Research Article
Irrigation
M. Fallahi khoshhi; A.R. Karbalaee Doree; Z. Hedjazizadeh; P. Hamezadeh
Abstract
Introduction
The large temporal and spatial changes of precipitation, especially in mountainous areas, have turned it into a controversial variable in climate models. Measuring precipitation (rain and snow) along with its distribution and changes is very important to improve our understanding of global ...
Read More
Introduction
The large temporal and spatial changes of precipitation, especially in mountainous areas, have turned it into a controversial variable in climate models. Measuring precipitation (rain and snow) along with its distribution and changes is very important to improve our understanding of global water cycle and energy, water resources monitoring, hydrological modeling. Lack of reliable data is one of the most important challenges in rainfall analysis. Due to the significant temporal and spatial variability of precipitation in mountainous areas, accurate spatially distributed data is crucial for effective water resource assessment and management. However, many mountainous regions have limited rain gauge stations. Today, satellite products are commonly used to measure precipitation in these areas, but the variability among these products raises concerns about their accuracy in mountainous regions. Additionally, the quality of satellite products differs between various products and across different climatic regions, making it essential to thoroughly evaluate them before use. The purpose of this research was to evaluate the precipitation data of two satellite products (GPM, PERSIAN) and reanalysis data (ECMWF) in the estimation of precipitation in mountainous areas without stations in Lorestan province.
Method
This study utilized rainfall data from 24 synoptic and rain gauge stations across Lorestan province. Emphasis was placed on stations situated in or near mountainous regions. The selected stations were chosen based on their suitable spatial distribution and record length. The rainfall data spanned the period from 2015 to 2021 and included daily, monthly, and annual measurements. To evaluate satellite rainfall algorithms and estimate rainfall in regions with limited data, data from the GPM and PERSIAN satellites were employed, along with ECMWF reanalysis data. The PERSIAN rainfall algorithm is a remote sensing-based method that utilizes artificial neural networks. It calibrates infrared data with passive microwave estimates and converts longwave infrared images into rainfall estimates using a three-step process. The spatial resolution of this product is 0.25° x 0.25°, and it offers hourly, daily, and monthly temporal resolution. The PERSIAN rainfall algorithm data can be accessed from https://chrsdata.eng.uci.edu. The GPM mission aims to provide continuous observations of Earth's precipitation. It employs the GPM Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR) to observe both snow and rain. The final product, called IMERG, is generated through multiple runs of the algorithm for each observation time. Initial estimates are quickly provided, and subsequent estimates improve as more information becomes available. The spatial resolution of the GPM product is 1° x 1°, and it offers hourly, daily, and monthly temporal resolution. IMERG data can be obtained from https://gpm.nasa.gov/data. CMWF reanalysis data is derived from the combination of short-term simulations of numerical weather prediction models with ground-based observational data. These simulations are controlled with observational data, and the resulting reanalysis database provides global coverage from 1979 with a spatial resolution ranging from 0.125° x 0.125° to 3°. The temporal resolution of ECMWF reanalysis data is hourly, daily, and monthly. More information about ECMWF data can be found at https://www.ecmwf.int/ (Azizi, 2019). To evaluate the accuracy of the products, R-squared correlation (R2), root mean square error (RMSE), standard deviation (MAD), correlation coefficient (R), error deviation (MBE) and Nash-Sutcliffe coefficient (NS) were used. Also, the probability of detection (POD), false alarm ratio (FAR), and critical success index (CSI) indices were used to validate the data.
Results
The results showed that none of the three products are suitable for estimating daily precipitation in mountainous areas. However, on a monthly scale, these products provide reasonable estimates. Among the three, the GPM satellite product demonstrated better accuracy on a monthly scale, based on error levels and the spatial distribution of estimated precipitation. On an annual scale, GPM also performed best, as indicated by both statistical errors and the spatial patterns of average annual precipitation. According to the MBE index, on daily and monthly scales, the ECMWF product tended to overestimate precipitation, while the PERSIANN and GPM products underestimated it. On an annual scale, GPM and ECMWF products overestimated precipitation, whereas PERSIANN underestimated it.
Research Article
Soil science
D. Parmah; H.R. Chaghazardi; F. Mondany; A. Beheshti Ale Agha; D. Kahrizi
Abstract
IntroductionOptimum yield production under rainfed cultivation directly depends on the amount of rainfall and moisture storage in the soil. The tillage system directly influences soil moisture retention as well as the soil’s physical and chemical properties. Selecting the appropriate tillage system ...
Read More
IntroductionOptimum yield production under rainfed cultivation directly depends on the amount of rainfall and moisture storage in the soil. The tillage system directly influences soil moisture retention as well as the soil’s physical and chemical properties. Selecting the appropriate tillage system can significantly impact crop yields. Oilseeds are particularly important among crops, representing the second-largest food reserve in the world after grains. These products are rich in fatty acids. Today, the oil extraction and production industry is one of the most strategic industries in most countries. Iran has vast arable land and favorable conditions for cultivating oilseeds. However, according to available statistics, over 80% of the country's oil needs are met through imports. Given the increasing demand for higher-quality oil products and the challenges posed by climate issues, such as recurring droughts, cultivating and developing crops with lower water requirements and greater resilience appears to be a promising solution. Implementing effective management practices and appropriate fertilizers aligned with conservation agriculture could help increase crop yields while maintaining and improving long-term soil quality. To explore the potential of oilseed cultivation, an experiment was conducted to examine the effects of tillage and fertilization on the yield and yield components of safflower under rainfed conditions. Materials and MethodsThis experiment was carried out as split plots based on random complete blocks design, with three replications under rainfed conditions. The treatments included tillage systems (conventional tillage, reduced tillage, and no-tillage) as the main factor and NPK fertilizer (a mixture of urea, triple superphosphate, and potassium sulfate) at four levels of zero, 33, 66, and 100% as a secondary factor. Potassium and phosphorus fertilization and 50% of nitrogen fertilizer were used at the same time as planting, and the remaining 50% of nitrogen fertilizer was used four months after planting. Each block had three main plots; the distance between each block was 3 meters, and between the main plots was 2 meters. In each main plot, four sub-plots were created, and the distance between the sub-plots was 1 meter. The area of the main plots was 21 × 15 meters, and the area of each sub-plot was 4.5 ×15 meters. The amount of seed used for safflower was 25 kg per hectare. The safflower seeds were sown in 5 rows and planted at a distance of 50 cm and a distance between plants of 10 cm. At all stages of planting, maintenance, and harvesting, agricultural management followed the traditional practices of the study area, as performed by the local farmers. The final sampling, or harvesting, was carried out manually at the physiological maturity stage. Before conducting variance analysis, a normality test was performed on the data. In this research, the LSD test was used to compare the mean at the 5% probability level, Excel software was used to draw graphs, and SAS 9.4 software was used to analyze the data. Results and DiscussionThe research showed that the traits examined, including leaf area index, dry matter content, thousand seed weight, seed yield, and biological yield, were affected by the tillage system, fertilizer, and their interaction effect. The highest safflower seed yield of 195.6 g/m2 was obtained from the fertilizer ratio of 33% and conventional tillage, and the lowest seed yield of 116.2 g/m2 was obtained from no-tillage and no fertilizer use. The results indicated that the conventional tillage system outperformed both reduced tillage and no-tillage systems. In reduced and no-tillage systems, the changes in the leaf area index of the safflower plant were similar, with the 100% fertilizer application under reduced tillage having a more pronounced effect compared to no-tillage. Additionally, in the absence of fertilizer in the no-tillage system, the leaf area index was lower. Fertilizer application increased the plant's biological yield, but its impact was greater under conventional tillage compared to reduced and no-tillage systems. Applying 33% of the required fertilizer in the conventional tillage system resulted in the highest biological yield for safflower, leading to a 94% increase in biological performance compared to the control. ConclusionIn most of the examined traits, the application of 33 and 66% of the fertilizer requirement caused the best results, and the 100% fertilizer ratio left adverse effects, which indicates the lower fertilizer requirement of this cultivar in the studied conditions compared to cultivars in other regions. Since the research was conducted in rainy years, conventional tillage was better than low tillage. It is suggested that this plant's production amount be evaluated under different irrigation conditions and moisture limitations so that tillage systems and management methods can be examined and selected more carefully.
Research Article
Soil science
F. Rakhsh; A. Golchin; A. Beheshti Ale Agha
Abstract
Introduction
Soil texture is one of the most influential characteristics that affects the decomposition and retention of soil organic matter, as it directly or indirectly impacts the soil's physical, chemical, and biological properties. Soil clays play an important role in soil organic matter stability. ...
Read More
Introduction
Soil texture is one of the most influential characteristics that affects the decomposition and retention of soil organic matter, as it directly or indirectly impacts the soil's physical, chemical, and biological properties. Soil clays play an important role in soil organic matter stability. Organic matter adsorbed on phyllosilicate clays is more resistant to microbial decomposition than organic matter that has not interacted with any mineral. Exchangeable cations through the influence of physical and chemical characteristics of the soil probably cause changes in the absorption and retention of organic matter. In previous studies, the effect of soil texture on organic matter retention has been investigated, but the impact of clay type and exchange cation has not been investigated. This study aimed to examine the effect of different contents of vermiculite and zeolite clays and exchange cations on the mineralization of organic nitrogen.
Materials and Methods
A factorial experiment was conducted in a completely randomized design with three replications to study the effect of the type and content of clay and the type of exchange cations on organic nitrogen dynamics. Experimental treatments include two types of clay (vermiculite and zeolite), four different levels of clay (0, 15, 30, and 45%), and three types of exchangeable cations (Na+, Ca2+, and Al3+). The experiment included 24 treatments and three replications. There were total of 72 experimental units. Artificial soil of 50 grams was prepared separately according to the amount and type of clay and the type of exchange cation. "Next, alfalfa plant residues were added to all samples at a rate of 5% w/w. After inoculating and air-drying the samples, the moisture content was adjusted to 60% of the field capacity (FC) using distilled water. To prevent excess water from affecting the final moisture readings, the samples were first air-dried, and then sufficient distilled water was added to each sample to achieve 60% of FC. The samples were then kept in the dark for 60 days at a temperature of 23 °C. Distilled water was added and sealed to the bottom of the incubation jars to keep the moisture content of the soil samples constant during incubation. The percentage of mineralized nitrogen, microbial biomass nitrogen, and the activity of acid and alkaline phosphatase and cellulase enzymes were determined in the prepared samples. The data were analyzed using ANOVA, and the means were compared using Duncan's Multiple Range Test (DMRT). Before applying ANOVA, the data's normality and variance homogeneity were checked using Kolmogorov- Smirnov and Levene tests, respectively. The SPSS software (Windows version 25.0, SPSS Inc., Chicago, USA) and SAS software (version 9.4, SAS Institute Inc., Cary, NC) were employed for data analysis.
Results and Discussion
The results of variance analysis of the data showed that the effect of the type and content of clay and the type of exchangeable cation on the percentage of mineralized nitrogen, microbial biomass nitrogen, and the activity of acid and alkaline phosphatase and cellulase enzymes were significant (p< 0.01). The results revealed that, regardless of the duration of the samples, with the increase in the amount of clay, the percentage of inorganic nitrogen and the activity of enzymes decreased, but the nitrogen of microbial biomass increased. The highest percentage of inorganic nitrogen was obtained 60 days after incubation of the samples and in clays saturated with calcium, and the lowest amount of these attributes was obtained 15 days after incubation of the samples and in clays saturated with aluminum. The results showed that nitrogen mineralization increased with the samples' incubation time. Also, the highest percentage of mineralized nitrogen, microbial biomass nitrogen, and enzyme activity were observed in soils with vermiculite.
Conclusion
The increase in the incubation duration enhanced the percentage of inorganic nitrogen. The percentage of mineralized nitrogen and microbial biomass nitrogen was higher in soils with vermiculite than in soils with zeolite. Moreover, regardless of the incubation duration of samples, with increasing clay content, the percentage of mineralized nitrogen and enzyme activity decreased, but with increasing clay nitrogen content, microbial biomass increased. The highest and lowest amounts of mineralized nitrogen and nitrogen of microbial biomass were measured in soils with calcium and aluminum, respectively. The results showed the effect of the clay type and content and the exchangeable cation type on organic nitrogen dynamics.
Research Article
Soil science
F. Jannati; F. Sarmadian
Abstract
IntroductionResearch and development in high-potential agricultural areas are of great importance for ensuring the food needs of the population and livestock. Neglecting these regions can lead to increased food prices and food shortages, which can have a negative impact on the economy and public health. ...
Read More
IntroductionResearch and development in high-potential agricultural areas are of great importance for ensuring the food needs of the population and livestock. Neglecting these regions can lead to increased food prices and food shortages, which can have a negative impact on the economy and public health. Land suitability maps provide essential information for agricultural planning and are vital for reducing land degradation and evaluating sustainable land use. The utilization of modern mapping techniques such as digital soil mapping and machine learning algorithms can significantly improve the accuracy of land suitability assessment and crop performance prediction. These methods have been widely employed as primary tools for mapping and evaluating land suitability in various regions worldwide. Materials and MethodsIn this study, a total of 288 soil profiles were utilized to compute the land suitability index for wheat, barley, and alfalfa crops. Various environmental variables were included, such as topographic factors derived from the digital elevation model and spectral indices obtained from Landsat 8 satellite imagery. Eight key factors, namely slope percentage, climate, texture, gypsum content, equivalent calcium carbonate, electrical conductivity (EC), and sodium absorption ratio (SAR), were identified as influential in the assessment of land suitability. To quantify the degrees of land suitability for the target crops, a parametric approach based on the square root method was employed. Moreover, the random forest machine learning model was utilized for spatial modeling, zoning mapping, and determining the significance of environmental variables in the land suitability evaluation process. By incorporating these comprehensive methodologies, a more detailed and accurate understanding of the land suitability for wheat, barley, and alfalfa cultivation can be achieved, facilitating informed decision-making in agricultural planning and land management strategies. Results and DiscussionThe spatial prediction results demonstrated the effectiveness of the random forest model in classifying land suitability for wheat, barley, and alfalfa. The model achieved high accuracy, with Kappa coefficients of 81%, 84%, and 85% for wheat, barley, and alfalfa, respectively. The overall accuracies were also impressive, reaching 86% for wheat, 88% for barley, and 89% for alfalfa. Analyzing the land suitability assessment results, it was found that barley had the highest land suitability class, covering a significant portion of 40% in class S1. Alfalfa followed closely with 35.5% of the total area, and wheat occupied 32% in the same class. Delving into the predictive environmental variables for barley, Diffuse, SHt, and MrVBF emerged as the most influential factors. These variables played a crucial role in assessing the suitability of land for barley cultivation. Similarly, for wheat, the variables Diffuse, MrVBF, and TWI were identified as significant indicators, contributing to the accurate prediction of wheat performance. Regarding alfalfa, the variables MrVBF, Diffuse, and Valley_depth stood out as the most important variables, providing valuable insights into land suitability for alfalfa cultivation. In general, the limiting factors for irrigated cultivation of these crops were primarily associated with soil properties. In the northern regions, soil texture was identified as a significant limiting factor, impacting the suitability of the land for crop cultivation. On the other hand, in the southern regions, soil characteristics such as the percentage of lime, gypsum, salinity, and alkalinity were recognized as the most influential limiting factors, affecting the suitability of the land for successful crop production. These findings provide valuable information for land planners, farmers, and decision-makers in determining suitable areas for wheat, barley, and alfalfa cultivation. By considering the identified influential factors and addressing the limiting soil properties, agricultural practices can be optimized to maximize crop productivity and ensure sustainable land use. ConclusionThe research aimed to evaluate land suitability for wheat, barley, and alfalfa crops under irrigation. Data selection focused on the most limiting factors for these crops. The model achieved acceptable predictions for wheat, barley, and alfalfa, with Kappa coefficients of 0.81, 0.85, and 0.84, and overall accuracies of 0.86, 0.89, and 0.88, respectively. Barley had the highest percentage of suitable land (40%), followed by alfalfa (39.5%) and wheat (32%). Soil constraints varied across the study area, including texture, stoniness, lime, gypsum, salinity, and alkalinity. The analysis identified 31 soil types, and the random forest model yielded a digital soil map with a Kappa coefficient of 0.76 and overall accuracy of 0.81. The findings support effective land management and agricultural planning.
Research Article
Soil science
Z. Movahedi Rad; M. Hamidpour
Abstract
Introduction Recently, layered double hydroxides (LDHs) have attracted significant attention due to their various applications, particularly as slow-release fertilizers for essential plant nutrients. Several studies have reported the release of nitrate and phosphorus from LDHs. Additionally, micronutrients ...
Read More
Introduction Recently, layered double hydroxides (LDHs) have attracted significant attention due to their various applications, particularly as slow-release fertilizers for essential plant nutrients. Several studies have reported the release of nitrate and phosphorus from LDHs. Additionally, micronutrients such as zinc (Zn), copper (Cu), and manganese (Mn) can be structurally incorporated into the metal hydroxide layers. Recent research indicates that LDHs have considerable potential for releasing these micronutrients. However, further studies are needed to enhance our understanding of the mechanisms and reactions of LDHs under different conditions. Currently, there is a lack of information regarding the divalent (M2+) to trivalent cation (M3+) ratios in LDHs and the influence of malic acid on the release of Zn, Mn, and magnesium (Mg) from these compounds. This study aimed to investigate the effects of malic acid and the ratio of M2+/M3+ on the kinetics release of Zn, Mn and Mg from Mg-Zn-Mn-Al-LDH intercalated with nitrate. Materials and MethodsAll chemicals used in this study including malic acid (C4H6O5), KCl, Zn(NO3)2.6H2O, Mn(NO3)2.4H2O, Mg(NO3)2.6H2O and Al(NO3).9H2O were of analytical grades, purchased from Chem-Lab or Merck Chemical Corporations. The solutions were made with the decarbonated ultrapure water (electrical resistivity = 18 MΩcm). The LDHs were synthesized by co-precipitation method at constant pH=9.2-9.6. Two types of LDHs were synthesized with varying the M+2(Zn+Mn+Mg)/M+3(Al) 3:1 and 4:1 in the precursor solution while being stirred vigorously in a nitrogen atmosphere. The pH was kept at 9.2-9.6 by adding volumes of 3 M NaOH. The crystals of LDH were ripened in the mixture for 2 h and after that, the precipitates were centrifuged at 3000 rpm for 20 min and washed several times with distilled water and placed in an oven at 70 °C for 8 h to dry. The chemical composition of the synthesized LDHs was determined by furnace atomic absorption spectrophotometry (SavantAA, GBC) after acid digestion. The physical, chemical, and morphological characteristics of the LDHs were determined using X-ray diffraction analysis (Panalytical x Pert ProX-ray diffractometer), Fe-SEM (Sigma VP), FT-IR (Nicolet iS10 spectrometer), and BET (BELSORP Mini II) techniques. A batch study was done to determine the effect of different ratios of M2+/M3+ in LDHs and the effect of malic acid on release of Zn, Mn, and Mg from LDH (3:1) and LDH (4:1). Briefly, 0.01 g of synthesized LDH were put in a centrifuge tube mixed with 10 ml background electrolyte (KCl 0.01 M) and 1.25 mM malic acid in initial pH=6-7 and constant temperature (25±0.5 °C). Blank samples (without ligand) were also considered. Suspensions were shaken at periods ranging from 5 to 720 min agitation (180 rpm). Then, the supernatant solution was separated using a centrifuge at a speed of 4000 rpm for 20 min. Zn, Mn, and Mg concentrations in supernatants solutions were determined by graphite furnace atomic absorption spectrophotometry. The effect of pH in the range of 5 to 10 on the release of Zn, Mn, and Mg from LDH was also studied. Two equations (pseudo-second-order and Elovich) were used to fit the kinetics data. Results and DiscussionThe results showed that the calculated molar ratio of divalent cation to trivalent cation was similar to their molar ratio in the solution prepared for the synthesis of LDH samples. The X-ray diffraction patterns of LDH (3:1) and LDH (4:1) samples showed the existence of strong and sharp peaks for 003 and 006 plates. Accordingly, the reflections of the 003 and 006 plates revealed the layered structure of the synthesized LDH materials. Two bands of FT-IR spectrums around 3480 and 1620 cm-1 for all synthesized LDH materials designated stretching vibrations of the O-H group of hydroxide layers and the interlayer water molecules. The sharp characteristic band around 1382 cm−1 in LDH (3:1) and band around 1354 cm-1 in LDH (4:1) was attributed to the antisymmetric stretching mode of nitrate anion in LDH. The specific surface area of LDH (3:1) and LDH (4:1) were 5.50 m2g-1 and 16.54 m2g-1 respectively. The average pore diameters in LDH (3:1) and LDH (4:1) were 1.92 nm and 2.55 nm, respectively. Time-dependent cumulative release of Zn, Mn, and Mg from LDH (3:1) and LDH (4:1) in the presence and absence of malic acid was investigated. Time-dependent Zn, Mn, and Mg release from LDH (3:1) and LDH (4:1) was accelerated in the presence of malic acid. The Zn, Mn, and Mg release from the LDHs was likely to be separated into two stages. In the initial stage from 0 to 60 min, the release rate of Zn, Mn, and Mg was rapid, then either remained constant or slightly enhanced during 60–720 min. In this research, among the non-linear models used to determine the release kinetics of Zn, Mn, and Mg, the result with the highest R2 values was chosen. The R2 values were 0.91–0.99, 0.93–0.99, 0.93–0.99, 0.89-0.99, and 0.55–0.86 for pseudo-first-order, pseudo-second-order, Elovich, power function, and parabolic diffusion, respectively. So, pseudo-second-order and Elovich models were used to analyze kinetic data. The amounts of release of Zn, Mn and Mg were higher from LDH (4:1) than from LDH (3:1) because of greater specific surface area, volume, and pore diameter in LDH (4:1). A comparison of metal release versus time profiles exhibited that dissolution was greatly dependent on the pH. ConclusionThe results of this research indicated that the release of Zn, Mn, and Mg from layered double hydroxides (LDHs) was influenced by factors such as time, ligand, solution pH, and the type of LDH. According to the kinetics models fitted to the experimental data, the release rate of Zn, Mn, and Mg from LDH (4:1) was higher than that from LDH (3:1). In both types of LDHs, the presence of malic acid significantly increased both the rate and amount of Zn, Mn, and Mg release compared to the absence of malic acid. While this study demonstrated that varying the ratios of divalent to trivalent cations can influence the amount and rate of Zn and Mn release, further greenhouse studies are required to confirm the effectiveness of LDH as a slow-release fertilizer in calcareous soils.
Research Article
Soil science
Z. Barati; H.R. Owliaie; E. Adhami; M. Najafi-Ghiri
Abstract
IntroductionRecently, layered double hydroxides (LDHs) have attracted significant attention due to their variousapplications, particularly as slow release fertilizers for essential plant nutrients. Several studies have reported therelease of nitrate and phosphorus from LDHs. Additionally, micronutrients ...
Read More
IntroductionRecently, layered double hydroxides (LDHs) have attracted significant attention due to their variousapplications, particularly as slow release fertilizers for essential plant nutrients. Several studies have reported therelease of nitrate and phosphorus from LDHs. Additionally, micronutrients such as zinc (Zn), copper (Cu), andmanganese (Mn) can be structurally incor porated into the metal hydroxide layers. Recent research indicates thatLDHs have considerable potential for releasing these micronutrients. However, further studies are needed toenhance our understanding of the mechanisms and reactions of LDHs under diff erent conditions. Currently, thereis a lack of information regarding the divalent (M 2+2+) to trivalent cation (M 3+3+) ratios in LDHs and the influence ofmalic acid on the release of Zn, Mn, and magnesium (Mg) from these compounds. This study aimed toinvesti gate the effects of malic acid and the ratio of M 2+2+/M 3+ on the kinetics release of Zn, Mn and Mg from MgZn Mn Al LDH intercalated with nitrate nitrate.Materials and MethodsAll chemicals used in this study including malic acid (C4H6O5), KCl, Zn(NO3)2.6H2O, Mn(NO3)2.4H2O, Mg(NO3)2.6H2O and Al(NO3).9H2O were of analytical grades, purchased from Chem-Lab or Merck Chemical Corporations. The solutions were made with the decarbonated ultrapure water (electrical resistivity = 18 MΩcm). The LDHs were synthesized by co-precipitation method at constant pH=9.2-9.6. Two types of LDHs were synthesized with varying the M+2(Zn+Mn+Mg)/M+3(Al) 3:1 and 4:1 in the precursor solution while being stirred vigorously in a nitrogen atmosphere. The pH was kept at 9.2-9.6 by adding volumes of 3 M NaOH. The crystals of LDH were ripened in the mixture for 2 h and after that, the precipitates were centrifuged at 3000 rpm for 20 min and washed several times with distilled water and placed in an oven at 70 °C for 8 h to dry. The chemical composition of the synthesized LDHs was determined by furnace atomic absorption spectrophotometry (SavantAA, GBC) after acid digestion. The physical, chemical, and morphological characteristics of the LDHs were determined using X-ray diffraction analysis (Panalytical x Pert ProX-ray diffractometer), Fe-SEM (Sigma VP), FT-IR (Nicolet iS10 spectrometer), and BET (BELSORP Mini II) techniques. A batch study was done to determine the effect of different ratios of M2+/M3+ in LDHs and the effect of malic acid on release of Zn, Mn,and Mg from LDH (3:1) and LDH (4:1). Briefly, 0.01 g of synthesized LDH were put in a centrifuge tube mixed with 10 ml background electrolyte (KCl 0.01 M) and 1.25 mM malic acid in initial pH=6-7 and constant temperature (25±0.5 °C). Blank samples (without ligand) were also considered. Suspensions were shaken at periods ranging from 5 to 720 min agitation (180 rpm). Then, the supernatant solution was separated using a centrifuge at a speed of 4000 rpm for 20 min. Zn, Mn, and Mg concentrations in supernatants solutions were determined by graphite furnace atomic absorption spectrophotometry. The effect of pH in the range of 5 to 10 on the release of Zn, Mn, and Mg from LDH was also studied. Two equations (pseudo-second-order and Elovich) were used to fit the kinetics data.Results and DiscussionThe results showed that the calculated molar ratio of divalent cation to trivalent cation was similar to their molar ratio in the solution prepared for the synthesis of LDH samples. The X-ray diffraction patterns of LDH (3:1) and LDH (4:1) samples showed the existence of strong and sharp peaks for 003 and 006 plates. Accordingly, the reflections of the 003 and 006 plates revealed the layered structure of the synthesized LDH materials. Two bands of FT-IR spectrums around 3480 and 1620 cm-1 for all synthesized LDH materials designated stretching vibrations of the O-H group of hydroxide layers and the interlayer water molecules. The sharp characteristic band around 1382 cm−1 in LDH (3:1) and band around 1354 cm-1 in LDH (4:1) was attributed to the antisymmetric stretching mode of nitrate anion in LDH. The specific surface area of LDH (3:1) and LDH (4:1) were 5.50 m2g-1 and 16.54 m2g-1 respectively. The average pore diameters in LDH (3:1) and LDH (4:1) were 1.92 nm and 2.55 nm, respectively. Time-dependent cumulative release of Zn, Mn, and Mg from LDH (3:1) and LDH (4:1) in the presence and absence of malic acid was investigated. Time-dependent Zn, Mn, and Mg release from LDH (3:1) and LDH (4:1) was accelerated in the presence of malic acid. The Zn, Mn, and Mg release from the LDHs was likely to be separated into two stages. In the initial stage from 0 to 60 min, the release rate of Zn, Mn, and Mg was rapid, then either remained constant or slightly enhanced during 60–720 min. In this research, among the non-linear models used to determine the release kinetics of Zn, Mn, and Mg, the result with the highest R2 values was chosen. The R2 values were 0.91–0.99, 0.93–0.99, 0.93–0.99, 0.89-0.99, and 0.55–0.86 for pseudo-first-order, pseudo-second-order, Elovich, power function, and parabolic diffusion, respectively. So, pseudo-second-order and Elovich models were used to analyze kinetic data. The amounts of release of Zn, Mn and Mg were higher from LDH (4:1) than from LDH (3:1) because of greater specific surface area, volume, and pore diameter in LDH (4:1). A comparison of metal release versus time profiles exhibited that dissolution was greatly dependent on the pH.ConclusionTheresults of this research indicated that the release of Zn, Mn, and Mg from layered double hydroxides(LDHs) was influenced by factors such as time, ligand, solution pH, and the type of LDH. According to thekinetics models fitted to the experimental data, the release rate of Zn, Mn, and Mg from LDH (4:1) was higherthan that from LDH (3:1). In both types of LDH s , the presence of malic acid significantly increased both the rateand amount of Zn, Mn, and Mg release compared to the absence of malic acid. While this study demonstratedthat varying the ratios of divalent to trivalent cations can influence the amount and rate of Zn and Mn release,further greenhouse studies are required to confirm the effectiveness of LDH as a slow release fertilizer incalcareous soils.
Research Article
Agricultural Meteorology
A. Khedri; A. Saberinasr; N. Kalantari
Abstract
Introduction The comprehension of the hydrogeological conditions of the aquifer and the determination of its hydraulic characteristics, such as hydraulic conductivity, transmissivity coefficient, and specific storage, are crucial for the management and preservation of groundwater resources. Various ...
Read More
Introduction The comprehension of the hydrogeological conditions of the aquifer and the determination of its hydraulic characteristics, such as hydraulic conductivity, transmissivity coefficient, and specific storage, are crucial for the management and preservation of groundwater resources. Various conventional methods, including empirical formulas, laboratory techniques (constant and falling head), tracer tests, field tests (Lugeon, Lefranc, slug, flowmeter, and pumping tests), and groundwater inverse modeling, are employed to establish these characteristics, particularly hydraulic conductivity. Empirical formulas are limited to ideal conditions, and in laboratory methods, the sample must be kept undisturbed. Due to the impracticality of measuring large-scale effective factors, the hydraulic conductivity determined through laboratory methods is also the only representative of the hydraulic conductivity at the sampling point. Tracer studies encounter numerous constraints, such as time, cost, porosity determination, and tracer dispersion in multilayered aquifers. It is also difficult to determine the average hydrodynamic properties of the heterogeneous aquifer based on the data obtained from a specific section of the Lefranc and Slug tests. Consequently, pumping tests are commonly selected for hydraulic parameter estimation. Although costly and time-intensive, these tests provide more precise coefficients. Geophysical methods have been greatly developed during the last two decades and have shown a significant correlation with the hydraulic parameters of the aquifer derived from borehole pumping tests or direct laboratory measurements. This approach minimizes uncertainties in numerical model calibration, improves data coverage, and reduces the time and cost of regional hydrogeological investigations. The conventional approach, known as the electrical resistivity method, is still widely used in global and local research projects for evaluating aquifer hydraulic characteristics (Ige et al., 2018; Arétouyap et al., 2019; Youssef, 2020; Ullah et al., 2020; de Almeida et al., 2021; Lekone et al., 2023). Therefore, this study aims to use the integrated approach of the geophysical method and pumping test as a cost-effective and efficient alternative for estimating the hydraulic parameters of the alluvial aquifer in the northeast of Gachsaran city. Material and Methods The research area is an alluvial aquifer located 5 km to the northeast of Gachsaran, between coordinates 50-52 to 51-09 E longitude and 30-15 to 30-28 N latitude. Using 86 vertical electrical soundings, Archie's equations, and the IPI2win software, the hydraulic characteristics of the aquifer under investigation were estimated. Subsequently, these characteristics were then compared to the coefficients derived from the data of two pumping test wells, which were calculated using the Aquifer test software and obtained via the Cooper-Jacob and Neuman methods. Results and discussion The hydrodynamic coefficients of the aquifer were initially determined using the Cooper-Jacob method in this study. The hydraulic conductivity values for wells one and two are 4.9 m/day and 5.7 m/day, respectively. Correspondingly, the storage coefficient values for wells one and two are 0.015 and 0.021, respectively. Based on the Cooper-Jacob approach, it is deduced that if the storage coefficient values exceed 0.001, the aquifer is classified as unconfined. In this study, the storage coefficient values for both pumping wells suggest that the aquifer is unconfined. Since the vertical flow component and the delayed yield phenomenon should also be taken into account in unconfiend aquifers, the Neuman analytical model has been used in the studied aquifer. The values of specific yield (Sy) for pumping wells one and two, which are related to delayed yield, are 0.05 and 0.04, respectively. These values were calculated by analyzing the first segment of the curve derived from the Neuman logarithmic drawdown-time plot. The storage coefficient values for pumping wells one and two, extracted from the second section of the curve, are 0.015 and 0.021, respectively. Furthermore, the transmissivity value for well number 1 was 323 m2/day, while for well number 2, it was 655.5 m2/day. The vertical electrical sounding (VES) data were subsequently initially analyzed and interpreted using the IPI2win software and the equalization curve method (partial curve matching technique). The coefficients denoted as m and n, indicative of the degree of cementation of the sediments, were determined based on the sedimentary composition prevalent in the area. Archie's equations were employed to calculate the formation factor and porosity parameters. The aquifer exhibits a porosity range of approximately 0.15 in the eastern and southeastern parts (near the outlet of the plain) and around 0.41 in the centeral, northern, and northwestern sections of the area (next to the Asmari Formation). The specific yield (Sy) of the aquifer was calculated using the provided formula: The minimum and maximum specific yield were estimated as 0.006 (in the eastern and southeastern regions) and 0.089 (in the western and northwestern regions of the plain), respectively, with an average value of 0.04. The transmissivity coefficients for the entire aquifer were then calculated based on the fitted relationship between hydraulic conductivity (K) and formation factor (F): The range of transmissivity coefficients varies from a minimum of 63 m2/day (in the western and northwestern sections of the plain) to a maximum of 608.9 m2/day (in the eastern and southeastern areas). The average transmissivity coefficient is calculated as 323.7 m2/day. To ensure the precision of the geoelectric method's coefficients, a comparative analysis was conducted with the hydrodynamic coefficients obtained from the two pumping test wells, as presented in the table below: Well No.K(m/d)T(m2/d)SyPT*VES*PTVESPTVES14.93.63232370.050.0525.75.5655.5632.50.040.03*PT: Pumping Test; VES: Vertical Electrical Sounding Conclusion The evaluation and comparison of the hydrodynamic coefficients derived from the aforementioned methods indicate that the geoelectric method coefficients exhibit acceptable agreement with the pumping test coefficients. In other words, the analysis of the pumping test conducted using the Neuman technique in the unconfined aquifer revealed that well number two displayed a greater transmissivity coefficient, while well number one presented a higher specific yield. These findings are confirmed by the geoelectric approach. Consequently, such hybrid approaches, which include simultaneous analysis of geophysical methods (such as VES) and pumping tests will be a great alternative to multiple costly pumping tests for evaluating the hydrodynamic coefficients of an aquifer. Moreover, employing this hybrid technique enables the generation of dense hydrodynamic coefficients in an aquifer for use as inputs in the groundwater model.
