atena mirbolook; Mirhasan Rasouli-Sadaghiani; E. Sepehr; A. Lakzian; M. Hakimi
Abstract
Introduction: Iron (Fe) is an important micronutrient that plays a role in several crop physiological processes such as photosynthesis, respiration, and synthesis of heme proteins, DNA, RNA, and hormones. The most common Fe source used in agriculture is Fe-EDDHA. However, the usage of this chelate may ...
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Introduction: Iron (Fe) is an important micronutrient that plays a role in several crop physiological processes such as photosynthesis, respiration, and synthesis of heme proteins, DNA, RNA, and hormones. The most common Fe source used in agriculture is Fe-EDDHA. However, the usage of this chelate may be problematic for plant growth. In the recent years, organic chelates have gained attention as they increase the microelements solubility and prevent iron precipitation in nutrient solution. Organic chelates such as amino acids and polysaccharides have many physicochemical (reactive OH, COOH and NH2 groups) and biological (biocompatible and biodegradable) properties that make these attractive materials usable for the agricultural practice. Biodegradability, low toxicity, immune system stimulation, the ability to coordinate metal, less sensitivity to photodegradation, and the effect on physical properties of rhizosphere and root growth dynamic are ideal properties of these components. The objective of this study was to evaluate Fe-organic-chelates efficiency as Fe sources for bean (Strategy I) and corn (Strategy II) growth in the hydroponic system. Materials and Methods: In this research, we synthesized Fe-amino acid chelates including Fe-Glycine (Fe-Gly), Fe-Phenylalanine (Fe-Phe), Fe-Tyrosine (Fe-Tyr), Fe-Methionine (Fe-Met), and Fe chitosan chelates in two forms of acidic hydrolyzed chitosan [Fe-C(A.hyd)] and enzymatic hydrolyzed chitosan [Fe-C(E.hyd)] and characterized by FTIR and CHN analyzer. The efficiency of these iron sources for bean (Strategy II) and corn (Strategy I) in hydroponic system was then evaluated. Seeds of bean and corn were washed with distilled water and transplanted into special containers containing coco peat, perlite and vermicompost (1:1:1) at 25 °C for germination and initial growth. The seedlings were transferred to polyethylene plastic lids fitting tightly over 8-L polyethylene containers under controlled conditions in the greenhouse with a light period of 8 hours per day, the temperature of 20 to 25°C and relative humidity of 65 to 75%. The pots were stacked in black color to prevent light reaching the root of the plant and the solution. In each pot, one plant seedling was placed and the basic nutrient solution was prepared in deionized water. The plants were harvested after 8 weeks, their root and shoot were separated and dried after washing with distilled water in an oven at 75 ° C. The dried samples were ground to fine powder to pass through a 20-mesh sieve. The analysis of Fe in samples was performed using atomic absorption spectrophotometer. Result and Discussion: Application of organic chelates of amino acids and chitosan increased the shoot dry matter per plant compared to Fe-EDDHA. Fe content in shoot of corn and bean was highest using Fe-Tyr, Fe-Met and [Fe-C(A.hyd)]. Uptake and accumulation of Fe in roots were observed by using all chelates, but the highest translocation factor was found for the treatments including [Fe-C(A.hyd)] and Fe-Tyr. Translocation factor in bean plants was higher than corn, and around half of Fe in bean plants was translocated from root to shoot. The use of iron chelates in plant growth medium increased the activity of ferric chelates reductase enzymes in bean and corn compared to Fe-EDDHA. However, the mean of this enzyme activity in bean was higher than that in corn. Therefore, the activity of this enzyme can be used as an indicator for determining the iron availability in leaf cells in Strategy I and Strategy II plants. In general, the plants need less energy to absorb Fe when the chelates with a simpler structure are used. Conclusion: The results indicated that using Fe organic chelates in the hydroponic system could supply sufficient amounts of iron for the plant uptake and also improve the root and the shoot growth of bean and corn. Overall, the effect of Fe organic chelates on Fe content of bean and corn shoots was in the following order: Fe- Chi(A.hyd) > Fe-Tyr > Fe-Met > Fe-Gly >. Activity of leaf ferric chelate reductase in bean was higher than that in corn.
Mirhassan Rasoulsiadaghiani; Vali Feiziasl; Ebrahim Sepehr; Mehdi Rahmati; Salman Mirzaee
Abstract
Introduction: In cereal crops, nitrogen is the most important element for maintaining growth status and enhancing grain yield. Nitrogen is an important constituent of the chlorophyll molecule and the carbon-fixing enzyme ribulose-1, 5-bis-phosphate carboxylase/oxygenase. Therefore, providing enough nitrogen ...
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Introduction: In cereal crops, nitrogen is the most important element for maintaining growth status and enhancing grain yield. Nitrogen is an important constituent of the chlorophyll molecule and the carbon-fixing enzyme ribulose-1, 5-bis-phosphate carboxylase/oxygenase. Therefore, providing enough nitrogen to achieve optimal yield is essential. Common chemical analyzes are used to determine the nutrient elements of plants using laboratory methods. Conventional laboratory techniques are expensive, laborious, and time-consuming. Determination of plant biochemical content by remote sensing could be used as an alternative method which reduce the problems of laboratory analyses. Expensive and time-consuming direct determination of the nutritional status of the plant play an important role in the quantitative and qualitative yield of the product. However, exposure to rainfed wheat nutrient stresses (in particular, nitrogen) compared to irrigated wheat resulting in attempts to evaluate these features with acceptable accuracy without the direct measurement. In this regard, remote sensing data and satellite images are of the basic dryland management and optimal wheat production methods. As such, it collects massive information periodically from the surface of the planet, and it is easy to use this timely information to identify the stresses and apply appropriate agronomic methods in order to counteract them or reduce their negative impact on the production of this strategic product. Therefore, the goal of this study was to determine the nitrogen concentration of dryland wheat in the laboratory and its fitting with ETM+ images, evaluate the accuracy of remote sensing in determining the total nitrogen content of the plant and establish a regression relationship to estimate the amount of canopy nitrogen in the plant.
Material and Methods: This research was undertaken in parts of the south of the West Azerbaijan Province in Iran. The sampling was done from 45 dryland wheat fields using a stratified random method in May 2016. The wheat canopy nitrogen was determined using the Kjeldahl method. Satellite images of the ETM+ were downloaded on the USGS website. Then the required pre-processing was performed on images to reduce systematic and non-systematic errors. Statistical analyses were performed by excel and SPSS. Descriptive statistics and correlations were obtained between reflectance data obtained from various satellite bands and nitrogen measured in the laboratory. Correlated variables among the reflectance data of different bands were analyzed by principal component to reduce repeat calculations. The regression relationship between the plant canopy nitrogen and the first principal component has been evaluated using the stepwise regression method. To draw the plant canopy nitrogen, map, the equation was obtained and the ETM+ image has been used for land uses. Finally, the map of canopy N distribution at the studied area was drawn.
Results and Discussion: The results showed that nitrogen content varied from 1.6% to 0.79%, with an average of 1.11%. The normality data was verified by the Shapiro Wilk test. The results of the Pearson correlation showed that the wheat canopy nitrogen has a high correlation with digital number values of all bands of satellite images except band 4, so that it has the highest and the least correlation with band 2 and band 4, respectively. The correlation between remote sensing data in different bands was also evaluated using bi-plot statistics, which results showed a high correlation between all bands except band 4 with the first one of the principal component (PC1). Therefore, only PC1 data has been used to study the regression relationships between wheat canopy nitrogen and remote sensing data. A regression equation between wheat canopy nitrogen and ZPC1 (R2= 0.71) was developed. ZPC1 is obtained according to the following formula: where ZPC1 is the standardized Z parameter, is the average of PC1 and the ????pc1 is the standard deviation of PC1. Finally, the map of canopy N distribution was drawn to the studied area. According to the results of this study, the application of remote sensing data such as Landsat ETM+ data is a very important variable for improving and managing the prediction of wheat canopy nitrogen.
Conclusion: Overall, the results indicated that the remote sensing data provide more accurate and timely information from the drylands of Iran to manage farm fertilization and prevent the decline in yields at critical points. However, proper management to avoid the fertilizer loss by precise and timely application of N-fertilizer is needed.
S. Ashrafi-Saeidlou; A. Samadi; M.H. Rasouli-Sadaghiani; M. Barin; E. Sepehr
Abstract
Introduction: Potassium (K) is abundant in soil, however, only 1 to 2 % of Potassium is available to plants. Depending on soil type, 90 to 98% of soil K is in the structure of various minerals such as feldspar (orthoclase and microcline) and mica (biotite and muscovite). About 1 to 10 % of soil K, in ...
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Introduction: Potassium (K) is abundant in soil, however, only 1 to 2 % of Potassium is available to plants. Depending on soil type, 90 to 98% of soil K is in the structure of various minerals such as feldspar (orthoclase and microcline) and mica (biotite and muscovite). About 1 to 10 % of soil K, in the form of non-exchangeable K, is trapped between the layers of certain types of clay minerals. The concentration of soluble K, which is directly taken up by plants and microbes in the soil and is exposed to leaching, varies from 2 to 5 mg l-1 in agricultural soils. Imbalanced use of chemical fertilizers, a significant increase of crop yield (depletion of soil soluble K), and the removal of K in the soil system result in a large rate of K fixation in the soil. As a result, K deficiency has been reported in most plants. The annual increase in the price of K fertilizers and the destructive effects of them on the environment have made it necessary to find a solution for the use of indigenous K of soil. The use of biofertilizers containing beneficial microorganisms is one of these strategies. Although K solubilizing bacteria can be an alternative and reliable technology for dissolving insoluble forms of K, lack of awareness among farmers, the slow impact of K biofertilizers on yield, less willingness of researchers to develop K biofertilizers technology and deficiencies of technology in respect to carrier suitability and proper formulation, are the major reasons for why potassium solubilizing microorganisms and K biofertilizers draw low attention.
Material and Methods: The purpose of this study was modeling and evaluating the effects of different vermicompost, phlogopite and sulfur ratios on the solubility and release of K by Pseudomonas fluorescens and indicating the optimized levels of these variables for efficient biofertilizer preparation. 20 experiments were carried out using the response surface methodology (RSM) based on the central composite design and the effect of different values of vermicompost, phlogopite and sulfur variables, in the four coded levels (+α, +1, 0, -1 and -α), was evaluated on K dissolution. The applied vermicompost, phlogopite and sulfur in the experiment were ground and filtered through a 140 mesh sieve and their water holding capacity were determined. According to experimental design, different amounts of mentioned materials were combined and samples were sterilized in autoclave. The required amount of water along with 1 ml of bacterial inoculant were added to the samples. The samples were kept in incubator for 2 months. At the end of experiment, amount of soluble K were measured by the flame photometer.
Results: The analysis of variance (ANOVA) depicted the reliable performance of the central composite predictive model of K dissolution (R2= 0.949 and RMSE=0.8). Based on the results, the interaction of vermicompost with sulfur (p < 0.038) and the interaction of phlogopite with sulfur (p < 0.0083) were relatively high and significant. Sensitivity analysis of the central composite design revealed that the vermicompost (X1), phlogopite (X2) and sulfur (X3) had positive and negative impact on potassium dissolution, respectively. Therefore, when sulfur content increased to 91.70%, K dissolution decreased to around 31.61%. According to the prediction under optimized condition, maximum potassium dissolution was obtained at the presence of 41.78, 24.35 and 10.25% of vermicompost, phlogopite and sulfur, respectively.
Conclusion: The results indicated that the applied fertilizer composition (vermicompost + phlogopite + sulfur) had a desirable impact on Pseudomonas fluorescens solubilizing ability on a laboratory scale. Due to the fact that Iran soils are often calcareous, there are high amounts of insoluble and unavailable nutrients. Under these unsuitable conditions, the application of these nutrients chemical fertilizers cannot reduce deficiencies. Therefore, we must use the ability of efficient microorganisms to dissolve and mobilize soil native elements. A combination of 41.78% vermicompost, 24.35% phlogopite and 10.55% sulfur could create a proper potassium biofertilizer by providing favorable conditions for bacterial activity. Along with solubilizing activities of bacteria, the presence of sulfur reduces soil pH and thereby nutrients availability and stability increase in these soils. Because of its acidity, sulfur has a significant effect on nutrients dissolution such as phosphorus, nitrogen and potassium, and micronutrients. On the other hand, the presence of vermicompost in this fertilizer, while meeting the carbon and energy requirements of bacteria and acting as a suitable carrier, improves the physicochemical properties of the soil, increases the biodiversity of the microbial community and, as a result, promotes the soil quality and health. The evaluation of this fertilizer composition efficiency (using optimal amounts of materials) at the greenhouse and field scales is suggested.
M. piri; E. Sepehr; A. samadi; KH. Farhadi; M. Alizadeh khaled abad
Abstract
Introduction: Some of the heavy metals such as cadmium (Cd) and lead (Pb) are toxic and represent hazardous pollutants due to their persistence in the environment. These metals have adverse effects on human health, which include growth retardation, cancer, damage to the nervous and heart system. Heavy ...
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Introduction: Some of the heavy metals such as cadmium (Cd) and lead (Pb) are toxic and represent hazardous pollutants due to their persistence in the environment. These metals have adverse effects on human health, which include growth retardation, cancer, damage to the nervous and heart system. Heavy metals can cause malfunctioning of the cellular processes via the displacement of essential metals from their respective sites. Mainly heavy metals discharge into the environment from industrial and urban sewage. There are different methods to reduce water pollution and the removal of heavy metals from water that one of them is sorption by using organic and inorganic adsorbents such as sepiolite. The low cost of sepiolite along with the high specific surface area, chemical and mechanical stability, and layered structure have made these clay minerals as excellent adsorbent materials for the removal of heavy metals from wastewaters. This study aims to investigate the sorption of Cd and Pb by sepiolite as an inorganic absorbent and optimize process variables (initial concentration, pH and ionic strength) using Response Surface Methodology (RSM) and Box–Behnken design (BBD).
Materials and Methods: Response Surface Methodology (RSM) is a statistical method that uses quantitative data from appropriate experiments to determine regression model equations and operating conditions. RSM is a collection of mathematical and statistical techniques for modeling and analysis of problems in which a response of interest is influenced by several variables. A standard RSM design called Box-Behnken Design (BBD) was applied in this work to study the variables for sorption of Cd and Pb by sepiolite from aqueous solution using a batch process. BBD for three variables (initial Cd and Pb concentrations, pH and ionic strength), each with two levels (the minimum and maximum), was used as an experimental design model. Sepiolite sample used in this study was taken from a mine in Fariman region, northeastern Iran. In the experimental design model, initial concentration (0-200 mg L-1), pH (3-6) and ionic strength (0.01-0.06 mol L-1) were taken as input variables. Design-Expert program was used for regression and graphical analysis of the data obtained. The optimum values of the selected variables were obtained by solving the regression equation and by analyzing the response surface contour plots. The variability independent variables were explained by the multiple coefficients of determination, R2 and the model equation was used to predict the optimum value and subsequently to elucidate the interaction between the factors within the specified range.
Results: The results showed that the sorption of Cd and Pb intensified by increasing initial concentration and pH but ionic strength had an inverse effect. The sorption of Pb and Cd ions onto the sepiolite minerals were lowest at pH =3 and IS=0.06 but increased with an increase in pH and initial concentration of the solution. High value for R2 (0.99) and adjusted R2 (0.99) showed that the removal of Cd and Pb can be described by the response surface method. One-way ANOVA showed (p< 0.0001) that the quadratic model is the best model for determining the interaction variables. According to optimization results, the sorption of Cd and Pb are maximized when pH: 6, concentration: 200 mg.L-1 and ionic strength: 0.02 mol.L-1. The predicted adsorption at these settings for Pb and Cd are 44.4 and 34.28 mg.g-1, respectively. It was found that the initial concentration is the most effective parameter in the sorption of Cd and Pb by sepiolite. Sepiolite adsorbed more lead ions than cadmium ions from aqueous solution.
Conclusion: Response surface methodology using BBD, proved a very effective and time-saving model for studying the influence of process parameters (pH, initial concentration and ionic strength) on response factor (sorb). This model significantly reduces the number of experiments and hence facilitating the optimum conditions. The experimental values and the predicted values are in perfect match with an R2 value of 0.99. The high correlation coefficient between the model and experimental data (R2=0.99) showed that the model was able to predict the removal of Cd and Pb from aqueous solution by using sepiolite. The model revealed that concentration, metal type and pH were the most effective parameters on the response yield (adsorption by sepiolite), respectively. According to the results, sepiolite showed a greater efficiency for sorption of Cd and Pb from aqueous solution, also usage of sepiolite as an inorganic absorbent due to its low cost and abundance can be economically justified.
S. Ashrafi-Saeidlou; A. Samadi; MH. Rasouli-Sadaghiani; M. Barin; E. Sepehr
Abstract
Introduction: Among the elements, potassium (K) is the third important macronutrient for plant nutrition that plays a significant role in plant growth and development. The development of intensively managed agriculture has led to the consumption of increasing amounts of K, low K supply has therefore ...
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Introduction: Among the elements, potassium (K) is the third important macronutrient for plant nutrition that plays a significant role in plant growth and development. The development of intensively managed agriculture has led to the consumption of increasing amounts of K, low K supply has therefore become an important yield-limiting factor in agriculture. However, more than 98% of potassium in the soil exists in the form of silicate minerals such as illite and lattice K in K-feldspars which K cannot be directly absorbed by plants. Potassium and other minerals can be released when these minerals are weathered. Some microorganisms can play a role in releasing K from minerals. They solubilize K-bearing minerals through different mechanisms including chelation, acidolysis, pH reduction, exchange reaction, complexation, biofilm formation and secretion of organic acid and polysaccharides. Since the use of potassium solubilizing microorganisms (KSMs) as K-biofertilizers reduces the agrochemicals application and supports eco-friendly agriculture, so it is imperative to isolate the KSMs and optimize various growth parameters so as to improve their activity.
Materials and Methods: The present study was an attempt to model and evaluate the effects of pH, incubation time and different amounts of carbon source on K release by Pseudomonas fluorescens using Placket-Burman design and response surface methodology with a central composite design. At the first step, 12 experiments based on Placket-Burman design were carried out to screen and identify the effective carbon source in potassium release. According to the results of the first step, response surface methodology with the central composite design was employed to evaluate and model the effects of the coded independent variables including pH (3-10), incubation time (1-18 days) and carbon source (0.6-12 g L-1) on K release from feldspar and phlogopite. After the completion of each period, samples were centrifuged at 3000 rpm for 10 minutes and filtered using Whatman paper (No. 41). Potassium concentration of samples was measured by flame photometer. Used minerals in the experiment including feldspar and phlogopite were grounded and filtered through a 230 mesh sieve. In order to remove exchangeable K, the samples were saturated by calcium chloride solution (with a ratio of 2:1), after washing with HCl, samples were then dried at 105oC for 48 hours.
Results: Results showed that there was no difference between carbon sources, applied at the first step of the experiment, so each can be employed as alternatives to each other in the culture medium. The central composite design showed R2 of 0.944 and 0.918 with RMSE of 0.82 and 1.47 for predicting K release of feldspar and phlogopite, respectively, indicating high efficiency. Sensitivity analysis of the central composite design revealed that the pH is the most important factor in K release. The highest concentration of the K was observed at the highest levels of pH. Incubation time also had an impact on potassium release. In the early stages of the incubation time, the trend of potassium release was increasing, in middle stages, K amount decreased but it was accelerated over long times of incubation. The maximum potassium release in presence of phlogopite and feldspar was 121.16 and 96/82 mg L-1, respectively, which was observed at pH= 10.36, sucrose amount= 6.5 g L-1 during 10 days. Potassium amount in this treatment hence increased by 31.52% as compared to feldspar. According to central composite design, maximum potassium release of feldspar and phlogopite was obtained at pH= 10.36 and 10.34, sucrose concentrations of 2.26 and 6.92 g L1 at 18 and 2 days, respectively.
Conclusion: Our results showed that pH had a significant impact on K release by Pseudomonas fluorescens using response surface methodology. Overall, increasing incubation time along with high pH leads to the high amounts of K release from minerals. Different minerals released different content of potassium. Application of soil K-bearing minerals in combination with efficient potassium solubilizing bacterial strains as biofertilizers is required to replace chemical fertilizers and reduce the crop cultivation cost. Many bacterial strains have been found to solubilize minerals and improve plant growth under laboratory and greenhouse conditions, but their ability under field conditions remains unexplored. The capability of these bacteria, considering the soil and plant type, and environmental factors, should be thus evaluated under field conditions.
R. Ranjbar; Ebrahim Sepehr; Abbas Samadi; MirHasan Rasouli Sadaghiani; Mohsen Barin; behnam Dovlati
Abstract
Introduction: Potassium (K) is one of the major essential macronutrients for plant growth. Soil has rich reserves of K, among which only 1–2% can be directly absorbed by plants. It may be more economically viable to transform the fixed slow-release K into available K that can be absorbed by plants. ...
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Introduction: Potassium (K) is one of the major essential macronutrients for plant growth. Soil has rich reserves of K, among which only 1–2% can be directly absorbed by plants. It may be more economically viable to transform the fixed slow-release K into available K that can be absorbed by plants. The ability of some microorganisms to dissolve soil K-bearing minerals, such as micas is an important feature for increasing the yield of high-K-demand crops such as tobacco. Also, these microorganisms have both economic and environmental advantage. A large number of saprophytic bacteria such as Bacillus mucilaginosus and fungal strains such as Aspergillus spp. are known for their potential in releasing insoluble native K-source in soil into a plant available nutrient pool. Tobacco (Nicotiana spp.) is one of the most important industrial crops. K plays a vital role in increasing the tobacco yield and controlling quality parameters such as leaf combustibility that is one of the key criteria taken into account by the tobacco industry for assessing quality. Thus, high ranges of K fertilizers are applied in tobacco fields based on plant K requirement to build up soil K in tobacco producing countries. Increasing cost of the fertilizers and environmental risks necessitates alternate means to fertilizers such as application of microorganisms. The use of chemical K fertilizers can be reduced by exploiting the potential of bio-inoculants which are inexpensive and eco-friendly. Information related to K-solubilizing microorganisms in tobacco rhizosphere and their suitability in increasing the available K in tobacco-cultivated soils is not well-documented. Hence, the present study was conducted to screen the KSB isolates from tobacco-cultivated soils and evaluate their potential in dissolving K bearing silicate minerals and increasing soil available potassium.
Materials and Methods: Soil samples were randomly collected from the rhizosphere of tobacco from 25 different locations in northwest of Iran. The serial dilutions of the soil samples were made up to 10-4 and 5 µl of diluted soil suspension plated on Aleksandrov medium plates (on the agar-based culture medium). Aleksandrov medium contained 5.0 g Glucose, 0.5 g MgSO4.7H2O, 0.1g CaCO3, 0.006 g FeCl3, 2.0 g Ca3PO4, 2.0 g insoluble mica powder as potassium source and 20.0 g agar in 1 liter of deionized water. The plates were incubated at 28±2°C in incubator for 10 days. Finally, nine isolates of potassium silicate solubilizing bacteria were isolated and purified. Solid and liquid Aleksandrov media were applied for qualitative (Solubility Index = Diameter of zone of clearance/ Diameter of growth) and quantitative (K content) evaluation, respectively, based on the completely randomized design (CRD) with three replication. Liquid Aleksandrov medium containing 2 g L-1 of mica and feldspar mixture, was inoculated with bacterial isolates. Bacterial isolates creating high solubility index and releasing more K from K-bearing minerals into liquid medium, were selected as effective isolates. In order to evaluate the efficiency of the potent bacterial isolates for increasing soil available K, an experiment was conducted with three replication and eight potent bacterial isolates along with a control (non-inoculated soil). Sterilized soil samples were inoculated with bacterial isolates separately and incubated at 25°C, with 75% field capacity moisture levels for 90 days. After incubation, available K in soil samples were extracted with Ammonium Acetate 1M. Variance of solubility index, K concentration into liquid Aleksandrov medium and soil available K were analyzed using SPSS (Statistical Package for the Social Sciences). Student-Newman-Keuls (SNK) test comparisons were also used to compare available soil K using SPSS 16.0.
Results and Discussion: Eight KSBs isolates, including KSB20, KSB30, KSB40, KSB22, KSB42, KSB90, KSB92 and KSB10, were isolated and purified as effective isolates for dissolving mica and feldspar minerals. Most isolates were gram-positive, rod-shaped, and white in appearance. The studied isolates, except KSB22, KSB40 and KSB20, had α-amylase enzyme activity. Bacterial isolates, including KSB20, KSB30, KSB42 and KSB10, were significantly superior in sucrose and glucose hydrolysis. The isolate of KSB10 also had fluorescence properties. The highest solubility index (2.8, 2.7 and 2.5) was obtained from the activity of KSB22, KSB42 and KSB10 isolates in solid Aleksandrov medium, respectively. The highest concentration of potassium into liquid Aleksandrov medium was found for the KSB42 and KSB10 isolates (9.40 mg L-1). The KSB42 and KSB10 isolates increased medium K concentration approximately three times more than non-inoculated medium. In addition, KSB42 and KSB10 isolates were more effective in releasing potassium from soil potassium-bearing minerals. The amount of available potassium in soil incubated with KSB42 and KSB10 isolates increased by 44 and 46 mg kg-1 compared to the control, respectively.
Conclusion: Among bacterial isolates purified from the tobacco rhizosphere, the KSB42 and KSB10 isolates increased more significantly the solubility of potassium minerals and potassium availability in soil compared to other isolates. These bacteria isolates increased potassium concentration into Aleksandrov liquid medium by more than three times and also increased soil available potassium by about 44 to 46 mg kg-1 compared with the control. As a result, these isolates (KSB42 and KSB10) can be used as a bio-fertilizer to reduce potassium fertilizer application and increase the quality of tobacco after field experiments.
N. Moradi; M.H. Rasouli-Sadaghiani; E. Sepehr
Abstract
Introduction: Biochar is a material produced from organic matters under high temperature and low oxygen conditions. In recent years, scientific attention has been focused on its effects on soil amendment and ecological restoration.Due to its properties related to surface area and porosity, bulk density, ...
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Introduction: Biochar is a material produced from organic matters under high temperature and low oxygen conditions. In recent years, scientific attention has been focused on its effects on soil amendment and ecological restoration.Due to its properties related to surface area and porosity, bulk density, nutrient content, stability, cation exchange capacity (CEC), pH value, and carbon content, biochar has the potential to improve physical and chemical soil properties and thus improve crop productivity and contribute to carbon sequestration. Biochars can have very different properties depending on the feedstock they are produced from and the pyrolysis conditions used to generate them.Biochar retains nutrients for plant uptake and soil fertility. The infiltration of harmful quantities of nutrients and pesticides into ground water and the runoff that erodes the soil and enters into the surface waters can be limited with the use ofbiochar. The actual effects of biochar on soil properties depend on the soil type and the plant species grown on the area of application, as well as biochar type and application rate.The aim of this study was to evaluate the effect of the biochar types and rates on some soil properties and nutrient availability in a calcareous soil.
Materials and Methods: An incubation experiment was conducted in a completely randomized design with three replications. The treatments were three type of biochar (apple pruning wastes, grape pruning wastes and wheat straw), and five biochar rates (0, 1, 2, 4 and 8% w/w). Biochars used in the experiment wereproduced at the final temperature of approximately 350°C for almost 3 hours. The biochars were ground and sieved over 1 mm sieve for the incubation experiment.100 g of soil sample was weighed into polyethylene pots and then thoroughly mixed with 1, 2, 4 and 8 g of the biochar samples. Soil controls were run without any amendment. Distilled water was added to the soil–biochar mixtures (soil samples) in order to keeptheir moisture content to 60% of their water-holding capacity. The incubation was carried out in a controlled incubation chamber at 25oC for incubation in aerobically controlled non-leached conditions during 8 weeks.After 60 days, the samples were dried andsoil pH and electrical conductivity (EC) were determined in 1:5 soil to water extracts. Also, to determine mineral N, the soil samples with biochar were extracted with 2 M KCl. Organic matter was determined by dichromate oxidation. Soil extractable P and K were extracted with 0.5 M NaHCO3 (ratio 1:10) (Olsen-P) and 1 N NH4Ac (1:20) (NH4Ac-EK), respectively. DTPA-extractable Fe, Mn, Cu, and Zn were analyzed by atomic absorption spectrometry method (Shimadzu AA-6300).
Results and Discussion: The results indicated that adding biochar changed some soil properties such as soil organic carbon, pH, electrical conductivity and the availability of some macro and micro nutrients. These changes were also more evident with increasingin the rate of biochar. Soil organic carbon (SOC) contentsin the amount of 8% apple pruning wastes, grape pruning wastes and wheat straw biochar were 3.78, 3.80 and 5.24 times more than control, respectively. Available potassium and phosphorus increased further in derived biochar from wheat straw in the amount of 8% compared with apple pruning and grape pruning wastes. Soil available potassium in wheat straw biochar was 2.19 and 1.88 times higher than apple pruning and grape pruning wastesbiochars, respectively. Wheat straw biochar greatly increased soil EC compared to control, and a higher biochar addition finally resulted in a higher value of soil EC. Also, the mineral – N, comprising of ammonium nitrogen (NH4-N) and nitrate nitrogen (NO3-N), concentrationshowed significant reduction when different rates of biochar were added to the soil. Increase in the rate of applicationmarkedly reduced the concentration of both NH4-N and NO3-N. Wheat straw biochar significantly reduced available iron. Also, soil available copper significantly decreased by increasing the rate of biochar. But, soil available manganesesignificantly increased by increasing the rate of biochar. The type and rate of studied biochars had no significant effect on available Zn.
Conclusions: Generally, the soil organic carbon (SOC) markedly increased with an increase in rate of application ofbiochar during the 60 days of incubation. This suggests that the biochar has great potential for carbon sequestration in soil.In conclusion, it became clear that in order to allow for accurate prediction of the effects ofbiochar on soil characteristics and nutrient availability, a deeper understanding of interactions between soil type, biochar production method, biochar feedstock, application rate and field crops is essential. Further research is needed to determine long term impacts of biochar on these soils.
H. Arfania; Abbas Samadi; F. Asadzadeh; E. Sepehr
Abstract
Introduction: Phosphorus (P) is an essential nutrient for all life forms. In aquatic environments, P is a double-edged sword. In some areas, habitat biodiversity is strongly limited by low P bioavailability, while in others, P inputs in excess of plant needs have led to pollution of water bodies and ...
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Introduction: Phosphorus (P) is an essential nutrient for all life forms. In aquatic environments, P is a double-edged sword. In some areas, habitat biodiversity is strongly limited by low P bioavailability, while in others, P inputs in excess of plant needs have led to pollution of water bodies and eutrophication. There is little information available on P status in river sediments by single chemical extraction and its correlation with algae growth in Iran. This study was performed to select proper single chemical extraction methods by algal bioassay. The quantity of P estimated by different extractions methods depends on sediment characteristics such as calcium carbonate, pH, clay and organic matter contents. Therefore, this study was conducted in western rivers of the Lake Urmia to get an insight into P status in sediments by using single chemical and biological P assay.
Materials and Methods: The lakeUrmia basin has the second largest water resources in Iran with Mediterranean climate. Italso has the largest hypersaline lake in the world. There is a significant phytoplankton growth and also some dense algal blooms occurring during years with low salinity in wetlands and lagoons. Thirty four river sediment samples from seven main rivers of the Lake Urmia basin were collected from depth of 0-10 cm to evaluate algae (SenedesmusObliquus) P bioavalability by single chemical extraction. Selection of extractantis based on different mechanism of extraction. Cluster analysis was conducted on 17 sediment samples selected for algal bioassay.Pearson simple correlation and multivariate analysis were also performed.
Results and Discussion:Average total P concentrations of the sediments were343-654, 456 mg kg-1. Sodium bicarbonate 0.5 Mextractable P (Olsen-P) varied from 0.48 to 8.42 mg kg-1. Sediments from upper reach had considerably higher total and bioavailable P concentration in comparison with lower reach sediment. The low reach sediments of two rivers had higher Olsen extractable P than the threshold value of 20 mg kg-1indicating possible release which poses a threat to aquatic environment.Upper reach sediments had higher restoration potential, but algal bloom was observed in low reach part of rivers, particularly Simineh and Mahabad Chai. Land use changes, discharge of sewage from rural and urban section, industrial activity and cycling of river borne P are the main reasons for algal bloom in wetlands and lagoons around the lake.Principal component analysis (PCA) performed on the data identified three PC which explained 83.3% of total variation and silt and sand had higher loading values. Active calcium carbonate equivalent (ACCE) was negatively correlated with sand in the first PC. Different extractions were positively correlated with each other. The Mehlich III and Olsen-P extraction methods were significantly correlated and the predicted values were same. The average rank order of P extraction by singleextractantswas Cowell >Mehlich III >NaOH 0.1 M > Olsen > Morgan > AB-DTPA > Bray II.Extractants had different long-term and short-term potential to extract algal available P. The Cowell extractable P concentrations of sediments varied from 1.44 to 88.0 mg kg-1.This extractant was correlated significantly with algal growth and selected as the best P single extraction method among allextractants. The high correlation between 0.1 M NaOH and algae growth indicates the sensitivity of P bioavailability to redox conditions in river system. Algae (SenedesmusObliquus) was able to use P from different sediment components because its growth was correlated with Cowell, Mehlich III, NaOH 0.1M, Olsen and Morgan.
Conclusion: Legacy P (sediment P) evaluation by chemical extractants gives new insight into P bioavailability in river sediments of the Urmia Lake. The results of this work showed that Cowell extractant could be used to estimate algal available P in studied river sediments. Similarity between Olsen-P and Mehlich-P in estimating bioavailable P suggests that Mehlich III-P can be substituted for Olsen-P in studied sediments.For sustainable P management, monitoring P status by single chemical extraction methods is necessary. Phosphorous fertilizer application around the Lake Urmia basin lands should be conducted based onthe P soil test to avoid any aquatic pollution. Care must be taken in lower reach river sediments because of fragile ecosystems such as wetlands and lagoons. Further investigations are also needed to evaluate legacy P bioavailability by temporal and spatial variability.
sanaz ashrafi saeidlou; Mirhasan Rasouli-Sadaghiani; Abbas Samadi; mohsen barin; ebrahim sepehr
Abstract
Introduction: Potassium is one of essential nutrients for plants and its importance in agriculture is well known. Non-exchangeable potassium that is mainly placed with in layers of K-bearing minerals, such as K-feldspar and mica, is considered as an important source of potassium for plant growth in most ...
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Introduction: Potassium is one of essential nutrients for plants and its importance in agriculture is well known. Non-exchangeable potassium that is mainly placed with in layers of K-bearing minerals, such as K-feldspar and mica, is considered as an important source of potassium for plant growth in most soils. Regarding that low molecular weight acids (LMW) play an important role in improving the bioavailability of soil nutrients such as non-exchangeable K (NEK), and the release rate of NEK plays a significant role in supplying necessary K for plants, the purpose of this study was comparison of potassium release kinetic from K-bearing including feldspar, illite as well as phlogopite minerals and choose the best kinetic equation describing potassium release process, influenced by organic as well as mineral extractants.
Material and Methods: The experiment carried out in a completely randomized design with three replications. Experiment factors were including extractant type (0.01 mol l-1 oxalic acid, 0.01 mol l-1 calcium chloride, control (deionized water)), potassium mineral type (feldspar, illite and phlogopite) and incubation time (1, 2, 4, 8, 12, 16, 24, 32, 48, and 64 hours). Elemental composition of minerals identified by Fluorescence spectroscopy device (S4 Pioneer). Used minerals in the experiment including feldspar, phlogopite and illite were ground and filtered through a 230 mesh sieve. In order to remove exchangeable K, samples were saturated by calcium chloride solution (with a ratio of 2:1), after washing with HCl, samples were dried at 105 °C for 48 hours. 100 mg of washed minerals, was weighed carefully and transferred to centrifuge tubes. Then 20 ml of each of extractants (oxalic acid and calcium chloride 0.01M) was added to the tubes. After 15 minutes shaking, tubes containing a mixture of minerals-extractants was carried out in a controlled incubation chamber for periods of 1, 2, 4, 8, 12, 16, 24, 32, 48 and 64 hours at 25 °C. After each period, samples were centrifuged at 3000 rpm for 10 minutes and filtered using Whatman paper (No. 41). pH and potassium concentration of samples were measured by pH meter and flame photometer, respectively. Data related to potassium release was fitted by zero order, first order, second order, power function, parabolic diffusion and ellovich equations.
Results and Discussion: Results showed that the effect of extractant type was significant on kinetic of potassium release, so that potassium release amount in samples extracted with oxalic acid was 1.48 and 2.35 times higher than samples extracted with calcium chloride and control (deionized water), respectively. Also, different minerals released various amounts of potassium. K release from phlogopite was 1.99 and 2.95 times higher than feldspar and illite, respectively. The maximum potassium concentration (440 mg kg-1) was seen in phlogopite which was extracted with oxalic acid. So that, amount of potassium in this treatment was 3.15 times higher than control one. Furthermore, the effect of extraction time on K release was significant. So that, at the beginning of incubation period the release of potassium by different extractants was more, but its amount decreased over time and finally continued with a constant speed. Kinetic equation fitting showed that zero order, first order, power function, parabolic diffusion and ellovich equations are able to describe potassium release but second order model cannot justify it. Among these five equation, the power function and parabolic diffusion equations with the maximum coefficient of determination (R2) and the least standard error of estimate (SE), could reasonably describe the K release kinetics, so they are introduced as the best models for data fitting. The slope (b) and interception (a) of ellovich equation indicate interlayer and initial K release, respectively. Oxalic acid and phlogopite had the most amount of interception, it means that the impact of oxalic acid on initial and interlayer release rate of K in phlogopite, is more effective than calcium chloride.
Conclusions: It is concluded that different factors like mineral and extractant type influence kinetic of potassium release and organic extractant have more ability in extracting non-exchangeable potassium from minerals structure. Also, the adjustment of the results of this study with first order, parabolic diffusion and power function equations suggest that nonexchangeable potassium release from minerals can be affected by diffusion process from the surface of the study minerals, indicating that NEK release rate is controlled by K diffusion out of the mineral interlayer.
M. Jiriaie; E. Fateh; A. Aynehband; E. Sepehr
Abstract
Introduction: Providing the nutritional requirements of agricultural crops by non-chemical resources is a new approach in the organic farming that has attracted the attention of both the researchers and the consumers in recent years. Therefore, it is highly important to find new fertilizer resources ...
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Introduction: Providing the nutritional requirements of agricultural crops by non-chemical resources is a new approach in the organic farming that has attracted the attention of both the researchers and the consumers in recent years. Therefore, it is highly important to find new fertilizer resources that are both economically able to provide the nutritional needs of the crop plants and have no adverse effects on the consumers and the environment.
Materials and Methods: With this approach, an experiment was conducted in the research station of Shahid Chamran University of Ahvaz, Iran in 2012-13. The experimental design was factorial based on randomized complete blocks design with three replications. The treatments including Mycorrhizal fungi in three levels (i.e. no use of strain; use of Glomus intraradices strain; and use of Glomus mosseae strain), bacteria Azospirillum lipoferum in two-levels (i.e. non-inoculated and inoculated) and wheat cultivars in three levels (i.e. Chamran; Dena; and Behrang). The measured parameters include the concentration of macronutrients (i.e. nitrogen, phosphorus and potassium) and some micronutrients (i.e. zinc, iron and manganese) in two part seed and the root of wheat.
Results and Discussion: Surveying the elements content in the root and the grain indicated a significant and positive effect of the use the Azospirillum and Mycorrhiza to improve the concentration of the elements in wheat cultivars. However, the simultaneous use of these microorganisms led to an increase of the effects of their application on their assessed traits.Finally the highest concentration of N (2.21 present), P (0.50 present) and Fe (33.88 mg.kg-1) were observed in the grain; the highest concentration of K (0.93 present and 0.54 present) and Mn (43.11 and 23.63 mg.kg-1) were observed in the grain and root, respectively. Moreover, the highest concentration of Zn in the root (19.70 mg.kg-1) was obtained from inoculation of C.V Dena seeds with Azospirillum and the use of G. mosseae. Also, in the general case of Mycorrhiza fungi use (between 6 to 20 present) and seed inoculation with Azospirillum lipoferum (between 8 to 25 present), the improved nutrient content in the seeds as well as greatest impact of Mycorrhiza use is in increasing the content of the grain Zn (20 present) and the lowest effect of Mycorrhiza using is in increasing the nitrogen content in seed (6 percent). Considering the elements content in the grain, the use of bacteria also showed that the greatest impact on increasing the use of bacteria Azospirillum lipoferum is in increasing the iron content in seeds (25 present) and the least impact of the use of Azospirillum lipoferum is in increasing the seed’s manganese (8 present). Moreover, the use of Mycorrhiza fungi (between 7 and 23 present) and seed inoculation with Azospirillum lipoferum (4 to 16 present) improved the contents of nutrients in wheat roots compared with the control group. Here, too, the greatest impact for Mycorrhiza application was in increasing the content of the Zn in the root (23 present) and the lowest effect of Mycorrhiza application was in increasing the potassium content in the root (7 percent). Moreover, considering the elements content in the roots in the case of being treated with Azospirillum lipoferum, the results showed that upon increasing the use of bacteria, the greatest impact of Azospirillum lipoferum in increasing elements content in the roots was an increased iron content in the root (16 present) and the minimum effect of the bactericidal application was in increasing the potassium root (4 present). Comparing the two species of Mycorrhizal fungi that have been used in the experiment, although application Glomus intraradices showed satisfactory results, the use of the species Glomus mosseae to increase the content of the element in seeds and roots has had a greater role. Moreover, the combined effects of these microorganisms have not only had an antagonistic effect of reducing the amount of content, they have also been more effective than being applied separately (between 7 and 12 present).
Conclusion: Generally associated with most of the measured elements, the treatment of seed inoculation with Azospirillum lipoferum and usage of Glomus mosseae in Dena cultivar that was a durum wheat, showed the highest concentration of the mentioned elements in the roots and seeds. Probably this has been due to the smaller grains in Dena than the other cultivars, which led to an increase in the ratio of the elements in the grain. Therefore, it seems that the use of the biofertilizers can be the perfect solution to eliminate the nutritional requirements of wheat. Moreover, it has the very important effect of the enrichment of this crucial product in the people’s dietary patterns in this country with the required elements.
Keywords: Azospirillum, Nutrition, Wheat, Root, Elements concentration, Mycorrhiza
R. Mosavi; E. Sepehr; A. Samadi; Mirhasan Rasouli-Sadaghiani; B. Sadeghzade
Abstract
Introduction: Phosphorus (P) is regarded as the most important soil nutrient after nitrogen (N) for plant growth and development as it plays key roles in plant metabolism, structure and energy transformation. Also, although soil P is often abundant in both organic and inorganic forms, it is frequently ...
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Introduction: Phosphorus (P) is regarded as the most important soil nutrient after nitrogen (N) for plant growth and development as it plays key roles in plant metabolism, structure and energy transformation. Also, although soil P is often abundant in both organic and inorganic forms, it is frequently a major or even the prime limiting factor for plant growth. Low phosphorus (P) availability is a major global global constraint to crop production. In most soils, soil and fertilizer P are easily bound by either soil organic matter or chemicals, and thus are unavailable to plants unless hydrolyzed to release inorganic phosphate. Phosphorus efficient plants play a major role in increasing crop yields due to shortage of inorganic P fertilizer resources, limited land and water resources, and increasing environmental concerns. Therefore, the development of P-efficient crop varieties that can grow and yield better with low P supply is a key for improving crop production. Enhancing P efficiency in plants can be achieved through enhancing P acquisition, utilization, or both.
Materials and Methods: In order to investigate the effect of microbial inoculation on phosphorus efficiency of different genotypes of barley, a glasshouse factorial experiment was conducted in a completely randomized block design with 10 barley genotypes and different phosphorus (P) treatments including control (P0), phosphate rock (RP), RP inoculated with phosphate solubilizing fungi (RP+F), RP inoculated with phosphate solubilizing bacteria (RP+B), RP inoculated with both fungi and bacteria inoculums (RP+B+F), and soluble phosphate (PS) in three replications. After sieving (2 mm sieve), and, air - drying of soil samples, basal nutrients mixed thoroughly at the following soil test results. Then, soils placed in plastic pots (3 kg). The P treatments as (KH2PO4 and Rock Phosphate) 80 mg kg-1 soil added at the depth of 5-cm of soil. After 9 weeks the plants were harvested, grain dry weight (GDW) and grain P concentration measured and then content P (TP), P efficiency (PE), P acquisition efficiency (PACE) and P utilization efficiency (PUTE) were calculated.
Results and Discussion: The results indicated that microbial inoculation had significant effect (P
R. Zebardast; E. Sepehr
Abstract
In order to investigate the effect of humic acid (HS) on P adsorption behavior, an experiment carried out with three levels of HS (0, 100, 200 mg/L) and various P concentration (0 to 30 mg/L) at two ionic strengths (IS) of 0.1 and 0.01 M. Adsorption data were fitted to Langmuir, Freundlich and Temkin ...
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In order to investigate the effect of humic acid (HS) on P adsorption behavior, an experiment carried out with three levels of HS (0, 100, 200 mg/L) and various P concentration (0 to 30 mg/L) at two ionic strengths (IS) of 0.1 and 0.01 M. Adsorption data were fitted to Langmuir, Freundlich and Temkin equations, and Langmuir was better fitted than others (R2=0.91 to 0.98). Results indicated that HS application significantly lowered the adsorption isotherm curves and Langmuir maximum mono layer adsorption (qmax) decreased up to %50 in comparison to control. Also sorption parameters including Langmuir bonding energy parameter (KL), Freundlich capacity and intensity factors (KF, n), and Temkin retention parameter (KT) decreased significantly by adding HS. Maximum buffering capacity (MBC), equilibrium buffering capacity (EBC) and standard buffering capacity (SBC) decreased more than %50 in HS200. Application of HS increased equilibrium phosphorus concentration (EPC) in both ionic strength, as EPC increased from 0.28 to 0.40 mg/L (IS=0.01 M) and 0.21 to 0.39 mg/L (IS=0.1 M). Finally, it was concluded that HS reduced P sorption due to competition on sorption sites and resulted in increasing P availability to plants.
E. Iranshahr; E. Sepehr
Abstract
A factorial completely randomized design experiment with three replications was carried out in greenhouse to evaluate the phosphorus (P) acquisition and utilization efficiency of 20 wheat genotypes in a river sand fertilized with rock phosphate (RP) and soluble P (PS). Results showed significant differences ...
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A factorial completely randomized design experiment with three replications was carried out in greenhouse to evaluate the phosphorus (P) acquisition and utilization efficiency of 20 wheat genotypes in a river sand fertilized with rock phosphate (RP) and soluble P (PS). Results showed significant differences in shoot dry weight (SDW), shoot P concentration, shoot P content, P acquisition (PACE), P utilization (PUTE) and P efficiency. Marvdasht and Hamun with 8.3 and 5.6 g dry weight showed the highest and lowest response to soluble P fertilizer application, respectively. The average of PACE for all genotypes was 0.04 which Azadi and Karaj1 were the most and least efficient in P acquisition compared to other genotypes. PUTE ranged from 0.6 (Azadi) to 1.12 (Moghan 1) with the average of 0.82 (RP) and 0.31 g DW mg-1 P (PS). Among wheat genotypes, Karaj 1 (4.5%) and Azadi (14.5%) showed the lowest and highest P efficiency, respectively. There was no correlation (R2=0.18) between P efficiency and shoot P concentration of genotypes, but the relationship between P efficiency and shoot P content was highly significant (R2=0.77).
M. Rasouli-Sadaghiani; E. Sepehr
Abstract
Abstract
Biological and chemical changes in rhizosphere following organic residues as well as manures application are important processes which influence nitrogen mineralization and nutrients bioavailibity in soils. This study was done to evaluation of organic residues effect on growth, nitrogen supply ...
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Abstract
Biological and chemical changes in rhizosphere following organic residues as well as manures application are important processes which influence nitrogen mineralization and nutrients bioavailibity in soils. This study was done to evaluation of organic residues effect on growth, nitrogen supply and rhizosphere characteristics of corn and sunflower plants in greenhouse experiment using sewage sludge (SS), poultry (Pl), cattle (Ct) and sheep (Sh) manures. The results showed plants acquired significantly more N, P, K, Ca, Mg, Fe, Mn, Zn and Cu in SS treatment than other manures. Sunflower in comparison with corn plants showed higher N, P, K, Ca and Cu uptake, which can be attributed to its higher nutrient-uptake efficiency. The highest mineralized nitrogen in rhizosphere and non-rhizosphere soil were achieved in Pl (214.8 mg kg-1) and SS (227.5 mg kg-1), respectively. Mineralized N in particular nitrate was observed at high concentration in rhizosphere compared to non-rhizosphere soil, which indicate higher microbial activity including nitrificators and high mineralization processes in sunflower rhizosphere. Net nitrogen mineralization (Nm) in rhizosphere was higher than that in non-rhizosphere which the microbial population in corn and sunflower rhizosphere were 3.7 and 2.3 times higher than non-rhizosphere soil, respectively . Treatments applied with SS showed the highest microbial activity compared to other organic residues. At rhizosphere, net nitrogen mineralization was occurred in Pl and SS treatments whereas Ct and Sh applied soil showed nitrogen net immobilization. Except for SS, all applied residues showed net immobilization in non-rhizosphere soil. The highest total mineralized N (mineralized N exist in soil and absorbed N by plants) were as fallows in treatments: Pl> SS> Sh> Ct.
Keywords: Sewage sludge, Manures, Nitrogen mineralization, Rhizosphere
