Soil science
H. Hatami; A. Fotovat
Abstract
Introduction
Boron (B) has a dual effect on living systems, so that the concentration range within which B is changed from a nutrient to a pollutant is rather narrow. Although B plays essential roles in all living organisms, its long-term excessive uptake has adverse effects on either human beings or ...
Read More
Introduction
Boron (B) has a dual effect on living systems, so that the concentration range within which B is changed from a nutrient to a pollutant is rather narrow. Although B plays essential roles in all living organisms, its long-term excessive uptake has adverse effects on either human beings or plants and animals. Furthermore, part of the B that can be used as fertilizer is highly soluble and easily leached into the soil profile leadsing to some problems such as decrease of fertilizer efficiency. Therefore, to improve agricultural productivity through its gradual uptake by plants, the increase of B adsorption in the soil solution is necessary. Many adsorbents have been used for the adsorption of B from aqueous solutions; however, layered double hydroxides (LDHs) have been considered as one of the most effective adsorbents as well as slow releaser fertilizers of inorganic anions such as nitrate, phosphate, etc. The formula of LDHs are typically denoted as [M1-x 2+M x 3+ (OH)2]x+ (An-) x/n .m(H2O), where M2+ and M3+ are divalent and trivalent cations, respectively, the significance of x is the molar ratio of M3+/(M3++ M2+) and An- is the intercalated anion. Although LDH materials are commonly prepared by combining two divalent and trivalent metals, more metals can be introduced in the brucite layer to achieve a large variety of composition and higher adsorption capacity. Stability of LDHs in soil can be affected by numerous factors (e.g. low molecular weight organic acids (LMWOAs)) leading to release of structural cations in addition to interlayer anion. However, there are scarce investigations that have evaluated the potential of ternary LDHs (e.g. Zn–Mn–Al LDH) in desorption of B (as interlayer anion) and release of Zn and Mn (as structural anions) in a simulated soil solution. Therefore, the objectives of this study were, i) to compare the desorption of B capacity of binary LDH (Zn–Al LDH) and ternary LDH (Zn–Mn–Al LDH) in the simulated soil solution, and ii) to investigate the effect of three different electrolytes (potassium nitrate, oxalic acid, and citric acid) on the release of Zn and Mn from synthesized LDHs.
Materials and methods
A modified urea hydrolysis method was employed to synthesize Zn–Al and Mn-substituted Zn–Al LDHs with Zn(+Mn)/Al molar ratio of 2. Herein the contents of Mn with respect to Zn corresponded to 2% and 10% molar ratio. Accordingly, the synthesized materials denoted as Zn–Al, Zn–Mn1 and Zn–Mn2 for the samples without Mn, with 2 and 10 mol% Mn with respect to Zn content. For investigation of B desorption at a concentration of 10 mM, 15 mL from equilibrium solutions were substituted with 15 mL of 0.03 M KNO3 and shaken for 240 min. Substitution was repeated four times and A modified urea hydrolysis method was employed to synthesize Zn–Al and Mn-substituted Zn–Al LDHs with Zn (+Mn)/Al molar ratio of 2. Herein the contents of Mn with respect to Zn corresponded to 2% and 10% molar ratio. Accordingly, the synthesized materials denoted as Zn–Al, Zn–Mn1 and Zn–Mn2 for the samples without Mn, with 2 and 10 mol% Mn with respect to Zn content. For investiigatigatingon of B desorption at a concentration of 10 mM, 15 mL from equilibrium solutions were substituted with 15 mL of 0.03 M KNO3 and shaken for 240 min. Substitution was repeated four times and B concentrations in extracts were measured by Azomethine-H method. Furthermore, the supernatant Zn and Mn concentrations were determined by GF-AAS (PG 900). This process was repeated for 1.25 mM oxalic acid and 1.25 mM citric acid to study the effect of these compounds on B desorption as well as release of Zn and Mn. B concentrations in extracts were measured by Azomethine-H method. Furthermore, the supernatant Zn and Mn concentrations were determined by GF-AAS (PG 900). This process was repeated for 1.25 mM oxalic acid and 1.25 mM citric acid to study the effect of these compounds on B desorption as well as release of Zn and Mn.
Results and Discussion
The adsorption and desorption isotherm were carried out to describe the distribution of B between the liquid and adsorbent. The isotherm data of synthesized LDHs were matched with Freundlich model. The values of 1/n in this model were found between 0 and 1 for all LDHs indicating favorable sorption of B on these compounds. The highest adsorption was observed for ternary LDHs (particularly Zn–Mn2) due to their higher specific surface area and also due to the ion exchange mechanism in combination with surface adsorption. However, the results showed that the percentages of B desorption by potassium nitrate, oxalic acid and citric acid were lower for Zn–Mn1 (19.4, 29.1 and 38.2%, respectively) and Zn–Mn2 (18.6, 28.2 and 35.9 %, respectively) than Zn–Al (30.8, 41.2 and 46.2%, respectively). This observation suggests that the type of LDH, B adsorption mechanism and background electrolyte can affect the amount of B desorption. Furthermore, after 4 successive desorption cycles, the concentration of Zn and Mn increased in the supernatants (particularly in organic acid electrolytes) suggesting dissolution mechanism possibility happened for the studied LDHs. Among the background electrolytes, citric acid was the most effective compound in releasing Zn and Mn, followed by oxalic acid and potassium nitrate. A reason for this such observations could be that with respect to chemical structure, citric acid by three carboxyl groups can form more chelate rings compared to oxalic acid, which contain two carboxyl groups. Therefore, it seems that B containing Zn–Mn–Al LDH may have potential to be used as a slow release fertilizer in soils to supply three essential elements, including B, Zn and Mn simultaneously. However, further studies are required to support such a hypothesis.
Hamidreza BEHRAVAN; REZA KHORASANI; Amir Fotovat; Abdol Amir Moezei; Mehdi Taghavi
Abstract
Introduction: Sugarcane cultivation has been revived in Khuzestan province of Iran since the 1960s and due to good results, it gradually began to grow from north to south of this region. Currently, sugarcane is cultivated in more than 100,000 hectares of the provinceand almost 25% of the country needs ...
Read More
Introduction: Sugarcane cultivation has been revived in Khuzestan province of Iran since the 1960s and due to good results, it gradually began to grow from north to south of this region. Currently, sugarcane is cultivated in more than 100,000 hectares of the provinceand almost 25% of the country needs for sugar arebeing produced in this region. Sugarcane fields of Khuzestan province are mainly rich in lime percentage and poor in organic matter and phosphorus. Soil pH in this region of the country also is about 8-8.5 and phosphorus uptake by plants and phosphorus fertilizer efficiency in these soils (alkaline and calcareous soils) are expected to be low. The optimum use of phosphorus fertilizer and proper phosphorus uptake is essential for the quantitative and qualitative function of sugarcane plants. Due to the very low mobility of phosphorus in the soil, its uptake by plants such as sugar cane is affected by number of soil and plant factors (especially plant root characteristics). Changes in these factors can lead to a reduction or increase of P uptake by the crop.
Materials and Methods: Because of the role of organic compounds in the improvement of mobility and phosphorus uptake, the use of organic material has been considered in many types of research. Organic compounds can play a direct and indirect role in plant factors and in phosphorous uptake improvement. In this regard, a greenhouse pot experiment was conducted in 2016-2017 at Farabi Agro Industry Co, 35 km south of Ahvaz, Iran (48º 36' E, 30º 59' N). This research carried out by using three levels of humic acid (immersion of settes in three concentrations of 0, 0.3 and 0.5% of humic acid) as well as three levels of phosphorus fertilizer (triple super phosphate) 0, 50 % and 100% of the recommended amount in the region (250 kg/ha) in two different harvesting periods (45 and 90 days after planting). The experiment set up as a factorial, based on complete randomized design with three replicates. In this experiment, the effects of different levels of phosphorous fertilizers and humic acid on aerial part (shoot height, shoot dry weight), underground part (root length, root dry weight and root hair length), and also root CEC of sugar cane plant in two harvest times were studied. Finally, uptake and influx of phosphorus in different treatments were investigated.
Results and Discussion: As the results show, although the range of the changes was different, the use of humic acid could improve almost all of these factors. Shoot height, shoot dry weight in humic acid treatments showed a significant increase in both harvests compared to non-used humic acid treatments and also in phosphorus fertilizer treatments as the fertilizer levels rose. These results show that humic acid can increase the uptake of phosphorus from the soil reservoir (treatments without phosphorus fertilizer) and source of soil and phosphorus fertilizer (phosphorus fertilizer treatments). The underground plant parts have also shown similar results. Root length and root dry weights have also been shown positive results in humic acid treatments. Therefore, an increase in phosphorus uptake in non-use phosphorous fertilizer treatments or phosphorous fertilizer treatments, along with humic acid, relative to non-humic acid treatments could be explained. The humic acid application seems to increase the uptake capacity of phosphorus from soil and fertilizer sources by increasing root length and root dry weight. In addition, the use of humic acid in alkaline soil can increase the solubility of phosphorus in water and therefore the phosphorus uptake by the roots of the plant could be increased. Based on the results, using humic acid due to improved phosphorus fertilizer use efficiency, phosphorous uptake by plant is expected to be increased and hence the fertilizer use would be reduced. Phosphorus influx results had not the same direction with uptake and application of phosphorus fertilizer. P influx results showed an inverse relationship with root length. In other words, phosphorus uptake was more dependent on the root growth.
Conclusion: This study showed that it is possible to use humic acid in the practical form during the cultivating of sugarcane setts, but it seems that further research is needed to examine other important points such as the use of humic acid during plant growth season and other its application forms, such as spraying or application in irrigation water.
S. Soleymani; A. Lakzian; A. Fottovat
Abstract
Introduction: Environmental contamination by crude oil and its various processing products is becoming a common phenomenon which severely damages soil and groundwater resources. Among the constituents of oil waste, polycyclic aromatic hydrocarbons (PAHs) are of environmental concern because of their ...
Read More
Introduction: Environmental contamination by crude oil and its various processing products is becoming a common phenomenon which severely damages soil and groundwater resources. Among the constituents of oil waste, polycyclic aromatic hydrocarbons (PAHs) are of environmental concern because of their toxic, mutagenic and/or carcinogenic effects. Bioremediation involves the use of living microorganisms, bacteria or fungi, for detoxification of soil and water organic pollutants by biodegradation, biotransformation, and/or mineralization. Collaboration between different microbes under co-culture conditions such as co-metabolism or antagonism makes the system to perform better than a single microorganism. Total petroleum degradation is a result of a microbial consortium action, which is composed of different species with specific biochemical roles. On the other hand, the majority of components of petroleum products has low solubility in water and tends to bind to soil particles reducing their availability to microorganisms for degradation. This has been well described as a major limitation to the bioremediation of hydrocarbon contamination. The surfactants can be employed to enhance hydrocarbon biodegradation by mobilization, solubilization, or emulsification. Some microorganisms synthesize a wide range of surface-active compounds, generally called biosurfactants, which increases the bioavailability of these compounds. The application of these microbial surfactants in the remediation of hydrocarbons aims to increase their bioavailability or mobilize and remove the contaminants by pseudo-solubilization and emulsification in a treatment process. This work aimed to investigate the impact of the biosurfactant producing consortium on the benzo(a)pyrene biodegradation.
Materials and Methods: Four gasoline contaminated soils were enriched in Bushnell-Hass mineral medium with Benzo(a)pyrene (200 mg/l) for three months at 30°C. After this time, to obtain Benzo(a)pyrene-degrading isolates, 0.1 ml of soil suspensions were plated on BH agar plates containing pollutant. Three colonies with different morphological distinct properties were purified on LB agar plates. The screening of the most potent surfactant strain was assayed quantitatively using measurement of surface tension by the Du Nouy ring method. For increasing the production of biosurfactant, medium conditions including pH (6, 7, 8), temperature (25, 30, 35) and carbon source (glucose, sucrose and ribose) were optimized with fractional factorial based on Taguchi. The capability of the isolates and consortium in hydrocarbon biodegradation was investigated in liquid medium of Bushnell-Hass with 150 ppm of Benzo(a)pyrene, during 14 days. Treatments included inoculation of isolates AP3 and BM1 and their consortium in presence and absence of extracted isolates biosurfactants and control (no isolate and biosurfactant). Based on the results of Benzo(a)pyrene degradation in the liquid medium, AP3 isolate, consortium and biosurfactant extracted from AP3 were selected for soil experiment. Four sets of biodegradation experiments were carried out with soil contaminated by 150 ppm of benzo(a)pyrene for 45 days, as follows: set 1: soil + AP3 isolate; set 2: soil + consortium; set 3: soil + consortium + AP3 biosurfactant and set 4: blank (soil). The residual concentrations of contaminant were extracted on days 15, 30 and 45 by dichloromethane solvent and analyzed using GC-FID.
Results and Discussion: The results revealed that strains AP3 and BM1 showed a significant potential to produce surface-active agents in the presence of Benzo(a)pyrene as substrate, reducing the surface tension to 43 and 46 mN/m, respectively. Taguchi experimental design method was applied in order to optimize the biosurfactant production by isolates. Results of experiments indicated that the optimum biosurfactant production conditions were found to be temperature of 35º C and pH of 7, and glucose as water soluble carbon source. The produced biosurfactant reduced surface tension to 31/52 mN/m and 30/81 mN/m for BM1 and AP3, respectively. Biodegradation experiments of Benzo(a)pyrene in liquid cultures showed that the overall biodegradation efficiency of the individual isolates after 14 days was lower than consortium. Bacterial consortium enhanced degradation of contaminant to 87.3% (with addition of biosurfactant) compared to 27.6% of removal in presence of BM1 isolate. However, there was no statistically significant change in the degradation rates of contaminant in consortium with addition of AP3 and BM1 surfactant and surfactant free (87.3, 85.6 and 86.8%, respectively). The degradation of Benzo(a)pyrene was significantly enhanced in presence of AP3 biosurfactant at individual BM1 treatments (28.3 and 44.5 to 74.8%). Maximum degradation of Benzo(a)pyrene in contaminated soil was found (100%) in set 3: soil + consortium + AP3 biosurfactant. Based on GC-MS analyses, it degraded around 100% of penzo(a)pyrene, used as the sole carbon and energy source, at an initial concentration of 150 mg L-1, after 45 days of incubation, while alone consortium and isolate were able to remove 86% and 68% of hydrocarbon, respectively. Overall, these results provide evidence that consortium and AP3 biosurfactant could be potential candidates for further bioremediation.
Conclusion: The results revealed that the hydrocarbon removal efficiency of the consortium was higher than single species, and the final removal efficiency for the consortium could be reached in a considerably shorter time. The results suggest that biosurfactant-assisted bioremediation may be a promising practical bioremediation strategy for aged PAH-contaminated soils. It is evident from the results that the consortium alone and its producer species are both capable of promoting biodegradation to a large extent.
Saman Hajinamaki; Hojat Emami; Amir Fotovat
Abstract
Introduction: Water scarcity is one of the important issues in agriculture, especially in arid and semi-arid regions of Iran. Therefore, the challenge for the agriculture in these areas is to find new sources of water for irrigation. One of the ways that has become more common in recent years is the ...
Read More
Introduction: Water scarcity is one of the important issues in agriculture, especially in arid and semi-arid regions of Iran. Therefore, the challenge for the agriculture in these areas is to find new sources of water for irrigation. One of the ways that has become more common in recent years is the reuse of wastewater as a secondary source and replaces drinking water. The effects of irrigation with wastewater on physical, chemical and biological properties of soil have been studied by many researchers, which most of them are based on the direct use of untreated wastewater in agricultural land irrigation. In fact, a large amount of wastewater used in the agriculture is indirectly entered into the rivers, and used in the agriculture lands. Irrigation with wastewater may have effects on soil properties such as pH, EC, nutrient content, sodicity, pollutants and etc.
Materials and Methods: In order to determine the effect of irrigation by wastewater on soil properties in May 2015, several points of the Kashafrood River in the north of Mashhad were selected. The studied points were located between 59˚36ʹ- 59˚41ʹ E and 36˚19ʹ- 36˚22ʹ N geographical position. The wastewater is refined in Parkandabad station, and used for irrigation. The samples were taken from a depth of 0-30 cm in each point and three replications were regarded for them. Sampling distance was one kilometer from each other. In general, 15 points were irrigated with wastewater were selected. 12 physical, chemical and biological properties including pH, soil texture, bulk density (BD), dispersible clay (DC), mean weight diameter of aggregates (MWD), sodium adsorption ratio (SAR), organic carbon (OC), available phosphorous (P), available potassium (k), total nitrogen (TN), microbial biomass and base respiration (BR) were measured as a total data set (TDS). According to Liu and Chen the main component with an Eigen value greater than one using the PCA method were chosen as minimum data set (MDS). Within each PC, highly weighted properties were defined as those with absolute values within 10% of the highest weighted loading. When more than one variable was retained in a PC, each was considered important and was retained in the MDS if they were not correlated (r < 0.60). Among well-correlated variables within a PC, the variable having the highest correlation sum was selected for the MDS. Data analysis were performed using SPSS Statistics22 software.
Results and Discussion: The results showed that irrigation with wastewater increased biomass and BR, OC, SAR, K and stability index of soil structure. The parameters of K, TN, pH and MWD have been increased compared to the control, but were not statistically significant. Using PCA, five PCs were obtained, which PC1 and PC2 with Eigen value of 50.6 % were the most important components. The parameters of OC, SAR, TN, pH, BD, MWD, BR and K were chosen as MDS due to be changed as a result of irrigation with wastewater. Then, the correlations between these parameters in two groups of irrigated soils with wastewater and control were investigated. Organic carbon in both soil groups had the highest correlation with the SI. The SAR in both soil groups was negatively correlated with nitrogen and phosphorus. Nitrogen in irrigated soils with control was positively correlated with the SI and OC. The MWD was not correlated with any parameter. PH had shown positive correlation with microbial biomass and OC was positively correlated with BR, TN and SAR in soil controls. Potassium in the irrigated soils with wastewater had the negative and significant correlation with OC, SI, BD and MWD. Microbial respiration had a high positive correlation with SI, OC and TN in irrigated soils, which is due to carbon and nitrogen in the wastewater and causes an increase in its amount compared with the control.
Conclusion: The results showed that irrigation with wastewater caused a significant increase in parameters SI, SAR, P, BR, MBC and organic carbon in irrigated soil with wastewater and pH, MWD, TN and K had no a significant difference. On the other hand, the principal component analysis of the two groups of irrigated soils with wastewater and control had two distinct groups indicating that the irrigation with wastewater had a significant impact on the soil properties. According to the principal components analysis, eight parameters including OC, SAR, TN, MWD, BD, pH, BR and K were selected as the most important parameters to study the effects of irrigation by wastewater.
zahra sharifi; Alireza Astaraei; A Fotovat; mojtaba baranimotlagh; Hojat Emami
Abstract
Introduction: Zinc is one of the essential micronutrients for plants, mining and industrial activities leading to pollution of heavy metals, including zinc metal contamination in soils. In addition to the total concentration, knowledge of the Zinc fractions is necessary to assess the mobility of zinc ...
Read More
Introduction: Zinc is one of the essential micronutrients for plants, mining and industrial activities leading to pollution of heavy metals, including zinc metal contamination in soils. In addition to the total concentration, knowledge of the Zinc fractions is necessary to assess the mobility of zinc in the soils. One of the sequential extraction methods is Tessier method. sequential extraction with plant cultivation simultaneously, is the appropriate approach for assessing the mobility of toxic metals. Therefore this study was conducted to evaluate the chemical forms and determine their relationship to the physical and chemical properties of soils in some fields under cultivation in Khorasan Razavi province.
Materials and Methods: The experiment was conducted in a completely randomized design with factorial arrangement includes 4 levels of contamination (0, 500, 1000 and 1500 (mg/kg)) and 10 soil types from different regions of Khorasan Razavi province of 0-30 cm depth in the range of electrical conductivity 1 up to 15 ds/m, with three replications at Research greenhouses of Ferdowsi University of Mashhad. An example of mining waste was prepared as a source of pollution. The soil samples were kept at field capacity moisture for 6 months. Then air-dried soil samples were used for planting borage and determine the Zinc fractions. Then soil samples were air dried and used for planting borage and determining the Zinc fractions. Texture, cation exchange capacity, organic carbon, electrical conductivity, pH and Available phosphorus and potassium were measured in the saturation extract. DTPA-extractable Zinc was measured by atomic absorption spectrometry. Borage was planted in greenhouses in 3 kg pots with three replications. During flowering, the plants were harvested and dry digestion method was used to measure the concentration of Zinc. Chemical forms and Pseudo total concentration of zinc in the samples were determined using Tessier and digestion by HCl and HNO3 acids (3:1) methods respectively. The concentration of the extracts was measured by atomic absorption spectrometry. Statistical analysis was done using Minitab and Excel softwares.
Results and Discussion: Chemical Forms Average of zinc in soils was as follows:
Exchangeable < iron and manganese oxides < organic < carbonate < residual
Despite the low percentage of organic matter in these soils, in high levels of Zinc contamination a large amount of zinc was saved. Lack of organic Zinc, in addition to the low amount of organic matter soil is related to the dominance of iron oxides. In high levels of soil contamination, increased concentrations of zinc in all fractions, especially organic and carbonate which leads to an increase in the availability of zinc, is a serious threat to environment. The amount of exchangeable zinc was insignificant. Also the exchangeable, forms a small part of total amount of metal in the soils. The correlation between the chemical forms with each other and with the pseudo total, absorbed by plant roots and shoots and extracted with DTPA together, was significant. Absence of correlation between the exchangeable and iron and manganese oxides is probably indicative of the fact that the main supplier of soluble and exchangeable zinc normally after carbonates are iron and manganese oxides, that have little role in these soils. There is a significant positive correlation between different fractions of zinc with each other and this indicate a dynamic relationship between the zinc chemical forms in the soil. Correlation coefficients between plant available and chemical forms of zinc showed that plant available zinc derived from all fractions. A higher correlation coefficient between the plant available with carbonate and organic zinc was obtained, which indicates that carbonate and organic are the major suppliers for available plants zinc.
Conclusion: In this study, the residual, carbonate and organic fractions are dominant form of zinc in soils, respectively. With increasing level of contamination, percentage of residual zinc decreased and percentage of other fractions increased, particularly organic and carbonate. Increasing the availability of zinc, is a threat to the environment. There is a high correlation coefficient between different fractions of Zinc with each other and with the pseudo total, amount of plant and available plant zinc showed that there is a dynamic relationship in the soil systems. There is a higher correlation coefficient between the available zinc and carbonate and organic fractions of soils, which indicate available plant zinc, are mainly derived from carbonate and organic fractions.
majid forouhar; Reza Khorassani; Amir Fotovat; Hossein Shariatmadari; Kazem Khavazi
Abstract
Introduction: Global warming is strongly linked to the increase in greenhouse gas emissions to the atmosphere. One of the most efficient ways to reduce the amount of atmospheric CO2 is to produce a lot of biomass and convert the biomass into a biochar. Biochar is an organic carbon-rich solid that can ...
Read More
Introduction: Global warming is strongly linked to the increase in greenhouse gas emissions to the atmosphere. One of the most efficient ways to reduce the amount of atmospheric CO2 is to produce a lot of biomass and convert the biomass into a biochar. Biochar is an organic carbon-rich solid that can be obtained from pyrolysis of various organic materials. In other words, biochar can be produced via thermal degradation of many organic materials such as vegetation biomass, animal waste, sewage sludge, etc. in absence or lack of oxygen. Biochar is more resistant to microbial degradation than its feedstock and has a mean resistance time of several decades. In connection with the use of biochar, the most researches have been done in non-fertile and highly weathered soils. The most significant effects of biochar application, have been also observed in strongly acidic soils. In many arid and semi-arid regions of the world, including Iran, the soil organic matter content is low. The lack of organic resources and their instability in the soil are considered as some of the most important challenges in improving soil fertility and plant growth and yield. To improve soil fertility by using insufficient existing organic resources, stabilizing organic matter by converting it into the biochar can be a fundamental strategy. If this strategy is applied in our country with calcareous soils, it is necessary to study the effects of different biochars on calcareous soils from different aspects .In this regard, in the present study, the effect of three types of biochar in a calcareous soil has been investigated in comparison with their feedstock.
Materials and Methods: The effects of three types of biochar and their feedstock in a calcareous soil were investigated in a 6-months period of incubation. A completely randomized design in the form of split plot experiment, was carried out. The main plots were consisted of Control, Municipal Waste Compost (MWC) and its biochar (BMWC), Sewage Sludge (SS) and its biochar (BSS) and Cow Manure (CM) and its biochar (BCW). The sub plots consisted of five sampling times as 10, 30, 60, 120 and 180 days after the beginning of incubation. Application rate of each treatment per kilogram of soil was calculated based on having the same weight of organic carbon content. So that all treatments contained 2.2 grams of organic carbon. After mixing the treatment with soil and adjusting the humidity to the moisture content of the field capacity (FC), they were transferred to the cans (with 3 holes embedded on their doors) and kept at 25°C in the incubator. During the 6-month incubation period, soil moisture was set at FC levels at intervals of two to three days. Sub samples were taken at five times. After air drying the sub samples, the chemical parameters such as EC of 1:2.5 extract, pH of 1:2.5 suspension, available phosphorus (extracted with sodium bicarbonate 0.5N) and available potassium (extracted with ammonium acetate 1N) were measured. After data collection, statistical analysis was performed using SAS software.
Results and Discussion: The soil texture was sandy loam with 21% of clay, 7% of silt and 72% of sand. Soil CaCO3 content and soil organic carbon content was 16% and 0.23% respectively. Available forms of potassium and phosphorous in soil were 76 and 6.3 mg kg-1, respectively. According to the results, under the influence of each treatment, the variation of soil available P, showed a significant increasing trend with the time. Changes in available potassium and soil pH were not significant over the time. Variation of soil salinity with time although showed an increasing trend but was not significant. Comparison of the effects of treatments showed that both biochars and their feedstock could significantly increase the available phosphorus and potassium in soil. In this regard, the effect of biochars was more pronounced than their feedstock. Among the feedstock, ranking for enhancing effect on available P, was SS > CM > MWC and among the biochars, it was BCM > BSS > BMWC. Ranking for enhancing effect on available K, was CM > MWC > SS and BCM > BMWC > BSS among the feedstock and biochars respectively. The increase in available phosphorus and potassium due to the use of biochars were much higher than that of total phosphorus and total potassium added by biochars. The soil pH decreased as a result of the application of each treatment compared to control. In this regard, the significant difference between biochars and their feedstock were not seen. Probable presence of some amounts of pyrogenic carbon with biochars can be one of the reasons for soil pH reduction. Electrical conductivity of 1:2.5 extract of soil was increased by all treatments compared to the control. Except for BSS, two other biochars significantly increased soil salinity more than their feedstock. This increasing effect on soil salinity can be partially due to the existence of some amount of ash accompanied with biochars.
Conclusions: Application of biochars derived from cow manure, sewage sludge or municipal waste compost in this experimental conditions, led to a significant increase in the amount of available phosphorus and potassium in soil compared to control and their feedstock. Therefore, the use of these biochars can have a high potential for reducing the consumption of some chemical fertilizers. From this point of view, the order of the superiority of the coal was as follows: biochar of cow manure > biochar of municipal waste compost> biochar of sewage sludge. The conversion of any of these feedstock to biochar did not have an effect on their potential for soil pH changes. Except for biochar of sewage sludge, in two other biochar, the potential for increasing soil salinity was higher than the feedstock. Considering that the durability of biochar in soil is much higher than that of its feedstock, it is possible to use suitable biochars such as those examined in this study as a great potential for the sustainable improvement of soil fertility and for reducing the use of chemical fertilizers in our country's agriculture. This requires extensive field researches for other soil properties in different soil and water conditions, with different kinds of biochars and crops.
Hadis Hatami; Amir Fotovat; Akram Halajnia
Abstract
Introduction: After nitrogen, phosphorus is the second most frequently limiting macronutrient for plant growth. It participates in metabolic processes such as photosynthesis, energy transfer and synthesis and breakdown of carbohydrates. H2PO4- and HPO42- are two forms of this element which are present ...
Read More
Introduction: After nitrogen, phosphorus is the second most frequently limiting macronutrient for plant growth. It participates in metabolic processes such as photosynthesis, energy transfer and synthesis and breakdown of carbohydrates. H2PO4- and HPO42- are two forms of this element which are present in the soil solution in the available form. Due to phosphorus reactions with soil components (oxy or hydroxides of Fe and Al in acidic soils and Ca2+ and Mg2+ ions in calcareous soils), the availability of this element is a limiting factor for production of agricultural crops in the whole world. To minimize this problem it is needed to improve the recycling of phosphorus and develop new technologies to reduce phosphorus losses and increase its effectiveness. In the recent decades, layered double hydroxides (LDH) have been extremely used as an effective sorbent for organic and inorganic anions sush as phosphate. Furthermore, some studies have suggested that the phosphate form LDH is applicable as a slow release phosphate fertilizer. Therefore, the objective of the present study was to compare the effect of using Zn-Al LDH and triple superphosphate (TSP) as fertilizers on the availability of phosphorus over time in a calcareous soil.
Materials and Methods: At the first, nitrate containing Zn-Al LDH (N-LDH) was synthesized by urea hydrolysis method and then ion exchange method was used for the phosphate anions intercalation into N-LDH. In this process, 5.0 g of the N-LDH was suspended in 1000 mL of a solution 0.05 mol/L of K2HPO4. The suspension was kept for 12 h at room temperature (25 °C) under stirring. Afterwards, the material was filtered, washed with distilled water and dried at 70 °C for 18 h. The LDH sample produced by the ion exchange method was nominated as P-LDH. To compare the effects of P-LDH and TSP application on the availability of soil phosphorus, an incubation experiment was carried out using a completely randomized factorial design with two sources of phosphorus (P-LDH and TSP), four levels of phosphorus (0 (control), 18, 45 and 90 mg P kg-1), eight levels of time (1, 5, 10, 20, 40, 70, 100 and 150 days) and three replications. Available phosphorus and zinc, pH and EC of samples were measured at the end of each time period. Available phosphorus was extracted with 0.5 M sodium bicarbonate and phosphorus concentration was determined using the ascorbic acid method. Available zinc content was determined by atomic absorption spectrometry following extraction of the sample by DTPA-TEA method. Also, pH and EC were measured in water (soil/water ratio 1:2). Data analysis was performed by MSTAT-C software, and the means were compared at α꞊5% by Duncan test.
Results and Discussion: The results showed that the use of P-LDH and TSP significantly improved available phosphorus compared to control treatment. However, in contrast to TSP, available phosphorus in P-LDH treatments increased with increasing of time, up to significant difference which was observed between the two sources after 150 days. This result is probably due to slow release of phosphorus from P-LDH and reduction of phosphorus reactions with different soil components. Moreover, available zinc was higher for P-LDH treatments than TSP treatments as dissolution of P-LDH may concurrently release zinc ions into the soil solution. It seems that the application of P-LDH not only increased the availability of phosphorus but also improved available zinc. Therefore, due to the zinc deficiency in calcareous soils, P-LDH can be used as a suitable dual purpose fertilizer for these soils. However, the possibility of Zn toxicity risk due to higher level of LDH application in soil is not ruled out. It is worth mentioning that the variation of pH and EC values in P-LDH treatments showed no significant difference compared to TSP tratments. In other words, application of P-LDH increased soil available phosphorus and zinc without any negative effect on soil pH and EC.
Conclusions: The results of this study illustrated that the P-LDH probably can be used as a slow release phosphate fertilizer to increase the phosphorus efficiency; however, care should be taken as the high levels of this fertilizer may not be recommended due to the high zinc content. It should be noted that the high levels of phosphorus are not appropriate for all phosphorus fertilizers but in the present study we used the different levels of fertilizers because the behavior of P-LDH was not clear for us.
faeze lotfi; amir fotovat; reza khorasani; Mahdi Bahraini
Abstract
Introduction: The pollution of soils by heavy metals due to human activities poses a serious concern for human and environmental health. In order to evaluate the risks of heavy metal contamination such as cadmium in soil, it is necessary to understand its bioavailability which depends on its chemical ...
Read More
Introduction: The pollution of soils by heavy metals due to human activities poses a serious concern for human and environmental health. In order to evaluate the risks of heavy metal contamination such as cadmium in soil, it is necessary to understand its bioavailability which depends on its chemical forms in the soil. According to Tessier (1979), heavy metals can be found in various chemical forms in soil including exchangeable, bound to carbonates, bound to iron and manganese oxides and bound to organic matter and residual. These fractions significantly influence the cadmium mobility and bioavailability. Distribution of metals in chemical forms in soil depends on soil pH, amount of organic matter, oxidation-reduction potential and ionic strength. Root exudation, soil texture, cation exchangeable capacity and amount of calcium carbonate may also impact chemical forms of cadmium. Many studies have showed that plant root may affect the chemistry of heavy metals in soil root zone. The objective of this study was to evaluate the effect of organic matter on the distribution of cadmium in corn root media.
Materials and Methods: To investigate the effect of organic matter (cow manure) and root activity on chemical forms of cadmium, a greenhouse experiment was conducted using rhizobox. The contaminated soil sample used in the study was collected from Zanjan. This greenhouse experiment was conducted in a factorial design, with 2 replications, two levels of organic matter (0 and 1.5%) and three zones classified based on their distance from root. The soil samples were air dried and crushed to pass through a 2-mm sieve. The cultivation was conducted using a rhizobox. The rhizobox consisted of three parts: 1.central compartment (rhizosphere), 2.close to rhizosphere, and 3. soil bulk. Soil samples were mixed with fertilizer and packed in rhizobox. Eight pre-germinated maize seedlings were transferred to the central compartment and five days after germination, thinned to four plants. Ten weeks after planting, corn plants were harvested for analysis. The compartments of rhizobox were separated. The collected plant samples (root and shoot) were rinsed with deionized water and oven-dried at 70 °C. Soil samples were also measured for pH, CEC and total organic carbon. The chemical forms of cadmium in the soil and plant samples were identified by the sequential extraction procedure proposed by Tessier (1979). Bioavailable cadmium in soil was also extracted by DTPA-TEA.
Results and Discussion: Results showed that the highest amount of soil cadmium was found in carbonate fraction. Adding organic matter increased the soil pH, CEC and organic carbon amount, whereas none of chemical forms of cadmium were significantly affected by adding organic matter. Bioavailability of cadmium, however, decreased by adding organic matter to soil, It can be therefore concluded that increment in cadmium uptake due to increased organic matter led to decreased cadmium bioavailability. The exchangeable cadmium was negatively correlated to soil organic carbon, while bioavailable cadmium was negatively correlated to soil pH, CEC and amount of soil organic carbon. Moreover, our results indicated that the fractions of cadmium were not significantly affected by distance from the root. Moreover, adding organic matter insignificantly increased concentration of cadmium in shoots, roots and total plants.
Conclusion: In this study, among different chemical forms of cadmium, only bioavailable cadmium was significantly affected by adding organic matter to soil. Additionally, soil pH, CEC and organic carbon were significantly increased by adding organic matter. These results indicate that addition of organic matter to soil may indirectly influence chemical forms of cadmium through impacting soil properties (soil pH, CEC and organic carbon). The addition of organic matter had the most influence on carbonate fraction of cadmium which may be potentially available to plant. It seems that addition of organic matter (cow manure) may result in increase of cadmium concentration in plant. Therefore, it can be concluded that addition of cow manure to calcareous soils with neutral to slightly alkaline pH may lead to increased cadmium uptake by the plant (corn) and reduced soil cadmium concentration.
V. Feiziasl; A. Fotovat; A. Astaraei; A. Lakzian; M.A. Mousavi Shalmani; A. Khorasani
Abstract
Introduction: Nitrogen (N) is one of the most important growth-limiting nutrients for dryland wheat. Mineral nitrogen or ammonium (NH4+) and nitrate (NO3−) are two common forms of inorganic nitrogen that can serve as limiting factors for plant growth. Nitrogen fertilization in dryland area can increase ...
Read More
Introduction: Nitrogen (N) is one of the most important growth-limiting nutrients for dryland wheat. Mineral nitrogen or ammonium (NH4+) and nitrate (NO3−) are two common forms of inorganic nitrogen that can serve as limiting factors for plant growth. Nitrogen fertilization in dryland area can increase the use of soil moisture, and improve wheat yields to some extent. Many researchers have been confirmed interactions between water stress and nitrogen fertilizers on wheat, especially under field conditions. Because of water stress affects forms of nitrogen uptake that leads to disorder in plant metabolism, reduction in grain yield and crop quality in dryland condition. On the other hand, use of suitable methods for determining nitrogen requirement can increase dryland wheat production. However, nitrogen recommendations should be based on soil profile content or precipitation. An efficient method for nitrogen fertilizer recommendation involves choosing an effective soil extractant and calibrating soil nitrogen (Total N, NO3− andNH4+) tests against yield responses to applied nitrogen in field experiments. Soil testing enables initial N supply to be measured and N supply throughout the season due to mineralization to be estimated. This study was carried out to establish relationship between nitrogen forms (Total N, NO3− andNH4+) in soil and soil profile water content with plant response for recommendation of nitrogen fertilizer.
Materials and Methods: This study was carried out in split-split plot in a RCBD in Dryland Agricultural Research Institute (DARI), Maragheh, Iranwhere N application times (fall, 2/3 in fall and 1/3 in spring) were assigned to the main plots, N rates to sub plot (0, 30, 60 and 90 kg/ha), and 7 dryland wheat genotypes to sub-sub plots (Azar2, Ohadi, Rasad and 1-4 other genotypes) in three replications in 2010-2011. Soil samples were collected from 0-20, 20-40, 40-60 and 60-80 cm in sub-sub plots in shooting stage (ZGS32). Ammonium measurement in the soil KCl extracts was down by spectrophotometry method and colorimetric reaction at 655 nm. Also, Absorption spectrophotometry method was used for determination of nitrate in soil extract based on its UV absorbance at 210 nm. In this method two measurements were carried out; one before (by Zn coated by Cu) and second after reduction of nitrate). Using the difference between these two measurements, concentration of nitrate in the extracts was determined. Soil water content was also measured with Diviner 2000 after calibration in 0-20, 20-40, 40-60 and 60-80 cm soil profile in sub-sub plots. After wheat harvest, the most suitable regression model between soil mineral nitrogen (Nm) and soil moisture (θ) was fitted with wheat grain yield by DataFit version 9.0 software.
Results and Discussion: The best model between soil N forms (nitrate, ammonium and mineral nitrogen) was calibrated between mineral nitrogen (Nm) and soil moisture (θ) with crop response (Y=a+bN_m+c ln〖(θ)〗+dN_m^2+eln〖(θ)〗^2+fN_m ln〖(θ)〗) that explained 80% of dryland wheat yield variations. In this model, the contributions of mineral nitrogen (NO3− +NH4+) were 26%, soil moisture 50% and their interactions 24%. According to this model, the effect of soil moisture on production of grain yield was 2.3 folds greater than the mineral N. These results are most suitable for sampling and calibration of mineral nitrogen in 0-40 cm in dryland wheat stem elongation (ZGS32). Critical value of soil mineral N was 41 kg/ha, equal to 18.0 mg Nm/kg in this layer for obtaining higher grain yield (over 2500 kg/ha). According to regression model, application of 50 kg N/ha in autumn was able to provide Nm critical level in 0-40 cm layer for dryland wheat genotypes under experimental conditions. Also simulation model showed that nitrogen fertilizer increased grain yield and it is more than the soil mineral nitrogen. If the soil mineral nitrogen is 20 kg/ha or less in 0-40 cm soil layer, there may be increase of grain yield up to 4000 kg/ha through the application of nitrogen fertilizers. Therefore, increasing of mineral nitrogen in the soil profile up to 20 kg/ha is not appropriate for wheat production in Northwest of Iran drylands.
Conclusion: It can be concluded that, there is a relationship between soil nitrogen and moisture content with dryland wheat response and suggested model can be used for nitrogen recommendations for dryland wheat. According to the model, the effects of nitrogen fertilizer application on grain yield were much more than the effect of soil mineral nitrogen. Therefore, the increasing of soil nitrogen storage is not recommended in dryland conditions.
Saeed Bagherifam; A. Lakzian; A. Fotovat; R. Khorasani
Abstract
Introduction: Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised ...
Read More
Introduction: Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised serious environmental concerns. Nearly all Arsenic-contaminated soils results from human activities and it has different environmental and sociological impacts. Various strategies and methods have been proposed for environmental management and remediation of contaminated soils. Among all methods, the phytoremediation is receiving more attention due to its cost effective and environmental friendly characteristics. In the case of arsenic contaminated soils, there are effective factors such as soil fertility, nutrients content and microorganisms function, which can improve the uptake of As by plants. Up to now, several studies have been evaluated the effects of symbiotic fungal association in plants on increasing nutrients and toxic elements uptake. Many of authors reported that the mycorrhizal symbiosis increases the uptake of toxic elements in root and shoot of plants and consequently improve the efficacy of phytostabilization and phytoextraction processes. There are conflicting results about the effect of arbuscular- mycorrhizal fungi (AMF) on As uptake by various plants. Chen et al. (4) found that Glomus mosseae symbiosis with plant reduces As concentration and enhance phosphorus content in shoot and root of plant. Whilst Cozzolino et al. (7) reported that the AMF increases as concentration in shoot and root of cabbage. Phosphorus has important role on mycorrhizal symbiosis and also As uptake by plants. Therefore, current study was conducted to evaluated effect of Glomus intraradices and Glomus mosseae symbiosis with sunflower and also soil phosphorus concentration on uptake of arsenic from arsenite and arsenate contaminated soils.
Materials and Methods:The soil sample (Typic Haplorthids) was collected, air dried and passed through 2 mm sieve and then were heated in 80 centigrade degree temperature for two times. A pot experiment was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition. The experimental factors included two species spices of inorganic As (50 mg kg-1 of Arsenite and Arsenate), two levels of phosphorus (0 and 60 mg Kg-1) and three spices of arbuscular mycorrhizae (control, Glomus intraradices and Glomus mosseae). Soil samples spiked with Na2HAsO4.7H2O, NaAsO2 (Arsenite and Arsenate) and Ca (H2PO4)2 (phosphorus) and incubated in greenhouse condition for 4 week. Sunflower seeds were planted and seedlings harvested after 60 day of sowing and then dry weight of sunflower, concentration of As and phosphorus in shoot and root of plant and root colonization percentage determined using standard methods.
Results and Discussion:The results revealed that Glomus intraradices (GI) and Glomus mosseae (GM) symbiosis significantly (P
Sh. Amirmoradi; P. Rezvani Moghaddam; A. Koocheki; Shahnaz Danesh; A. Fotovat
Abstract
Introduction: Accumulation of heavy metals in agronomic soils continuously by contaminated waste waters not only causes to contamination of soils but also it affects food quality and security. Cadmium and lead are one of the most important heavy metals due to long permanence and persistence in soil can ...
Read More
Introduction: Accumulation of heavy metals in agronomic soils continuously by contaminated waste waters not only causes to contamination of soils but also it affects food quality and security. Cadmium and lead are one of the most important heavy metals due to long permanence and persistence in soil can cause problems to human and animal health. Some medicinal plants are able to accumulate of heavy metals from contaminated soils. Heavy metals are not able to enter in the essential oil of some aromatic plants. Study of these plants helps human to select them for cultivating the resistant medicinal plants in contaminated soils.
Materials and Methods: This experiment was carried out in the research greenhouse of agriculture faculty of Ferdowsi university of Mashhad in 2011. Seeds were cultivated in planting aprons into peat moss medium. Then the uniform plantlets were transferred into soil in the plastic boxes (30×50×35 cm) at two leaf stage. In each box 6 plantlets were sown with distance of 15 cm on the planting rows and 20 cm between rows. Experiment was set up as factorial on the basis of randomized complete block design with three replications. The first factor was cadmium concentrations consisted of 0,10,20,40 mg per kilogram and the second factor was lead concentrations consisted of 0,100,300 and 600 mg/kg. Plants were irrigated during of15 weeks with cadmium and lead nitrogen nitrate solutions and then irrigated with distilled water. The differences of nitrogen amounts in treatments were compensated with ammonium nitrate on the basis of differences between level of the highest treatment and the treatment which obtained lower amount of nitrogen. Plants were harvested after 180 days at the beginning of flowering. All shoots and roots were weighted separately as fresh weight and then were dried under shading and then were weighted. The essential oil sage was determined by using of 30 grams of dried sage leaves with distillation method with Clevenger. Cadmium and lead contents in shoot and root were measured by wet digestion method (digestion by Perchloric and Nitric acid). Cadmium and lead contents were detected by atomic absorption apparartus. Data were analyzed by MSTATC software and all means were compared by DMRT at 5% of probability.
Result and Discussion: Results argued that fresh weight of sage at 40 mg/kg of cadmium were decreased 4.61% as compare as control. Dry weight of sage decreased at 600 mg/kg of lead 11.08 % as compare of control. Mean comparisons indicated that at the highest concentrations of cadmium and lead fresh and dry weight of sage were dropped. Growth decrement due to toxicity of cadmium causes to photosynthesis and respiration decline, carbohydrate metabolism decreasing and leaf chlorosis. Researchers observed lead ions by interfering with water balance lead to water stress. High concentrations of lead may cause to decrease the availability of water for plant and high concentrations of cadmium causes to disturb the protein synthesis and lead to protein decline in plant cells. Plant height of sage was declined at 40 mg/kg and 600 mg/kg as compared as control 14.17 and 10.83, respectively. Essential oil in sage was dropped in high levels of cadmium and lead as compare of control 12 and 14.51, respectively. Researchers stated that cadmium concentrations of 2,6 and 10 mg/lit and 50,100 and 500 mg/kg of lead had no significant effect on peppermint, but caused to drop the essential oil percentage of dill and basil.
Disturbance of carbon nutrition in plant cells during the photosynthesis process by heavy metals lead to a decrease in the essential content. The most cadmium absorption by sage shoots belonged to 40 mg/kg and 600 mg/kg of cadmium and lead, respectively and then 40 mg/kg cadmium and 300 mg/kg lead were ranked as second treatment. Increase of cadmium and lead concentrations in irrigation water led to increase of these heavy metals into sage shoots. Increase of lead and cadmium concentrations caused to antagonistic effects of cadmium and lead absorption into shoots of sage. In this experiment cadmium and lead concentrations of all treatments were too below to detect by atomic absorption apparatus. In this study cadmium and lead could not enter to essential oil. Researchers stated that high doses of cadmium, lead, zinc and copper concentrations could not enter into essential oil in sage. Some researchers showed that cadmium, lead and copper were not transferred to essential oil of peppermint, dill and basil during the essential oil distillation process. This finding confirmed that selection of medicinal plants as alternative plants with crops in cadmium and lead contaminated soils.
Conclusion: Fresh and dry weight of Sage in the condition of contaminated soil by 100 mg/kg cadmium and 600 mg/kg lead were declined 4.61 and 5.16 % as compare as control, respectively. At the highest doses of cadmium and lead the essential oil of sage were dropped but, these heavy metals were not detected in essential oil. So, it is seems that this medicinal plant may be applied in the contaminated soil or in the condition of using of contaminated irrigated water by cadmium and lead.
S. Akbari; Ali reza Karimi; A. Lakzian; A. Fotovat
Abstract
Introduction: Parent materials as one of the main soil formation factors have a great impact on the concentration of heavy metals in the soil. Heavy metals are released to the soil during weathering and pedogenic processes. Ultrabasic rocks are known as the potential natural source of heavy metals, especially ...
Read More
Introduction: Parent materials as one of the main soil formation factors have a great impact on the concentration of heavy metals in the soil. Heavy metals are released to the soil during weathering and pedogenic processes. Ultrabasic rocks are known as the potential natural source of heavy metals, especially Ni, Cr and Mn in the soil. Average concentrations of Ni and Cr in the soils are 84 and 34 mg kg-1, respectively; while, in soil derived from ultrabasic parent material, the concentration of these elements may reach up to 100000 mg kg-1. Binaloud zone in northeastern composed of different geological materials. There is a narrow band of ophiolitic rocks in this zone that located along Mashhad city. The geochemical behavior of ultrabsic rocks and the associated soil have been frequently studied mostly in humid regions. But, there are a few research works done in arid environments. The objective of this study was to investigate the physical and chemical properties and concentrations of Ni, Cr and Mn in soils formed along a toposequence of ultrabasic rocks in western Mashhad.
Materials and Methods: The study area is located in the hilly land landscape of Binaloud zone in the Western part of Mashhad. Mean annual precipitation and temperature is 260 mm and 13.7 oC, respectively. Soil temperature and moisture regimes are thermic and aridic boarder on mesic, respectively. Studied soils developed on hornblendite rocks that are ultrabasic rocks with SiO2 less than 45% and contain ferromagnesian minerals. A toposequence was selected and, three soil profiles on shoulder, backslope and footslope geomorphic positions were described acoording to key to soil taxonmy 2014 and the soil horizons were sampled. Air-dried samples were passed through 2 mm sieve and were used for laboratory analysis. Pseudo-total concentrations of Ni, Cr and Mn were extracted by aqua regia digestion procedure. Free iron oxides (Fed) and amorphous iron oxides (Feo) were extracted by citrate-bicarbonate-dithionite (CBD) and oxalic acid methods, respectively and were measured by atomic absorption spectroscopy. The soil was extracted by ammonium acetar 1N and concentration of Ca and Mg were measured by EDTA titrimetric method. Calcium carbonate equivalent, gypsum, pH, Sand, silt and clay fractions and soil organic materials were measured using custom laboratory methods.
Results and Discussion: Solum thickness of the studied soils is less than 45 cm. Calcification and gypsification are the two main soil formation processes leading to formation of calcic (Bk) and gypsic (By) horizons. Calcium carbonate equivalent and gypsum contents in the studied soils varied from 5.1 to 30 and 5.9 to 40.1 %, respectively. Regarding the type of parent material, presence of large amounts of gypsum and carbonates can be attributed to aeolian addition to the soil system. The presence of discontinuous and thin loess deposits in the study area confirms the dustfall deposition. High amount of these minerals cause Ca/Mg ratio is up to 33.3. Concentration of Fed and Feo were less than 6.8 and 0.2 g kg-1 reflecting weak wethering state of the soils. Morphological characteristics are the indications of weak soil development and weathering. Concentrations of Ni, Cr and Mn varied from 52.6 to 312.5, 35.2 to 135.3 and 375.3 to 628.9 mg kg-1 that are low values in comparison to soils in humid regions due to weak soil weathering and eolian addition of materials containing gypsum and carbonates. The Ni and Cr contents increase from shoulder to foot slope. Direct and concordant variations of Ni with Cr and Mn with Fed indicate the similar mineralogy and trend of weathering of these elements. Regarding the high concentration of Ni and Cr in the studied soils, the bioaccessibility of these elements should be investigated.
Conclusion: Results of this study indicated the weak development of soil formed on ultabasic rocks in the western Mashhad that was expected regarding the arid climate of the study area. Because of the low weathering status of the soil, the concentration of Ni, Cr and Mn were less than that of similar soils in humid areas. Also aeolian addition of carbonates and gypsum to the soil system dilutes the concentration of these elements. To evaluate risk assessment of Ni, Cr and Mn in the studied soils, successive extraction and pot experiments are suggested.
H. Emami; A.R. Astaraei; A. Fotovat
Abstract
Soil quality is important for evaluating the soil fertility and physical condition. Soil physical and chemical indicators should be regarded for determining the soil quality. This research was conducted to study the effect of organic matter on quantitative value of soil quality. Three level (15, 30, ...
Read More
Soil quality is important for evaluating the soil fertility and physical condition. Soil physical and chemical indicators should be regarded for determining the soil quality. This research was conducted to study the effect of organic matter on quantitative value of soil quality. Three level (15, 30, and 60 ton/ha) of different organic compounds including municipal waste compost, sewage sludge, cattle manure, and wheat straw to gether with control treatment in three replications were applied into loamy soil. The treated soils were kept for 6 months at 70% of field capacity moisture in greenhouse condition. Then soil quality determined based on non-linear score function by using of 14 physical and chemical indicators. The results showed that the score of control treatment was 52.7, which it belong to class 4, i.e. low quality. Addition of different organic matter into studied soil led to improve soil quality score and soil quality class was increased one to 2 degrees. Among the studied treatments, the highest score of soil quality was obtained in 60 ton/ha sewage sludge and 30 and 60 ton/ha compost. Also, addition the other organic treatments cause to increase the quantitative soil quality score in relation to control, and soil quality class increased one degree. Among the studied indicators, iron (Fe), Manganese (Mn), zinc (Zn) micro-nutrients, aeration porosity (AC), and mean weight diameter of aggregates (MWD) were the important limiting indictors in degrading the soil quality in control treatment, and applying the compost and sewage sludge increased their scores.
Hadis Hatami; Ali reza Karimi; A. Fotovat; H. Khademi
Abstract
Aluminosilicates such as K-feldspar and micaceous minerals are the main source of potassium in soils. The objectives of this study were to investigate the release of K from micaceous minerals (biotite, phlogopite, muscovite) and K-feldspars (Zanjan and Yazd) using sequential extraction by 0.05 M BaCl2 ...
Read More
Aluminosilicates such as K-feldspar and micaceous minerals are the main source of potassium in soils. The objectives of this study were to investigate the release of K from micaceous minerals (biotite, phlogopite, muscovite) and K-feldspars (Zanjan and Yazd) using sequential extraction by 0.05 M BaCl2 and determine the effect of mineral grain size and application of kinetic models to describe K release. For this purpose, sequential extraction with BaCl2 was conducted on two sizes of 50-100 and less than 50 micron for the periods of 2-600 hours. The amount of K released into the solution was measured by flame photometer. The results indicated that after 13 times of extraction, in the both sizes, biotite and muscovite had the highest and lowest values of K release, respectively. Meanwhile, the released K increased by decreasing the mineral size. The kinetics of K release from minerals consisted of two phases, the first phase was relatively rapid and then continued with a slow rate to end of the experiment. Regarding the high determination coefficient (R2) and low standard error of the estimate (SE), parabulic diffusion and exponential function equations could reasonably describe the K release kinetics. Therefore, it may be concluded that the release of K is controlled by diffusion process from the surface of the study minerals.
V. Feiziasl; A. Fotovat; A. Astaraei; A. Lakzian; M.A. Mousavi Shalmani
Abstract
In order to determination of water stress threshold and dryland wheat genotypes water status in different nitrogen managements, this experiment was carried out in split split plot RCBD design in three replications in 2010-2011 cropping year. Treatments included: N application time (whole fertilization ...
Read More
In order to determination of water stress threshold and dryland wheat genotypes water status in different nitrogen managements, this experiment was carried out in split split plot RCBD design in three replications in 2010-2011 cropping year. Treatments included: N application time (whole fertilization of N at planting time , and its split fertilization as 2/3 at planting time and 1/3 in early spring), N rates (0, 30, 60 and 90 kg ha-1) and 7 wheat genotypes. Also these genotypes were grown in supplemental irrigation condition for calculation of crop water stress index (CWSI) parameters. Canopy temperature (Tc) was measured in flowering and early milking stages. Crop water stress index (CWSI) was calculated. A non-water stressed baseline (lower baseline) were fitted as Tc-Ta=4.523-3.761×VPD; R2=0.92 and non-transpiring baseline (upper baseline) determined 6 ºC for rainfed wheat genotypes. Water stress threshold was 0.4 and crossing of that occurred 8 days before heading stage. In water stress threshold boundary, was depleted 60 mm available water from 0 to 50 cm soil depth. There was negative significant relationship (p >0.01) between CWSI and grain yield in all treatments and different nitrogen rates. Nitrogen application reduced water stress and increased grain yield of rainfed wheat genotypes. Ohadi and Rasad genotypes showed highest resistance to water stress and high grain yield production for N30 in split and planting time application, respectively. Cereal4 and Rasad genotypes were suitable for N60 application in split and planting time application, respectively.
S. Saeidi; A. Fotovat; A. Lakzian
Abstract
The biodegradation of normal-hexadecane by bacteria is one of the important aspects of bioremediation.
The aim of this study was to investigate degradation of normal hexadacane (with level of contamination,
2500 mg.kg-1) by Pseudomonas aeruginosa, Pseudomonas putida and native bacteria of contaminated ...
Read More
The biodegradation of normal-hexadecane by bacteria is one of the important aspects of bioremediation.
The aim of this study was to investigate degradation of normal hexadacane (with level of contamination,
2500 mg.kg-1) by Pseudomonas aeruginosa, Pseudomonas putida and native bacteria of contaminated regions in the presence of NPK (three types of fertilizer: urea with 46% nitrogen, ammonium phosphate with 21% nitrogen and 46% phosphor and potassium sulphate with 40% potassium) as nutritious source. The experiment was carried out as a completely randomized design (CRD) with factorial arrangement in three replications. Experimental factors included six levels of bacteria (Pseudomonas aeruginosa, Pseudomonas putida, three strains from contaminated regions Ahvaz, Sarakhs and Tehran and control), three levels of fertilizers treatment (0 and 2 ton.ha-1 of NPK) and two levels of soil condition (sterile and non-sterile) at two times (30 and 60 days). Then, soil total organic carbon (TOC) as index for the degradation of normal hexadacane in samples was measured. The results showed that degradation of normal hexadecane in sterilized soil samples were higher than non sterilized soil samples. the highest degradation of normal hexadecane was observed in the presence of Sarakhs strain. The amount of degradation by this strain with nutritious source was 45% whereas this value was lower (one third) in the absence of NPK. Moreover, the results indicated that the amount of degradation by the bacteria increased with time. Biodegradation value in the presence of NPK was 4-fold higher compared to no-NPK treatment after 60 days.
A. Lakzian; M. Fazeli Sangani; Alireza Astaraei; A. Fotovat
Abstract
This study was conducted to evaluate using terrain attributes derived from digital elevation model (DEM) as ancillary data to predict soil organic carbon (SOC) by implementing different statistical and geostatistical techniques. A linear regression model (LR), Artificial Neural Network model (ANN), ordinary ...
Read More
This study was conducted to evaluate using terrain attributes derived from digital elevation model (DEM) as ancillary data to predict soil organic carbon (SOC) by implementing different statistical and geostatistical techniques. A linear regression model (LR), Artificial Neural Network model (ANN), ordinary kriging (OK), ordinary co-kriging (OCK), regression kriging (RK) and kriging with an external drift (KED) were performed to predict spatial distribution of SOC in an area of 2400 km2 in mashhad, iran. The SOC was measured for 200 soil samples of the study area and their corresponding Terrain attributes value was extracted from derived from 10-m resolution DEM. correlation between measured SOC and individual terrain attributes was determined, the number of 160 data were used for model development and 40 as validation data set. Resulting maps of different interpolation methods were compared to evaluate map quality using MAE and R2 criteria calculated from plotting measured versus estimated data. The results showed that there is a significant but not strong correlation between SOC and terrain attributes. The comparison of estimation techniques showed that the KED technique with wetness index as ancillary data has the best performance (MAE=0.18 %, R2=0.67) of all, but no significant difference with RK. There were modest differences between maps created with geostaistical technique but sensible difference with LR and ANN ones. The results of this study propose that although there is a significant correlation between SOC and terrain attributes therefore It can be use for enhancing the quality of map, but it is not able to express the spatial variability of SOC as it is necessary for detailed soil map. Because there is other factors controlling SOC spatial distribution
F. Akbarnejad; A. Astaraei; A. Fotovat; M. Nasiri Mahalati
Abstract
Recently Application of municipal solid waste compost and sewage sludge on the farm land had received considerable attention. These organic wastes provides a valuable source of organic matter and enhances crop yield and soil fertility by improving soil physical, chemical and biological properties. To ...
Read More
Recently Application of municipal solid waste compost and sewage sludge on the farm land had received considerable attention. These organic wastes provides a valuable source of organic matter and enhances crop yield and soil fertility by improving soil physical, chemical and biological properties. To evaluate the influences of municipal solid waste compost (MSWC) and sewage sludge (SS) on chemical properties of soil an experiment was conducted with Municipal solid waste compost at 0, 15, 30 ton/ha (C0, C15 and C30) and sewage sludge at 0, 15, 30 ton/ha (S0, S15 and S30) in a factorial experiment based on completely randomized design with three replications in greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad. Results showed that municipal solid waste compost and sewage sludge and their interaction effects had significant effects on soil chemical properties. With increasing amounts of municipal solid waste compost and sewage sludge, organic carbon and electrical conductivity of soil increased. Portion of Sewage sludge compared to municipal solid waste compost in increasing of organic nitrogen is lower. The most amount of soil organic nitrogen was observed in municipal solid waste treatments. Also use of these wastes together decreased soil acidity.
A. Hosseinpour Buri Abadi; Gh. Haghnia; A. Alizadeh; A. Fotovat
Abstract
Increasing population, limitation of water resources, and also enormous volume of municipal wastewater and need to dispose of these wastewaters safety, has been increased of necessity of reuse of wastewater. Disposal of wastewater in soil is one of the most economical methods of their disposal. Different ...
Read More
Increasing population, limitation of water resources, and also enormous volume of municipal wastewater and need to dispose of these wastewaters safety, has been increased of necessity of reuse of wastewater. Disposal of wastewater in soil is one of the most economical methods of their disposal. Different soil characteristics, type of wastewater and method of its application are issues that affect wastewater treatment efficiency in the soil. For this purpose, an experiment was carried out in 12 polyethylene columns during 7 periods of 15 days in Ferdowsi University of Mashhad. A statistical “factorial design” was used. Raw and treated wastewaters from Parkandabad Treatment Plant were applied under continuous and intermittent flood conditions in columns filled with silty loam soil. At the end of experiment, soil columns were divided and soil samples from depths of 0-25, 25-50 and 50-100 cm each column were collected. Properties such as pH, salinity, concentration of NO3, PO4, TOC, Ni and Cd were measured in soil solution samples and also Leachates were taken in each period of experiment. The result showed that the mean values of each of the above mentioned parameters, with exception of pH and salinity, were lower in leachate compared to the wastewaters entering the soil. However, with continuous application of wastewaters increase in the amount of these components (with exception of salinity and Ni) were observed. The amount of Cd in leachate samples of any periods was undetected. Considering the effect of wastewater application on soil chemical properties, value of all parameters (except salinity) in comparison to their initial values have increased in the soil solution. Based on the above results, disposal of wastewaters (especially raw wastewater) on soil should be managed carefully. So that by sound usage of wastewaters, environmental risks resulting from disposal of them are reducing to the lowest level in nature.
Sh. Shafaei; A. Fotovat; R. Khorasani
Abstract
Iron (in zero-valent and oxide forms) is used to remove numerous organic and inorganic contaminants in environment. However, there are few reports, especially in nano scale, on the remediation of heavy metals contaminated soils using zero-valent iron in the literature. In this study, the effect of iron ...
Read More
Iron (in zero-valent and oxide forms) is used to remove numerous organic and inorganic contaminants in environment. However, there are few reports, especially in nano scale, on the remediation of heavy metals contaminated soils using zero-valent iron in the literature. In this study, the effect of iron on the availability of heavy metals was evaluated in a calcareous soil spiked with cadmium, zinc, lead and nickel. The soil samples, in a randomized complete design with two replications, were amended with four iron materials including micrometric zero-valent iron (ZVI), nanoscale zero-valent iron (nZVI) and nano and micro scales iron oxides. Then, after 1, 2 and 4 weeks of the experiment, DTPA-extractable heavy metals in soil were determined. Results showed that DTPA extractable heavy metals significantly decreased in soil treated with zero-valent iron, compared to untreated soil The stabilization efficiency of Ni, Cd, Zn and Pb was 28%, 32%, 37% and 28% for ZVI and 12%, 0%, 25% and 21% for nZVI, respectively. In contrast, presence of iron oxides caused significant increase of DTPA extractable heavy metals in soil except for Ni. Moreover, Ni-DTPA decreased significantly with time whereas it was constant for the other elements examined. In this study, the observed capacity for heavy metals removal by ZVI was higher than other treatments whereas the stabilization efficiency of nZVI was not significant in the soil.
M.H. Ravanbakhsh; A. Fotovat; Gh.H. Haghnia
Abstract
Abstract
A study was conducted to evaluate the effect of incubation time, sewage sludge and clay content on the distribution of nickel and cadmium in different fractions of selected calcareous soils. To meet this purpose, an experiment with two different soils (4 and 30 percent CaCO3), two different ...
Read More
Abstract
A study was conducted to evaluate the effect of incubation time, sewage sludge and clay content on the distribution of nickel and cadmium in different fractions of selected calcareous soils. To meet this purpose, an experiment with two different soils (4 and 30 percent CaCO3), two different textures (8 and 40 percent clay), two levels of nickel (0 and 100 mg.kg-1), two levels of cadmium (0 and 25 mg.kg-1) and organic matter in the form of sewage sludge in two levels (0 and 50 t ha-1) was carried out. Two incubation times (0 and 60 days) and three replications in a completely randomized design were mentioned. The samples were incubated for two months at temperature of 25±2 °C and soil moisture condition close to field capacity. Distribution of Cd and Ni in fractions soluble+exchangeable, organically bound, carbonate bound and residual fractions was determined by a sequential extraction method. The results illustrated that, in both soils, residual form of Ni and carbonate form of Cd were dominant and showed a significant change with sewage sludge treatment and time. Sewage sludge application increased the amount of organic and carbonate bound of Ni and Cd significantly. The proportion of organic and carbonate bond Cd and Ni was higher in soil with 33 percent lime. In contrast, in soil with 4 percent lime, the percentage of Ni and Cd in the residual fractions was higher. Residual fraction of Ni and Cd in Clay soil was significantly higher than sandy loam soil. Increasing the amount of Ni and Cd increased all fractions of these metals significantly. The organic forms of Ni and Cd decreased significantly in the course of time. In general, based on the results, it may be concluded that calcium carbonate, clay percent and sewage sludge treatment play a key role in the distribution of Ni and Cd in different fractions of soils.
Keywords: Fractionation, Calcium carbonate, Sewage sludge, Clay percent, Time
M. Mohammadi San; A.R. Astaraei; A. Fotovat; A. Lakziyan; M. Taheri
Abstract
Abstract
With increasing population, Mine activities for metal proceeding are also increasing, so environment will be influenced by contaminant especially heavy metals. In situ immobilization of heavy metals using inexpensive amendments is considered as a simple and cost-effective approach for reducing ...
Read More
Abstract
With increasing population, Mine activities for metal proceeding are also increasing, so environment will be influenced by contaminant especially heavy metals. In situ immobilization of heavy metals using inexpensive amendments is considered as a simple and cost-effective approach for reducing heavy metal contamination. In this research we used sequential extraction for assessing reduction in availability of heavy metal in lead and zinc mine waste (bama mine around Isfahan). The effects of chemical amendments consist of 3 level of Zeolite 0 (Z1), 5% (Z2) and 10% (Z3) and 3 level of Triple Super Phosphate 0 (P1), 0.25% (P2) and 0.5% (P3) on speciation of Pb, Zn and Cd was investigated by sequential extraction based on tesier method. Total concentration of Pb, Zn and Cd were 2300, 16500 and 27.4 mgkg-1 d.m. Result showed that TSP transform heavy metal specially Pb from exchangeable and carbonate fractions to residual and organic, sulfides fractions. Zeolite also transformed Pb and Zn from carbonate fraction to residual fraction. But eth effect of phosphorous was superior to zeolite. There was no interaction between Zeolite and TSP.
Keywords: Soil pollution, Heavy metals, Fractionation, In situ immobilization
M. Mohammadi Aria; A. Lakzian; Gh. Haghnia; H. Besharati; A. Fotovat
Abstract
Abstract
A large number of studies have shown that direct application of rock phosphate dose do not have enough efficiency to release phosphorus compared to chemical fertilizers. The main purpose of this study was to increase the efficiency of direct application of rock phosphate. Incorporation of rock ...
Read More
Abstract
A large number of studies have shown that direct application of rock phosphate dose do not have enough efficiency to release phosphorus compared to chemical fertilizers. The main purpose of this study was to increase the efficiency of direct application of rock phosphate. Incorporation of rock phosphate with sulfur, organic matter and inoculation with sulfur-oxidizing bacteria and phosphorous-solubilizing fungus, seems to be a suitable alternative for increasing the efficiency and applicability of rock phosphate. This experiment was carried out in laboratory condition, using completely randomized factorial design with 12 treatments and 3 replications. The treatments included sulfur at three rates, 0% (S0), 10% (S1), 20% (S2), vermicompost at two rates, 0% (V0), 15% (V15), and inoculation with Thiobacillus thiooxidanc, Aspergillus niger (BF) and without inoculation. Water soluble phosphorus and pH were measured during incubation time (15 and 60 days). The results of experiment showed that water soluble phosphorous increased over the time and the maximum level of water soluble P was observed using treatment of 20% sulfur, 15% vermicompost and inoculated with Thiobacillus and Aspergillus (BFS2V1). The amount of water soluble phosphorus in BFS20V15 was significantly higher than other treatments.
Keywords: Rock phosphate, Organic matters, Water soluble phosphorus
M. Mossadeghi; A. Lakziyan; Gh. Haghnia; A. Fotovat; A. Halajnia
Abstract
Dissolved Organic nitrogen (DON) is an important constituent of Dissolved Organic Matter (DOM). It has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. Dissolved inorganic nitrogen, which is another form of ...
Read More
Dissolved Organic nitrogen (DON) is an important constituent of Dissolved Organic Matter (DOM). It has a considerable effect on total dissolved soil nitrogen and it is very important as a nitrogen source of many aquatic and terrestrial ecosystems. Dissolved inorganic nitrogen, which is another form of total soil dissolved nitrogen, includes NO3, NO2 and NH4, which is very important for plant nutrient. Soil managements such as fertilizer application affects the flux and concentration of DON and DIN in soils. The purpose of this study was to evaluate the effects of different N-fertilizers application on DON and DIN content of two Alfisols located in near the Caspian Sea in the north of Iran. An experiment carried out using complete randomized design with factorial arrangements. Four level of N-fertilizers (Urea, Ammonium nitrate, Ammonium sulfate with Control)) and six different times (0, 7, 14, 28, 42, 60 day) with three replications in two different soils. Changes in DON, DIN, pH and soil respiration were monitored during the period of 60 days. The results showed that dissolved organic nitrogen decreased significantly by N- fertilizer application in both soil samples however, NO3, NO2 and NH4 increased. Ammonium sulfate showed the maximum effect on DON reduction and it can be due to the pH reduction. Changes in DON during the experiment varied from 11 to 75 % in both soil. At the end of experiment, NO3 + NO2 formed a major part of total Dissolved nitrogen in soils.
A. Hosseinpour; Gh. Haghnia; A. Alizadeh; A. Fotovat
Abstract
Abstract
Population increase, limitation of water resources, and increasing volume of municipal wastewater, has caused the necessity of wastewater reuse. Application of wastewater on soils seems to be the most economical method of its disposal and by percolating wastewater through the soil, its chemical ...
Read More
Abstract
Population increase, limitation of water resources, and increasing volume of municipal wastewater, has caused the necessity of wastewater reuse. Application of wastewater on soils seems to be the most economical method of its disposal and by percolating wastewater through the soil, its chemical quality is improved. For this purpose, a greenhouse experiment was carried out with polyethylene columns (150 cm in length and 11 cm in diameter) during 7 periods of 15 days in Ferdowsi University of Mashhad. A statistical completely randomized design was used. Raw and treated wastewaters from Parkandabad Treatment Plant were applied intermittent in columns filled with sandy loam soil. At The end of experiment, sampled of leachate were analyzed for parameters sach as pH, salinity, SAR, NO3-N, PO4-P, TOC, and two heavy metals of Cd and Ni. The results showed that the mean values of each of the above mentioned parameters, with the exception of pH, were lower in the leachate compared to the wastewaters entering the soil. However, with continuous application of wastewaters increase in the amount of these components was observed. Considering the effect of type of wastewater on values of above parameters, mean of pH value was significantly lower for raw wastewater (7.65) in the leachate as compared to the treated wastewater (7.71). NO3-N, PO4-P and Ni showed an opposite trend. The mean values of these parameters leached out from soil columns were 21.96, 0.055 and 0.015 (mg/l) for raw wastewater and 20.48, 0.024 and 0.012 (mg/l) for treated wastewater, respectively. Type of wastewater did not have any significant effect on other parameters. In generall, with respeet to the amount of SAR, NO3-N and TOC in the leachate as well as Ni and Cd specially in the raw wastewater and their hazardous consequences, their long-term disposals on soils need sound and suitable management practices.
Key words: Raw wastewater, Treated wastewater, Chemical characteristics of leachate, Soilu column