Search Results (126)

Heavy metal pollution remains a major global environmental challenge due to persistent ecological risks and potential threats to food safety. Microbial remediation and phytoremediation represent sustainable alternatives to conventional treatments; however, their effectiveness is strongly influenced by number of factors including nutrient availability. This review critically examines how nutritional regulation governs microbial metabolism, plant physiological responses, and rhizosphere interactions to enhance heavy metal transformation and removal. Metal bioavailability depends on type, concentration, soil pH, redox potential, and microbial processes. Interventions including fertilizers, chelating agents, inoculation with arbuscular mycorrhizal fungi and plant-growth-promoting rhizobacteria enhance phytoremediation processes through regulating plant nutrient and heavy metal uptake, while selection between ammonium/nitrate changes rhizosphere pH consequently affects plant metal uptake. Similarly, nutrients, i.e., phosphate, iron, zinc and manganese competitively affect metal uptake. Organic amendments enhance phytostabilization, especially for selenium and mercury, while enhancing chromium reduction. Sulfur-reducing bacteria precipitate metals as insoluble sulfides with 90% efficiency. In addition, soil amendments including plant-growth-promoting rhizobacteria, arbuscular mycorrhizal fungi, and metal-chelating agents can be strategically used to enhance the phytoextraction from metal from contaminated soils. We suggest that the future integration of modern approaches such as multi-omics and cisgenesis supported by artificial intelligence tools can help to accurately predict the efficiency of nutrient regulation strategies and their remediation outcomes, thereby supporting evidence-based soil management. Full article

Endophytic bacteria are beneficial microbes that live within plant tissues and promote growth through nitrogen fixation, phosphate solubilization, and phytohormone production. Two endophytic isolates from bell pepper (Capsicum annuum L.) root were identified based on their morphology and biochemical properties using 16S rRNA gene sequencing. Winter barley seeds were inoculated with two PGP (plant growth-promoting) bacterial strains (C-14 and C-27), previously characterized for indole-derived compound (IDC) production, and evaluated in a pot experiment with four treatments: Treatment A1 (C-14), Treatment A2 (C-27), Treatment A3 Consortium (C-14 + C-27), and Treatment A4 (non-inoculated control). The results indicated that root and stem lengths increased in plants inoculated with bacteria compared to the uninoculated control. Among treatments, A2 produced the greatest root and shoot lengths (17.23 and 26.2 cm), while A3 showed the lowest (15.8 and 21.5 cm). SPAD values also increased by 6%, 10%, and 3.2% in Treatments A1, A2, and A3, respectively. This study clearly demonstrated that the endophytic isolates (C-14 and C-27) obtained from bell pepper roots significantly enhanced the growth of barley due to their ability of IDC production, thereby offering a promising alternate to chemical fertilizers. Full article

The large-scale use of compost in arable cropping systems is often limited by the large quantities required to meet the crop’s nutritional needs. Palletization can increase the nutrient density of organic fertilizers and improve their logistical feasibility by reducing storage, transport and application costs. This study evaluated the agronomic and environmental performance of compost pellets derived from pig slurry solids and olive pomace, using them as an alternative nitrogen source for wheat (Triticum aestivum L.) cultivated under Mediterranean conditions. A field experiment was conducted during the 2022–2023 growing season, with four treatments arranged in 24 m² replicated plots: an unfertilized control (C); pelletized compost (PSCOP); fresh pig slurry (PS); and mineral fertilization based on monoammonium phosphate and urea (IN). Excluding the control treatment, all fertilized plots received a uniform nitrogen rate of 150 kg N ha⁻¹. Soil chemical properties and nutrient availability (Pext, NH₄⁺-N and NO₃⁻-N) were evaluated at the beginning and end of the experiment, while wheat yield and grain quality were assessed at harvest. Greenhouse gas (GHG) emissions were monitored throughout the cropping season to evaluate environmental impacts. The results showed that the wheat yields achieved with PSCOP were comparable to those obtained with PS, although they remained lower than those achieved with mineral fertilization. Grain quality was not adversely affected by the application of PSCOP. Furthermore, PSCOP resulted in lower GHG emissions than mineral fertilization, with values closer to those observed in the unfertilized control. These findings suggest that pelletized organic fertilizers such as PSCOP may be a promising way to enhance nutrient circularity and reduce reliance on synthetic fertilizers and maintain crop productivity and limit environmental impact in Mediterranean agricultural systems. Full article

Baby maize (Zea mays L.) is widely cultivated across Asia due to its short growth cycle and adaptability to diverse agroecological conditions. However, its production is frequently constrained by low soil fertility, leading to the excessive use of chemical fertilizers, which in turn contributes to environmental degradation. Endophytic bacteria with the ability to fix atmospheric nitrogen and solubilize inorganic phosphate represent a sustainable alternative for improving nutrient availability. This study aimed to isolate and characterize endophytic bacteria exhibiting dual nitrogen-fixing and phosphate-solubilizing capabilities from baby maize roots. A total of ten bacterial isolates were obtained and screened using nitrogen-free Burk medium and NBRIP medium. Among these, strain CMB2 demonstrated superior functional traits. Molecular identification based on 16S rRNA gene sequencing confirmed that the isolate belongs to Bacillus stercoris. In vitro assays revealed that B. stercoris CMB2 exhibited significant nitrogenase activity, as determined by the acetylene reduction assay, and strong phosphate-solubilizing ability, indicated by a clear halo zone and a high solubilization index. These findings suggest that B. stercoris CMB2 is a promising multifunctional endophytic bacterium for enhancing nutrient availability under controlled conditions. Further validation under greenhouse and field conditions is required to assess its potential for improving plant growth and nutrient uptake in baby maize. Full article

Ammonia is one of the most important and widely produced basic chemicals worldwide. However, this highly toxic gas is also produced in livestock farming and a variety of industrial processes, posing a potential threat to humans, animals and the environment and also significantly contributing to the formation of persistent particulate matter. The aim of this project was to develop a textile-based adsorber material and to demonstrate a suitable test system for purifying ammonia-contaminated air from production-related sources using the example of pig fattening and PCB production. This aim was achieved through the wash-resistant immobilization of polyacrylic acid on a polyester needle felt at laboratory, pilot plant and industrial scales. In addition, various system concepts have been developed in which air or phosphoric acid can flow through the adsorber textile, whereby in the latter case, the phosphoric acid is both actively involved in ammonia adsorption and also serves to elute the bound ammonia, enabling continuous and low-maintenance operation. Concurrently, the high-quality inorganic fertilizer ammonium phosphate is produced. In summary, an efficient alternative to existing solutions for ammonia minimization has been developed, which is fundamentally characterized by its universal applicability in different load scenarios, including small mobile systems in production facilities with local ammonia pollution, in addition to scenarios for large-scale agricultural operations. Full article

In recent years, phosphorus (P) nanoparticles have emerged as promising alternatives to conventional fertilizers. This study evaluated zeolite-fixed hydroxyapatite nanoparticles (nHAP) for greenhouse tomato cultivation, comparing their efficiency with phosphate rock (positive P input) and quartz sand (negative P Carrier). Material characterization by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and zeta potential analysis revealed that zeolite was identified predominantly as clinoptilolite, phosphate rock as phosphate-bearing aluminosilicates, and quartz sand as crystalline quartz; in all cases, the materials exhibited negatively charged surfaces. Hybrid fertilizers were formed through electrostatic interactions between zeolite and nHAP, confirming the successful development of a zeolite-based carrier for nanohydroxyapatite delivery. Application of 0.01 g·L⁻¹ nHAP increased the effective quantum yield of Photosystem II by 0.64 compared to the control at midday. Fruit firmness showed no significant differences among treatments. The highest sugar and soluble solids content was observed with 0.1 g·L⁻¹ nHAP (6.84 °Brix), whereas the 1 g·L⁻¹ treatment enhanced pigment concentrations, reaching 5.9 mg·g⁻¹/g chlorophyll a, 2.92 mg·g⁻¹ chlorophyll b, and 2.82 mg·g⁻¹ carotenoids. The 0.01 g·L⁻¹ dose of nHAP maintained quality characteristics and marginally increased yield; however, yield decreased at higher nHAP concentrations, opening new research opportunities to optimize this nanofertilizer. Full article

Cool-season (C3) forage grasses are a cornerstone of temperate grassland systems, where improving productivity, nutritive value, and stress resilience is essential for sustainable forage production. In this context, plant growth-promoting microorganisms (PGPMs) have gained increasing attention as potential alternatives or complements to mineral and organic fertilization in grassland management. This review synthesizes current knowledge on the role of bacterial and fungal PGPM in enhancing the growth, nutrient use efficiency, and stress tolerance of C3 forage grasses, with particular emphasis on species of the genus Lolium. Available evidence indicates that PGPMs can substantially improve biomass production and plant performance under both optimal and stress conditions through a range of direct and indirect mechanisms. These include phytohormone production, nitrogen fixation, phosphate solubilization, as well as the activation of antioxidant defense systems and stabilization of plant water relations under stress. While Lolium perenne L. and Lolium multiflorum Lam. remain the most extensively studied model species, comparable growth-promoting responses have also been reported for Dactylis glomerata L., Festuca species, and Festulolium hybrids. Increasing attention is being directed toward bacterial and fungal endophytes, which may provide more persistent physiological benefits due to their close association with plant tissues. However, PGPM effects are often strongly species-, genotype-, and environment-dependent, particularly in complex grassland systems. Overall, PGPMs represent a promising tool for sustainable grassland management, although their effective application will require long-term field studies conducted under realistic meadow and pasture conditions. Full article

The excessive use of chemical fertilizers has depleted agricultural soils, necessitating a paradigm shift toward eco-friendly alternatives such as plant-beneficial microbes. However, the integration of plant-beneficial bacteria into global agroecosystems requires strategic and comprehensive analyses, as well as the development of optimally designed bioinocula to maximize their benefits. In this study, twenty-one rhizobacteria isolated from the maize rhizosphere were systematically screened for plant-beneficial traits, including phosphate and zinc solubilization, indole-3-acetic acid (IAA) production, and the synthesis of extracellular hydrolytic enzymes, followed by their evaluation for plant growth promotion. Among all bacterial isolates, Pseudomonas sp. NCR2 displayed the most comprehensive plant growth-promoting traits. In a pot-scale experiment, maize plants inoculated with multifaceted Pseudomonas sp. NCR2 showed significantly increased root growth, chlorophyll, soluble proteins, and phenolic contents as compared to untreated plants. This study underscores the significance of systematic screening of host-adaptive rhizobacteria for developing promising and tailored bioinocula. Furthermore, the results of this study also demonstrate the use of multifunctional biofertilizing inoculum for the systematic decrease of chemical inputs while simultaneously maintaining the crop productivity. Full article

Nutrient surpluses in regions with intensive livestock farming challenge sustainable crop production and have driven interest in alternative fertilization strategies and microbial biostimulants. Although microbial inoculation (MO) has been extensively studied in plant production, its agronomic relevance under field conditions remains controversial due to inconsistent outcomes. To address these inconsistencies, we conducted three-year field trials on two well-fertilized sandy sites in northern Germany. A microbial consortium consisting of Rhizoglomus irregulare, Funneliformis mosseae, Funneliformis caledonium, and Bacillus atrophaeus Abi05 was applied to silage maize (cultivar Amaroc S230) under contrasting fertilization regimes. In two of three years, microbial inoculation increased dry mass yield in the absence of starter fertilization, whereas both a high nutrient input variant (100 kg ha⁻¹ diammonium phosphate, DAP) and a lower nutrient input organo-mineral microgranular fertilizer (25 kg ha⁻¹) suppressed inoculant effects. Notably, yields from plots amended solely with the microbial inoculant reached at least the same level as those obtained with starter fertilization. In the third year, under drought conditions, defined as soil water contents below 10% in the 0–30 cm depth, no positive yield responses to microbial inoculation were observed. Quantitative PCR-based analyses of pre-sowing soils revealed that the abundances of Firmicutes, β-Proteobacteria, and total fungi were associated with yield responses, with Firmicutes and β-Proteobacteria showing negative and fungi showing positive correlations; together, these microbial predictors explained 38% of the variance in inoculant-induced yield response. Our findings demonstrate that soil microbiome characteristics can predict inoculant performance and that microbial inoculation is most effective without starter fertilization and under adequate soil moisture. Full article

The overreliance on non-renewable phosphate fertilizers necessitates sustainable alternatives for phosphorus recycling in agriculture. This study aimed to characterize and enhance the metabolic activity of phosphate-solubilizing microorganisms isolated from compost by eliciting them with two distinct mesoporous silica nanoparticles: standard SBA-15-S and short-pore SBA-15-C. Bacterial strains with broad-spectrum P solubilization and mineralization capacities were isolated from the mesophilic phases of tomato greenhouse and cow manure composts. These isolates received treatment with nanoparticle concentrations of 0.1, 10, and 100 ppm. The results demonstrated that nanoparticle elicitation significantly altered microbial growth, solubilization halos on tricalcium phosphate, and the specific activity of acid, neutral, and alkaline phosphatases in a strain- and nanoparticle-dependent manner. Notably, SBA-15-C at 100 ppm consistently enhanced multiple P-recycling properties across several strains, including Proteus and Myroides species. Principal component analysis revealed distinct behavioral clusters between composting phases and isolation methods. The findings indicate that tailored silicon oxide nanostructures can serve as eustressors to modulate and enhance the P-solubilizing and mineralizing functions of compost-derived microbiota, offering a promising nanobiostimulation strategy for developing enhanced biofertilizers. Full article

To mitigate the exhausting of phosphate rock (PR) reserves and the widespread water eutrophication due partially to excessive phosphorus (P), efficient adsorbents are valuable. Calcium (Ca) and aluminum (Al) containing layered double hydroxides (CaAl-LDHs) showed high P adsorption capacity and potential as slow-release P fertilizers, which merits further investigation. Two P proportions (5% and 10%) of P-adsorbed CaAl-LDHs (P-LDHs) were prepared, and its effects on various soil P contents and oilseed rape (Brassica napus L.) growth were evaluated. The main components of 5%P-LDH were P-intercalated CaAl-LDH and brushite, while 10%P-LDH mainly consisted of brushite. The proportions of P were extracted from 10%P-LDH and increased in the order of 4.9% (deionized water) < 48.9% (Olsen method) < 63.5% (Bray method) < 67.4% (citric acid), which suggested that 10%P-LDH could be citrate-soluble P fertilizer. 10%P-LDH showed similar effects on soil available P with single superphosphate (SSP). Both 5%- and 10%P-LDHs showed comparable improvement with SSP on aboveground dry weight of oilseed in the red soil, while being inapparent in the Fluvo-aquic soil. The CaAl-LDH appeared capable of providing Ca for rape growth in the low initial P concentration red soil, which showed the highest dry weight when combined with SSP. The recycled P-LDHs, especially 10%P-LDH, could supply P in a comparable manner with SSP for oilseed rape P uptake. Based on trials conducted under controlled conditions, our study suggested a promising production route of commercial P fertilizer alternatives via water P removal by CaAl-LDH. Further validations with realistic wastewater P removal by CaAl-LDH and via field scale growth trials are still needed before wide application of the alternative P fertilizer production procedure reported in the present study. Full article

The use of Bacillus spp. in combination with mineral fertilizers represents a sustainable alternative to conventional agricultural practices. This study evaluated the effects of inoculation with Bacillus amyloliquefaciens BV03 (Ba) on corn fertilized with phosphorus (P) sources of different solubilities. Two experiments were conducted under greenhouse conditions in a completely randomized design, following a 2 (without and with Ba) × 4 [control (without P, –P), triple superphosphate (TSP), Bayóvar natural phosphate (BNP), and Pratápolis natural phosphate (PNP)] factorial arrangement. Plant growth parameters, chlorophyll a fluorescence, gas exchange, photosynthetic pigments, nutritional status, biomass accumulation, and grain yield were assessed. Corn responses to Ba inoculation varied with P source and season. Inoculation with Ba, Ba + TSP, and Ba + BNP at sowing enhanced biometric traits (height, stem diameter, and leaf area); physiological parameters (F_v’/F_m’, ΦPSII, ETR, E, g_s, WUE); biochemical variables (Chl a, Chl b, and carotenoids); nutritional contents (N, P, K, Ca, and Mg); and yield traits. Overall, our results highlight the potential of Bacillus amyloliquefaciens BV03, alone or in combination with triple superphosphate or Bayóvar natural phosphate, as a sustainable alternative for phosphorus fertilization to improve corn growth and development. Full article

Phosphorus is one of the elements necessary for life and the proper growth of organisms, including humans, yet its natural resources are very limited. The bioavailability of phosphorus is especially critical during the initial phases of plant growth. A deficiency at this stage cannot be fully compensated for later, even despite increased phosphorous supplementation. Global reserves of phosphate rocks, the main source of phosphorus used in fertilizer production, are gradually being depleted. This situation prompts the need to search for alternative sources and to pay closer attention to the sustainable management of available resources. In this article, we focus on the Vistula–Bug interfluve in southeastern Poland, where relatively high phosphate concentrations have been documented. Our goal is to present geochemical and mineralogical data from bedrock in the areas richest in phosphorus and to discuss their significance in the context of domestic phosphorous management, with particular reference to southeastern Poland. We also discuss phosphate fertilizer production in Poland and its use in agriculture as well as phosphorus content in groundwater and surface water in the study area, with emphasis on the most readily assimilable forms, orthophosphates. Finally, we address the challenges of sustainable phosphorous management at both the local and global scale. Full article

Although pastures cover nearly half of Brazil’s agricultural land and form the backbone of national livestock production, they have historically received limited attention regarding management and fertilization, resulting in widespread degradation. Sustainable intensification of these pasture-based systems is therefore essential to meet growing global demand for animal products while minimizing environmental impacts. This review highlights recent technological innovations in pasture fertilization in Brazil, with a particular focus on alternative phosphorus sources such as natural reactive phosphates, which offer slow-release nutrients at lower costs compared to conventional fertilizers. Efforts to enhance nitrogen use efficiency through nitrification and urease inhibitors show promise in reducing nutrient losses and greenhouse gas emissions, despite current cost constraints limiting adoption. The integration of grass-legume intercropping, especially with Arachis pintoi, has been shown to enhance forage quality and system persistence when appropriately managed. Moreover, plant growth-promoting microorganisms emerge as sustainable biotechnological tools for restoring degraded pastures and boosting forage productivity without adverse environmental consequences. Properly treated agro-industrial residues also present a viable nutrient source for pastures, provided environmental regulations are strictly followed to prevent pollution. Together, these innovations offer a comprehensive framework for enhancing the productivity and sustainability of Brazilian livestock systems, highlighting the pressing need for continued research and the adoption of advanced fertilization strategies. Full article

Phosphorus (P) is an essential element for plant growth, yet it is only available to plants in the form of orthophosphate. In most soils, P occurs predominantly in insoluble forms, such as calcium phosphates in alkaline soils and aluminum/iron phosphates in acidic soils, limiting plant uptake. Fertilization is commonly used to overcome this limitation; however, large fractions of applied P rapidly become unavailable. Phosphorus-solubilizing bacteria (PSB) are a sustainable alternative to enhance P availability. This study evaluated the P-solubilization capacity of bacterial strains belonging to different genera isolated from different host plants, soil types, and climates (mainland Portugal, Cape Verde, and Angola). Following initial screening, the most efficient strains were tested under greenhouse conditions in soils with pH 7 and 8. Strains exhibited diverse solubilization capacities, with highly efficient PSB (phosphate solubilization index ≥ 2) accounting for 5% of the total isolates, predominantly originating from the Namib Desert (Angola) and Southern Portugal, and mainly belonging to the genera Pseudomonas, Flavobacterium, Enterobacter, Chryseobacterium and Pantoea. At pH 7, most PSB promoted maize growth, with strain C11 increasing plant P content around 2-fold compared to the control. At pH 8, fewer strains were effective, but strains F and C11 enhanced shoot weight and M shoot length by 28%, 27%, and 10%, respectively. These findings highlight the potential of selected PSB strains as next-generation bioinoculants for sustainable agriculture. However, strain selection must consider geography, crop type, and management practices to ensure consistent efficacy, thereby supporting the broader application of PSB as a precision tool for improving food security. Full article