najmeh salari ardsiri; Majid Hejazi-Mehrizi; hormazd naghavi; rabi Behrooz; Majid Fekri
Abstract
Introduction providing the food needed by the world's ever growing population has led to changes in cultivated areas, water resources, and the overuse of chemical fertilizers and consequent environmental pollution. Providing essential nutrients to the plant is one of the most important factors related ...
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Introduction providing the food needed by the world's ever growing population has led to changes in cultivated areas, water resources, and the overuse of chemical fertilizers and consequent environmental pollution. Providing essential nutrients to the plant is one of the most important factors related to the optimum production of agricultural crops. In recent years, most of essential nutrients are provided through the natural fertility of the soil and chemical fertilizers. Today, one of the most important ways to increase soil fertility is the use of fertilizers. Consistent and excessive use of fertilizers such as nitrogen and phosphorus (in the form of ammonium salts, urea, nitrate or phosphate compounds) in recent years has caused problems in the agriculture and environment. In recent years, the efficiency of application of nitrogen, phosphate and potash fertilizers has been about 30-35, 18-20 and 35-40-40, respectively. This indicates that a large part of the fertilizer used remains in the soil or enters the aquatic ecosystems and negatively affects the natural balance and biodiversity of agricultural lands. Accordingly, to overcome these problems, it is necessary to use solutions such as better water and fertilizer management, change in the structure of fertilizers and the use of new technologies. One of the effective methods to overcome the problems of low efficiency of chemical fertilizers is to develop the controlled release fertilizers. Slow-release fertilizers can be a good way to overcome the problems expressed by common chemical fertilizers. Release control fertilizers are usually prepared using the coating method and reducing the solubility of water-soluble fertilizers by creating a physical barrier. The biggest problem with slow release fertilizers is their high production cost. Therefore, it is necessary that the fertilizers covering chemical fertilizers be economical and compatible with the environment and have desirable coating properties. Nanocomposites are among the polymer coatings that have received much attention in recent research. Among the many materials used to form nanocomposites, polysaccharides such as cellulose, starch for economic reasons, biocompatibility, non-toxic and biodegradable are widely used compared to synthetic polymers. Despite many studies in the field of fertilizer production, the use of slow release fertilizers as a source of required nutrients and also the use of hydrophilic and hydrophobic polymers such as pure cellulose compounds with conventional fertilizers have not been studied. The need for this research is to use cellulose from agricultural waste in slow release of chemical fertilizers in order to increase the efficiency of fertilizers, prevent its overuse in agriculture, and also waste agricultural waste around orchards. In this study, cellulose compounds were extracted from paper, palm and pistachio branch and these cellulose compounds were then used to slow the release of urea fertilizers.Materials and Methods First, the sufficient amounts of pruned wastes from branch of palm, pistachio, and paper waste, were collected from agricultural regions in Kerman Province; then they were transferred to the laboratory of Kerman Agricultural Research Center. After washing and drying, the samples were ground. In the next step, 10 g of each of the air-dried cellulosic sources was passed through a 60-mesh sieve in an Erlenmeyer flask with 200 ml of 1% NaOH solution for 1 h. Then, it was entirely washed with distilled water and the resulting contents in the Erlenmeyer flask were re-boiled along with a mixture containing 300 ml of 80% acetic acid plus 30 ml of 67% nitric acid for 30 min at 120°C. At the end of the reaction time and partial cooling of the mixture, the cold distilled water was added to the reaction mixture and the resulting cellulose pastes were then washed thoroughly with distilled water until reaching the neutral pH. At the end, the samples were air-dried. Finally, the cellulose samples were washed with distilled water and air dried. In the second stage, slow release of urea fertilizer with cellulose from palm wastes in a ratio of 1 to 2 (fertilizer to cellulose) was made and they were made in the form of small tablets. Nitrogen release kinetics from these fertilizers in soil up to 90 days were measured and kinetic equations were also investigated.Results and Discussion After cellulose extraction of wastes, FTIR device was used to identify the extracted celluloses and compare them with Sigma Aldrich pure cellulose. The peaks obtained from the FTIR apparatus were similar to the pure cellulose peaks. The yield of extracted cellulose in the form of paper waste was 70%> palm branch 33%> branch of pistachio 28%. In the second stage, the extracted cellulose was used to cover urea fertilizer in a ratio of 1 to 2 (urea fertilizer to cellulose) and the desired fertilizer was made in the form of small tablets with diameter of 0.5 cm and height of 2 cm. The SEM scanning electron microscope was used to study the structure of the manure. Microscopic images showed that the urea fertilizer placed as white spherical particles around the cellulose rod particles, indicating that the urea fertilizer particles adhered to the cellulose particles without any adhesive. The FTIR diagram of the fertilizer showed that the shift of the diagram upwards at the common wavelengths in urea and pure cellulose and a strong physical bond is established between them. Nitrogen release kinetics for all treatments that were less than pure urea fertilizer and significant differences observed between treatments and pistachio branch cellulose caused a slower release of urea fertilizer. The kinetic equation of the power function was selected as the best model for fitting the kinetic data. The studied wastes in this study have a high potential for producing pure cellulose to slow the release of urea fertilizer.
M. Hejazi-Mehrizi; A. Saadatfar
Abstract
Introduction Salinity is one of the common stresses in agricultural lands of arid and semi-arid regions in Iran. Furthermore, excessive CaCO3, high pH, nutritional disorders have been known as limited factors for plant growth and productivity in such soils. The cultivation of salt tolerant plants such ...
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Introduction Salinity is one of the common stresses in agricultural lands of arid and semi-arid regions in Iran. Furthermore, excessive CaCO3, high pH, nutritional disorders have been known as limited factors for plant growth and productivity in such soils. The cultivation of salt tolerant plants such as rosemary (Rosmarinus officinalis L.) is important from the point of view land reclamation. Rosemary is a woody plant, evergreen, perennial herb belonging to Lamiaceae family. It is native to Mediterranean but it can tolerate undesirable conditions such as drought and salinity stresses. Zinc (Zn) and copper (Cu) are essential micro-nutrients that play important roles in plant metabolic processes and can increase plant tolerance to salinity. Zn is vital for protein synthesis, protein stability, and different enzyme activities such as Zn/Cu superoxide dismutase and carbonic anhydrase. On the other hand, chlorophyll production, photosynthesis and enzyme activities are the most important role of Cu in plants. Superoxide dismutases (SOD) are metalloproteins that catalyze superoxide radicals (O2-) produced under salinity stress into oxygen molecules and hydrogen peroxide, resulting to increased tolerance of plants to salinity. The most abundant superoxide dismutase isozyme in plants is Cu / Zn SOD, in which the role of Zn is structural and copper plays a catalytic role. Materials and Methods There is limited information about the effect of micronutrient application on the growth and salinity tolerance of rosemary. This study was conducted to investigate the effect of Zn and Cu co-application on some physiological and biochemical characteristics of rosemary under saline condition. For this purpose, a completely randomized design was carried out in a factorial experiment. The factors consisted of four types of fertilizer treatments (T1: control, T2: control + zinc, T3: control + copper and T4: control + copper + zinc) and three levels of salinity stress (S0: 0, S1: 60 and S2: 120 mM as NaCl) in four replications in a calcareous soil under greenhouse conditions. After 90 days, the plants were harvested and some growth characteristics including shoot and root fresh and dry weight were measured. Some physiological and biochemical properties such as leaf relative water content (LRWC), membrane permeability (MP), malondialdehyde (MDA), shoot and root Na concentration, and shoot and root K concentration were also measured. Results and Discussion The results showed that salinity had no significant effect on fresh weight of shoots, while shoot dry weight of rosemary decreased as 60% in control treatment, 44% in zinc treatment, 38% in copper treatment and 27% in zinc + copper treatment. Leaf relative water contents of rosemary decreased in response to salinity stress, and the only co application of zinc and copper under 120 mM NaCl stress resulted to a significant increase of LRWC (9%). Salinity stress increased the membrane permeability of rosemary leaves. In contrast, at all salinity treatments, addition of Zn and Cu caused a significant decrease in membrane permeability of rosemary leaves. However, there was no significant difference between fertilizer treatments. Salinity stress induced a significant increase in the malondialdehyde content of rosemary. For example, MDA content increased by 39% in control and by 24% in Cu treated plants when salinity level reached from 0 to 120 mmol L-1. Based on the results, in soil treated with 60 mmol L-1, addition of Zn and Cu and at the higher salinity level (120 mmol L-1) addition of Zn to soils had a significant effect on leaf and root Na concentration and thereby improvement of plant salt tolerance. Also, the result showed that co-application of Zn and Cu could reduce the undesirable effect of salinity on shoot and root K concentration and thereby improving plant tolerance to salinity stress. Conclusion In conclusion, zinc and copper, especially in combination form, increases the tolerance of rosemary to salinity by reducing of cell membrane damage, malondialdehyde content, shoot and root plant Na concentration and increasing of LRWC and shoot and root K concentration.
Soil Chemistry and Pollution
Hasan Bolbol; Majid Fekri; Majid Hejazi-Mehrizi; Naser Bromand
Abstract
Introduction Phosphorus (P) is an essential nutrient for all forms of life on the earth, but in excess concentrations, it can act as a serious water pollutant through eutrophication. Thus, it is very important to remove P from aqueous solutions before their release into natural water resources. Among ...
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Introduction Phosphorus (P) is an essential nutrient for all forms of life on the earth, but in excess concentrations, it can act as a serious water pollutant through eutrophication. Thus, it is very important to remove P from aqueous solutions before their release into natural water resources. Among the various P removal techniques that have been developed, the sorption process is widely accepted to be an effective water treatment technique because of low cost, ease of operation, simplicity of design, and high sorption capacity in dilute solutions. Layered double hydroxides (LDHs) are a type of two-dimensional nanostructure anionic clays with high capacities to sorption of anions. These non-silicate clays consist of positively charged brucite-like octahedral sheets which neutralize by a negatively charged interlayer containing relatively weak bonded anions and water molecules. The positive charges generated by the isomorphous substitution of trivalent cations for divalent cations are balanced by interlayer anions that can be exchanged by other anions making them good anion-exchangers with high selectivity. LDHs have been widely used as environmental sorbents because of their high charge density, large interlayer areas, good thermal stability, and high anion exchange capacities of the interlayer anions. The aim of the present study was to synthesize a Mg-Fe LDH as a sorbent for P removal from aqueous solution. Materials and Methods The Mg-Fe LDH was synthesized using the co-precipitation method. In brief, a mixture solution containing 0.03 mol MgCl2. 6H2O, and 0.01 mol FeCl3. 6H2O was added dropwise into a flask containing 100 ml of 1 M NaOH solution under vigorous stirring at pH=10. The obtained slurry was filtered and washed repeatedly with DW until the filtrate pH reached neutral. Mg-Fe LDH particles were then obtained by drying the filtrate at 70 °C in an oven overnight. The crystallinity of the sample was studied using X-ray diffraction (XRD) analysis. In order to investigate the performance of the synthesized LDH as a P sorbent, batch experiments were carried out in polyethylene centrifuge tubes. The suspensions were shaken for 24 hours at 250 rpm, and the supernatant was then separated by centrifugation at 4000 rpm for 10 minutes and were filtered by Whatman ashless grade 42 filtration papers. Equilibrium P concentration was determined according to the ascorbic acid method using UV-vis spectrophotometer at the wavelength of 880 nm. The effects of pH, initial P concentration, and contact time on P sorption were investigated in the ranges of 2-10, 0-300 mg/L and 0-1440 min, respectively. Results and Discussion The XRD pattern of the LDH sample showed typical structure of hydrotalcite-like compounds with sharp and reflection peaks corresponding to the (003), (006), (012), (015), and (110) crystal planes which are characteristic planes of hydrotalcite-like compounds. The efficiency of LDH to remove P decreased with the increasing of initial P concentration and the maximum removal efficiency of LDH occurred in the range of 5-20 mg/L of initial P concentration. With increasing of initial P concentration from 20 to 300 mg/L, the P removal efficiency of LDH decreased from 98.7 to 24.6 %. The P removal efficiency was increased with time and reached equilibrium at 60 min. The P removal rate of LDH in this time was about 66 % and no significant decrease in residual P concentration was observed after 60 min. The sorption of P on LDH was highly pH dependent, and the maximum P removal was found at pH of 4. The sorption kinetic and isotherm data were well described by pseudo-second-order and Langmuir equations, respectively. According to the Langmuir equation, the maximum P sorption capacity (Qmax) of LDH was obtained as 13.96 mg/g. Conclusion It was found from the results of this study that the mechanisms involved in the P sorption onto LDH included electrostatic attraction, ligand exchange, and surface complex formation. In addition, the results suggested that the synthesized Mg-Fe LDH can be potentially used as an effective sorbent for the removal of P from aqueous solutions. Further research is needed on the regeneration of the LDH after P sorption and the evaluation of desorption behavior of P from LDH under different conditions.
Plant Nutrition, Soil Fertility and Fertilizers
Majid Hejazi
Abstract
Zinc (Zn), an essential micronutrient for both plants and humans, is involved in a number of physiological and biochemical processes. Calcareous soils cover more than 30% of the earth’s land and are characterized by the high pH and low availability of plant nutrients. Zinc (Zn) that is freely available ...
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Zinc (Zn), an essential micronutrient for both plants and humans, is involved in a number of physiological and biochemical processes. Calcareous soils cover more than 30% of the earth’s land and are characterized by the high pH and low availability of plant nutrients. Zinc (Zn) that is freely available in acid soils is only sparingly available in calcareous soils, due to their poor solubility at high pH. Zinc deficiency in most of the world’s soils has resulted in significant loss of agricultural yields. Information about Zn availability in soils is very important in the view point of Zn nutritional status of plant and human. Several soil physicochemical properties including organic matter, CaCO3, pH, moisture and total Zn concentration affect soil Zn availability to plants. Under Zn deficiency, plants tend to release organic acid in the rhizosphere which in turn increases soil Zn availability. Oxalic acid is the simplest dicarboxylic acid with two pKa values, 1.23 and 4.19 and it occurs in sediments, forest soils, and agricultural soils, especially in the rhizosphere. Oxalic acid is able to chelate with the poorly soluble nutrients in the soil and consequently influence their bioavailability. It is known that Zn availability is controlled by adsorption, release, precipitation and dissolution reactions. Study of kinetic models is a useful method to describe the changes in the nutrient availability with time. A knowledge of desorption kinetics may provide important information concerning the nature of reaction and the rate of Zn supply to plants via soil solution. Materials and methods Composite samples of the two soils were collected from 0-30 cm depth of agricultural areas in Kerman province, Eastern Iran. The samples were air dried, crushed and passed through a 2mm sieve. Some soil chemical and physical properties of soil sample including Particle size distribution, Electrical conductivity and pH, Organic carbon, carbonate calcium equivalent, cation exchange capacity, available Zn and Total content of Zn were done according to standard procedures. For the kinetic study, soil samples were weighed (1.5g), placed in a 20 mL centrifuge tube and then 15 mL of oxalic acid with two concentrations of 1.1 and 2.2 mµ L-1 was added. The tubes were shaken from 1 to 72h at 25±2°C. Two drops of toluene were added to each tube to inhibit microbial activity. After shaking, the solutions were centrifuged and filtered through Whatman filter paper No. 42. Zinc concentration was determined in the filtrate using a Vario atomic absorption spectrometer. Several kinetic equations including zero-, first-, second- and third order, parabolic diffusion, Power function and simple elovich were also fitted to experimental data. Results and discussion Zn release by oxalic acid increased with time and the amount of Zn release differed between soils. The difference in the amount of Zn release may be attributed to differences in (i) the total amount of labile Zn which sorbed in the soil; (ii) types, quantities and relative proportions of the soil components by which the Zn is retained and (iii) other soil properties such pH and CEC. The release pattern of Zn included an initial fast reaction followed by a slow reaction that continued up to 72 h. The two phases of Zn release can be due to the heterogeneity of adsorption site with different adsorption affinities. The release kinetic of Zn in soils was poorly described by first- and second-order equations while Time dependent Zn release was best modeled by the simple Elovich, power function and parabolic diffusion equations. Based on the relatively higher values of r2 and the lower values of S.E., the simple Elovich showed the best fitness on the cumulative release of Zn. At each specified time, the lower dose of oxalic acid released Zn from soil more than the higher dose. Organic acids may increase the sorption of metal ions on soil particles through electrostatic interactions, ternary metal–ligand–surface complex formation or surface precipitation. It seems that Zn may interact with oxalic acid where adsorbed to solid phases and resulted in decreased Zn release. The rate parameters derived from the best-fitted model were used to compare Zn release by different concentrations of oxalic acid. The results showed that the rate parameters “ab”, Kp and β decreased with the oxalic acid concentration. Conclusion From the present study, oxalic acid, especially at the lower rate, can increase Zn release and its bioavailability in calcareous soils.
