https://dlsr.iut.ac.ir/ Dryland Soil Research (DLSR) en daily 1 Sat, 01 Mar 2025 00:00:00 +0330 Sat, 01 Mar 2025 00:00:00 +0330 https://dlsr.iut.ac.ir/article_3730.html Sulfur (S) is an essential element for plants, playing a crucial role in various biochemical processes that are vital for their health.. Insufficient sulfur in the soil can profoundly affect plant health and crop yield. Agriculture commonly relies on sulfur fertilizers containing either sulfate or elemental sulfur (So) as a sulfur source. However, So, being more cost-effective and less prone to leaching than sulfate (SO4-2) is favored, but, So must undergo oxidation to sulfate before plants can readily utilize it, a process largely facilitated by soil microorganisms. The environmental conditions affecting microorganism populations and activities significantly influence So oxidation. Sulfur-oxidizing bacteria (SOB) are instrumental in sulfur cycling within soil ecosystems, impacting their availability and transformation. This review delves into the intricate connections among S dynamics, SOB, soil improvement, and plant nutrition. It explores how plants obtain and employ S, stressing its significance in protein synthesis, enzyme activation, and secondary metabolites production. Additionally, the review scrutinizes SOB's role in mediating S oxidation, which influences soil pH, nutrient availability, and plant-microorganism interactions. Moreover, it discusses the potential of SOB as biofertilizers to enhance sulfur availability and bolster plant growth. Various strategies for leveraging the beneficial effects of SOB in sustainable agriculture are examined, such as microbial inoculation. The review also addresses the environmental implications of sulfur cycling, emphasizing the importance of maintaining balanced sulfur levels in soil ecosystems to mitigate environmental pollution and optimize agricultural productivity. In conclusion, this review offers valuable insights into the dynamic relationship between sulfur, SOB, soil fertility, and plant nutrition. It underscores the potential applications of this understanding in sustainable agriculture and ecosystem management, emphasizing the necessity of sulfur management for fostering agricultural productivity and environmental sustainability. https://dlsr.iut.ac.ir/article_3731.html Calcareous soils are widely distributed in the arid and semi-arid regions, where most agricultural soils in Iran, due to climatic conditions and geological formations, are calcareous and have a high pH. In such soils, some nutrients like phosphorus, are fixed and utilizing acid-forming substances may increase the availability of this element. Sulfur is considered to be the most affordable acid-producing material and is a byproduct of gas and oil refineries with an annual production of more than two million tons in Iran. In this research, the effects of bentonite-sulfur produced by a new process were tested on maize silage (Single Cross 704 cultivar) on agricultural soil research farms at three sites (Isfahan, Shiraz, and Jiroft) using a factorial experiment. For this purpose, 0, 0.5, 1, and 2 t ha-1 of the elemental sulfur as well as 0, 65, and 100% of recommended phosphorus were applied. Application of elemental sulfur was combined with the inoculation of Thiobacillus bacteria (1 kg per 50 kg of elemental sulfur). Results indicated that sulfur, phosphorus, and their co-application brought about significant increases in maize shoot dry and fresh weights only at Shiraz site. Sulfur application enhanced the shoot uptakes of zinc and iron at Shiraz and Jiroft sites. The highest Fe uptake was observed with application of 2,000 kg ha-1 of sulfur. No significant effects were, however, detected on shoot phosphorus uptake at any of the study sites. Elemental sulfur was observed to have a limited effect on soil nutrient availability and plant growth because of the high buffering capacity of the studied sites calcareous soils, counteracting the acidification of sulfur oxidation. https://dlsr.iut.ac.ir/article_3732.html Sustainable agriculture demands innovative strategies to optimize water use amid growing climatic uncertainties, resource limitations, and to bolster the resilience of farming systems worldwide in the face of climate change. This review provides a critical synthesis of state-of-the-art modeling approaches that integrate crop growth dynamics with soil hydraulic processes to support precision irrigation management. Emphasizing the vadose zone's central role as the critical interface governing soil-plant-water interactions, the paper examines a suite of widely used, process-based crop models (e.g., WOFOST, CERES, AquaCrop, DSSAT, APSIM) alongside specialized hydrological models (e.g., HYDRUS, SWAP, SWAT). It highlights their synergistic capability to simulate the complex, nonlinear feedback between root water uptake, soil moisture dynamics, evapotranspiration, and solute transport, which is fundamental for predicting crop water requirements and responses to irrigation. The primary challenge for this approach is the accurate determination of often unknown or highly variable soil hydraulic and crop parameters. This review demonstrated that 1) Advanced inverse modeling techniques provide a powerful alternative to direct measurements by using optimization algorithms to estimate critical parameters from field data. 2) Sensitivity analysis (both local and global) is indispensable for evaluating model robustness, identifying influential parameters, and mitigating calibration issues like equifinality. 3) Well-calibrated, integrated models enable a robust, physically sound framework for generating site-specific irrigation schedules, moving beyond traditional homogeneous management. We also identify key challenges, including data scarcity and computational demands. To address these, we advocate for the future development of quasi-3D hybrid modeling platforms that leverage high-resolution data from easily available resources, laboratories, remote sensing, and IoT networks. This integrative approach holds significant promise for advancing next-generation precision irrigation, enhancing water use efficiency, and strengthening global agricultural resilience. https://dlsr.iut.ac.ir/article_3733.html Nowaday, plastic contamination is one of the most pressing environmental challenges. With annual production exceeding 360 million tons, plastics have infiltrated into various parts of ecosystem and are alarmingly prevalent in gardens, agricultural fields, and soils of industrial zones worldwide. Over time, these larger plastic particles degrade into smaller fragments, including microplastics (MPs) and nanoplastics (NPs). Among these, NPs pose the most significant threat due to their diminutive size, allowing them to be absorbed by living organisms and subsequently move into the food chain and leading to potential bioaccumulation. This review article aims to synthesize current knowledge on the impact of micro and nanoplastics (MNPs) on soil health, plant physiology, and human health by identifying key themes and knowledge gaps in the literature. Recent studies have highlighted the detrimental effects of MNPs on soil health, revealing that agricultural practices, such as utilizing plastic mulch and synthetic fertilizers, have contributed to the elevated MNP concentrations in soils worldwide. The uptake of MNPs by plants can alter their physiological and morphological characteristics, as well as their gene expression profiles, leading to unpredictable consequences for plant health, growth, and productivity. These contaminants can be absorbed directly into plant tissues or adhere to root surfaces, raising concerns about the potential transfer of MNPs into the food supply. The implications for human health are profound, as the consumption of contaminated crops may lead to adverse health effects, including endocrine disruption and inflammatory responses. While the impact of traditional soil pollutants, such as heavy metals, has been extensively studied, the emerging risks posed by plastic contaminants require urgent attention. This review contributes to existing literature by broadening our understanding of MNPs and their effects, ultimately aiming to safeguard both plant and human health despite escalating environmental plastic contamination. https://dlsr.iut.ac.ir/article_3734.html Accurate estimation of saturated hydraulic conductivity (Ks) is essential for soil and water management, yet the reliability of the pedotransfer functions (PTFs) is often overlooked.Tthis study compares the predictive performance and the robustness of field estimates of Ks obtained by three types of PTFs: Multiple Regression (MR), Artificial Neural Networks (ANN) and the Group Method of Data Handling (GMDH) developed using 134 soil samples collected in north-western Iran, which is a region with semi-arid conditions and mixed agricultural uses whereas the dataset encompasses a wide range of structural and textural variationsto Ks prediction. In addition to traditional soil properties soil moisture deficit compared to the optimum value at the time of sampling, θd, was used as a proxy indicator of soil structural condition. Model precision was evaluated using Root Mean Square Error (RMSE) and the Nash–Sutcliffe efficiency; reliability was determined through repeated data splitting. Even though ANN provided good accuracy for the training set, its performance for the validation set was inconsistence. MR produced consistent, albeit limited performances over both the training and validation subsets. Conversely, GMDH appears to strike a good compromise between prediction accuracy, reliability, parsimony of the predictor set, and texture versus structure variables. The results point to the importance of including structural measures such as θd in PTF development and provide a basis for considering model repeatability a long with accuracy. In general, the results indicate that GMDH is a robust and feasible technique to develop accurate PTFs for Ks predictions with limited amount of data. https://dlsr.iut.ac.ir/article_3735.html A quantitative understanding of the factors regulating potassium (K) distribution in soils is essential for optimizing nutrient management in agricultural systems, as K availability directly influences crop productivity and soil health. To systematically evaluate the drivers of K dynamics, a suite of artificial neural networks, coupled with Deep Learning Important FeaTures (DeepLIFT) attribution analysis, was employed to quantitatively assess the relative influence of key soil properties, including clay, silt, and sand content, pH, organic carbon (OC), cation exchange capacity (CEC), and electrical conductivity (EC), on four distinct K pools: water-soluble K, non-exchangeable K, fixed K, and total K. Additionally, the study investigated the association of soil initial water-soluble K and fertilizer K application rate with the fixation of K fertilizer to elucidate the relationship between them. Key findings revealed divergent drivers across K fractions, highlighting the complexity of K dynamics in soils. CEC emerged as the dominant factor influencing water-soluble K variability (+22.43%), underscoring its role in regulating K mobility. Clay content exhibited contrasting effects, positively influencing non-exchangeable K (+13.42%), total K (+20.59%), and fixed K (+13.81%), while negatively impacting water-soluble K (-14.38%). EC was the primary determinant of non-exchangeable K (+34.27%), suggesting salinity’s role in K retention. In contrast, pH showed a strong association with fixed K (+26.58%), reflecting its influence on interlayer trapping within 2:1 clay minerals. To bridge predictive modeling and practical applications, a genetic algorithm was integrated into an open-source, user-friendly Excel-based tool. This tool enables farmers and agronomists to optimize soil conditions for maximizing the sum of water-soluble and exchangeable K (plant-available K), thereby supporting precision nutrient management. By elucidating soil-specific K dynamics and providing actionable insights, this research advances sustainable K stewardship. The tool is accessible for download at: https://drive.shahroodut.ac.ir/index.php/s/fayE0zUH16TQe2M https://dlsr.iut.ac.ir/article_3802.html Soil microbiome, the foundational engine of terrestrial ecosystems, is critical for global food security and environmental sustainability. For decades, agricultural science has pursued microbial inoculants as "silver bullet" solutions, yet this approach has yielded inconsistent results and failed to deliver the systemic resilience required for long-term soil health. This review synthesizes a growing body of evidence to argue that a paradigm shift is necessary: moving from a focus on inoculation to one of habitat managements. The central thesis posits that fostering the indigenous soil microbiome—by enhancing its organic matter, habitat complexity, and biodiversity—represents a more robust, resilient, and sustainable path forward. Evidence is presented demonstrating that management practices such as amending soil with organic matter, cover cropping, and practicing reduced tillage, enhance microbial diversity, functional redundancy, and self-regulation, and ultimately providing broader, more durable, and economically viable benefits than the introduction of single-strain microbes. https://dlsr.iut.ac.ir/article_3803.html Salt accumulation in the agricultural soils are inevidable when irrigation is performed by saline water. This phenomenon is a global challenge especially in the drylands. Vesicular-arbuscularmycorrhizal fungi (VAM) as biofertilizers that form symbiotic associations with plant roots are natural and suitable amendments for somehow overcoming this problem. The currentc study aimed to investigate the potential of mycorrhizal fungi (VAM) to enhance the growth of ornamental sunflowers (Helianthus annuus L.) cultivated under salinity stress conditions in a pot culture system. The overarching objective was to identify sustainable strategies that mitigate environmental challenges, such as soil salinity, and decrease reliance on chemical fertilizers. A 3×4 factorial experiment was conducted using a completely randomized design with three replications. The experimental factors included three salinity levels (a control without NaCl, 50 and 100 mM NaCl) and four VAM species (uninoculated plant as the control, and plants inoculated with Rhizophagus irregularis, Funneliformis mosseae, and Glomus howei species). Plant growth parameters, including flower diameter, fresh and dry weights of flowers, shoot and root biomasses, proline level, chlorophyll content, relative water content, malondialdehyde content, ion leakage, and root colonization percentage were measured after plant harvest. The results showed that salinity stress, VAM inoculation, and their interaction significantly affected most plant growth indices. Higher salinity levels led to a decrease root and flower weights, flower diameter, and chlorophyll content, while proline contents and ion leakage were positively affected by high soil salt content. At high salinity levels (100 mM), inoculation with F. mosseae had the greatest effect on improving plant growth. The fresh weight of flowers (16.4 g), shoots (27.6 g pot-1), roots (6.57 gpot-1), and total chlorophyll (36.0 mg g-1 of fresh weight) were higher in the treatment inoculated with F. mosseae and without salinity. The highest proline content (5.6 μmol g-1 fresh weight) and ion leakage (76.4%) values were observed in the non-VAM and 100 mM NaCl treatments. The symbiotic relationship between arbuscular mycorrhizal fungi and plants constitutes a mutually advantageous biological interaction, substantially enhanced plant growth and productivity. The findings suggest that VAM inoculation can improve plant growth and ornamental value under salinity stress. Compared to other species, Funneliformis mosseae showed greater capacity to enhance the quantity and quality of ornamental sunflower production. https://dlsr.iut.ac.ir/article_3804.html Azotobacter spp. are free-living, obligately aerobic, Gram-negative diazotrophic bacteria widely distributed in neutral to alkaline soils. Although they generally occur at relatively low abundance in agricultural ecosystems, these microorganisms have attracted considerable scientific and agronomic interest because of their diverse functional traits and significant potential for promoting sustainable agriculture. As non-symbiotic nitrogen-fixing bacteria, Azotobacter species convert atmospheric nitrogen into bioavailable forms while enhancing plant growth through a broad range of direct and indirect mechanisms. These include the production of phytohormones, such as indole-3-acetic acid (IAA), gibberellins, and cytokinins; phosphate solubilization; mineral nutrient mobilization; siderophore production; and improved nutrient uptake efficiency. Moreover, several Azotobacter strains have been shown to enhance plant tolerance to abiotic stresses, including salinity, drought, and heavy metal toxicity, while suppressing certain soil-borne phytopathogens. Beyond their agricultural applications, members of this genus possess considerable ecological and biotechnological importance. Their capacity to produce extracellular polysaccharides, accumulate polyhydroxyalkanoates, form stress-resistant cysts, and participate in the transformation or immobilization of environmental pollutants has stimulated increasing interest in their use for soil restoration, bioremediation, and environmental management. Furthermore, advances in microbial genetics, genomics, and molecular biology have established Azotobacter vinelandii as an important model organism for investigating biological nitrogen fixation, respiratory protection mechanisms, alginate biosynthesis, and microbial adaptation to environmental stress. This review summarizes current knowledge of the taxonomy, evolutionary history, morphology, physiology, ecology, and functional characteristics of the genus Azotobacter. Particular emphasis is placed on its plant growth-promoting mechanisms, agricultural applications, and environmental significance. The review also critically examines the major factors limiting the field performance of Azotobacter-based inoculants, including environmental constraints, carbon availability, competition with indigenous microbial communities, and formulation-related challenges. Finally, current knowledge gaps and future research priorities are discussed to facilitate the development of more effective inoculants and integrated microbial technologies. A deeper understanding of plant–microbe–soil interactions, together with strain-specific functional diversity, will be essential for improving the reliability, consistency, and large-scale application of Azotobacter in sustainable agricultural systems. https://dlsr.iut.ac.ir/article_3805.html Improving the productivity of wheat, Iran's most important staple crop, remains a major agricultural challenge, highlighting the need for more effective nutrient management strategies. Plant-based foods can be enriched with essential micronutrients by increasing their concentration in edible tissues, enhancing their bioavailability, or both. Micronutrient concentration in the edible portions of forage and food crops is governed by multiple complex, dynamic, and interacting factors, including plant genotype, soil properties, environmental conditions, and nutrient interactions. Compositional Nutrient Diagnosis (CND) was applied to evaluate the nutritional balance of macro- (N, P, K) and micronutrients (Fe, Mn, Zn, and Cu) in wheat grain (Triticum aestivum L.) cultivated under different fertilization systems in Iran. For the low-yielding subpopulation, the dominant CND indices controlling yield variability in the dataset were IFe, IP, and IK, whereas for the high-yielding subpopulation, IMn, IK, and IP were most influential. These findings indicated that Mn deficiency was determined as the most yield-limiting factor, followed by K and P. In contrast, Zn and Fe were not identified as critical limitations, as their bioavailability was enhanced by micronutrient fertilizer application. Zinc treatments recorded the highest frequency in the excellent and good clusters (96.9%), followed by compost (93.8%) and Fe treatments (87.5%). This study identifies previously unreported limiting factors in grain wheat following the application of nutrients from inorganic, organic, and integrated nutrient sources. Practically, by identifying the most limiting nutrients, the CND approach may enable more precise fertilizer recommendations, thereby improving nutrient use efficiency, grain quality, and wheat yield in future crop management. https://dlsr.iut.ac.ir/article_3806.html Wind erosion is among the most important land degradation processes especially in the arid and semi-arid regions. The use of clay mulches has gained attention as a novel and environmentally friendly method for soil stabilization and reduction of dust emissions. However, it is not yet fully clear how these mulches influence the development and reinforcement of soil surface seals (crusts), nor how the resulting changes affect soil shear strength (SS) and penetration resistance (PR).. This study aimed to experimentally evaluate the effects of bentonite clay mulch, applied at rates of 20 to 60 g m⁻², on the SS, PR, and saturated hydraulic conductivity (Ks) of the surface seal of a salt affected soil sample from the Segzi region (Isfahan Province). The results showed that both rainfall application and hand spraying, when applied alone, formed a surface seal with higher SS and PR and lower Ks compared to the untreated soil. Application of clay mulch, at 30 g m⁻² rate, significantly increased shear strength (up to 36%) and reduced Ks (28-33%) compared to the control. However, with increasing mulch application rate from 30 to 50 g m⁻², the relative effect of mulch on increased shear strength diminished (from 36% to 7%), indicating the dominant role of sprayed water on initial seal formation. Microscopic examination revealed that the soil had very high salinity, which led to the formation of a mixed clay-salt type surface seal. The morphology of salt crystals in the presence of clay mulch differed markedly from that in the control sample. Considering both the seal SS and its Ks, the application of 20 g m⁻² bentonite clay is proposed as the optimal rate for soil stabilization and dust suppression. However, due to the high soil salinity, generalization of the results to non-saline or low-salinity soils requires further investigation. https://dlsr.iut.ac.ir/article_3807.html Despite benefits of using chicken manure as an organic amendment to soils deficient in organic metter, there are several conerns on direct application of the manure. The composting is a common process which help to overome the restrictions of using raw manure in agricultural soils, A better knowledge on the optimum conditions for composting is necessary to improve the efficiency of composting and achieveing a proper product. In this study, we investigated the optimum carbon-to-nitrogen ratio of raw chicken manure for composting process. For this purpose, the raw materials with three C:N ratios including 1:20, 1:25, and 1:30 were prepared by combination of chicken manure and various amounts of sawdust. The amounts of sawdust were chosen by considring the target ratio of carbon to nitrogen of the raw materials and the C and N contents of sawdust. The composting materials were sampled from different piles (75-cm depth). Results showed that the composting resulted in significant loss of nitrogn from the chicken manure; about 45% recudtion in nitrogen of compost was found in comparison with the raw chicken manure. The EC of the compost decreased at all C:N treatments over time. In contrast, an increase in pH of composting pile (increased to about 7) was observed at the final step that might be an indictor for compost maturity. In two weeks, a significant reduction in the concentration of NH4+ and micrbial activity of compost was observed while after 2 weeks, the NH4+ concentration and microbial activity remained unchanged to the end of compositng. In conclusion, a chicken manure with carbon-to-nitrogenn ratio of 30 led to the lowest loss of nitrogen in the form of NH3 and produced a compost with lower pH containing higher amounts of N and organic matter. https://dlsr.iut.ac.ir/article_3810.html Sustainable soil management and precision nutrient application in irrigated wheat systems require a detailed understanding of the spatial variability of soil properties and their implications for site-specific practices. This study aimed to quantify the spatial variability of some key soil fertility attributes and to delineate soil fertility management zones (MZs) for site-specific nutrient management in irrigated wheat fields of Alborz province, Iran. A total of 222 geo referenced surface soil samples (0–30 cm) were collected on a 1,650 × 1,650 m grid. Soil pH, electrical conductivity (EC), soil organic carbon (SOC), total neutralizing value (TNV), particle-size distribution, and available macro and micronutrients (P, K, Ca, Mg, Fe, Mn, Zn, Cu) were determined by the standard laboratory methods. Descriptive statistics and Pearson correlations were computed, and geostatistical analyses (semivariograms and ordinary kriging) were used to characterize and map spatial variability. Principal component analysis (PCA) followed by fuzzy c means clustering were applied to delineate soil fertility MZs. Most soil properties exhibited moderate to high coefficients of variation, with only low variability for the pH, while clay and TNV fell into the moderate class and EC, SOC, and most available nutrients showed high variability. Semivariogram modelling indicated exponential and Gaussian models as the best fit for the majority of properties, with moderate to strong spatial dependence and ranges varying from 1.65 to 105.6 km. Kriged maps revealed that about 78% of the area was non saline (EC <4 dS m⁻¹), whereas roughly 22% was saline, and more than half of the fields had SOC <1%, highlighting significant constraints on yield and soil health. Micronutrient maps showed widespread Zn and Fe deficiencies in the western, more alkaline and lighter textured parts of the province. PCA identified four principal components explaining 66.6% of the total variance, capturing major gradients in overall fertility, lime–nutrient–texture status, salinity–pH conditions, and macronutrient availability. Using the first four PCs as input, fuzzy c means clustering and cluster validity indices (fuzzy performance index and normalized classification entropy) indicated that four MZs provided the most appropriate partitioning of the fields. These MZs differed significantly in SOC, EC, pH, texture, and nutrient status. In zones with high K and P but adequate Fe and Zn, further K and P fertilization is unnecessary, whereas zones with low P, Fe, and Zn and low SOC require targeted P and micronutrient inputs and organic matter management. The delineated MZs and associated maps offer a practical framework for variable rate fertilization and more efficient soil sampling, supporting sustainable intensification of irrigated wheat production in Alborz province and similar semi arid regions.