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The effect of biochar application rate on soil nutrient and heavy metal phyto-availability may differ depending on soil properties. To investigate this hypothesis, a pot experiment was conducted with three soil types (yellow soil (YS), yellow-brown soil (YBS) (slightly alkaline), and calcareous soil (CS) (neutral soil)), using five biochar application rates: 0, 0.1%. 1.0%, 2.5%, and 5.0%. The results showed that the total organic carbon increased progressively in all three soil types, while the labile organic carbon only increased progressively in yellow soil with an increasing rate of biochar from 0% to 5%. The ammonia and Olsen-phosphorus concentrations increased with higher biochar rates for the slightly alkaline soils, but decreased significantly at higher rate for the neutral soil. Additionally, the application of biochar at 2.5% and 5.0% significantly reduced soil nitrate concentrations in slightly alkaline YS soil (by 31.10% and 37.83%) and YBS soil (by 65.96% and 76.70%) compared to the control, but did not change significantly in the neutral soil. Biochar application increased soil exchangeable potassium (K) concentration more significantly in high K soils compared to low K soil. The exchangeable calcium (Ca) concentration increased with increasing biochar rate if the exchangeable Ca was < 10.6 cmol kg−1. The effect of biochar application rate on phyto-availability of cadmium, copper, and nickel concentrations varied with the background soil value and soil pH. For all three types of soil, the phyto-availability of lead, chromium, and arsenic decreased significantly with increasing biochar rates. In conclusion, it is important to carefully consider soil type and pH when utilizing biochar as a soil amendment to maximize its efficiency. [ABSTRACT FROM AUTHOR]

Screening a suitable genotype is important for nutrient recovery and its acquisition potential. Twenty genotypes of tomato were studied under different doses of B-application. The indices of B use efficiencies, viz. apparent B recovery (ABR), fruit production efficiency (FPE), physiological efficiency (PE), agro-physiological efficiency (APE) and utilization efficiency ratio (UER) were worked out for tomato genotypes. The field experiment was laid out in a split-plot design for the two consecutive years, assigning three B levels (control i.e. without B application, @ 2.0 kg B ha−1 through borax and 0.25% boric acid foliar spray twice) in main plot and location-specific twenty tomato genotypes in subplots, replicated thrice. Soil applied B produced greater fruit yield than the twice foliar spray of 0.25% boric acid B. However, the tomato fruit yield was improved by 2–12% over control by soil applied B @ 2.0 kg B ha−1 through borax and twice foliar spray of B. Irrespective of genotypes, B content in fruit and shoot of tomato plant improved upon application of B. The apparent B recovery (ABR) and agronomic efficiency (AE) of B suggested that foliar application was more effective in comparison to soil application. The use efficiencies were highest in the cultivars NS–812 followed by NS–512 and B–9–2 in B-deficient calcareous soils with the application of 0.25% boric acid foliar spray twice. These genotypes could be a promising lines for breeding program for B enrichment in tomato for cultivation in B-deficient soils. [ABSTRACT FROM AUTHOR]

The low bearing capacity and high erosion potential of calcareous soils are major concerns in marine environments. Lime stabilization is one of the earliest and most widely used methods for improving the mechanical properties of these weak deposits. Nonetheless, the significant amount of air pollution and high energy consumption associated with lime production have led researchers to the exploration of alternative strategies, such as the utilization of supplementary materials to partially replace lime in the stabilization process. In this study, the mechanical behavior of calcareous sand specimens stabilized with 4%, 6%, and 8% of hydrated lime and zeolite-to-lime replacement proportions of 0%, 15%, 30%, 45%, 60%, and 75% was examined through a comprehensive set of unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) tests. The specimens were also subjected to consecutive wetting and drying cycles so that the effects of hydrated lime and zeolite proportions on the durability characteristics of treated calcareous sands were discussed. Results indicated that, in all lime contents, the UCS and constrained modulus (D) of treated samples reached their peak values when lime was substituted with zeolite at an optimum percentage of 60%. Additionally, it was observed that after four and eight wet–dry cycles, the optimum zeolite replacement ratio decreased to 45% and 30%, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests were also conducted to achieve a better understanding of the microstructural changes in calcareous sands due to the stabilization with hydrated lime and zeolite. Practical Applications: The stabilization of noncohesive soils such as marine calcareous sands with lime has been a subject of interest among geotechnical engineers in recent decades. Due to the significant air pollution and high energy consumption associated with lime production, alternative strategies, such as using supplementary materials to partially replace lime, are deemed an attractive approach. In this study, the mechanical behavior of a calcareous sand (obtained from Hormuz Island as a strategic island in the Persian Gulf) stabilized with 4%, 6%, and 8% of hydrated lime and zeolite-to-lime replacement proportions of 0%, 15%, 30%, 45%, 60%, and 75% was evaluated through a series of UCS and UPV tests. Additionally, the influence of wetting and drying cycles on the strength and stiffness characteristics of treated Hormuz Island soil has also been studied; the topic which can be very significant due to the effects of waves and sea tides on the soil and structures of marine regions. Based on the experimental results, replacing lime with zeolite could efficiently improve the mechanical behavior of calcareous sand specimens, specifically when subjected to consecutive wet–dry cycles. In particular, 45% and 30% of zeolite replacement were shown to be the best substitutes for lime after four and eight cycles of wetting and drying, respectively. [ABSTRACT FROM AUTHOR]

Healthy ageing plays an important role in ageing societies in many countries, and centenarians are a sign of longevity. Longevity and its determinants have become issues of global concern and also a focus of research. Although many disciplines have conducted out a series of studies on longevity phenomena, few studies have systematically considered the impact of geographical environmental factors. Guangxi is one of the provinces with the highest centenarian ratio in mainland China, while Hechi City has the highest ratio of centenarians in Guangxi Province, and contains the world-famous longevity belt. This study took Hechi City, "the world's longevity city", as a model research area. First, the basic characteristics of the geographical environmental factors in Hechi City were analysed, and then geographical information system techniques and eXtreme Gradient Boosting machine learning methods were applied to systematically analyse the coupling relationship between the spatial distribution of the longevity population and the geographical environmental factors. In addition, the geographical environmental factors closely related to longevity were filtered and investigated. It was found that the centenarian is distributed along a belt-like pattern. It is mostly located in rocky mountainous areas with low elevations, small to medium undulations, medium slopes and brown calcareous soils, but is rarely found near the non-ferrous mining industry. This work provides a scientific basis for identifying the mechanisms that contribute to regional longevity and theoretical references for improving the health level of the elderly population according to local conditions. [ABSTRACT FROM AUTHOR]

AbstractZinc is a critical mineral nutrient for plants and animals, yet soils in the Mediterranean region often have low zinc levels. Mineral fertilizers, commonly used to address this deficiency, pose environmental risks, making mycorrhizal fungi a sustainable alternative. These fungi enhance nutrient uptake, including zinc, from the soil. This study investigated the effects of Funneliformis mosseae mycorrhizal inoculation on the mycorrhizal dependency of pepper (Capsicum annuum L.), tomato (Lycopersicon esculentum Mill), and eggplant (Solanum melongena L.) under varying zinc fertilization conditions. Seedlings were cultivated in glasshouse conditions, with sterile and non-sterile Zn-deficient calcareous soils, both with and without 6 mg Zn kg−1 application. Mycorrhizae were introduced at transplanting, and parameters such as shoot dry weight, root colonization, and shoot zinc and phosphorus concentrations were measured at harvest to calculate mycorrhizal dependency. Results revealed that under low zinc and phosphorus fertility, mycorrhizal inoculation significantly enhanced root colonization, plant biomass, and nutrient concentrations. While zinc fertilization improved tissue zinc and phosphorus concentrations, mycorrhizal inoculation alone had a greater impact, particularly in pepper plants, which displayed twice the mycorrhizal dependency of tomato and eggplant. In zinc-deficient conditions, mycorrhizal inoculation contributed up to twice as much to plant development compared to zinc fertilization alone. The study concluded that mycorrhiza inoculation could effectively replace or compensate the zinc fertilizers, providing a sustainable solution for enhancing plant growth and Zn and P uptake. [ABSTRACT FROM AUTHOR]

Excessive and inappropriate nitrogen (N) fertilizer applications on calcareous soils result in significant losses, necessitating a targeted approach for improved efficiency and yield. Field experiments were conducted over two seasons to develop a strategy for root-zone (RZ) N fertilization for wheat. In the first season, three methods of N fertilizer application were used: surface (SF), in the RZ at a depth of 10 cm (RZF10), and in the RZ at a depth of 20 cm (RZF20). The N fertilizer was applied in a range of 0–280 kg N ha−1. In the second season, another experiment was carried out to validate the results. The data showed that to achieve maximum yield levels, N fertilizer rates of 264 kg ha−1 for SF, 218 kg ha−1 for RZF10, and 183 kg ha−1 for RZF20 were required. The findings also revealed that relocating the application from the surface to depths of 10 and 20 cm resulted in an increase in recovery efficiency by 11.2% and 31.2%, respectively. A linear equation established the relationship between the response index at harvest (RI-Harvest) and the corrective N rate for RZF20. The in-season response index of the normalized difference vegetation index effectively predicted RI-Harvest, leading to the development of an empirical equation to predict the corrective N rate. The validation experiment demonstrated the effectiveness of the proposed strategy in adjusting N rates based on crop-specific needs. This approach allows growers to optimize profits by carefully applying N in the RZ, eliminating both excessive and inadequate use. [ABSTRACT FROM AUTHOR]

Introduction Soil pollution with heavy metals such as cadmium has become a global environmental concern. Adsorption is widely used as a remediation method due to its advantages, including cost-effectiveness and high performance in removing metal ions. Biochar is an effective way to improve soil properties and act as a sorbent for various toxins. In particular, nanobiochar, with its unique properties such as high specific surface area, has the potential to be one of the most effective soil amendments. Nanobiochar has gained attention recently due to its unique properties and potential applications in various fields. Its high specific surface area and small particle size make it an effective adsorbent for polluted soils and water contaminants. Nanobiochar has demonstrated the ability to adsorb many pollutants, including heavy metals, organic compounds, and nutrients, making it a promising material for environmental remediation. Despite the potential applications of nanobiochar, more research is needed to fully understand its properties and potential uses. The field of nanobiochar is still emerging, and many questions remain unanswered. Furthermore, the importance of nanobiochar in remediating polluted calcareous soils is not well known. This study aimed to investigate the effect of nanobiochar made from reed on the cadmium adsorption isotherms and kinetics in polluted calcareous soil. Materials and Methods For this research, a composite soil sample was collected from a depth of zero to 30 cm from the farm of the Faculty of Agriculture, Shahid Chamran University of Ahvaz. The soil sample was air-dried and passed through a two-mm sieve, then some physical and chemical characteristics of the soil were measured. To prepare biochar, the raw common reed was collected, air-dried, and passed through a two-mm sieve, and the common reed was soaked in 0.5 M FeCl2. The raw and Fe-soaked common reed biomass was then pyrolyzed at 500 °C for three hours with a heating rate of six °C min−1 in an electrical furnace under anaerobic conditions. Nanobiochar was prepared using a ball milling method, and its properties were analyzed. To investigate the effect of the adsorbents on the Cd adsorption isotherm and kinetic in soil, an incubation experiment was conducted with three types of adsorbents, including common reed biochar, iron-modified common reed biochar, and common reed nano-biochar at three application rates of 0, 0.5, and 1 % in three replicates for 60 days at a temperature of 25°C. At the end of the incubation period, some soil properties were measured, and the isotherms of cadmium adsorption at different concentrations (zero, five, 10, 20, 30, 40, and 50 mg L-1) were determined. The kinetics of cadmium adsorption at Cd concentration of 40 mg L-1 under different periods (0.5, 1, 2, 4, 8, 12, 24, and 48 h) were also studied. Then, the experimental data were fitted using nonlinear adsorption and kinetic models, and the model parameters were calculated. Results and Discussion The results showed that reducing the size of biochar to nano-scale increased the specific surface area and cation exchange capacity. The application of nanobiochar at one percent application rate increased the percentage of soil organic matter compared to other treatments. Soil treated with nanobiochar at 0.5 percent and one percent application rates increased soil organic matter by 33.02% and 83.02% compared to the control treatment, respectively. Nanobiochar gave rise to the highest Cd adsorption in the soil. The Langmuir model provided a better fit to the experimental data than the Freundlich and Temkin models. The maximum adsorption capacity of cadmium (qmax) boosted upon adsorbents application, and the highest adsorption capacity was obtained in soil treated with nanobiochar at one percent application rate with maximum Cd adsorption capacity of 1048 mg kg-1 of soil. The pseudo-second-order kinetic model provided the best fit to the kinetic adsorption data due to its high coefficient of determination (R² ) and low standard error (SE). The adsorption capacity of cadmium (qe) increased with the use of reed biochar, iron-modified reed biochar, and nanobiochar compared to the control treatment, with a higher increase observed at the one percent application rate compared to 0.5 percent. Additionally, the rate constant K² showed a higher surface adsorption rate of cadmium in soil treated with nanobiochar compared to the other treatments. Conclusion In general, the study findings confirmed the effectiveness of nanobiochar produced by ball milling in cadmium adsorption in polluted calcareous soils. The results showed that the nanobiochar amending cadmium-polluted soils demonstrated better improvement compared to biochar treatments. Nanobiochar at one percent application rate was the best treatment for improving soil properties and increasing Cd adsorption due to its exceptional properties (high surface area and improved adsorption capabilities). As a result, the application of nanobiochar as an adsorbent offers environmental and economic advantages. The application of nanobiochar as a strong and effective adsorbent for cadmium removal from the soil can be considered as an effective solution to protect the environment and human health. [ABSTRACT FROM AUTHOR]

Introduction Water infiltration into soil is one of the most important soil physical processes for hydrological and agricultural applications. It plays a key role in hydrological studies, water resource management, soil conservation, irrigation systems, drainage systems, and soil erosion control in watersheds. There are various equations for determining how water infiltrates into the soil. Some of these (e.g., Philip and Green-Ampt equations) are based on the physical properties of the soil and the results of solving the relationships governing water flow in the soil. The others (e.g., Kostiakov, Kostiakov-Lewis, Horton, and US Soil Conservation Service equations) are empirical relationships obtained from analyzing the curve between infiltration rate and time without any physical background. Using these relationships avoids the waste of time and high cost required to measure infiltration in the field, especially on a large scale. The coefficients of these equations, like other soil characteristics, depend on the soil type and conditions and are subject to spatial and temporal variations. Therefore, this research aimed to study the spatial variability and model of the spatial dependence of the coefficients of different theoretical and empirical infiltration equations in the calcareous soils of Bajgah, Shiraz. Materials and Methods Infiltration tests were carried out at 50 points of the studied soil using the single-ring method. Different infiltration equations, including Horton, Kostiakov, Kostiakov-Lewis, US soil conservation service (SCS), Green-Ampt, and Philip equations were fitted to the measured data, and the coefficients of the equations were determined. Preliminary statistical checks included determining the summary statistic (measure of location, measure of spread, and shape parameters of data distribution), checking the normality of the distribution of the infiltration coefficients data, and performing necessary transformations if required. To check the spatial dependency of the data, the experimental semivariogram of the data was calculated. Various theoretical models, including spherical, exponential, and Gaussian models, were fitted and the best semivariogram model and its characteristics were determined using statistical criteria. Coefficients at unmeasured points were also estimated using the normal kriging method and the inverse distance weighting (IDW) method with different weight powers. The evaluation of the estimation methods was also carried out using the jack-knife method and the appropriate estimation method was identified. Estimation of the coefficients at points without data and zoning was done using the appropriate estimation method. The statistical and geostatistical analyses mentioned above were carried out using the software packages Excel and GS+ . Results and Discussion The coefficient of variation (CV) of the studied infiltration equation coefficients varied between 12.5 and 478%, with the highest and lowest CV for the coefficients “A” of the Kostiakov-Lewis equation and “b'” of the SCS equation. The isotropic spherical model was the best-fitted model to the semivariogram of the coefficients of the Kostiakov (K and b), Horton (c, m, and a), Philip (“A”), and Kostiakov-Lewis (b') equations. Whereas, the isotropic exponential model was the best-fitted model to the coefficients of the SCS (a and b), Philip (“S”), and Kostiakov-Lewis (K and A) equations. The range of variation (the radius of influence) of the coefficients of the infiltration equations varied from 1.96 to 211 m, respectively, for the “K” coefficient of the Kostiakov equation and the coefficients of the Kostiakov-Lewis, “a” of Horton, “S” of Philip, and “b”' of SCS equations. Among the coefficients studied, the highest and lowest nugget effect (C0) to threshold (C+C0) ratio was obtained as 0.648 and 0.5, respectively. The spatial correlation class of the infiltration equation coefficients was moderate, and the maximum and minimum radius of influence were 211 and 6.4 m, respectively, which corresponded to the “S” coefficient of Philip, the coefficients of Kostiakov-Lewis, the “a” coefficient of Horton, and the “b” coefficient of the SCS equations. The most precise and the least precise estimates were related to the “A” coefficient of Philip, “b” of Kostiakov, and “b'” of Kostiakov-Lewis equations, respectively. Conclusion In this study, spatial variations of the coefficient of various infiltration relations were investigated and modeled, and estimation and zoning were performed using the best model. Results showed that the spatial dependence class of the coefficient of infiltration relations in the study area is medium, and also, the maximum and minimum radius of influence of 211 and 6.4 m are related to the coefficient S of the Philip and the coefficients of the Kostiakov-Lewis and the coefficient a of Horton and the coefficient b of the US Soil Conservation Service equations, respectively. In other words, this study suggests geostatistical methods and limited measurements to estimate the coefficients of the infiltration equations with reasonable precision and to save time and cost when zoning or estimating these coefficients at large scales. However, due to the weak and unsuitable spatial structure, the IDW method outperformed the kriging method in some cases in the studied area and its use can lead to more precise estimates. Therefore, in cases where the spatial structure of the desired feature is weak and inappropriate, methods such as Kriging that rely on strong spatial correlation are unsuitable, and in these cases, other alternative estimation methods, such as IDW which does not depend on the presence of strong and appropriate spatial structure in the data should be used. [ABSTRACT FROM AUTHOR]

Introduction Due to the presence of refineries and oil-rich areas in our country, the need for cost-effective and environmentally friendly methods is strongly felt. Biochar is a soil conditioner produced from the pyrolysis of organic residues. In addition to improving the quality of contaminated soils, it also improves the biological conditions of microorganisms involved in bioremediation. Using biochar in biological processes is both economical and affordable. Another point is that this material, compared to other similar products, is more economical and generally creates more tolerance in microorganisms against toxic compounds based on this, a study was implemented to compare the changes in the properties of biochar obtained from sugarcane bagasse and date palm through surface chemical activation with hydrogen peroxide (modified biochar) and unmodified biochar focusing on metabolic, enzymatic activities and the amount of microbial biomass in a saline calcareous soil. Contaminated with crude oil was implemented. Materials and Methods In this research, an experiment was carried out in the form of repeated measurements in time intervals. In the middle and at the end of the experimental period (60 and 120 days), the effect of different levels of unmodified and modified biochar of sugarcane and unmodified palm bagasse (one and two percent) along with microorganisms (with biochar and without biochar and a total of 57 test samples at two times) some biological characteristics and eco-physiological indicators of soil including basic microbial respiration, substrate-induced respiration, microbial carbon dioxide, dehydrogenase enzyme, microbial contribution and metabolic contribution were investigated. The biochar used was prepared from sugarcane bagasse and date palm waste. The wastes were prepared, dried, and pounded. Then they were heat treated at 400 °C for four hours. Then kept for a while to cool. Then they were modified with 10% hydrogen peroxide and kept at room temperature for 24 to 48 hrs. After that, they were placed in the oven at a temperature of 80 °C for 24 hrs and then they were ready to use. To measure basic microbial respiration using the method of Anderson et al. (2011) substrate-induced respiration using the method of Alef and Nannipieri (1995) microbial carbon dioxide using the fumigation method, dehydrogenase enzyme activity using the method of Cassida et al. (1964) and the microbial contribution was obtained by dividing the microbial biomass carbon by the organic carbon, and the metabolic contribution was obtained by dividing the basal respiration by the microbial biomass carbon. Results and Discussion The analysis of the variance table of repeated measurement of the effect of unmodified and modified biochar and microorganisms on the examined traits in the soil showed that in the outgroup effects, all treatments have significant differences with each other at the one percent level. In the intragroup effects, time had a similar status in all the investigated treatments. The interaction of time and treatments also showed a significant difference except in microbial biomass carbon and substrate-induced respiration in the rest of the treatments. The best results in dehydrogenase enzyme, microbial carbon dioxide, basal, and substrate-induced respiration were observed in the treatment of mixture four (a mixture of modified bagasse two percent and bacterial consortium two percent) for 60 days, showing an increase in these traits by 70.98, 8.96, 53.97, and 53.54 %, respectively compared to the control treatment. The highest amount of microbial contribution was found in the control treatment of 120 days and the highest amount of metabolic contribution also was found in the treatment of a mixture three (mixture of unmodified bagasse one percent and bacterial consortium one percent) for 120 days, which has increase of this trait by 76.70% compared to the control treatment of 120 days. Conclusion In this research, all the microbial indicators measured in the soil showed a significant difference compared to the control treatment. Also, the results of this research showed that the addition of organic matter in soils contaminated with crude oil, such as unmodified and modified biochar, either alone or in interaction with microorganisms, can partially reduce the destructive effect of the stress caused by the pollutant (crude oil) and the microbial community. Biochar modification using hydrogen peroxide, as a relatively cheap and environmentally friendly modifying agent, increased the effect of biochar on the studied biological and ecophysiological properties, with the best results observed in the modified treatments. Sugarcane bagasse biochar had better results than date palm waste. This improvement was even greater when combined with microorganisms. It should be noted that biochar is not only effective in remediation but also stabilizes and neutralizes toxins. By using the results of this research, we can propose suitable solutions for their biological restoration according to the type of soil. Sugarcane bagasse biochar compared to date palm waste and the presence of microorganisms improved soil biological indicators. Therefore, biochar modification using hydrogen peroxide, as a relatively cheap and environmentally friendly modification agent, increased the effect of biochar on the studied biological and ecophysiological characteristics. [ABSTRACT FROM AUTHOR]

Soils on red-colored calcareous substrates occupy vast areas in Eastern Siberia. The objects of this study are located in the southern part of the Lena–Angara Plateau and are represented by loamy-clayey soils with a high content of total and dithionite-soluble iron. The mineralogical composition of the clay fraction reflects the spatial heterogeneity of red-colored substrates characterized by the illite–chlorite association of clay minerals with a predominance of dioctahedral minerals (micas and, in some cases, dioctahedral chlorites). Red-colored residual-calcareous soils reflect the development of structural metamorphism and textural differentiation of the soil mass. The intensity of these processes at the macro- and microlevels depends on the absolute altitude of the area, which determines the degree of climate humidity. Texturally differentiated soils (raw-humus podzolic soils, or Calcaric Albic Rhodic Luvisols) are formed in the most humid conditions at altitudes above 1000 m a.s.l. They are characterized by the vertical homogeneity of the parent material, weak color differentiation with preservation of the reddish tint in the upper horizons, and distinct differentiation of the clay fraction with a reduced thickness of the illuvial horizon due to the close occurrence of the hard carbonate substrate. At lower altitudes, the signs of clay illuviation are less pronounced, though they can be traced in the profiles of raw-humus podzolized or clay-illuvial brown soils (burozems) (Calcaric Chromic or Calcaric Rhodic Luvisols). [ABSTRACT FROM AUTHOR]

Soil calcium carbonate (CaCO 3) affects plant nutrient acquisition and consequently shoot mineral homeostasis leading to chlorosis and yield losses in maladapted crops. Different tolerance strategies have been identified, notably Ca flux regulation, biomineralization, and secretion of root exudates to remobilize unavailable soil nutrients. Recent intraspecific genomic analyses revealed that wild species detain a pool of alleles, notably for ion transporters, that could be exploited to improve plant tolerance to calcareous soil. Contrary to soil water content, the effects of air and soil temperature and CO 2 concentration on plant performance in calcareous soil are largely unknown. Metabolic engineering in Arabidopsis thaliana to increase Ca biomineralization is an attractive strategy to improve plant tolerance to CaCO 3 in the context of climate change. Soil calcium carbonate (CaCO 3) impacts plant mineral nutrition far beyond Fe metabolism, imposing constraints for crop growth and quality in calcareous agrosystems. Our knowledge on plant strategies to tolerate CaCO 3 effects mainly refers to Fe acquisition. This review provides an update on plant cellular and molecular mechanisms recently described to counteract the negative effects of CaCO 3 in soils, as well as recent efforts to identify genetic bases involved in CaCO 3 tolerance from natural populations, that could be exploited to breed CaCO 3 -tolerant crops. Finally, we review the impact of environmental factors (soil water content, air CO 2 , and temperature) affecting soil CaCO 3 equilibrium and plant tolerance to calcareous soils, and we propose strategies for improvement in the context of climate change. [ABSTRACT FROM AUTHOR]

Copyright of Menoufia Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Zinc (Zn) deficiency in crops is a global issue, particularly in plants grown in calcareous soils, where Zn is often adsorbed or precipitated by calcium carbonates. The aim of this study was to identify and quantify, through bibliometric analysis, the scientific production related to Zn deficiency in calcareous soils over the last 36 years (1989–2024). A total of 374 documents were retrieved through a search on the Web of Science (WOS) platform, specifically in the Science Citation Index Expanded (SCIE) and Social Science Citation Index (SSCI) databases. Of these, only 198 articles were directly relevant to the topic and were used for the analysis. Unidimensional and multidimensional bibliometric indicators were evaluated using Excel and VOSviewer software. The results confirm that the number of articles has increased in recent years. The most influential authors, journals, articles, institutions, and countries in this research area were identified. In addition, collaboration networks between authors and countries, as well as the predominant research topics, were determined. This study provides a comprehensive overview of this field on a global scale and serves as a useful reference for scientists interested in conducting future research on related topics. [ABSTRACT FROM AUTHOR]

Different methods have developed to reduce the risks of potentially toxic elements in contaminated soils. Among them, adsorption is one of the most important and effective strategies. In this research, kinetics of Cd adsorption by biochar, activated carbon, and zeolite in some calcareous soils were investigated. A factorial experiment was conducted based on a completely randomized design with three replications. The factors included three types of adsorbents (sunflower's biochar, activated carbon, and zeolite), four levels of Cd (0, 20, 50, and 100 mg/L as Cd (NO3)2), and three soil samples, differing in their cation exchange capacity, soil organic matter, and calcium carbonate equivalent. Batch experiments were carried out to evaluate Cd adsorption isotherms and kinetic models. Furthermore, the effect of adsorbent dosage, contact time, and initial pH on the adsorption efficiency was examined. Optimizing studies revealed that the best pH for Cd adsorption was 5, while the optimal equilibrium time was achieved at 24 h. The results showed that the Freundlich model fitted to the experimental data slightly better than the Langmuir model. Moreover, the pseudo‐second‐order kinetic model better described the kinetic behavior of Cd adsorption for the investigated adsorbents. The maximum Cd removal efficiency (99%) belonged to soil No. 2 with biochar. Lastly, it was concluded that sunflower biochar, a cheap and cost‐effective adsorbent, had high efficiency in Cd adsorption in calcareous soils. Core Ideas: Sunflower biochar, a cheap and cost‐effective adsorbent, had high efficiency in Cd adsorption in calcareous soils.The effects of several adsorbents on cadmium adsorption also kinetics in some calcareous soiBiochar has high efficiency in Cd stabilization in the calcareous soils. [ABSTRACT FROM AUTHOR]

This study investigated the factors affecting bacterial diversity in purplish and calcareous soils under the same vegetation type. The results showed that obvious differences in pH, water content, total phosphorus (TP), free iron oxide (Fed) and amorphous iron oxide (Feox) existed between the two soils. The bacterial Shannon indexes of the two soils varied significantly, and Shannon index of purplish soil were higher than that of calcareous soils. The co-occurring network structures in two soil bacterial communities showed obvious variations, with higher edge counts, average degrees and clustering coefficients in calcareous soils than that in purple soils. The key species group identified in the two soils was Acidobacteria; belonging to the family Thermoanaerobaculaceae in purplish soil, and to the family Vicinamibacterales in calcareous soil. Also, the results of multivariate stepwise linear regression showed that Feox was a significant explanatory factor for changes in bacterial diversity (68.8%, P < 0.01) compared to other physical and chemical factors. Overall, our study indicated that soil parent material may be an important factor influencing soil bacterial communities. [ABSTRACT FROM AUTHOR]

Self-regenerating fallows are areas left to regenerate naturally after agricultural use and are typically characterized by diverse plant species and minimal human intervention. To measure the efficiency of this natural fallow system, we evaluated soil organic carbon (SOC) and nutrient concentrations vis-à-vis the fallow duration. The study site was located in the Onigbedu community, Ogun State, Nigeria, with large commercial limestone deposits. Mining and agriculture are the main land use types. The study was oriented on 100 hectares of land previously cultivated at different times and left to fallow. The fallow duration ranged between less than 3 years and more than 20 years. At the end of this study, it was observed that the soils are within a large group of calcareous soils. SOC ranged from 15 to 26 mg/g, available phosphorus from 3.0 to 6.0 mg/kg, total nitrogen from 0.5–2.0 mg/g, effective cation exchange capacity (ECEC) from 2.0–24.0 cmol(+)/kg, calcium from 2.0–20 cmol(+)/kg, Mg from 1.0–2.0 cmol(+)/kg, 0.1–0.4 cmol(+)/kg, manganese from 19 to 80 mg/kg, and zinc from 1.5–2.0 mg/kg in increasing order of fallow duration. Soil nutrients and SOC improved consistently with increasing fallow periods. While fallow duration influenced soil nutrient build-up, other management practices and environmental factors also play significant roles. Farmers can enhance soil fertility and nutrient levels by optimizing fallow durations and using efficient soil management practices, leading to sustainable agriculture and improved crop yields. [ABSTRACT FROM AUTHOR]

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When irrigation is introduced in a region, it adds salts and mobilizes those already present in the soil, changing the soil-plant-atmosphere continuum. These changes may lead to higher salt loads in the drainage water which, in turn, can have an impact on waters further downstream. Knowing the dynamics of these loads at the sub-basin scale is key to accounting for the possible impact that irrigation may have and to determining what improvements could be applied. This study aimed to characterise the different salt types present and to investigate drainage salt loads and their dependence upon irrigation input and their implications in irrigation management in a new, and well-managed, 8000 ha irrigation district located in the Ebro basin, NE Spain. In addition, it is relevant to highlight that the Ebro basin suffered a period of significant drought in 2023. As a result, irrigation restrictions were applied in many irrigation districts. We sought to investigate how these reductions influenced irrigation return flows and salt discharges within a selected irrigation district. The present study was undertaken during the irrigation periods of 2021, 2022, and 2023. We monitored water inputs and outputs in two representative sub-basins belonging to the Algerri-Balaguer irrigation district (Ebro basin, NE Spain). We also analysed water inputs and outputs in order to characterise and establish the salt balances in both of the sub-basins that we studied. Our results showed that during 2023, a reduction in irrigation delivery of 31% led to a reduction in drainage volume of 73%, resulting in a decrease in salt exports through drainage of 70%. These data revealed that the application of irrigation restrictions not only led to an increased availability of downstream water resources, but also to a decrease in drainage volume and salt load, resulting in an improvement in irrigation management by farmers. However, it should also be underlined that this drastic reduction in irrigation was, in turn, responsible for a reduction in yield. Re-utilising drainage waters and/or improving irrigation management at the field scale may help to find this point of balance in areas with high water demands. [ABSTRACT FROM AUTHOR]

Factors such as topography, mineralogy, physicochemical properties, and climate can affect the distribution of soil potassium (K) forms. However, often the special effects of physiographic units are neglected. Therefore, this study aimed to investigate the factors controlling the distribution of chemical fractions of K in different physiographic units of calcareous soils (piedmont plain, flood plain, alluvial plain, lowland, badland, and plateau) in southern Iran. The XRD analyzing patterns showed that the distribution of K forms is controlled by K-bearing minerals (i.e., illite) in finer particles of the soils. Physiographic units significantly affect the distribution of K forms due to different microclimates (such as soluble, exchangeable, and non-exchangeable). In addition, different correlations between the K forms and some physicochemical properties of the soils such as soil texture (i.e., silt (r = 0.511** to 0.527**) and sand (r = -0.357* to -0.389*)), electrical conductivity (EC) (r = 0.617** to 0.723**), sodium absorption ratio (SAR) (r = 0.478** to 0.577**), pH (r = 0.347* to 0.519**), and gypsum (r = 0.372* to 0.475**) were found in soils of the study area. It is recommended that cultivation sites are chosen with a deeper understanding of land conditions e.g., slope, elevation, microclimatic conditions, soil development, and clay mineralogy. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) is an exciting source of organic matter (OM) for agricultural soil. In recent years, the application of MSW compost has received considerable attention. On the other hand, simultaneous use of organic and chemical fertilizers can lead to better plant growth and soil fertility. The main purpose of this study was to evaluate the impact of MSW compost and nitrogen fertilizer (N-fertilizer) on soil physicochemical properties. Treatments consisted of three levels of MSW compost 0, 10, and 20 t ha−1 (C0, C10, and C20), three rates of N-fertilizer 0, 100, and 200 kg ha−1 (N0, N100, and N200). Application of N-fertilizer and MSW compost alone or in combination significantly affected some physical and chemical properties of soil. The addition of N-enriched compost to the soil increases electrical conductivity (EC), N-NO3− contents (in C20N200 treatment) and available iron (Fe) and zinc (Zn), field capacity (FC) and available water (AW) contents (in C20N100 treatment). While the bulk density (BD) of the soil decreased. Our results show that the use of MSW compost and N-fertilizer is a beneficial option for improving the physicochemical properties of soil, especially physical properties under arid and semi-arid conditions. [ABSTRACT FROM AUTHOR]

Phosphorus is a very important plant nutrient for the development of plants and its production is not unlimited in the world. In addition, excessive use can lead to soil and water pollution. In this respect, phosphorus should be used effectively in plant production, especially in calcareous soils. The aim of this study was to comparatively determine the effects of phosphorus-enriched organomineral fertilization (p-OMF), chemical phosphorus fertilization (CF), and organic fertilization (OF) on some chemical properties of a calcareous soil. The experiment was established in Söke county of Aydın province in the Southwest of Türkiye. In this study, four doses of dairy manure (DM1: 10, DM2: 20, DM3:30, and DM4: 40 t ha−1) in OF, four phosphorus doses (P1: 10, P2: 20, P3:30, and P4: 40 kg P ha−1) in the CF system, and sixteen different doses of OMF formed by the combinations of these two fertilizers were applied excluding control. According to the main research findings, p-OMFs increased the soil organic matter (SOM), salinity, total nitrogen (N), available phosphorus (P), and potassium (K) by 60.1%, 20.9%, 22.1%, 140%, and 17.2%, respectively. They also decreased soil pH by 4%. As a result, it was determined that the most effective organomineral fertilizer combination that maintains soil properties at appropriate levels in calcareous soils is DM3+P2 (30 t ha−1 dairy manure +20 kg P ha−1). [ABSTRACT FROM AUTHOR]

The history of effective citrus nutrition programs is as old as the cultivation of citrus, regardless of the nature and properties of the soil. Citrus cultivation in Iran is predominantly confined to calcareous soils with a minimum of 5% calcium carbonate equivalent calcareousness. Citrus raised on such calcareous soils is exposed to altogether different dynamics of lime-induced multiple soil fertility constraints such as large-scale deficiencies of essential nutrients under the dominating influence of pedogenic/geogenic accumulation of calcium carbonate, chronically deteriorating the soil tilth through dispersion of clay particles with a cascading influence on soil water relations and microbiological properties, compared to either acid or other alkaline non-calcareous soils. Incidentally, calcareous-linked boron toxicity is another pedological problem, yet so formidable to deal with in sustaining an uninterrupted production. Rootstocks (Carrizo, Citranges, Cleopatra) have though played a very handful role in moderating the impacts of soil calcareousness on citrus yield, but still, long-term studies are missing, besides changes in rhizosphere microbiome concerning citrus decline, an analog to negative rhizosphere effect. The authors have attempted analysis of different issues relating to diagnosis (coupled with test interpretations) and management of nutrient constraints (dynamic synergy between citrus-microbes–organics-inorganic) exclusively on calcareous soils with emphasis on Iranian citrus. Finally, the outcome of such analysis has provided a solid blue-print as future researchable issues. [ABSTRACT FROM AUTHOR]

Comparing the absorption and translocation efficiency of the nutrients in olive cultivars can lead to the selection of cultivars with higher efficiency. This research was conducted with the aim of comparing the uptake and translocation capacity in 20 olive cultivars (12 domestic and 8 foreign) in a commercial orchard on calcareous soil in a randomized complete block design. Except for copper (Cu), leaf concentration of other elements was within the optimal range. In ʻAmphesis,ʼ high translocation (5.28%) and in ʻAmigdalolia,' high uptake capacity (12.6) caused an increase in leaf phosphorus (P). Leaf K in all cultivars was higher than the deficiency limit (0.77%). In none of the cultivars, leaf sodium (Na) concentration was higher than the toxicity limit (0.2%), it accumulated in the root of ʻZard-Aliabadʼ and ʻShengeh,ʼ and reduced in their leaf. Leaf iron (Fe) concentration of all cultivars was in the sufficient range (>63 mg kg−1) and the highest was in ʻGorgan-Aʼ and ʻZardʼ and the lowest in ʻKazeroon,ʼ ʻArbequinaʼ and ʻMission.ʼ Although the leaf Cu in ʻAmphesisʼ (4.32 mg kg−1) and ʻArbequinaʼ (4.03 mg kg−1) was above the sufficient limit, in the rest of the cultivars it was below this critical limit. The highest leaf manganese (Mn) concentration (61.35 mg kg−1) and the highest Mn translocation percentage (84.59) were in ʻFeshomi.ʼ Among these cultivars, ʻAmphesisʼ was higher than others in terms of P, potassium (K), Cu and zinc (Zn) leaf concentrations and ʻAmigdalolia in terms of P, K and Zn, and in most cases the reason for this is the higher translocation efficiency. [ABSTRACT FROM AUTHOR]

Low organic matter content is one of the main constraints in arid and semiarid regions. This constraint and its negative influences on soils and plant growth may be alleviated by biochar (BC). Furthermore, improving soil physical and hydraulic attributes by application of biochar has received increased attention. Therefore, in the present study, the effects of sugarcane bagasse-derived biochar on the structural stability, water availability, and pore-size distribution (PSD) of three texturally different calcareous soils collected from different agro-climatologically regions were examined during a long-term experiment. Low and high-temperature biochars, produced in a muffle furnace by the traditional slow pyrolysis method at 300 °C (BC300) and 600 °C (BC600) were evaluated. Pots (15 kg) were filled with three different silty-clay Inceptisols (SCInc), silty-clay-loam Alfisols (SCLAlf), and loam Aridisols (LArid) soils mixed with 0 (control), 1, 2, and 3 w/w% of BC300 and BC600 during 540 days of incubation. The high energy moisture characteristic (HEMC) data was modeled using a modified van Genuchten function to quantify aggregate stability through stability ratio (SR) and structural stability index (SSI). The plant available water (PAW), least limiting water range (LLWR), and integral water capacity (IWC) were calculated with two matric suctions (h) of 330 cm for field capacity (FC) and 15,000 cm for permanent wilting point (PWP). Then the integral energy (EI) values were calculated (EIIWC). Results indicated that the incorporation of 3 w/w% biochar significantly (p < 0.01) increased SR (35 to 100%) and SSI (21 to 28%) indices in all three soils. Biochar significantly increased modal suction (MS) in LArid soils (5 to 158%); whereas, decreased MS of the other soils (3 to 43%). MS, SR, and SSI of BC300 and BC600-treated soils were not significantly different. PAW, LLWR, and IWC significantly decreased in the SCInc (18 to 61%, 8 to 44%, and 6 to 35%) and SCLAlf (8 to 44%, 18 to 35%, and 20 to 47%) soils and increased in LArid (4 to 54%, 3 to 61%, and 24 to 111%) soil with increasing biochar doses. There were no changes in EIIWC in biochar-treated LArid soil where PAW, LLWR, and IWC increased. Biochar increased EIIWC across the studied soil from 1% to 3.38 folds, thereby increasing the gradient of water potential to absorb the available water. Soil and soil-biochar mixtures exhibited heterogeneous and multimodal pore-size distribution (PSD). Biochar promoted the PSD peaks related to water-transmitting pores in SCInc and SCLAlf soils while decreased in LArid soil. In conclusion, results indicated that among the applied levels of biochar, the application of 3 w/w% biochar is suggested as a suitable way to improve soil physical behavior and structural stability. [ABSTRACT FROM AUTHOR]

We assessed the effects of soil type on the concentrations of seven elements (calcium, potassium, sulfur, phosphorus, iron, manganese, zinc) in plants using x‐ray fluorescence (XRF) analysis and plant specimens collected from calcareous and ultramafic soil areas, and 'general soils' (other types of soil represented by Brown Forest soils and Andosols) of Japan. Compared with the plants from other types of soils, the means of these seven elements were lower in plants originating from ultramafic soils, especially in phosphorus. Plants from calcareous soil areas had high iron and zinc concentrations on average, but this tendency was biased by plants collected on Mt. Fujiwara, which had extremely high average values of these elements. Calcium concentration in plants had a negative correlation with zinc or iron from calcareous or general soils, respectively, and iron showed positive correlations with zinc, manganese, and sulfur in plants from calcareous, ultramafic, and general soils, respectively. These correlations were not found in plants from general soils, suggesting that these relationships reflect the chemical characteristics of soil types. On the contrary, plants from all soil types showed a positive correlation between sulfur and phosphorus, whereas a positive correlation between potassium and phosphorus was found in plants from calcareous and general soils, but not in ultramafic plants, which instead showed a weak, but statistically significant correlation between potassium and sulfur. Statistically, iron and sulfur concentrations were positively correlated in all soil types, but manganese showed a low correlation with the other elements. [ABSTRACT FROM AUTHOR]

Vivianite precipitation is gaining attention in phosphorus (P) removal from water purification. It is an iron (Fe)- and P-rich compound that can be used as a slow-release P fertilizer. However, this slow release can constrain P supply to crops in the initial growing stages. This limitation can be overcome by mixing with soluble P fertilizers and with banding application. Thus, the objective of this study was to assess the fertilizer effect of vivianite and superphosphate mixtures and determine the most effective application method for vivianite and its mixture with superphosphate as a soluble fertilizer. A pot experiment was conducted by growing sunflowers in calcareous soil under controlled conditions involving two factors. The first factor was the combinations of vivianite and superphosphate: 100% Vivianite + 0% Superphosphate –T2–, 70% Vivianite + 30% Superphosphate –T3–, 30% Vivianite + 70% Superphosphate –T4–, 0% Vivianite + 100% Superphosphate –T5—at a single P rate of 50 mg P kg−1 and a non-fertilized control –T1–. The second factor was the application method: (i) mixing vivianite powder with the bulk soil and (ii) applying it in bands at three points around the plants. The dry matter (DM) yield in the roots and shoots of the sunflower when all P was applied as superphosphate was higher than when it was applied as vivianite. However, the combination of superphosphate and vivianite in different proportions (T3 and T4) led to a considerably higher DM yield compared to sole vivianite application (T2). The highest plant P uptake was observed in T5, while the lowest was in T1 and T2. The replacement values on a dry matter (PFRVDM) and P uptake (PFRVP Uptake) basis and the nutrient use efficiency of T3 and T4 were higher than that of T2. However, the PFRVDM and the PFRVP Uptake were in the same range as the proportion of the superphosphate added to the fertilizer mix. Thus, increased P use efficiency could be achieved with mixtures of vivianite and superphosphate. However, the contribution of vivianite to the fertilizer mix is difficult to access in a short growing cycle. Hence, further research is recommended on the residual effect of vivianite in such fertilizer mix on subsequent growing cycles. [ABSTRACT FROM AUTHOR]

The effect of breakable particle corners is often overlooked in research on pile–soil interaction, which hinders the understanding of the uplift pile behaviors in calcareous sand. This research examines the breakable corner effects on uplift pile–soil interaction in calcareous sand from macro to micro, through model tests and coupled discrete element method–finite difference method. Results revealed that compared to that in silica sand, the higher bearing capacity and relatively abrupt failure behavior of uplift piles in calcareous sands were attributed to the corner interlocking effect and corner breakage effect, respectively. The unstable load transmission along piles in calcareous sand was thoroughly explained by a coupled effect of corner interlocking and breakage. Furthermore, the reduction in effective contacts and alterations in soil skeletons were identified as critical factors contributing to the distinctive soil behaviors in calcareous sand. Moreover, the relative sliding distance of particles was found to be the key factor in determining the amount of corner breakages due to stress concentration at corners. Lastly, a positive feedback loop involving corner breakage effects was proposed, successfully explaining the distinctive phenomenon of uplift piles in calcareous sand. This study provides new perspectives to clarify distinctive pile–soil interaction behaviors in calcareous sand. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency in calcareous soils is a significant agricultural challenge, affecting crop productivity and nutritional quality. This study aimed to isolate, characterize, and evaluate Fe solubilizing rhizobacterial isolates from maize rhizosphere in calcareous soils as potential biofertilizers. Forty bacterial isolates coded as SG1, SG2, ..., SG40 were isolated and screened for siderophore production, with ten showing significant Fe solubilizing capabilities. These isolates were further assessed for phosphate solubilization and exopolysaccharides production. The selected bacterial isolates were also screened under axenic conditions for their ability to improve maize growth. The isolates SG8, SG13, SG24, SG30 and SG33 significantly enhanced growth parameters of maize. Notably, SG30 showed highest increment in shoot length (58%), root length (54%), root fresh and dry biomass (67% and 76%), SPAD value (67%), relative water contents (69%), root surface area (61%), and Fe concentration in shoots (79%) as compared to control. The biochemical characterization of these strains showed that all these strains have capability to solubilize insoluble phosphorus, produce indole-3-acetic acid (IAA), and ammonia with catalase, urease and protease activity. Molecular identification through 16s rRNA gene sequencing confirmed high similarity (99.7–100%) of the selected isolates to various Bacillus species, including B. pyramidoids, B. firmicutes, and B. cereus. The study provides a strong base for developing eco-friendly, cost-effective biofertilizers to address Fe deficiency in crops and promote sustainable agriculture. [ABSTRACT FROM AUTHOR]

A large part of ocean surface is covered by calcareous deposits. The Low stiffness and weak particles of calcareous soils deposited by marine organisms showed significant particle breakage under applied loads, which resulted in different behavior compared to terrigenous soils. A series of compression drained triaxial tests were carried out to evaluate the monotonic shear behavior of crushable and non-crushable soils. Three different soils, including Firoozkuh siliceous sand (as a non-crushable soil) and Hormuz and Bushehr calcareous sands (as crushable soils) which were different in mineralogy compositions were obtained from northern and southern Iran. The specimens were prepared in different relative densities (i.e., loose, medium and dense conditions) and consolidated under confining pressures ranging from 100 to 600 kPa. The monotonic shear and dilatancy behaviors of the soils have been presented in detail and the effect of particle breakage has been discussed. The results showed that particle breakage has a significant effect on the mobilized friction and dilatancy angles of marine crushable soils. There is a linear relationship between the amount of particle breakage occurring during a triaxial test and breakage angle. In addition, the mineralogical difference influences the breakage properties of calcareous deposits. [ABSTRACT FROM AUTHOR]

Winter rapeseed production has completely changed in Hungary in recent years. The use of hybrids has become commonplace, and intensive cultivation techniques are widespread. At the same time, average yields also increased, making rapeseed one of the most profitable crops. Maintaining profitability is a priority task, and in addition to further increasing average yields, improving quality parameters and crop safety is also decisive. Rapeseed production today faces significant challenges. As a result of climate change, the cultivation routine of decades is changing, and biostimulators are becoming more and more perspective in addition to foliar fertilisation with macro- and microelements. During this research, a 3-year small-plot field experiment was set up with a winter rapeseed indicator. The main objective of the experiment was to study the physiological reactions of rape plants to different doses of Zn and the combined reaction of the biostimulator and Zn. During the experiment, the reaction of the rapeseed test plant on zinc-deficient calcareous chernozem soils was investigated under the influence of different doses of Zn and combined doses of Zn and biostimulation. The aim of the study is to determine whether rapeseed plants respond to zinc supplementation and the combined effect of the bio stimulator and zinc with increased yield and improved nutritional values (protein content, oil content). In the first annual study, two treatments were performed, one in autumn (BBCH 16-18 phenological stage) and one in spring (BBCH 29 phenological stage). Zinc tetramine hydroxide was used in 4 different doses (2, 5, 10, 20 L/ha), zinc tetramine hydroxide enriched with copper in 2 different doses (5 and 10 L/ha), Quantis in the manufacturer's prescribed dose of 2 L/ha, biostimulant enriched with zinc, and a usual foliar fertiliser used in rapeseed growing with Wuxal boron at the dose recommended by the manufacturer. During the growing season, the development of root mass, root length, SPAD values, as well as the yield and oleic acid content were evaluated by mathematical statistical method. It can be stated that there was no significant difference in the root mass, root length, and SPAD values, but there was a significant yield difference in the amount of the crop in the second-year experiment (P = 10 %). Studies have shown that biostimulants have the greatest influence on the development of measured parameters. [ABSTRACT FROM AUTHOR]

Forest fires are a major global environmental problem, especially for forest ecosystems and specifically in Mediterranean climate zones. These fires can seriously impact hydrologic processes and soil erosion, which can cause water pollution and flooding. The aim of this work is to assess the effect of forest fire on the hydrologic processes in the soil, depending on soil properties. For this purpose, the infiltration rate has been measured by ring infiltration tester, and the hydrophobicity has been quantified by the "water drop penetration time" method in several soils of burnt and unburnt forest areas in the Mediterranean mountains. The infiltration rates obtained are higher in burnt than in unburnt soils (1130 and 891 mm·h−1, respectively), which contradicts most of the research in Mediterranean climates in southeast Spain with calcareous soils. Burnt soils show no hydrophobicity on the surface, but it is there when the soil is excavated by 1 cm. Additionally, burnt soils reveal a low frequency of hydrophobicity (in less than 30% of the samples) but more severe hydrophobicity (above 300 s); whereas, in unburnt soils, the frequency is higher (50%) but the values of hydrophobicity are lower. The results obtained clearly show the infiltration processes modified by fire, and these results may be useful for land managers, hydrologists, and those responsible for decision-making regarding the forest restoration of burnt land. [ABSTRACT FROM AUTHOR]

Abstract Plant growth-promoting microorganisms can enhance sulfur uptake and boost crop production. This study was conducted to evaluate the changes in physiology, metabolism, and yield of chickpeas following the application of sulfur and two microbial consortia: (1) Thiobacillus sp., Bacillus subtilis, Paraburkholderia fungorum, and Paenibacillus sp.; and (2) Enterobacter sp. and Pseudomonas sp. The soil amendment involving a combination of sulfur and sulfur-oxidizing bacteria (SOB) in any quantity had positive effects on the availability of phosphorus, nitrogen, and potassium in the soil. A combination of 90% sulfur with Enterobacter sp. and Pseudomonas sp. resulted in a decrease in soil pH after harvesting in both years. Both years showed a strong correlation between soil pH and soil macronutrient concentration. In both years, the maximum grain yield was achieved through a combination of increased sulfur levels and SOB. The results reveal that sulfur application and SOB can increase nutrient availability, nutrient uptake, and yield of chickpea growth in calcareous soils.

AbstractSaline calcareous soil presents significant challenges for crop production due to its poor nutrient availability and adverse effects on plant growth. Hence this study aimed to investigates the impact of integrating organic amendments—specifically Moringa seed residues, biogas manure, and vermicompost (Ver)—with and without phosphate-solubilizing bacteria (PSB), alongside two types of phosphatic fertilizers, ordinary super phosphate (OSP) and rock phosphate (RP), on the growth, yield, and nutrient uptake of wheat plants in saline calcareous soil conditions. The results indicate that the combined application of Ver + PSB, particularly when paired with OSP, consistently yields superior outcomes across all measured parameters, followed by Ver + PSB with RP. Notably, the Ver + PSB with OSP treatment exhibits the highest values across several key parameters: chlorophyll levels (chlorophyll a at 1.8, chlorophyll b at 0.84, and carotenoids at 0.72 mg g−1f wt), proline at 38.5 μg g−1 DW, relative water content at 80.76%, membrane stability index at 67.62%, as well as net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (gs). Furthermore, this treatment showcases the highest antioxidant enzyme activities (Superoxide dismutase, SOD at 9.27 A564 min−1 g−1 protein, Catalase, CAT at 78.53 A564 min−1 g−1 protein, Peroxihdase, POX at 1.86 A564 min−1 g−1 protein), as well as NPK content and uptake in wheat straw and grains. Additionally, it leads to significant increases in wheat growth parameters, including plant height, straw weight, grain weight, 1000 grain weight, and protein content. However, it also results in a notable decrease in other parameters such as total soluble sugars and nonenzymatic antioxidants (Ascorbate, AsA; Total glutathione, GsH; and α-Tocopherol, α-TOC). [ABSTRACT FROM AUTHOR]

In order to clarify the effect of calcium carbonate (CaCO3) on arsenic validity in calcareous cinnamon soil, the effect of 5% (mass fraction) CaCO3 on the main physicochemical parameters, arsenic morphological characteristics and arsenic uptake of maize in calcareous lignite soil were studied by setting exogenous arsenic pollution with mass ratios of 0 mg ⋅ kg-1, 50 mg ⋅ kg-1, 100 mg ⋅ kg-1 and 200 mg ⋅ kg-1. The results show that under the same exogenous arsenic mass ratio, CaCO3 addition significantly increases soil pH value by 2.14% ~ 3.09%, and soil organic matter mass ratio decreases by 9% ~ 19%. With the increase of exogenous arsenic mass ratio, the soil pH value gradually increases, and the organic matter mass ratio decreases first and then increases. The proportions of soil exchangeable arsenic (Ae-As) and calcium-bound arsenic (Ca-As) increase significantly after the addition of CaCO3, and the proportion of Ca-As is the largest. The arsenic mass ratio of each part of maize increases with the increase of exogenous arsenic mass ratio, and the results are roots>leaves>stems>grains. The addition of CaCO3 increases the As mass ratio in roots, leaves, stems and grains of maize. The arsenic mass ratio in roots increases by 15.0% ~ 28.9%, and the arsenic mass ratio in grains increases by 3.35% ~ 6.98% among them, and the As mass ratio in the grains of each treatment does not exceed 0.5 mg ⋅ kg-1. The addition of 5% CaCO3 will activate arsenic in calcareous cinnamon soil, but corn planting can still be safely produced, so it is recommended to plant corn on arsenic-contaminated calcareous cinnamon soil. [ABSTRACT FROM AUTHOR]

Meta-analyses show an overall decrease in soil N2O emissions after biochar (BC) amendment. Nonetheless, N2O mitigation with BC cannot be extrapolated to every BC-soil combination, inasmuch as an increase in soil N2O release has been occasionally reported. We hypothesized that BC characteristics are key, and performed two microcosm experiments to advance in the understanding of the properties associated. We first investigated how 22 well-characterized BCs affect N2O emissions in a calcareous soil under denitrification conditions. Whereas most BCs decreased N2O emissions, some substantially increased N2O emissions. In a second experiment, we selected and further characterized eight of the 22 previous BCs. We applied the 15N-gas-flux method to study how these BCs affect denitrification products (N2O and N2) in the same soil. Results indicate that the interaction between BC and the denitrification process depends on the temperature of pyrolysis. Whereas BCs produced at 400 °C tended to increase total denitrification (N2O+N2) by an average of 28%, BCs produced at 600 °C significantly reduced total denitrification by 53%. Nevertheless, this decline in overall denitrification did not result in a decrease of N2O emissions, as there was a strong shift in the N2O/(N2+N2O) ratio favoring N2O. A redundancy analysis revealed a direct correlation between carboxylic groups on BCs surface and N2O emissions. This research enhances our understanding of the interaction of BC with denitrification, particularly concerning the relevance of the temperature of pyrolysis, and opens up new paths for investigation, crucial for optimizing the application of BCs in different soil environments. Highlights: High concentration of –COO- groups on BCs surface correlated with the highest N2O emissions. Biochars produced at 600 °C decreased total denitrification (N2O+N2). Biochars with high electrical conductivity and pH increased NO2−/NO3− ratios. [ABSTRACT FROM AUTHOR]

Acid or base modification of biochars has shown promise for enhancing the immobilization of potentially toxic elements (PTEs) such as cadmium (Cd) in contaminated soils. However, limited information is available on the interaction between soil textural classes and modified biochar application for Cd stabilization in contaminated calcareous soils. Therefore, the objective of the study was to examine the extent of Cd immobilization in contaminated calcareous soils with diverse textural classes, utilizing both acid (HNO3) and alkali (NaOH) modified and unmodified biochars derived from sheep manure and rice husk residues. The modified or unmodified biochars were applied at a rate of 2% (w/w) to Cd-contaminated silty clay loam, loam, and sandy loam soils, followed by a 90-day incubation at field water capacity. Sequential extraction and EDTA-release kinetics studies were used to assess the effect of the treatments on the extent and mechanisms of Cd immobilization. Among the treatments, acid-modified manure biochar was most effective at reducing water soluble and exchangeable Cd fractions (-20.5%), by converting them into metal oxide and organic matter bound fractions. This effectiveness was primarily attributed to the significant increase in surface oxygen functional groups in the acid-modified biochar which could promote Cd complexation. However, the acid-modified manure biochar released more immobilized Cd during EDTA extraction than the base-modified manure biochar, suggesting that EDTA extraction of R-O-Cd complexes was easier than extracting Cd associated with insoluble compounds. This difference was likely due to the acidic pH and lower ash content of the acid-modified biochars compared to the base-modified manure biochars. Additionally, the extent of Cd immobilization was lower in sandy loam soil, highlighting the importance of immobilizing Cd in light-textured soils to prevent its transfer to organisms. [ABSTRACT FROM AUTHOR]

This study investigates the impact of long-term water immersion on the mechanical and hydrochemical properties of cemented calcareous soil, emphasizing the critical role of carbonate content in mechanical performance. Utilizing hydrochemical analysis and triaxial testing, the research revealed that prolonged immersion disrupts the acid-base balance of the solution, resulting in an increased concentration of ions and chemicals. Significant dissolution of carbonates and soluble minerals occurs, which reacts with carbon dioxide to generate bicarbonate ions, thereby elevating the alkalinity of the soaking solution. Additionally, the gradual dissolution of clay minerals compromises the cementitious structure, leading to particle reorientation and interlocking. The study quantitatively assesses the changes in soil properties, demonstrating a substantial reduction in soil cohesion by up to 86.1% and an increase in the internal friction angle by 37.5%. Furthermore, the gradual dissolution of clay minerals compromises the cementitious structure, resulting in particle reorientation and interlocking that contribute to the observed mechanical changes. The findings underscore the importance of understanding the effects of extended immersion on the stability and engineering applicability of cemented calcareous soils. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency is a frequent problem in calcareous soils of Pakistan because of P-fixation, which poses significant threats to pearl millet productivity. The use of P-solubilizing bacteria (PSB) is regarded as a promising approach for improving P-availability in soil-plant systems. However, it needs optimization of P application into the soil. Therefore, this 2-year field study was conducted to optimize P doses in combination with PSB (Bacillus sp. MN54) inoculation to improve phosphorus use efficiency (PUE), yield, economic returns, and grain quality of pearl millet. Five P doses, i.e. 0 (native soil P only - control), 30, 60, 90, and 120 kg P2O5 ha−1 combined with and without PSB inoculated seeds were used in the study. The application of 90 kg P2O5 ha−1 + seed inoculation with PSB improved the grain yield by 36.8% and 36.0% during 1st and 2nd year, respectively. The same treatment significantly improved the PUE, grain protein, zinc (Zn), and total grain P contents compared to the control treatment. Furthermore, the highest economic returns (1053.3 and 1050.5 $ ha−1) and benefit:cost ratio were observed under 90 kg P2O5 ha−1 + seed inoculation with PSB during both years. In conclusion, application of 90 kg P2O5 ha−1 combined with PSB seed inoculation is a pragmatic option to improve P uptake, grain yield, PUE, grain quality and economic returns of pearl millet grown on calcareous soils. [ABSTRACT FROM AUTHOR]

AbstractThis study investigates the effects of combining different nitrogen fertilizers with organic amendments and Azospirillum brasilense on wheat growth, yield, and nutrient uptake in saline calcareous soil, with a goal of enhancing crop productivity while reducing environmental impacts. The objective was to evaluate treatments involving ammonium sulfate (AS), urea, and sulfur-coated urea (SCU), mixed with organic amendments such as Moringa seed residues (MSR), biogas manure (BM), and vermicompost (Ver), along with Azospirillum brasilense (ASB). Among these treatments, SCU emerged as the most effective nitrogen source, especially when combined with Vermicompost and ASB. Key results include the following: the highest Chlorophyll a content of 1.96 mg/g f wt was observed in the SCU treatment with Ver and ASB; Likewise, the same treatment exhibited the highest values of Chlorophyll b, carotenoids, and proline; the tallest plant height (117.50 cm) was also achieved with this combination; and the highest straw and grain weights (2.63 g/plant and 2.22 g/plant, respectively) came from the same treatment. Additionally, this treatment yielded the highest protein content at 19.29%. In terms of nutrient uptake, SCU-based treatments consistently demonstrated the highest values. The SCU with Ver + ASB treatment recorded the highest nitrogen uptake in straw at 78.64 mg plant−1, phosphorus uptake at 12.86 mg plant−1, and potassium uptake at 61.66 mg plant−1. Similarly, this combination yielded the highest N, P, and K uptake in grains, with 68.05, 10.88, and 53.15 mg plant-1, respectively. e [ABSTRACT FROM AUTHOR]

In this study the fertilizing effect of ZnEDTA (zinc ethylenediaminetetraacetate), and ZnSO4ּ 7H2O (ZnSO4ּ) (zinc sulphate heptahydrate) was compared on calcareous loam soil. A pot experiment was set up with maize (Zea mays L. var. ‘P37N01’). Plants were treated with basic NPK doses and with Zn at increasing rates: 0, 2.5, 5.0 and 10 mg kg-1 Zn in ZnEDTA and in ZnSO4 form, respectively. The ZnEDTA and ZnSO4 treatments increased the dry matter production compared to control by an average of 16%. Applying 2.5 mg kg-1 Zn, shoot Zn uptake was 1.3-fold greater by plants treated with ZnEDTA, than that of treated with ZnSO4. In the case of higher rates (5.0 mg kg-1 Zn and 10 mg kg-1 Zn), Zn uptake from ZnEDTA was approximately twice as much as that of ZnSO4. This result confirms that ZnEDTA as Zn complex is more effective than ZnSO4 on calcareous soil. The increasing ZnEDTA and ZnSO4 doses enhanced the soil’s initial diethylenetriaminepentaacetic acid (DTPA) Zn concentration to 1.8, 3.0, 6.3 mg kg-1 and 1.9, 3.5, and 6.5 mg kg-1, respectively. Contrary to our expectations, DTPA soil extractant was not able to indicate the difference in Zn availability between soils treated with ZnEDTA and ZnSO4. During the experiment, 0.6-1.7% of the added Zn doses were absorbed by the plants, and 48-59% of it could be measured back in the form of DTPA-Zn for both Zn fertilizers, the other half of the added Zn presumably converted to less available Zn forms. [ABSTRACT FROM AUTHOR]

Potassium behavior in calcareous soils are very complex and are affected by several factors, such as the content of carbonates and soil heating. In the present research, the comparison of four calcareous soils with varying amounts of carbonates, different mineralogy, and texture (collected from Fars province, southern Iran) was compared to analyze the content of K species, K release by solutions of 0.01 M CaCl2 and 1% wood vinegar, and K re-fixation. The study also investigated the impact of heating K-depleted soils to 100°C on the secondary release and re-fixation of K. The results showed that the studied soils contained 3–60% carbonates, 14–53% clay, and a relatively similar mineral composition: smectite, illite, chlorite, palygorskite (in dry areas), and vermiculite (in humid areas). Wood vinegar extracted more K from soils with less carbonates than CaCl2, while this difference was not significant for Fluvisols, which contains about 60% carbonates. Mollic Vertisols with low carbonate content (about 3%) and high levels of clay and smectite released less K in the initial phase. However, K release by this soil decreased less in the second phase, indicating the higher buffering capacity of Mollic Vertisols in providing soluble K. Heating the soil increased the secondary release of K, but decreased the amount of K re-fixation in soils treated with CaCl2. Generally, Mollic Vertisols fixed more K than other soils. In addition, the type of extractant had no effect on the content of K fixation in the studied soils except Mollic Vertisols. However, wood vinegar reduced the K fixation content in Mollic Vertisols compared to CaCl2. In general, it can be concluded that wood vinegar can provide more K to the plants without dissolving K-bearing minerals compared to CaCl2. In addition, soil heating can influence the process of K release and fixation in K-depleted soils. [ABSTRACT FROM AUTHOR]

Nitrogenous fertilizer drift from farmlands accelerates nitrogen loads in groundwaters. Biochar potential to mitigate nitrogen leaching in urea treated sandy soil was monitored in a four weeks screenhouse leaching column experiment. The trial was a factorial combination of two biochar types (B1 and B2 applied at 5 t/ha) and two urea treatments (with urea at 120 kg/ha and without urea) laid in completely randomized design with three replications. Control that received neither urea nor biochar was compared. Four weekly leaching events were conducted in each leaching column containing 300 g soil amended with appropriate treatments. Amaranthus hybridus was the test crop. The NH4-N and NO3-N leached were generally highest during the week 2 leaching event such that total NO3-N leached was 427.3 % higher than total NH4-N leached with highest contributions from sole urea treatment. Biochar pretreatment reduced total N leached by 9.5 (B1) and 26.8 % (B2) relative to sole urea. Percentage of N added lost to leaching was highest (34.1 %) in sole urea treatment with B1 and B2 pretreatment reducing the value by 54.5 and 46.9 % respectively. Correlation analysis revealed electrical conductivity of the leachate and soil as dominant indicators for N leached in the soil studied. [ABSTRACT FROM AUTHOR]

Application of appropriate organic amendments as the carriers of bacterial consortium may improve the remediation efficiency of HMs-polluted soil. A greenhouse experiment was designed and carried out to investigate the capability of biochar, and activated carbon prepared from ostrich manure and almond husk as the carriers of bacterial inoculants in the phytoremediation of a calcareous soil polluted with Pb, Ni, Cd and Zn by maize. Results showed that the application of biochar and activated carbon prepared from ostrich manure increased root (78–129%) and shoot (72.3–272%) dry weight, as compared to the control. The values of metal accumulation in both maize root and shoot were in the order of Cd>Zn>Ni>Pb. While biochar and activated carbon prepared from ostrich manure significantly increased both root and shoot metals uptake, those prepared from almond husk drastically decreased the uptake of some metals. The foremost mechanism involved in the phytoremediation of Cd, Ni and Pb was phytostabilization while that of Zn was due to the phytoextraction. Results of the present study demonstrated the effectiveness of ostrich manure-derived biochar and activated carbon as an efficient treatment in the phytoremediation of multi-metal-polluted soils and the mitigation of HMs phytotoxicity. [ABSTRACT FROM AUTHOR]

Biochar is a carbon-rich product obtained by biomass pyrolysis and is considered as a means of carbon sequestration. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC in a calcareous soil. In this study, different biochar AS, TS, PP, CS were applied to the soil at different rates (0.5, 1.0, and 1.5%) The highest increase in soil organic C content was observed in the TS treatment, while the AS treatment caused a slight increase of soil organic C. The highest MBC content was recorded in AS treatment and the lowest was observed in TS. The highest CO2-C emission was recorded in the TS treatment. In contrast, the lowest CO2-C emission was observed in the PP treatment due to its high recalcitrant C content and was attributed to a positive priming effect, stabilizing BC mineralization to improve the soil. The highest β-galactosidase enzyme activity was observed in the CS treatment and the lowest activity was observed in AS. The highest change in β-glycosidase enzyme activity was observed of PP treatment and the lowest was in AS biochar application. Thus, TS treatment is recommended to increase the organic C content of soils, and the PP biochar can be used to reduce CO2-C emission. The TS, PP, and CS can be applied to increase enzyme activities. The study clearly shows that the addition of BC to arid soils may have a high potential to improve soil enzyme activities and subsequent carbon sequestration and biochemical cycles. [ABSTRACT FROM AUTHOR]

Many years ago, widespread and ineffective technologies led to significant ecological contamination, primarily due to heavy metals (HMs), particularly lead (Pb) and cadmium (Cd). Plant growth in heavy metals contaminated and calcareous soil is a challenge for all the growers worldwide. Several organic and inorganic amendments are used by researchers in different types of soils. However, their impact on soil contaminated with toxic metals and alkaline in reaction is still unclear. Therefore, the current pot experiment investigates the relative effect of organic (wheat straw biochar and farmyard manure) at 10 and 20 t ha−1 and inorganic (diammonium phosphate and gypsum) at 100 and 150 kg ha−1 amendments on NPK availability, soil organic matter, soil properties, and maize growth under Cd and Pb stress. Highest soil pH (7.61), soil electrical conductivity (0.25 dS m−1), soil organic matter (1.40%), plant height (92 cm), shoot dry weight (41 g), and root dry weight (5.5 g) were observed because of biochar application at 20 t ha−1. While the highest total nitrogen (N) (0.13%), and phosphorus (P) (8.16 mg kg−1) were recorded with diammonium phosphate application at 150 kg ha−1, moreover, application of farmyard manure at 20 t ha−1 increased the soil potassium (K) (108.14 mg kg−1). Biochar application at 20 t ha−1 greatly reduced the toxic metals bioavailability with a high immobilization index, that is, Cd (52%) and Pb (43.79%) lead to lower concentrations of metals in roots and shoots as well. A negative correlation was identified between soil pH, soil organic matter, and soil Cd, Pb, demonstrating the positive impact of biochar in terms of the reduction of toxic metals by enhancing pH and soil organic matter, found to be the most effective amendment for soil improvement and plant growth under Cd and Pb stress condition. [ABSTRACT FROM AUTHOR]

Background: This study aims to explain the mechanism of formation of calcite and it's to shed light on the synthetic carbonate crystallization on the surface of roots due to this mechanism is poorly understood and highly controversial. It is accepted that calcite formed originally from parent rocks and not in soils. Method: The origin of calcite in calcareous soil, in Aldiwaniya city, Iraq was investigated, by selecting two soil samples, one from the contact zone with root surface and the other sample from bulk soil and out of the root system. Results: X-ray diffraction showed that the calcite has two types, first one is well crystallized and ordered, with only minor deviations in lattice unit cell parameters relative to typical calcite. The clay-sized calcite (active calcite) is enriched in A and Chorizons relative to biogenic calcite and this mineral exist in larger size separates, and it's clearly appears in the shape of white crystals around eucalyptus root surfaces as shown in graphs. The results of X-ray showed that the appearance of smectite mineral which was diagnosed by the peak 14.21 A° in air dry magnesiumsaturated treatment which expanded to 16.28 A° when saturated with ethylene glycol, where clarity of peak was increased, Also, the results showed that the appearance of peak 14.21 A° in magnesium saturation air dried, as a shoulder on the peak of the mica (10.14 A°). Conclusion: In general, calcite minerals have characteristic x-ray diffraction peaks at the following angles: 29.5, 31.7, 34.5, 35.7, 47.3, 56.4, and 63.4 degrees. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: A rapidly increasing human population has resulted in the expansion of urban areas and an associated increase in the demand for food. Consequently, urban and peri-urban agriculture, using waste water as a source for irrigation, is increasingly common around the world, particularly in developing countries. In the Kurdistan region of Iraq, the soils within Agriculture areas have the potential to accumulate trace elements originating from various sources of contamination like municipal waste disposal and the use of wastewater for irrigation. The main aim of this study was to assess the levels and sources of trace elements in this specific region and to analyze the potential health hazards linked to toxic elements present in the soil. METHODS: Elemental analyses were conducted on soil samples using the total digestion method, involving the use of Hydrofluoric acid. Subsequently, 118 soil samples, each with a fraction size of less than 2 millimeters, were analyzed. These samples were collected from seven different urban and peri-urban agriculture areas in Sulaimani province. The analysis was carried out using Inductively coupled plasma mass spectrophotometry, which operated in collision cell mode with 7 percent hydrogen in helium to minimize polyatomic interferences. FINDINGS: The study findings indicated that the soils, with a potential hydrogen range of 7.5 to 8.18, are mainly calcareous and have textures that vary from silty loam to sandy or silty clay. Additionally, the organic matter content of these soils ranges from 1.4 percent to 5.47 percent. It was noted that soils subjected to wastewater irrigation do not show significant contamination by trace elements, whereas those affected by waste disposal sites showed high levels of chromium (134 milligrams per kilogram), copper (263 milligrams per kilogram), zinc (773 milligrams per kilogram), cadmium (4.19 milligrams per kilogram) and lead (161 milligrams per kilogram). Evaluation of enrichment factors indicates that the concentrations of trace elements generally remain within the anticipated background levels, with the exception of the municipal waste disposal site. The hazard indices derived for the trace elements indicate that the potential health risks associated with exposure routes are minimal. These indices consistently remain below the internationally recognized threshold of one, which signifies that the health concerns are insignificant fall within acceptable boundaries. CONCLUSION: The concentrations of trace elements exhibited a notable increase in locations allocated for waste disposal, demonstrating a gradual decline in comparison to other agricultural regions. Throughout all the locations examined, the levels of nickel consistently remained elevated, suggesting that the geological attributes of the region have a significant impact. [ABSTRACT FROM AUTHOR]

Phytoremediation is an important method for refining heavy metals, but the main limitation is the low bioavailability of the metals. Chelating agents, by releasing heavy metals from the soil solid phase, can increase their uptake by the plants. In this research, the effects of some chelating agents on the phytoremediation of Vicia faba in a calcareous soil contaminated with Cd were investigated. A factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of Razi University. The factors included Cd at four levels (0, 5, 10, and 15 mg kg-1 soil as CdCl2), and three chelating agents including ethylene di-amine tetra acetic acid (EDTA), citric acid (CA), and oxalic acid (OA), at two levels (4 and 8 mmol kg-1 ). The results showed that the highest Cd concentration in the root and shoot (39.90 and 27 mg kg-1, respectively) was obtained at 15 mg kg-1 of Cd and 8 mmol kg-1 of EDTA, CA, and OA. The highest values of transfer factor (0.67) and biological accumulation factor (5.65) were obtained at the highest level of Cd pollution and 8 mmol kg-1 of chelating agents. This indicates that firstly, cadmium was mainly accumulated in the root and was less transferred to the shoot. Secondly, it shows the potential of bean in phytoremediation and Cd uptake. Also, the amounts of the measured factors with citric and oxalic acid were not much different from EDTA, and therefore, these two environmentally friendly natural chelating agents could be used instead of EDTA. [ABSTRACT FROM AUTHOR]