Akbar Karimi; abdolamir moezzi; Mostafa Chorom; Naeimeh Enayatizamir
Abstract
Introduction: Zinc is a key micronutrient which takes part in plant physiological functions. One of the extensively wide range abiotic stresses arises from Zn shortage in agricultural calcareous soils. Zn is one of the most prevalent disorders among various crops. Zinc deficiency is very common in most ...
Read More
Introduction: Zinc is a key micronutrient which takes part in plant physiological functions. One of the extensively wide range abiotic stresses arises from Zn shortage in agricultural calcareous soils. Zn is one of the most prevalent disorders among various crops. Zinc deficiency is very common in most calcareous soils. Different mechanisms are involved in the deficiency of Zn In calcareous soils. The presence of calcium carbonate, lack of organic matter and high pH lead to Zn deficiency. Knowledge on the total Zn contents of in soil gives little information for their bioavailability. In order for better understanding availability of Zn to plant, knowledge about their mobility, and distribution in soil fractions is necessary. Biochar is a carbon-rich material produced by pyrolysis of biomass under oxygen-limited conditions and relatively low temperature. Biochar as a valuable soil amendment has received much attention due to its beneficial effects on carbon sequestration, soil physiochemical properties, soil microbial activity as well as soil fertility. Pyrolysis temperature has a significant influence on biochar physicochemical properties. Furthermore, biochar may alter the distribution of Zn fractions in calcareous soils. The impact of produced biochars at different pyrolysis temperature on distribution of Zn fractions in calcareous soils has been less studied. Therefore, the objective of this research was to evaluate the changes in distribution of Zn fractions in a calcareous soils treated with sugarcane bagasse derived biochars at different pyrolysis temperature.
Materials and Methods: An incubation experiment was carried out in laboratory condition as a factorial experiment based on a randomized complete design with two factors: (1) biochar type in four levels including control (without biochar) and biochar produced at 200 (B200), 350 (B350) and 500 ˚C (B500), (2) biochar application rate in two levels including 1 and 2% (w/w), and in three replications. Biochars were produced at 200, 350 and 500˚C pyrolysis temperatures under slow pyrolysis conditions with a heating rate of 5 °C min−1. Heating at this temperature lasted for 2 h. Then biochars were sieved to pass through 2 mm sieve and some properties were measured using the standard methods. The soil used in this study was sampled from the surface layer (0 to 20 cm depth), then, air-dried and sieved through 2 mm. Biochars produced at 200, 350 and 500˚C were mixed at 1 and 2% (w/w) with the 300 g of soil sample and incubated in ambient temperature at laboratory conditions (25 ± 2°C), for 90 days. Soil moisture content was maintained at 80% of field capacity. The samples were weighted every day and the required amounts of distilled water were added. At the end of incubation period, soil samples were air-dried and soil chemical parameters such as pH, cation exchange capacity (CEC), total organic carbon (TOC) and dissolved organic carbon (DOC) were measured.Chemical fractions of Zn in the incubated soil were determined according to the Tessier fractionation method. The Tessier sequential extraction method categorized Zn into 5 different fractions including: the exchangeable (Exch), bound to carbonate fraction (Car), bound to organic matter (OM), bound to Fe and Mn-oxides (FeMnOx) and residual fraction (Res).
Results and Discussion: Result indicated that application of different biochars significantly increased soil CEC and TOC. Maximum CEC and TOC were measured in B200 and B350 treatments, respectively, while their minimum values were observed in control treatment. In B200 treatments (B200, 1% and B200, 2%), pH significantly decreased compared to control, while this value significantly increased in B350, 1% , B500, 1% and B500, 2% treatments. B350 1% treatment did not have a significant effect on the soil pH. Application of 1 and 2% B200 significantly enhanced DOC (23.9 and 38%, respectively), compared to the control, but increase of DOC in B350 and B500 treatments was not significant compared to the control. Results showed that concentration of exchangeable Zn fraction decreased by 9.3, 19.5 and 9.5 % in B350, 2%, B500, 1% and B500, 2% treatments, respectively, compared to the control. However, B200 treatments (B200, 1% and B200, 2%) caused a significant increase in concentration of exchangeable Zn fractions (12.5 and 21.6%) compared to the control. The concentration of OM and Car Zn fractions increased in all biochar treatments compared to control. The highest concentration of OM and Car Zn fractions was observed after application of 2% B200 and 2% B500, respectively. Results showed that application of B350 and B500 had no significant effect on concentration of FeMnOx Zn fraction, while, this concentration significantly increased after B200 was applied. There were no significant (P ≤0.05) differences in concentration of residual Zn fraction among all the biochar treatments. The mean comparison results showed that the concentration of residual Zn in B200 treatments was significantly (P ≤0.05) lower than B350 and B500 treatments. There were no significant differences in this concentration among B500, B350 and the control treatments. Results revealed that in all treatments, different Zn fractions in the soil were distributed in the following order: Res > FeMnOx > Car > OM > Exch. The largest effect of biochars on the change in distribution of Zn fractions of soil was observed at 2% application rate.
Conclusion: It can be concluded that biochar B200 application could be an effective amendment for improving chemical properties and conversion of Zn from less available fractions to fractions with more bioavailability in the calcareous soil. Moreover, the biochar produced at 350 and 500˚C is better suited for enhancing soil organic carbon and Zn stabilization in calcareous soil.
N. Enayatizamir; A. Landi
Abstract
Introduction: Potassium (K) is the third major essential macronutrient for plant growth. Without adequate potassium, the plants will have poorly developed roots, grow slowly, produce small seeds and have lower yields. Due to imbalanced fertilizer application, potassium deficiency is becoming one of the ...
Read More
Introduction: Potassium (K) is the third major essential macronutrient for plant growth. Without adequate potassium, the plants will have poorly developed roots, grow slowly, produce small seeds and have lower yields. Due to imbalanced fertilizer application, potassium deficiency is becoming one of the major constraints in crop production. The concentrations of soluble potassium in the soil are usually very low and more than 90% of potassium in the soil exists in the form of insoluble rocks and silicate minerals. Soil microbes have been reported to play a key role in the natural K cycle and therefore, potassium solubilizing microorganisms present in the soil could provide an alternative technology to make potassium available for uptake by plants. Thus, identification of microbial strains capable of solubilizing potassium minerals quickly can conserve our existing resources and avoid environmental pollution hazards caused by heavy application of chemical fertilizers.
Materials and Methods: This study aimed to isolate and identified potassium solubilizing bacteria and evaluate those effect on K availability from muscovite and vermiculite sources to wheat crop under in vitro condition. The study was conducted as factorial in completely randomized design at three replications included bacterium inoculation (control, isolate1, isolate 2) and four k sources (muscovite, vermiculite, muscovite+ K2HPO4, vermiculite+ K2HPO4). Bacterial isolates were obtained from wheat rhizosphere on modified Aleksandrov medium containing muscovite and vermiculite powder as potassium source. Nutrient broth medium was used to prepare an overnight culture of bacteria to inoculate in Aleksandrov medium, which was used to study the dissolution of silicate minerals. The zone of solubilization recorded on Aleksandrov medium. Then the ability of two bacterial strains, including Bacillus subtilis and Corynebacterium glutamicum to release mineral K from muscovite and vermiculite was investigated. After 18 days of seed culture, aerial part of plant growth was dry digested and K concentration was determined by flame photometry. Dry and fresh weight of aerial part and root, plant height and root length was recorded.
Results: Three K-solubilizing isolates from 15 isolates identified by biochemical and molecular methods which belonged to Bacillus subtilis, Pseudomonas putida and Corynebacterium glutamicum. The potassium solubilization zone of each strain on Aleksandrov medium containing muscovite were 8.1, 65.1 and 6.3, respectively. The zone was also 9, 8 and 5.8 in Aleksandrov medium in the presence of vermiculite as insoluble potassium source. According to these results potassium release from vermiculite was more than muscovite, in spite of more potassium content of muscovite. According to the obtained results two strains Bacillus subtilis and Corynebacterium glutamicum were selected for in vitro experiment because of halo to colony diameter ratio. The ratio of halo to colony diameter in the presence of muscovite for Bacillus subtilis, Pseudomonas putida and Corynebacterium glutamicum was 1.5, 0.72 and1.3, respectively. These ratios were 2, 1.4 and 0.8, respectively in the medium containing vermiculite as insoluble potassium source. The results showed that the effect of bacteria inoculation was significant (p
F. Arzaghi; A. Farrokhian Firouzi; N. Enayatizamir; B. Khalilimoghaddam
Abstract
Introduction: Wind erosion is the most important agent of environmental degradation, poverty of soil, air pollution and the dust spread. Wind erosion is causing a lot of damage to crops, buildings, facilities and vehicles. The first step of the wind erosion control is the stabilization of soil particles. ...
Read More
Introduction: Wind erosion is the most important agent of environmental degradation, poverty of soil, air pollution and the dust spread. Wind erosion is causing a lot of damage to crops, buildings, facilities and vehicles. The first step of the wind erosion control is the stabilization of soil particles. Soil stabilizing methods to control wind erosion can be classified into mechanical, biological and chemical stabilization. Mechanical soil stabilization type is relatively time-consuming and costly. Biological stabilization is a traditional way that exhibits a long-term validity but sandy soil cannot provide essential water and nutrition elements needed by plant. Recently, chemical stabilization such as high-molecular-weight anionic polyacrylamide (PAM) has attracted the attention of researchers because of its advantages in easy and quick construction, and the improvement of the growing conditions for plant. However PAM has been mainly used to control water erosion and there is still little available information regarding the effectiveness of PAM on preventing soil loss by wind erosion. The main objective of this study was to investigate the feasibility of using PAM in wind erosion controlling. Also, effects of PAM on some soil physical and chemical properties and their temporal variability were evaluated.
Materials and Methods: In this study polyacrylamide polymer was used as a restoration of soil and soil structure stabilizer on sandy soil of Azadegan Plain (Khuzestan province, Iran). Consequently, an experiment was conducted as factorial based on completely randomized design with three replicates. The experimental treatments were consist polyacrylamide polymer (PAM) at three levels (0, 0.5, and 1 %), soil moisture at two levels (80% FC and dry) and time duration at three levels (15, 30 and 45 days). The emulsion of PAM was sprayed homogeneously on the soil surface. After passing each time treatment, penetration resistance and some physical and chemical properties of soil was measured. Finally after doing all measurements, the treatment with maximum penetration resistance were selected and the sample was prepared for wind tunnel testing. The wind erosion experiments were conducted in a wind tunnel. Soil samples were located in removable trays. The width and length of the trays was 30 and 100 cm, respectively. The wind erosion experiments were performed under wind velocity of 12 m s−1 according to the actual situation of study area.
Results and Discussion: The results indicated that in comparison to control, soil acidity decreased at both levels of the polymer with increasing time. The decreasing of soil acidity in wet treatments was more than dry treatment. The lowest amount of pH was obtained in the 30-day wet treatment at 1% polymer level. The results show from the 30th day onwards, soil pH increased, which is probably due to the polymer degradation. With passing time, soil electrical conductivity (EC) at both levels of the polymer (0.5 and 1%) increased and decreased respectively after 30 days. These observations are probably because after 30 days the properties of polymer-hydrophilic units gradually decrease and water adsorption was reduced or that soil soluble salts were adsorbed by polymer particles. The results also showed with passing time, Mean Weight-Diameter of Soil Aggregates (MWD) increased and then after 30 days declined. The largest MWD was observed in 30 days treatment at 1% polymer level. After thirty days, its effect has probably diminished due to polymer degradation. Furthermore, the results showed no significant difference of bulk density among treated soil with different level of polymer, but application of polymer caused to decrease bulk density comparison to control. Polymer application increased soil penetration resistance significantly. Using 1% of polymer increased it to 6 kg/m2. The results also indicated that the soil resistance at first increased with time and then decreased significantly. The amount of soil penetration resistance at 45-day was less than 15-day. The results of wind tunnel with a maximum 12 m/s wind velocity showed that application of the polymer reduced the erosion of sands samples to zero.
Conclusion: The research results indicated that PAM application increased soil penetration resistance and MWD. The polymer could improve the structure of soil aggregates and increase the amount of dry-stable aggregates and therefore decrease soil bulk density. Spraying PAM solution on the surface of soil significantly decreased the wind erosion amounts. Therefore, this inexpensive and easily usable polymer can be considered as a soil stabilizer to control wind erosion in arid and semiarid areas.
hamidreza boostani; mostafa chorom; abdolamir moezzi; najafali karimian; naimeh enayatizamir; mehdi zarei
Abstract
Introduction: Zinc (Zn) is an important nutrient element for humans and plants that controls many biochemical and physiological functions of living organisms. Zinc deficiency is common in high pH, low organic matter, carbonatic, saline and sodic soils. Salinity is a major abiotic environmental stresses ...
Read More
Introduction: Zinc (Zn) is an important nutrient element for humans and plants that controls many biochemical and physiological functions of living organisms. Zinc deficiency is common in high pH, low organic matter, carbonatic, saline and sodic soils. Salinity is a major abiotic environmental stresses that limits growth and production in arid and semi-arid regions of the world. Bioavailability of Zn is low in calcareous and saline soils having high levels of pH and calcium. Desorption of Zinc (Zn) from soil as influenced by biological activities is one of the important factors that control Zn bioavailability. Few reports on the effects of salinity on the availability and desorption kinetics of Zn are available. Rupa et al. (2000) reported that increasing the salt concentration led to increase Zn desorption from soil due to ion competition on soil exchangeable sites. Different kinetic equations have been used to describe the release kinetics of nutrients. Reyhanitabar and Gilkes (2010) found that the power function model was the best equation to describe the release of Zn from some calcareous soil of Iran, whereas Baranimotlagh and Gholami (2013) stated that the best model for describing Zn desorption from 15 calcareous soils of Iran was the first-order equation.less attention has been paid to kinetics of Zn release by DTPA extractant over time by inoculation of plant growth promoting rhizobacteria and mycorrhizae fungi in comination with soil salinity.The objective of this study was to evaluate the effect of plant growth promoting rhizobacteria (PGPR) and mycorrhizae fungi (MF) inoculation on release kinetic of Zn in a calcareous soil at different salinity levels after in cornplantation
Materials and Methods: A composite sample of bulk soil from the surface horizon (0-30 cm) of a calcareous soil from southern part of Iran was collected, air dried, passed through 2 mm sieve, and thoroughly mixed. Routine soil analysis was performed to determine some physical and chemical properties. The experiment was conducted in the greenhouse of agriculture college of Shahid Chamran University, Ahvaz, Iran. A factorial experiment as a completely randomized design with three replications was conducted in greenhouse conditions. The first factor consisted of salinity levels (0, 15 and 30 cmol(c) kg-1 salt supplied as a 3:2:1 Na:Ca:Mg chloride salts) and the second factor was microbial inoculation (without inoculation, fungi, bacteria, bacteria + fungi).Soil samples were extracted using DTPA extractant for periods of 0.5, 1, 2, 6, 12 and 24 hours. Cumulative Zn released (q) as a function of time (T) was evaluated using seven different kinetic models. A relatively high values of coefficient of determination (r2) and low values of standard error of estimate (SEE) were used as criteria for the selection of the best fitted models. Statistical analysis of data was done using MSTATC package (Mstatc, 1991). Comparison between means was performed using Duncan's multiple range test (DMRT) at the significant level of P < 0.05. Also, charts were drawn by excel computer package.
Results and Discussion: Investigation of Zn release patterns showed that the control and all treated soils had a uniform pattern of Zn release. Overall, Zn release patterns were generally characterized by an initial fast reaction at first two hours, followed by slower continuing reaction. It seems likely that the release of zinc is controlled by two different mechanisms. Two-step process of releases (rapid and subsequent slow) is attributed to the existence of places with different energy. The use of all microbial treatments increased the initial release of Zn compared to control. The most and the least Zn initial release observed in fungi-bacterial and bacterial treatment respectively. By application of all microbial treatments, Zn release rate declined compared to control and the lowest decrease observed in fungal treatment. In general, Zn initial release was increased and Zn desorption rate was decreased by increasing of salinity levels. Also, soluble and exchangeable forms of Zn had the highest influence on Zn release control.
Conclusions: Results showed that simplified Elovich, two constant rate and parabolic diffusion kinetics models showed good description of the Zn release. Based on the highest correlation coefficient and the lowest mean standard error of the estimate, simplified elovich determined as the best kinetic model. So it seems that the main mechanism controlling the Zn release in the tested soil is diffusion phenomena.
Abstract
Biofertilizers can be used as complementary in sustainable agriculture. The main target of this study was effects of nitrogen and phosphorus fertilizers and chemical fertilizers on wheat yield and yield components in two soil types. Experimental design as the factorial formed completely randomized design ...
Read More
Biofertilizers can be used as complementary in sustainable agriculture. The main target of this study was effects of nitrogen and phosphorus fertilizers and chemical fertilizers on wheat yield and yield components in two soil types. Experimental design as the factorial formed completely randomized design with three replications was executed. Experiment Factors included two soil types (sandy loam and clay loam) and 9 fertilizer treatments. For the experiment implementation used 100 gram per hectare of Nitrokara (Azorhizobium caulinodans) and Barvar 3 phosphorus (Pseudomonas putida, Strain P13, Pantoea agglomerans, Strain P5 and Pseudomonas putida, Strain MC1) biofertilizers in single and combined forms by method of seed inoculation. The results showed positive effects of clay loam type and inoculation of two biofertilizer types especially in the presence of 50% of chemical fertilizers on shoot dry weight, root dry weight, number of grains per spike, 1000 grain weight and wheat grain yield. The results showed 100% chemical fertilizer and phosphorus biofertilizer in combination with 50 % of chemical fertilizer treatments showed the highest effect in most characteristics and control treatment showed the lowest effect in this characteristics. Nitrokara biofertilizer in combination with 50% of chemical fertilizer had the maximum 1000 grain weight. Phosphorus biofertilizer in combination with 50% of chemical fertilizer on wheat yield and yield components showed a better effect than Nitrokara biofertilizer.The results of this research showed by combining biological and chemical fertilizers can reduce consumption of chemical fertilizers.