Soil Chemistry and Pollution
Alireza Abdollahpour; Mojtaba Barani Motlagh; Amir Bostani; Farshad Kiani; Farhad Khormali; REZA GHORBANINASRABADI
Abstract
Introduction Soil organic carbon (SOC) is the largest source of terrestrial organic carbon and small changes in its components have many effects on global warming and carbon cycle. Soil organic matter (SOM) is considered as the most complex and least known component of soil, because it consists of plant, ...
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Introduction Soil organic carbon (SOC) is the largest source of terrestrial organic carbon and small changes in its components have many effects on global warming and carbon cycle. Soil organic matter (SOM) is considered as the most complex and least known component of soil, because it consists of plant, microbial and animal masses in various stages of decomposition and is a mixture of heterogeneous organic materials that are closely related with mineral components. Soil organic matter has beneficial effects on the chemical (buffering and changes in pH) and biological (precursor and supply of nutrients for microbes) properties of the soil and thus affects the fertility capacity of the soil. The quality and quantity of soil organic matter is the most important criterion for sustainable soil management. Total organic carbon (TOC) consists of labile and non-labile forms of SOC and have different degrees of sensitivity to different types of land use changes and management operations. The purpose of this research is to investigate the effect of changing land use on the chemical components of soil organic carbon and carbon recalcitrant index in Toshan Watershed, Golestan provinceMaterials and Methods For this research, four major and dominant types of land use were considered in the study area, including forest, cropping land, garden and abandoned lands in the Toshan watershed in the northwest of Gorgan city of Golestan province. The soil organic carbon and total C of soils were measured. Furthermore, the soil carbon fractionation was performed by Young's method (using hydrolysis methods with HCl and Labile fraction). In this research, Acid hydrolysis method was used to separate the recalcitrant SOM pool. For this purpose, one gram of SOM sample was treated with 25 ml of 6 M hydrochloric acid solution at 105°C for 18 hours in a Pyrex tube in a hydrolysis package. After cooling, the remaining non-hydrolyzed materials were separated by centrifugation. Then, they were dried in an oven at a temperature of 60 degrees Celsius and considered as a part of resistant organic matter. The resistant part of the soil organic carbon was determined with the CHNS Analyzer device. The Labile fraction consists of water soluble carbon, microbial biomass carbon and mineralizable carbon are measured using the following methods and the labile part of carbon is calculated from their sum. Water-soluble organic carbon is extracted by adding 20 ml of distilled water to 10 grams of wet soil. The mixture will be shaken and centrifuged, filtered. Then they will be quickly analyzed by TOC Analyzer. Microbial biomass carbon will be determined by the chloroform fumigation-extraction method. Mineralizable carbon determined as follow. The amount of CO2 will be measured by titration of NaOH solutions with 0.1 M HCl in the presence of BaCl2. Cumulative amount of CO2-C emitted in 30 days of incubation is called Mineralizable carbon. The data were analyzed based on the factorial test in the form of a completely randomized design (CRD) with two levels of soil depth and four land uses with five replications. Correlation between traits was also estimated. Statistical analyzes were performed using SAS software. Therefore, it can be concluded that depending on the climatic conditions and the condition of the soil, the forest, in terms of natural cover, the correct management of agricultural lands (using modern methods of no-tillage or low-tillage) can be a potential practice. It is to store carbon in the soil as well as various soil components and increase soil formation, which will subsequently reduce the concentration of carbon dioxide in the atmosphere.Results and Discussion The results showed that the first depth of forest use has the highest amount of total carbon and soil organic carbon (6.12% and 3.5% respectively). Also, the highest amount of resistant organic carbon (HCl hydrolysis), water-soluble organic carbon, microbial biomass carbon, and microbial mineralizable carbon were observed in forest land use. The second depth (10-20 cm) of forest land use had the highest and the second depth (10-20 cm) of garden land use had the lowest organic carbon resistance index (82.1% and 50.17%, respectively). In all land uses, except for the forest, the soil organic carbon resistance index decreased with increasing sampling depth. Due to the fact that the carbon management index can be easily calculated, it can be a suitable index for quick assessment of soil quality.Conclusion The results showed that with the change of land use and cultivation, the soil organisms received more oxygen and the speed and intensity of respiration in the soil increased in the short term, which caused more decomposition of organic matter and with the decrease of organic matter in the long term, the quality of soil decreases after a while.
Soil Biology, Biochemistry and Biotechnology
Elham Sadeghi; REZA GHORBANINASRABADI; Seyed Ali Reza Movahedi Naini; Mojtaba Barani Motlagh; Mostafa Khoshhal Sarmast; Mohammad Reza Pahlevan Rad
Abstract
Introduction Plant growth and crop productivity may be adversely affected under unfavorable environmental conditions, such as a lack of organic matter in the soil. To counteract the negative impacts of these challenges, a unique strategy is required. The paucity of organic inputs, which is common in ...
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Introduction Plant growth and crop productivity may be adversely affected under unfavorable environmental conditions, such as a lack of organic matter in the soil. To counteract the negative impacts of these challenges, a unique strategy is required. The paucity of organic inputs, which is common in conventional agricultural production, can lead to soil degradation, erosion, and loss of soil organic matter, which are unfortunate consequences. Soil organic amendments have been shown to have beneficial effects on crop production and a wide range of soil properties in agricultural systems. However, the limited availability of phosphorus (P) in soil can significantly restrict crop growth and productivity, particularly in maize crops. Adequate P supply has been found to enhance early maturity, crop quality, and yield. However, the prolonged use of chemical fertilizers such as NPK has been found to have adverse effects on soil fertility and crop quality. As a result, the combined application of organic and chemical fertilizers has been proposed as an effective approach compared to the single application of organic or chemical fertilizer alone. Therefore, this study aimed to assess the potential benefits of using compost and Triple Super Phosphate fertilizer (TSP) application on the chemical and biological properties of soil, as well as the properties of forage maize (cv. SC704), in loess soil.Materials and Methods A factorial experiment was conducted using a completely randomized design with three replications. A total of 36 samples were performed in two separate cultivated and incubated experiments. A pot experiment was conducted to invwstigate the effects of simple and enriched compost, containing urea and Streptomyces, and varying amounts of TSP fertilizer (0, 10, 40, and 100 mg/kg), on soil properties and maize plant growth. In addition, an incubation experiment was conducted to measure the effects of the same treatments on soil microbial biomass and activity. The effect of treatments were analyzed as factorial under a completely randomized design. The biomass of maize plants was measured at the time of harvesting (the time from planting to harvesting of forage maize was 80 days). Some parameters such as available phosphorus, substrate-induced respiration, microbial biomass carbon, and some enzyme activity (acid phosphatase, alkaline phosphatase, catalase and urease) were measured in soil.Results and Discussion The findings of this study indicated that the application of compost and TSP fertilizer had significant effects on plant biomass. Specifically, compost application led to an increase in microbial biomass carbon and enzymes activity (acid phosphatase, alkaline phosphatase, catalase and urease) in the soil, ultimately promoting plant growth. Moreover, the combined application of compost and TSP fertilizer increased the availability of phosphorus, substrate-induced respiration, and microbial biomass carbon in the soil. Based on the findings, the combined application of TSP and compost resulted in further increases in substrate-induced respiration (63-168%), microbial biomass carbon (72-167%), available phosphorus (29-103%), and enzyme activity (acid phosphatase (4-21), alkaline phosphatase (14-34%), catalase (13-32%), and urease(54-159%)) compared to the application of each amendment alone. This suggests that the addition of both TSP and compost promotes the availability of easily accessible nutrients for microbial growth and soil enzymes (acid phosphatase, alkaline phosphatase, catalase and urease) activity. The highest amount of available phosphorus, microbial biomass carbon, substrate-induced respiration, catalase activity and urease activity in cultivated soil (23%, 270%, 93%, 68%, 1.8%, respectively) and incubated soil (18%, 243%, 90%, 53%, 1.2%, respectively) were observed in C2P3 treatment. The results also indicated that the enriched compost+TSP treatment led to the highest substrate-induced respiration and microbial biomass carbon, followed by simple compost+TSP, enriched compost only, simple compost only, TSP fertilizer only, and the control. The increase in enzyme activity (P<0.01, r=0.90), and available phosphorus (P<0.01, r=0.60) in the soil positively influenced plant growth. Specifically, the simultaneous application of compost and TSP had a greater effect on maize plant biomass. The highest root biomass (2.80 g), stem biomass (10.4 g), and leaf biomass (2.27 g) were observed in the enriched compost and 100 mg kg-1 TSP treatment, which differed significantly from the other treatments.Conclusion The results of this study demonstrated that the addition of compost and TSP to loess soils can promote microbial biomass carbon, substrate-induced respiration, enzyme activity (acid phosphatase, alkaline phosphatase, catalase, and urease), available phosphorus, and maize plant growth. Moreover, the use of compost can protect soil microbial and enzymatic activities in loess soils. Thus, the simultaneous application of enriched compost with TSP can reduce the use of chemical fertilizers and their negative environmental impacts.
Soil Chemistry and Pollution
Mina Hashemi Tazangi; Soheila Ebrahimi; Reza Ghorbani Nasrabadi; Seyed Alireza Movaheddi Naeeni
Abstract
Background and objectives: Hydrocarbons derived from petroleum and gas have gained increased attention as the most important fossil resources of energy as well as crude material for petrochemical industries. However, environmental issues such as pollution due to extraction, exploitation and transportation ...
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Background and objectives: Hydrocarbons derived from petroleum and gas have gained increased attention as the most important fossil resources of energy as well as crude material for petrochemical industries. However, environmental issues such as pollution due to extraction, exploitation and transportation of these materials has raised concerns as an environmental warning. In recent years, utilization of biochar (via biomass burning) has been regarded as a soil refiner to reduce or eliminate pollution, especially in in situ studies. Biochar is a product rich in carbon, which is produced during the pyrolysis of various types of woods, fertilizers, leaves, straws as well as agricultural wastes under abiotic conditions. It seems that biochar can be suggested as a suitable compound to manage biomass wastes as well as to enhance soil fertility. Thus, kinetic behavior of biochar in reduction of gasoil pollution of soil, its changes of this pollutant over time and changes in the microbial activity in this time period were investigated.Materials and methods: The soil polluted with gasoil was collected from the vicinity of the gasoil tanker located in Shiraz refinery. The soil had been polluted for years due to the leakage of gasoil. Then, after the measurement of the initial total petroleum hydrocarbon content and physical and chemical properties (soil texture via hydrometry, electrical conductivity in the saturated paste, available phosphorous using the Olsen method, total nitrogen using the Kjehdahl method, pH of soil in the saturated paste, soil carbon using the Walkey and Black method) of the polluted soil, 700 gram soil samples containing wheat straw biochar at one and two mm sizes and 20, 40, 60, 80 and 100 g kg-1 weight doses were prepared as split-split-plot experiment based on a completely randomized design with three replicates. The samples were then rested in a 50% constant humidity for four weeks at 28 ± 2 °C, and were aerated two times a week. Finally, the results of the changes in the total petroleum hydrocarbon and microbial activity over time were recorded. A three- parameter sigmoidal function was fitted to the data related to the total petroleum hydrocarbon and microbial activity over time. Analysis of variance was carried out using the SAS software v. 9.0. The leas significant difference method (LSD) was used to compare the means. The changes in the total petroleum hydrocarbons and microbial activity were analyzed using the SigmaPlot software v. 12.5. Microsoft Excel v. 2013 and SigmaPlot v. 12.5 were used to draw the figures. Results: According to the results of the present study, the application of biochar had a significant effect on the reduction of gasoil pollution of the soil. The results related to determination of the kinetic model for the reduction of pollution during the biochar application process showed that the kinetic of reduction in total petroleum hydrocarbon was of first order equation; so that in the first 28 days of the experiment, the rate of total petroleum hydrocarbon degradation was increasing, whereas it decreased 35 days after the beginning of the experiment. Biodegradation constant (k) was higher for the soil treated with the refiner and these soils had a lower half-life compared with the polluted control. The rate of reduction in half-life and Biodegradation constant rate increased with increasing refiner weight. On the contrary, half-life increased and Biodegradation constant decreased with increasing refiner size. The results indicated a significant difference in the traits as a result of applying various sizes and weights of refiner. Weekly monitoring of the pollution degradation and bioremediation performance in all refiner sizes and weights showed that the lowest time to 50% pollutant removal was obtained in 100g kg-1 and 1 mm size treatment. Investigation of the respiration under the mentioned conditions showed that the lower sizes and higher weights of biochar led to improved hydrocarbon degradation. Also, according to the results, biological efficiency (E%) of biochar was calculated 40.05 at the end of the 60 day period.Conclusion: According to the present study, biochar refiner has a great potential for utilization as a cheap and relatively new strategy to eradicate or reduce soil hydrocarbon pollution. This method is compatible with the in situ bioremediation in the soils polluted with petroleum and other petroleum derivate compounds, due to being less costly and posing less hydrocarbon threat to the environment. It is also a suitable tool to devise bioremediation strategies.
Alireza Abdollahpour; Mojtaba Baranimotlagh; Amir Bostani; Farshad Kiani; Farhad Khormali; REZA GHORBANINASRABADI
Abstract
Introduction Globally, deforestation is the dominant land use change process and has severe effects on soil biogeochemical properties. Large areas of the north facing slopes of the Alborz mountain range in northern Iran are covered by extensive loess deposits. Loess often contain little clay results ...
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Introduction Globally, deforestation is the dominant land use change process and has severe effects on soil biogeochemical properties. Large areas of the north facing slopes of the Alborz mountain range in northern Iran are covered by extensive loess deposits. Loess often contain little clay results in a loss of SOC under cultivation. Deforestation and cultivation on the loess hillslopes in northern Iran have resulted in a deterioration of soil quality, particularly significant reduction in SOC. Loess lands of Golestan province in northern Iran is densely being cultivated following deforestation. Labile fractions of soil organic matter (SOM), rather than total SOM, have been used as sensitive indicators of soils' quality and response to agricultural management changes. Several physical, chemical, and biological methods have been used to distinguish between labile (or biologically active) and recalcitrant pools of SOM. So, this research aims to investigate the effect of land use change from pristine and undisturbed forest as a reference to other land uses on soil organic carbon components and fractions as an important indicator in the sustainable soil management system and maintaining fertility and controlling soil erosion. Also, the effect of these land use changes on total carbon, soil organic carbon, and finally on the physical and chemical components of soil organic carbon.Materials and Methods The study area is the Toshan watershed, which is located in the northwest of the city of Gorgan (Golestan province) in the north of Iran. Four major and dominant types of land use were considered in the study area, including a) garden (olive), b) agricultural (cotton), c) virgin or untouched forest, d) abandoned (raspberry). Soil carbon fractionation was done by two physical methods (soil aggregate fractionation method) and chemical method (hydrolysis of organic matter with hot water). The selection of soils in different land uses was such that they have similar initial conditions and therefore the change in soil carbon in each use is related to the change in land use. The obtained data were analyzed based on the factorial design in the form of completely randomized design and using SAS software.Results and Discussion The results showed that the highest amount of total carbon and soil organic carbon was observed in the forest treatment and in the first depth (6.02% and 3.5%, respectively), which had a significant difference compared to other land use treatments studied. The results showed that despite the absence of a significant difference between the two depths, the amount of stable organic carbon increased with increasing soil depth in agricultural and abandoned uses. The forest land use had the highest amount of stable organic carbon at the depth of 0-10 cm at the rate of 2.51%, followed by garden treatment at the same depth. The lowest amount of stable organic carbon was recorded in the abandoned land use treatment. The highest amount of organic carbon dissolved in water at both investigated depths was obtained in the forest management treatments and then in the abandoned management. While no significant difference was observed between the two investigated depths in the abandoned land use. A significant decrease in organic carbon fractions that can be extracted with hot water was observed in abandoned and agricultural uses, as well as their increase in forest land uses. After the forest land use, the olive garden land use had the highest amount of total and organic carbon, however, there was no significant difference between the agricultural and abandoned treatments. In forest and garden treatments, the amount of stable carbon at a depth of 0-10 cm is significantly higher than the amount of stable organic carbon at a depth of 10-20 cm. In the garden use treatment, the amount of organic carbon in the soil at a depth of 10-20 cm showed a significant increase of 35% compared to the first depth.Conclusion A significant decrease in organic carbon fractions that can be extracted with hot water was observed in abandoned and agricultural uses, as well as their increase in forest uses. In total, the results showed that the carbon of labile fraction was more responsive to the type of land use than other fractions, and among the different methods of carbon fractionation, physical methods showed a clearer response to land use change.
Reza Khodadadi; REZA GHORBANINASRABADI
Abstract
Introduction Streptomyces is the most important and dominant genus of actinomycetales with more than 664 species which some of its species may stimulate plant growth through nutritional and physiological mechanisms that include: dissolution of phosphates, production of siderophores and phytohormones, ...
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Introduction Streptomyces is the most important and dominant genus of actinomycetales with more than 664 species which some of its species may stimulate plant growth through nutritional and physiological mechanisms that include: dissolution of phosphates, production of siderophores and phytohormones, biological Nitrogen fixation and production of antifungal metabolites. Silicon has significant positive effects on improving the growth and physiological characteristics of the plant by improving the root system, biosynthesis of phytohormones, resistance to biological and non-biological stresses and nutrient uptake. Improvement of the silicon concentration in the plant depends on its availability in soil. Soil application of resources with appropriate amount of silicon is of great importance in increasing the availability and uptake of silicon. It is also documented that the co-application of plant growth promoting bacteria and silicon is a useful and efficient method to increase plant growth and yield under normal and stress conditions. Due to beneficial effects of plant growth promoting bacteria and silicon in improving crop growth and also the importance of soil application of different silicon sources, the aim of this study was to Investigate the effect of Streptomyces isolate, silicon application using calcium-magnesium silicate source and the combined application of Streptomyces + silicon on growth parameters, chlorophyll content and accumulation of some nutrients in soybean (Glycine max L.)Materials and Methods A pot experiment was designed as factorial in a complete randomized design with 3 replications under natural light and temperature conditions. Experimental treatments included soil application of calcium-magnesium silicate source (37.9% silicon dioxide) at four levels 0 (M1), 200 (M2), 400 (M3) and 600 (M4) kg Si ha-1 and two levels of inoculation with Streptomyces isolates (no inoculation (B0) and inoculation with Streptomyces (B1). Surface-sterilized seeds were inoculated with a suspension of (107 CFU mL-1) Streptomyces isolate. The effect of experimental treatments on plant development stage (late vegetative growth period) was investigated. The soybean plants were harvested after 10 weeks of growth period from soil surface. Plant growth parameters including shoot and root biomass, root volume and plant height were determined. Also, chlorophyll content (a, b, Total) and concentration of nitrogen, silicon, phosphorus and potassium in the shoot were measured.Results and Discussion The results of the present study showed a positive and significant effect of the co- application of silicon and Streptomyces inoculation on improvement of the growth characteristics and chlorophyll content compared to their separate application. The highest amounts of shoot biomass (19.3 g per pot), root biomass (7.6 g per pot), root volume (38.07 cm3), plant height (98 cm) and chlorophyll a (18.07 mg / g), chlorophyll b (14.4 mg / g) and total chlorophyll (32.4 mg / g) were measured in the co-application of 600 kgha-1 Si (M4) and Streptomyces inoculation (M4B). .Our results showed the improvement of soybean growth parameters could be due to the positive effect of Streptomyces isolate on plant growth promotion and utilization of calcium-magnesium silicate in soil. Combined application of silicon and Streptomyces inoculation increased the concentration of silicon, nitrogen, phosphorus and potassium in the M4B treatment compared with the lonely application of highest level of silicon source (M4) by 16.25, 7.45, 45.6, 51.7%, respectively.Conclusion Based on the results of the present study soil application of calcium-magnesium silicate increased plant growth and physiological factors. Streptomyces inoculation improved the effects of calcium-magnesium silicate levels to enhance growth parameters, chlorophyll content and nutrient concentration (silicon, nitrogen, phosphorus and potassium) in soybeans. This study was carried out in pot experiment at the vegetative growth stage of soybean. Therefore, supplementary studies are necessary in field and harvest stage.Keywords: Streptomyces, inoculation, silicon, soybean, plant growth
Elham Sadeghi; REZA GHORBANINASRABADI
Abstract
Introduction: Soil microorganisms play an important role in maintaining soil quality through the decomposition of organic matter and nutrients cycling. The quantity of plant residue has a positive effect on the accumulation of organic carbon in the soil. One of the most important problems hampering the ...
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Introduction: Soil microorganisms play an important role in maintaining soil quality through the decomposition of organic matter and nutrients cycling. The quantity of plant residue has a positive effect on the accumulation of organic carbon in the soil. One of the most important problems hampering the release of nutrients from plant residues is the high content of lignocellulose in their structure. Therefore, biological treatment has been considered as a candidate to improve lignocellulosic conversion and more release of nutrients from them. Salinity reduces microbial biomass and decreases their activity in decomposition of soil organic matter and organic matter input into soil. Due to the importance of the role of microorganisms in the storage and release of energy and nutrients in the soil, in recent years, increasing attention has been paid to the estimation of microbial activity and biomass in soil. Therefore, the aim of this study was to study the effect of salinity, inoculation of Pleurotus astreatus and wheat residue on respiration, microbial biomass carbon, organic carbon, carbon availability index and metabolic quotient.Materials and Methods: The experiment was conducted as a completely randomized design with factorial arrangement in three replications under controlled laboratory conditions at Gorgan University of Agricultural Sciences and Natural Resources. Factors included three salinity levels (0, 8 and 15 dS m-1), two fungal levels (0 and 5%) and two wheat residue levels (0 and 1%, w/w). Salinity treatments including (control), 8 and 15 dS m-1 was applied using a mixture of salts (NaCl, KCl and MgCl2 with a molar ratio of 3:2:1). Wheat straw was treated pleurotus fungus and the treated straw was then thoroughly mixed into the soil. To activate the microbial population, soil moisture was adjusted to about 70% of the field capacity and the containers were pre-incubated at room temperature for 2 weeks. The samples were incubated at 25±2°C for 90 days. Microbial biomass carbon, organic carbon was measured at monthly intervals, microbial respiration was measured weekly and substrate-induced respiration (SIR) was measured once at the end of the incubation period.Results and Discussion: The results show that salinity has a negative effect on microbial activity and population, but wheat residues reduce the effect of salinity stress on soil microbial community. Inoculation of Pleurotus into the soil also increased the respiration and microbial biomass. The interaction of wheat residues and Pleurotus on microbial activity in saline soil was greater than their effect alone. According to the results, the simultaneous addition of Pleurotus and wheat residue increases organic carbon (%98), microbial respiration rate (90%), substrate respiration (69%) and microbial biomass carbon (79%) and decreases the metabolic coefficient (6%). Salinity reduced respiration (78%), microbial biomass carbon (81%) and carbon availability index (23%), which indicates a decrease in carbon for microbial activity in saline soils. The lowest and highest microbial activity and biomass were in saline soil (15 dS m-1) not treated with wheat residues and Pleurotus (S2F0R0) and in non-saline soils treated with wheat residues enriched with Pleurotus (S0F1R1), respectively. The results showed that higher salinity level (15 dS m-1) further decreased the measured characteristics including carbon availability index, respiration and microbial biomass carbon compared with 8 dS m-1 salinity level in all treatments. In non-treated soil with wheat residue and Pleurotus, salinity level of 8 dS m-1 reduced MBC by 43, 46 and 44 % compared to control (non-saline) soil. The results showed that there was a significant negative correlation between microbial respiration rate and salinity (P <0.01, r = - 0.87). Salinity reduced microbial respiration rate and the effect of salinity on reducing microbial respiration rate of soil with EC 15 dSm-1 was higher than lower salinity level (8 dSm-1). Also, inoculation of Pleurotus in soil led to increase microbial respiration rate compared with non-treated one. According to the results, salinity levels of 8 and 15 dSm-1 reduced carbon availability index in soil treated with Pleurotus and wheat residue by 18% and 23%, respectively, compared to non-saline soil.Conclusion: The addition of wheat straw enriched with Pleurotus astreatus increased microbial respiration, organic carbon, microbial biomass carbon, substrate-induced respiration and carbon availability index due to the increase of available substrate. Therefore, in saline soils with carbon restriction, increasing the level of organic matter, increased microbial activity and biological potentials in the soil. However, further information on responses of microbial indicators to the joint effect of salinity and Plant residues enriched with other microorganisms is required.ReceivedReceived in revised formAcceptedKey words:Carbon availability index, Microbial biomass carbon, Microbial respiration rate, Soil organic carbon, Substrate-induced respiration
T. Nazari; M. Baranimotlgh; E. Dordipour; R. Ghorbani nasrabadi; S. Sefidgar Shahkolaee
Abstract
Introduction One of the most important needs in crop planning is the evaluation of different systems of plant nutrition. plant nutrition in a correct way can preserve the environment and increase efficiency of agricultural inputs. Humic acid contains many nutrients that increase the soil fertility and ...
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Introduction One of the most important needs in crop planning is the evaluation of different systems of plant nutrition. plant nutrition in a correct way can preserve the environment and increase efficiency of agricultural inputs. Humic acid contains many nutrients that increase the soil fertility and soil organic matter content and thus affect plant growth and yield. In the present study, the effect of soil and foliar application as well as fertigation application of humic acid on iron and phosphorous availability of canola (Hyola 308) was evaluated. Materials and Methods The soil was air-dried and ground to pass through a 2-mm sieve and then was analyzed to determine soil physical and chemical properties using standard methods. A greenhouse experiment was carried out with 10 treatments in four replications. Treatments include humic acid soil application at three levels (1, 2 and 4 g.kg-1 soil), foliar application at three levels (0.1, 0.2 and 0.4%) and three fertigation levels (1000, 2000 and 4000 mg L-1) and control). Soil application in the form of humic acid powder and in cropping time based on the soil weight of the pots and for spraying and use along with irrigation water, each of the spraying and together with irrigation water levels is divided into three equal parts and in three stages (plant establishment, stem elongation and flowering). At the end of growth period (for 139 days), vegetative growth indices were determined and then plants were harvested and stem and leaves were separated. Phosphorous content in plant extracts was measured by molybdate vanadate method (yellow method) and iron concentration in the samples was determined by atomic absorption (AAS-Unicam-919). Statistical analysis was conducted via SAS software and mean comparisons carried out by LSD test at 5% probability level. Results and Discussion Results show that the application methods and the different levels of humic acid had significant impacts (p < 0.01) on the all parameters but they had no significant effects on the numbers of leaves. The maximum leaf fresh weight was 4.34 gr per plant which obtained water irrigated treatments with 2000 mg/lit. However, there was no significant difference between water irrigation with 4000 and 2000 mg/lit humic acid concentrations. Besides, maximum leaf dry weight was 0.37 gr in the plant that was water irrigated with 4000 mg/lit, however there was no significant difference between water irrigation with 4000 and 2000 mg/lit humic acid concentrations. Also, the maximum stem dry and fresh weight was 5.92 and 1.53 gr which observed in water irrigated with 2000 mg/lit. The application methods and the different levels of humic acid had significant impact (p<0.01) on the content and absorption of Fe and P excluding the Fe content in the root. The maximum Fe content in stem and seed were 321.25 and 85 mg/kg was observed in the treatment of humic acid with water irrigation of 2000 mg/lit. Also, in the treatment of spraying with 0.4 % of humic acid, the maximum of Fe concentration (245.46 mg/kg) was obtained. The humic acid molecules can pass from the cell membranes and cause iron reduction in the Apoplast and increase the availability of Fe. Because of the reduction effect of humic acid on the availability and accumulation of Fe in the plant tissue, increasing in the Fe absorption with humic acid treatment is observed. The increase in the accumulation of Fe by humic material might be due to the releasing phenolic material in the root rhizosphere. The maximum P concentration in the leaf, stem and seed were 0.40, 0.72 and 0.897 respectively that was observed in the treatment of water irrigation with 2000 mg/lit with humic acid. Due to the availability of phosphorus and other nutrients for wheat, humic acid increases the plant yield in the reproductive stage of seeding. Conclusion Results of the study show that humic acid can ameliorate the negative effect of a large amount of phosphorus on iron availability. In fact, humic acid, due to providing nutritional balance for the plant, prevents negative effects caused by the high amounts of specific elements such as phosphorus. Also, the results showed that all three humic acid application methods increased vegetative growth parameters, and iron and phosphate availability for canola plant compared to control. But in general, 2000 mg/L acid humic with irrigation water was more effective than two methods of soil and foliar application.
M. Soleimanzadeh; F. Khormali; M. Sohrabi; R. Ghorbani Nasrabadi; M. Kehl
Abstract
Introduction Biological soil crusts are a widespread community of cyanobacteria, green alga, lichens, mosses, and other organisms. These crusts play important roles in arid and semi-arid ecosystems, such as carbon and nitrogen fixation, soil protection against water and wind erosion, and water retention. ...
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Introduction Biological soil crusts are a widespread community of cyanobacteria, green alga, lichens, mosses, and other organisms. These crusts play important roles in arid and semi-arid ecosystems, such as carbon and nitrogen fixation, soil protection against water and wind erosion, and water retention. In arid and semi-arid regions, the biological soil crusts also possess a key role in the global carbon cycle due to the carbon fixation (photosynthesis) and its release (respiration) into the atmosphere. These organisms increase the organic carbon content of the soil in arid and semi-arid regions by performing photosynthesis. Soil organic carbon is a mixture of various components and one of the important characteristics for soil quality evaluation. Biological attributes of soil quality include many soil components and processes related to the organic material cycle, such as total organic carbon and nitrogen, microbial biomass, carbon and nitrogen mineralization, labile fractions of elements, the activity of enzymes, and animals and plants in soil. These biological attributes respond rapidly to natural and human-derived changes, and therefore they are used as indices for quality of soils. Biological soil crusts are the main cover of the loess soil surface in the northern parts of Golestan Province. The region that was selected to be studied in the province was Maraveh Tappeh. This region has arid and semi-arid climate and is attributed to low vegetation, especially on the slopes to the south. In these slopes, biological and physical crusts are dominant. Therefore, a study was conducted to investigate the effect of lichen biological soil crusts on organic carbon and different fractions of labile carbon. Materials and Methods After extensive field studies, two species of lichen biological soil crusts were collected and transferred to the laboratory for identification. The results elucidated that the studied species were Diploschistes Diacapsis (Ach.) Lumbsch, and Fulgensia Fulgens (Sw.) Elenk, based on taxonomical identification. Soil sampling was done from 0-2 and 2-5cm depths under lichen biological and physical crusts. Soil samples were transferred to the laboratory, and then the organic carbon, carbohydrate, permanganate oxidizable carbon, microbial biomass carbon, cold-water extractable organic carbon, and hot-water extractable organic carbon were measured by standard methods. Results and Discussion Results show that lichen biological soil crusts led to the increase in soil organic carbon and different fractions of labile organic carbon related to the physical crust. As a result, the highest values for these traits were observed in soils affected by lichen biological soil crusts. Soil covered by the Diploschistes Diacapsis species had the highest amount of soil organic carbon and different fractions of labile organic carbon in comparison to the Fulgensia Fulgens species in 0-2cm depth, which had a significant difference at 5% probability level. the physical crusts had the least amount of soil organic carbon and different fractions of labile organic carbon related to the lichen biological soil crusts, which was caused by the loss of topsoil and the lack of biological coverage. There was a positive correlation between the measured traits. There was a high correlation between hot water-extractable carbon and carbohydrate. There were high correlation coefficients between organic carbon with microbial biomass carbon, hot water-extractable carbon, and carbohydrate. In general, there was a high correlation coefficient between hot water-extractable carbon with organic carbon and other labile fractions of organic carbon except for cold water-extractable carbon, whereas there was low correlation coefficient between hot water-extractable carbon with organic carbon and other labile fractions of organic carbon. Conclusion According to the results attained from the following study, the presence of biological soil crusts on loessial soils led to the increase in organic carbon, carbohydrate, permanganate oxidizable carbon, microbial biomass carbon, cold-water extractable organic carbon, and hot-water extractable organic carbon. Diploschistes Diacapsis Species have the highest impact on organic carbon and different fractions of labile organic carbon. The High correlations show that the best attributes to evaluate the quality of soil organic carbon in the studied area are microbial biomass carbon, carbohydrate, and hot water-extractable carbon and these may be used as a good indicator to evaluate soil quality. The studied area falls within the arid and semi-arid climate, and given the erosion-prone nature of loess deposits, improper management may lead to severe problems, such as erosion and dust production. Hence, protecting lichen biological loess crusts against human activity and livestock grazing may result in lower water and wind erosion, and increase soil quality in this region.
Soil Biology, Biochemistry and Biotechnology
Maryam Talebi Atouei; mohsen olamaee; REZA GHORBANI NASRABADI; seyed alireza movahedi Naeini
Abstract
Introduction Salinity is the most important challenge in arid and semi-arid regions. Salt stress, ionic and osmotic components, like other abiotic stresses, lead to oxidative stress that damage cellular membranes, nucleic acids, oxidizing proteins, and causing lipid peroxidation through overproduction ...
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Introduction Salinity is the most important challenge in arid and semi-arid regions. Salt stress, ionic and osmotic components, like other abiotic stresses, lead to oxidative stress that damage cellular membranes, nucleic acids, oxidizing proteins, and causing lipid peroxidation through overproduction of reactive oxygen species (ROS). Antioxidant capacities and osmolytes play a vital role in protecting plants from salinity that causes oxidative damages. Applying biological methods such as using of halotolerant plant growth promoting rhizobacteria (PGPR) is very important to reducing the harmful effects of salinity on plants. Also exopolysaccharide production by plant growth-promoting strains helps in binding cations, including Na+, and thus decreases the content of Na+ available for plant uptake. This is especially useful for alleviating saline stress in plants. Biochar can also alleviate the negative impacts of salt stress in crops. Biochar can enhance plant growth either by its direct or indirect mechanisms of actions. The direct growth promotion relates to supplying mineral nutrients, such as Ca, Mg, P, K and S etc., to the plant, whereas, indirect mechanisms involve improving soil physical, chemical and biological characteristics. Materials and Methods In this research, the effect of halotolerant plant growth promoting bacteria, biochar and gypsum was investigated on enzymatic and non-enzymatic defense mechanisms of barley such as Catalase, Superoxide Dismutase, Proline and Membrane stability under salinity stress. The experiments were carried out as a factoria with a completely randomize design in greenhouse conditions for 2016-2017. The factors included: bacteria (without inoculation (T0), bacterial isolate T5 (megaterium Bacillus), bacterial isolate T17 (licheniformis Bacillus ), biochar (0 and 5percent w/w), gypsum ( 0and 50 percent gypsum requirement ) and soil leaching (without and leaching with) with three replications. The activity of catalase (CAT) was determined by changes in absorbance at 240 nm (IUg−1FW) (Aeby, 1984). Superoxide dismutase (SOD) activity was determined by nitroblue tetrazolium (NBT) reduction, according to Minami and Yoshikawa (1979) and the enzyme activity was expressed as (IUg−1FW). Proline content was estimated according to Bates et al., (1973) and expressed as µ mol g−1 fresh weight (FW). Membrane stability was estimated according to Sairam and. Saxena (2001). All statistical analyses were performed using SAS software. The means of different treatments were compared using LSD (P ≤0.05) test. Results and Discussion The results showed that using halotolerant bacteria and biochar reduced the activity of antioxidant enzymes in barley plants. This reduction was higher in the treatment containing bacteria T17 (Bacillus licheniformis) biochar and with leaching. Also, inoculated plants with both bacteria had the highest concentration of proline, which was significantly higher in the treatment containing bacteria T17 (Bacillus licheniformis) biochar and gypsum. Also, application of halotolerant bacteria, biochar and gypsum improved the membrane stability of plant. This increase has been remarkable in inoculated treatments with T17 bacteria (Bacillus licheniformi) in saline soil with leaching associated with 50 percent gypsum requirement Conclusion Generally, results showed that halotolerant bacteria, biochar and gypsum can be used as a tool for reducing adverse effects of salt stress. Inoculation of soil with these bacteria has helped in alleviating saline stress by changing several physiological, enzymatic, and biochemical agents in plant. Bio-remediation of salt affected soils is one of the cheap and eco-friendly approaches for remediation of salt affected lands as the traditional physical and chemical techniques are becoming costly. The plant growth promoting halotolerant bacteria helps in Bio-remediation of salt affected soils and thereby improving the agricultural crop yields. Incorporation of biochar into salt-affected soil could diminish salinity stress by decreasing soil bulk density, increasing in soil cation exchange capacity, potassium and calcium concentrations, water holding capacity and nutrient and water availability in soil. Also, bichar due to high organic matter content can play a dramatic role in salt affected soil with organic compound defficiency. According to these amended features of biochar in soil, we suggest, more experiments conducted by biochar with different material and ratios under saline - sodic soils.
Plant Nutrition, Soil Fertility and Fertilizers
Elham Mirparizi; Mojtaba Barani motlagh; Alireza Movahedi; REZA GHORBANINASRABADI; Somayeh Bakhtiary
Abstract
Introduction: Among the micronutrients required by plants, iron deficiency has the maximum limitation for agricultural crops. Iron plays an important role in synthesis of chlorophyll, energy transfer in plants, formation and synthesis of special enzymes, and fixation of nitrogen. Deficiency of iron in ...
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Introduction: Among the micronutrients required by plants, iron deficiency has the maximum limitation for agricultural crops. Iron plays an important role in synthesis of chlorophyll, energy transfer in plants, formation and synthesis of special enzymes, and fixation of nitrogen. Deficiency of iron in plants causes chlorosis or yellowing of young leaves. Iron deficiency is developed due to imbalance of metal ions including copper and manganese, large phosphorus in soil, poor aeration, low temperatures, soil iron deficiency, low organic content, and high concentration of bicarbonate in the root environment. To solve the problem of iron deficiency in plants, very expensive methods are used. Usage of solid wastes of copper melting factories such as slag as soil modifying materials can be useful in iron nutrition. The possibility of using reverb furnace slag of Sarcheshmeh Copper complex as an iron fertilizer was examined in a calcareous soil. Since copper slag contain considerable amount of iron (53.8% iron oxides), therefore, its proper management can solve the problem of iron deficiency in calcareous soils. Materials and Methods: To investigate the effect of copper slag and organic compounds on iron availability and growth of Sorghum plant, (Speed Feed cultivar), a soil sample was harvested with low soil absorbable iron and organic compound. After air-drying, the soil samples were passed through a 2-mm sieve. Some physiochemical properties of the soil sample used, organic compounds, and the slag were characterized by typical experimental methods. The experimental design was performed as a factorial experiment (copper slag and organic compounds) in a completely randomized design with three replicates. The experimental treatments included five levels of organic compound (pistachio shell and cow manure at two levels of 2% , 4% and the control sample) and 10 levels of iron (copper slag, copper slag with sulfur, copper slag with sulfur and thiobacillus, acidic slag (each at two levels), Fe-EDDHA, and control sample). The experimental treatments were incubated for 3 months. Treatments were then applied to 3 kg samples of soils and the treated samples were incubated in plastic containers at field capacity (FC) moisture content for up to 90 days. At the end of incubation period, 10 sorghum seeds were cultivated in each pot. Foliar application of Fe-EDTA with a concentration of 5 ppm in addition to the mentioned treatments. Harvesting sorghum shoot was performed 90 days after the cultivation. The plant samples were dried for 48 h at 70°C. After digestion of the plant samples by wet oxidation method, concentration of iron, zinc, nickel and cobalt were measured by atomic absorption spectrophotometer. Soil samples were also taken from the pots. After being air-dried, the soil samples were passed through a 2-mm sieve. Amount of electrical conductivity, soluble sodium, concentration of calcium and magnesium as well as iron, zinc, nickel, and cobalt were measured. All statistical analyses were performed using SAS software. Means of different treatments were compared using LSD (P ≤0.05) test. Results and Discussion: Application of acidic slag increased the soluble sodium and sodium absorption ratio and decreased the soil absorbable iron content. Application of 4 times critical level as slag (S4) increased iron and zinc absorbable by soil, as well as increased concentration of the plant iron. The copper slag with sulfur and thiobacillus developed the maximum absorbable zinc in soil. Comparison of the organic compounds indicated that cow manure has a greater influence on the amount of absorbable iron in soil, iron concentration and uptake by the plant than pistachio shell. On the other hand, with reduction of the concentration of heavy metals, its application is recommended in comparison with pistachio shell. The content of zinc, nickel, and cobalt in the studied plant did not exceed the toxicity level. Heavy metals have low mobility in the soil and are often stabilized by soil colloids or precipitate as different compounds. For this reason, their mobility and transference to shoot diminish. Conclusion: The slag from copper melting has micro nutrient including iron and zinc. Therefore, it can be concluded that the copper slag has the potential of a source supplying elements for plants. These results confirm the lack of use of acidic treatments. In addition of iron and zinc availability for plants, measurement of other heavy metals in the plant showed that the concentration of measured heavy metals was below their toxicity level. Therefore, suitability of this compound for agriculture will be confirmed. Since addition of heavy metals to soil has various environmental effects, thus repetitive use of slag and its use in large amounts are not recommended. As in absorption of nutrients, immobility in soil, stabilization of metal in the root, and preventing its transference to shoot organs are among the mechanisms of plant when exposed to high concentration of heavy metals, it is suggested that the amount of heavy metals be studied in the root.
Soil Physics, Erosion and Conservation
Motahareh Noorzade Roshan; Reza Ghorbani Nasrabadi
Abstract
Introduction Soil quality has been defined as a “The potential of soil to play a positive relationship with the other parts of ecosystem”. Soil biological indicators provide insight into the living component of the soil. Similar to physical and chemical indicators, biological indicators have ...
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Introduction Soil quality has been defined as a “The potential of soil to play a positive relationship with the other parts of ecosystem”. Soil biological indicators provide insight into the living component of the soil. Similar to physical and chemical indicators, biological indicators have a relationship to soil functions and can evaluate soil functions to assess soil quality. Between biological indicators, an index that can be measured quickly and easily is more useful to show the changes. In many studies an indicator of microbial respiration, microbial population, nitrogen mineralization and enzymes activity can be used. Special ability is required to measure quickly and show the quality of soil microorganisms and reaction to environmental changes. Soil health is defined by chemical and physical parameters such as soil texture, soil pH, electrical conductivity, etc., that are not quantifiable completely. Therefore, conservation practices planting and forestry may directly or indirectly affect a organism’s activities. The results of land-use systems without consideration of the consequences on soil quality have been environmental degradation. Agricultural management systems have been generally adopted without attending to soil conservation and soil quality, and this therefore causes significant decline in agricultural soil health worldwide. Different methods of soil conservation have been proposed to prevent erosion and improve soil quality destructive phenomena. In Golestan province due to topographical and climatic conditions and less soil sensitivity to erosion, more attention should be given to this issue. But it remains unclear how far this conservation practice can take to prevent damage. This study aimed to investigate the role of conservative practices to improve the soil quality indicators.Materials and Methods The watershed of Chehelchai is located between North latitudes 36° 59´ and 37° 13´ and Earth longitudes 55° 23´ and 55° 38´. The history of land use in the region shows that more than about 40 years ago, all the study area was covered by forest. Agricultural land use changes occurred on a large scale. With emphasis on conservation operation, parts of the agricultural land were changed to productive gardens, partly forested, partly pasture with native species. Different land uses were selected in loess formations, and slope of 41 %, with life operations was about 6 to 7 years. Protective Operations Garden species, terraces and forestry were selected and quality of soil was compared with agricultural land, pasture and natural forest. In this regard, 10 soil samples were taken. After preparation of the samples, physical, chemical and biological analysis were measured. Additionally, soil properties (pH, Electrical Conductivity, Calcium carbonate, organic matter, texture, bulk density, aggregate stability, microbial respiration, microbial biomass population count of micro- arthropods, biological soil quality) were analyzed. The data were analyzed using software SAS. Ver 9. and the results were compared in a randomized complete block design. Analysis of variance in the form of randomized complete block design was done using the LSD multiple comparison. Results and Discussion Our results showed that the dominant soil texture class in land uses was silty loam. It seems that soil texture is less affected by the land use changes. The results showed that the changes of forest and pasture to agricultural lands have destroyed the soil quality. Soil quality indicators such as organic matter and aggregate stability have declined by 60 and 70 percent respectively. Like wise, biological indicators such as microbial respiration, microbial biomass carbon and QBS (biological soil quality indicators based on the population of micro- arthropods) and EMI (index dependence of soil to soil organisms) showed a similar trend. In contrast, the Conservation practices improved the indices. Biological indicators in the forestry and gardening showed an increase of 40 percent in EMI Microbial biomass carbon and 80 percent in microbial respiration. Terracing had less improvement than other operations in about 11 to 20 percent in EMI and microbial biomass carbon. Conclusion Conservation operations had fewer effects on indicators such as aggregate stability and organic matter. Under estimation of effects in certain indicators maybe due to short time of conservation practices. It seems that these operations will show better results in the future Received: 19 July, 2016Accepted: 10 April, 2018
Soil Biology, Biochemistry and Biotechnology
S. A. Hosseini; mhsen olamaee; S. A. Movahedi Naeini; F. Khormali; R. Ghorbani Nasrabadi
Abstract
Introduction Potassium is one of the essential and macro elements in the growth of plant cells. This element plays an important role in improving the quality of agricultural products. The amounts of available potassium levels in most soils decrease more quickly and potassium balance is disturbed in many ...
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Introduction Potassium is one of the essential and macro elements in the growth of plant cells. This element plays an important role in improving the quality of agricultural products. The amounts of available potassium levels in most soils decrease more quickly and potassium balance is disturbed in many fields. Cultivation and lack of the application of potassium fertilizers in agricultural soils of Iran have caused the depletion of potassium and the amount of available potassium in most soils has reached below the critical level. The compensation of depleted potassium in the soil through indigenous resources and use of potassium bio-fertilizers is therefore very important. Weathering of silicate minerals by bacteria is considered as one of the essential K source for plant growth and development. The objective of this study was to isolate and identify potassium solubilizing bacteria from the shale containing glauconite mineral in Golestan Province and determine some traits related to plant growth promotion and selecting a superior strain in order to incubate in wheat lands. Materials and Methods Accordingly, a total of 5 samples 1 kg of rhizosphere of wheat from a depth of 0 to 30 cm and 5 samples 1 kg from shale stone (containing glauconite) were collected from Aitamir formation in Golestan Province in May 2015 and were transferred to the laboratory of Gorgan University of Agricultural Science and Natural Resources. Isolates were transferred to Aleksandrov media containing glauconite and muscovite and incubated for 10 days and the isolated strains were stored in the refrigerator at 4 oC. The amount of potassium release in solutions after 10 days was measured. Some biochemical and morphological properties of isolates were determined based on standard methods. PGPR tests were done in the isolates which were morphologically different and had high potential in releasing K. Finally, a strain whith high ability in releasing potassium and growth promoting properties was identified using nucleotide sequence of 16S rRNA gene. Results and Discussion Results showed that 40 strains from the first stage, 20 strains from rhizospherial soil and 20 strains from the soil resulting from glauconite mineral powders were isolated. Biochemical and potassium release tests showed that the highest released potassium was related to isolate No. 39 with an amount of 34.2 mg l-1 in muscovite, and 31.8 mg. l-1 in glauconite. The amount of siderophore produced in the superior strains showed that the lowest and the highest ratios of the diameter of the colony, were 1.12 and 3.1 related to isolate No. 19 and No. 39, respectively. The highest and the lowest auxins produced were also related to the isolate No. 39 and No. 27 with the amount of 52.25 and 5.15 mg per liter, respectively, measured at 72 and 96 hours. The results showed that the soluble phosphorus between different isolates was significantly different (P <0.05), its greatest concentration at 72 hours was related to isolates No. 39 with an amount of 295 mg per liter and the lowest at 24 hours was related to isolate No. 31 with an amount of 80 mg per liter. Also, the production of hydrogen cyanide test showed that none of the isolates was capable of producing siderophore. The obtained results from nucleotide sequence of 16S rRNA gene showed that the selected strain belonged to Arthrobacter phenanthrenivoran species. Conclusion It can be concluded that silicate bacteria contribute to the dynamics and mineralizing of elements in the soil and eventually K release from glauconite containing shale minerals mainly by reducing rhizosphere pH, the secretion of organic anions and complex formation with the surface cations of mineral and secreted extracellular Polysaccharides and soluble compounds and decomposition of soil organic matter. Among 40 isolated strains and the various tests and the results of released potassium in both minerals, the results showed that the potential of potassium releasing was different between the tested strains. Moreover, this study showed that in addition to the effect of these strains on potassium releasing, siderophore production, auxin and inorganic phosphate solubility, they can be effective in plant growth and in land inoculation. This study revealed the potential of indigenous bacteria species in the release of K from shale containing glauconite. It is anticipated that shale containing glauconite can provide a part of the need of the crops for potassium.
A Ardeshiri Lajimi; R Ghorbani Nasrabadi; M Barani Motlagh; S A Movahedi
