plant growth and sugarcane yield.