Integrated waste management through vermicomposting combined with biochar amendments represents an innovative approach for sustainable resource recovery. This study evaluated the effects of sugarcane bagasse biochar (SBB) at 0%, 5%, and 10% application rates on Eisenia fetida performance and vermicompost quality during preincubation-vermicomposting of sewage sludge and press-mud mixtures. The 10% SBB treatment significantly (p < 0.05) enhanced earthworm biomass (72.3% increase) and cocoon production (24.8 ± 1.8 per earthworm vs. 12.3 ± 1.2 in control). Lignocellulosic degradation improved substantially, achieving 22.6%, 10.7%, and 38.8% degradation for cellulose, hemicellulose, and lignin, respectively. Macronutrient concentrations increased significantly: TN by 38.4%, TP by 15%, and TK by 21.4% compared to initial mixtures. Moreover, total heavy metal concentrations decreased significantly during vermicomposting, with reductions of 8.1–8.7% for Pb, 5.3–7.6% for Cd, and 3.0–4.8% for Cr, with reduced bioavailability factors indicating enhanced metal stabilization. The final vermicompost exhibited optimal maturity indices, including a C:N ratio of 15.4 ± 0.2 and improved electrical conductivity. Results demonstrate that 10% sugarcane bagasse biochar amendment facilitates efficient concurrent management of sewage sludge and sugarcane industrial wastes while producing high-quality organic fertilizer with enhanced nutrient content, reduced heavy metal bioavailability, and accelerated stabilization for sustainable agricultural/horticultural applications.

The influence of functionalized biochar on the leachability and bioavailability of metal cations in contaminated soils remains insufficiently explored, particularly under aging conditions and multiple leaching cycles. This study investigated the performance of pristine, Mg-, and Fe-functionalized biochar in reducing the leachability of Cd, Cr, and Pb in co-contaminated soil. Preliminary screening revealed that pristine chicken manure biochar (CB), and Mg (MCB)-, and Fe (FCB)-functionalized biochars were more effective in decreasing metals leachability. Consequently, their effects on metals leachability, bioavailability, and fractionation were evaluated through nine leaching cycles and aging experiments (aged soil for 1, 10, 20, 30, 40, and 50 days). Addition of CB to the soil columns significantly decreased the metals concentrations in the leachate. Specifically, Cd concentration (mg L-1) decreased from 5.84 in CK to 0.41 in FCB, 0.53 in MCB, and 0.52 in CB treatments; Pb concentration (mg L-1) decreased from 114.2 in CK to 4.4 in FCB, 5.9 in MCB, and 10.5 in CB treatments; and Cr concentration (mg L-1) decreased from 34.6 in CK to 1.6 in FCB, 1.8 in MCB, and 3.2 in CB treatments. The FCB and MCB redistributed the metals mobile fraction to the residual fraction thereby reducing their mobilization (CaCl2-extrcated form) and availability (DTPA-extracted form) in the treated soil compared to CK soil. The immobilization effect of FCB and MCB remained stable during aging periods, leaching cycles, and under acidic pH, indicating their strong ability for metal capturing. However, long-term investigation of biochar-immobilized metals in aged soils is needed. These findings confirm that functionalizing CB with Fe and/or Mg effectively immobilized Cd, Cr, and Pb in aged soil, reducing the leaching of these toxic metals into groundwater, making this engineered biochar a viable option for soil remediation.

Insufficient K content and uncoordinated chemical compositions represent critical bottlenecks limiting the industrial value of flue-cured tobacco. This study investigated the effects of foliar-applied liquid potassium silicate (SikL) on the yield and quality of Nicotiana tabacum cv. Yunyan 87 and its metabolic mechanisms. Field experiments revealed 1500 mg/L as the optimal concentration, significantly increasing yield and output value by 16.53% and 27.79%, respectively, relative to the control, outperforming traditional KH2PO4. Physiologically, SikL significantly increased the K and Si content in the leaves and led to a non-significant downward trend in Na accumulation, thereby optimizing ionic homeostasis. Regarding quality, SikL effectively improved the carbonnitrogen (C/N) balance, refining the reducing sugar/nicotine ratio from an uncoordinated 13.58 to an ideal range (8.79-9.58) and significantly increasing the chemical composition coordination score (P).Metabolomic analysis confirmed that SikL induced systemic metabolic reprogramming: it strengthened the energy metabolism infrastructure by up-regulating energy cofactors ( FAD and pantothenate); redirected metabolic flux toward nitrogen pathways (e.g., arginine and glutamate) to provide precursors for nicotine synthesis, thus optimizing the C/N ratio; and activated phenylpropanoid and flavonoid pathways to promote the accumulation of lignin monomers and antioxidants. These changes synergistically enhanced tobacco yield, chemical coordination, and physiological defense. Furthermore, a decline in performance at 2000 mg/L confirmed a concentration threshold effect. In conclusion, foliar application of 1000-1500 mg/L SikL is an efficient strategy for enhancing tobacco yield and quality through energy-driven metabolic reorganization centered on C/N balance.

Introduction:Soil co-contamination with cadmium (Cd), lead (Pb), and antimony (Sb) poses significant environmental and health risks, highlighting the need for effective remediation strategies. Sulfate-reducing bacteria (SRB) are promising for bioremediation, but require optimization to improve effectiveness. Methods:Here, we developed SRB@nZVI@BC, a novel composite integrating SRB, nano zero-valent iron-modified biochar (nZVI@BC), and sodium alginate (SA). Its optimal preparation conditions were identified as 2% SA, 2% CaCl2, 30% SRB solution, and 0.1% nZVI@BC based on mass transfer performance, mechanical strength, and sulfate reduction rate. Results:The application of SRB@nZVI@BC increased the proportion of stable forms of Cd, Pb, and Sb in soil and achieved removal efficiencies of 60.22%-63.93% for Cd, 57.13%-59.45% for Pb, and 56.02%-70.37% for Sb in leachate. Compared to alone SRB treatment, SRB@nZVI@BC significantly enhanced SRB activity, promoting sulfur cycling and the generation of S2-, thereby facilitated heavy metal precipitation as insoluble sulfides. SRB@nZVI@BC could improve the adsorption capacity of soil for heavy metals by activating the oxygen-containing functional groups such as C-O-C. Moreover, SRB@nZVI@BC reshaped the soil microbial community by enriching sulfate-reducing genera such as Desulfosporosinus and Desulfitobacterium, driving heavy metal transformation and stabilization. The composite further enhanced soil nutrient availability (N, P, K) and increased enzyme activities, contributing to soil fertility recovery. Discussion:Overall, SRB@nZVI@BC provides an eco-friendly solution for stabilizing multi-metal-contaminated soils and promoting the restoration of barren lands through synergistic adsorption and biomineralization.

Iron (Fe) deficiency remains a prevalent nutritional challenge, particularly among populations with limited access to diverse and nutrient-rich diets. In this study, a greenhouse experiment was conducted to identify high-Fe-accumulating Pakchoi ( Brassica chinensis L.) genotypes. The effects of foliar Fe fertilization on Fe bioaccessibility and bioavailability were then evaluated using the in vitro digestion/Caco-2 cell model. The results showed that cultivating high-Fe-accumulating Pakchoi genotypes combined with applying precision Fe fertilization significantly increased Fe bioaccessibility (7.33-31.7%) and bioavailability (46.3-96.7%) compared to the non-biofortified control genotype (MGQG). Foliar Fe application improved or maintained the overall nutritional quality of Pakchoi genotypes. Consuming biofortified Pakchoi could contribute over eight times more to the daily reference intake (DRI) of Fe compared to the control. These findings highlight the potential of an integrated biofortification strategy, genotypic screening coupled with foliar fertilization, as a practical and efficient approach to mitigate health risks associated with "hidden hunger" in nutritionally vulnerable populations.

Intensified industrialization, urbanization, and agricultural activities have led to excessive heavy-metal accumulation in agricultural products, threatening food safety. Recent studies suggest that foliar exposure under atmospheric deposition is the dominant route for controlling metal accumulation in edible tissues. However, their specific mechanisms remain poorly understood. This Review synthesizes the foliar uptake and translocation of atmospheric heavy metals, focusing on the interactions among particle size, metal speciation, and leaf morphology. Key debates include the form of entry (ionic vs particulate), the mechanism of uptake (passive vs active), and the transporters involved. Emerging evidence shows that micrometer-sized particles enter leaves through stomata via passive diffusion, although intracellular transport may involve active mechanisms. In contrast, nanosized particles can penetrate both cuticular and stomatal pathways. Notably, leaves preferentially take up ionic heavy metals over particulate forms. The trichome pathway emerged as an additional route. However, whether it governs direct uptake or enhanced retention and if the chemical form taken up is ionic or particulate remains elusive. Specific transporters that mediate translocation to edible tissues have not yet been identified. This review represents a paradigm shift in crop safety, moving beyond the traditional root uptake perspective to foliar uptake of atmospheric matter.

The present work assessed the efficiency of innovative functional biochars (HCMP0-3) produced via co-pyrolysis of hydrothermally treated coal (HT-coal), chicken manure (CM), and plastic mulch (PM) for the adsorption and remediation of Cd and Pb in contaminated soils. Compared with the HCMP0, the fixed carbon contents, surface area, porosity, and metal adsorption capacity of HCMP3 increased significantly, which can facilitate multipathway adsorption. Incubation of HCMP2 and HCMP3 promoted the conversion of exchangeable fractions of Cd and Pb into residual fractions by increasing soil-pH, cation exchange capacity (CEC), and dissolved organic matter (DOM). Multi-spectral techniques, including EEM fluorescence, FTIR, Raman, XPS, and EDS, provided comprehensive insights into structural variations and adsorption mechanisms during the interactions of Cd and Pb with biochar. The reduction in it-electrons, carboxyl O=C-O, and C=C after the Cd/Pb adsorption highlights the synergistic integration of cation-it interactions, aromatic rings, and surface functional groups (SFGs). According to spectral and mapping results, the participation of C and O-containing SFGs indicated the binding of metal species, primarily driven by organo- and surface complexations, ion exchange, precipitation, and it-it interactions. A higher Id/Ig ratio observed in Raman mapping clearly indicated an increased graphitic disorder and more amorphous carbon structures after metal adsorption. This reflects the enhanced role of tri-biomass copyrolytic functional biochar in metal adsorption. Similarly, HCMP3 enhanced the enzymatic activities and reduced leachate Cd/Pb by adsorbing metal ions, shifting soil-DOM, and promoting humification. Overall, these results position HCMP3 as a low-cost, high-performing, sustainable material for soil stabilization, enabling a circular economy approach to environmental protection and waste management.

Scaling up biochar production through slow pyrolysis of biomass wastes presents a promising strategy for mitigating greenhouse gas emissions, remediating degraded agricultural soils, and promoting resource reuse. We evaluated the predictive performance of three classical machine learning (ML) models, including Random Forest (RF), eXtreme Gradient Boosting (XGB), and Support Vector Regression (SVR) by employing both single-task and multi-task optimizations across a comprehensive dataset of 666 entries. Among them, the multi-task XGB model demonstrated the superior performance, achieving an average test coefficient of determination (R2) of 0.90 and a root mean squared error (RMSE) of 2.59 across nine critical biochar properties essential for soil improvement and carbon sequestration. Model interpretability analysis revealed that biochar properties were primarily governed by the biomass proximate and ultimate compositions, alongside pyrolysis related parameters, with final temperature exerting the most pronounced effect, while heating rate exhibited the minimal impact. Based on the optimized model, both forward and reverse optimization strategies were applied, and experimental validations confirmed the reliability and robustness of the optimized model. To facilitate the practical application, an opensource web platform was developed for predicting biochar properties and designing optimal pyrolysis conditions to produce tailored biochar.

Magnesium (Mg) deficiency is common in acidic orchard soils and can limit fruit crop growth and quality. This study evaluated whether foliar-applied magnesium oxide nanoparticles (MgO NPs) could improve Mg nutrition and fruit quality in 'Ninghaibai' loquat grown under Mg-deficient acidic soil conditions. Pot and field experiments were conducted using water as the control and MgSO4-50eq as an equimolar Mg comparator. MgO NPs showed a concentration-dependent effect, and 200 mg/L produced the best overall performance among the tested concentrations. At this concentration, total biomass increased by 47.27%, compared with CK, accompanied by enhanced chlorophyll accumulation, antioxidant enzyme activities, and Mg uptake. In fruit, 200 mg/L MgO NPs increased soluble solids content by 45.67% and reduced titratable acidity by 53.26%, while also improving fruit size and sugar-acid balance. Leaf transcriptome analysis suggested that MgO NPs altered the expression of genes involved in metabolism, stress response, and secondary metabolite biosynthesis. At the 50 mg/L level, MgO NPs produced stronger responses than the equimolar MgSO4 treatment in Mg uptake, nutrient acquisition, and several fruit-quality traits. However, excessive application at 500 mg/L weakened growth and quality improvement. Overall, foliar application of 200 mg/L MgO NPs may represent a promising strategy for improving loquat growth and fruit quality under the tested Mg-deficient conditions.

Optimal co-fertilization of nitrogen (N) and zinc (Zn) offers a promising approach for promoting the growth of tea plant (Camellia sinensis (L.) O. Kuntze), sustaining stable yield, and improving tea quality. However, the specific roles of rhizosphere microorganisms in mediating the tea yield and quality after N-Zn co-fertilization remain unclear. Here, a field experiment was carried out to assess the influence of N-Zn co-fertilization on the growth of tea plant, as well as the structure and functions of rhizosphere microbial communities in tea plantations. Results showed that N application contributed more to the increment of tea yield than Zn fertilization, whereas Zn supply significantly promoted the synthesis of free amino acids and reduced tea polyphenol contents as well as TP/AA at moderate N level. Zn addition decreased the level of soil NO3 --N but increased NH4 +-N concentrations at both moderate and high N levels. Soil metagenomic sequencing indicated that Zn supply significantly increased the relative abundances of microbial taxa involved in denitrification, such as Arthrobacter, Bacillus, Terrabacter and Burkholderia, as well as up-regulated the relative abundances of narH, nasA, nasB, napB, nirB, nirD and norB genes at high N level, which are related to some metabolic potential pathways like denitrification and nitrate reductase. Partial least squares path models showed that fertilization initially altered soil properties and enzyme activities, thereby affecting rhizosphere microbial communities and functional gene profiles, which sequentially contributed to the nutrient accumulation in tea plants and ultimately influenced tea yield. Random forest analysis further identified soil properties such as pH, OM, AP, NH4 +-N, NO3 --N and AZn as the most influential factors affecting tea yield and quality. Overall, our results highlight the relationship between tea yield and quality with rhizosphere microbial communities and functional gene profiles under different N-Zn co-fertilizations. All these findings provide new perspective for nutrient use and management in tea plantations.

Synthetic communities (SynComs) of plant growth-promoting bacteria (PGPB) could enhance cadmium (Cd) phytoextraction and promote plant growth in Brassica juncea L. However, the precise molecular mechanisms of facilitated Cd uptake and accumulation remain unclear. Here, using a Cd-specific fluorescent probe, we demonstrated that SynComs application markedly improved Cd distribution and uptake within plant roots. Integrated transcriptomic and metabolomic analyses under Cd stress revealed that SynComs mitigate Cd-induced stress by activating plant antioxidative defense system, encompassing antioxidants glutathione, key enzymes such as peroxidase, catalase, ascorbate peroxidase, and superoxide dismutase. Furthermore, SynComs inoculation facilitated root exudates secretion which contributed to plant growth. Weighted Gene Co-expression Network Analysis (WGCNA) identified 17 and 14 Cd- and antioxidant-related gene modules in shoots and roots, respectively, with critical hub genes functionally associated with metal transport, redox homeostasis, and secondary metabolisms. Continuous determination of gene expression levels verified that SynComs inoculation upregulated the metal transporters such as Nramp1, NRT1, ZIP4 and ZIP6 to increase Cd uptake. These results implied that SynComs could facilitate Cd uptake and eliminate Cd-induced damage through the coordinated regulation of specific hub genes and a broad spectrum of plant secondary metabolites. These findings lead to augmented plant growth and enhanced Cd phytoextraction in B. juncea, strengthened a comprehensive understanding of the molecular mechanisms underlying PGPB-mediated Cd uptake and accumulation. This research verified SynComs application as an effective agent in the future field application to enhance phytoremediation efficiency, which also contribute to soil health, and maintain sustainable, safe crop production in Cd-contaminated agricultural systems.

Identifying key soil parameters and rhizobacterial communities that control cadmium (Cd) transfer throughout the soil-microorganism-rice-human continuum is crucial to guarantee rice consumption safety and safeguarding human health. Here, a pot experiment investigated that how edaphic properties of four different soils and their associated microbial communities influence Cd buildup and bioavailability in two different rice cultivars. Results demonstrated that Cd-low accumulating rice cultivar exhibited significantly lower grain Cd concentration than Cd-high accumulating rice cultivar. Grain Cd concentrations (total and bioavailable) showed strongest correlations with soil total Cd (T-Cd), phytoavailable Cd (A-Cd), and available potassium (AK) contents. Notably, in vitro-in vivo assays revealed lesser Cd bioavailability in rice despite elevated Cd levels in soils, with significant interactions observed between grains T-Cd and bioaccessible and bioavailable Cd concentration. Additionally, high-throughput sequencing revealed that rhizobacterial community composition, diversity and network were influenced with soil type. Specific taxa involved in organic matter decomposition (Blastocatellales and Anaerolineae) were associated with reduced grains Cd absorption and accumulation by changing the rhizosphere Cd availability. Moreover, Partial least squares path modeling (PLS-PM) confirmed that Cd accumulation and bioavailability in rice grains was affected not only by edaphic properties and Cd exposure level, but also by soil rhizobacterial community composition. This study advances understanding of how soil properties and rhizobacterial communities jointly regulate Cd transfer across the soil-microorganism-rice-human continuum in diverse soil environments.

Phosphorus-enriched greenhouse vegetable soils can sustain crop nutrition while remaining vulnerable to phosphorus (P) mobilization because much of their legacy P persists in soluble or weakly buffered pools. We tested whether eggshell-derived calcium (Ca) could reduce indicators of legacy P mobility without compromising crop performance. A cross-scale framework integrating incubation, P fractionation, sorption-desorption, pot, and field experiments was used to compare washed eggshell (WES), unwashed eggshell (ES), and reagent-grade calcium carbonate (CC). Ca amendments increased soil pH by 0.9-2.3 units and reduced available P (AP) by 10-35% during incubation. After six weeks, H2O-P and NaHCO3-Pi declined, whereas HCl-extractable P fractions increased, indicating an operational redistribution of legacy P toward less labile pools. P retention was also strengthened, with markedly higher Langmuir sorption capacity and lower desorption at high solution P concentrations. In both pot and field experiments, lower bulk-soil AP did not reduce pak choi growth or P uptake. Under field conditions, WES applied at 4.8 t/ha decreased AP and water-soluble P but increased pak choi P uptake and fresh yield by 27.9% and 11.2%, respectively. These results indicate that eggshell-derived Ca can reduce indirect indicators of potential P mobility while maintaining agronomically effective P supply. Because Ca-P mineral phases and runoff or leaching P losses were not directly measured, the environmental implication should be interpreted as reduced potential P mobility rather than confirmed reductions in off-site P export.

Fertilization in hyperaccumulator-crop rotation systems provides an effective strategy for enhancing cadmium (Cd) phytoremediation and mitigating food safety risks in contaminated agricultural soils. Accordingly, we assessed the effects of soil application of zinc (Zn) fertilizer (EDTA-Zn, ZnSO4, and ZnO NPs) during S. alfredii planting on Cd phytoextraction, rice productivity, and rice grain safety in the S. alfredii-rice rotation system. Results showed that the application of Zn fertilizers increased S. alfredii shoot biomass (21.7%-33.0%) and Cd concentration (20.1%-28.4%), thereby improving phytoextraction efficiency (28.8%-56.5%) relative to the control. After the harvest of S. alfredii, residual soil Zn significantly reduced Cd accumulation in aboveground rice tissues at both the tillering and maturity stages. Specifically, Cd concentrations in brown rice were significantly decreased by 11.3%-43.2%. Soil physicochemical analysis indicated that Zn treatments influenced Cd uptake in S. alfredii and rice by altering soil Cd bioavailability. Moreover, Zn application reduced health risks associated with Cd exposure by 19.7%-45.8% based on Cd bioaccessibility in polished rice. Treatments with ZnSO4 and ZnO NPs also enhanced rice yield and improved nutritional traits, including grain Zn concentration and amylose content. Overall, ZnSO4 was identified as the most suitable fertilizer for improving both phytoremediation efficiency and rice production safety in the S. alfredii-rice rotation system.

Selenium (Se) biofortification represents a critical strategy for addressing micronutrient deficiency while enhancing fruit nutritional quality. This study investigated foliar applications of Se and Si nanoparticles (NPs) for peach Se biofortification and quality enhancement. Se NPs (95.2 nm) were synthesized and characterized using SEM, EDS, and FTIR analyses. Six treatments were applied: control (Ck), SeNPs-5, SeNPs-10, SiNPs-10, Se5Si10, and Se10Si10. SeNPs-10 achieved maximum Se biofortification (0.47 mg kg−1), representing 5.4-fold increases over controls, with 85% organic Se accumulation. Combined treatments demonstrated synergistic effects on multiple quality parameters. Se5Si10 led to the highest antioxidant enzyme activities (peroxidase: 2254 U g−1, catalase: 61.7 U g−1) and phenolic compound enhancement (chlorogenic acid: 267 mg kg−1, total phenolics: 12.8 mg GAE g−1). Flavonoid biosynthesis was optimized with Se10Si10 achieving maximum rutin accumulation (53.9 mg kg−1) and ascorbic acid content (60.7 mg/100 g). Physical quality improvements included enhanced firmness (100.9 N cm−2) and sugar accumulation (14.1% soluble solids). Combined treatments reduced oxidative stress markers (MDA: 22.11 μmol g−1) while enhancing protein metabolism. These findings demonstrate that Se-Si nanoparticle combinations showed optimal biofortification with synergistic quality enhancement, establishing effective strategies for nutritionally enriched peach production.

Understanding the effects of different fertilization timing on crop selenium biofortification is of great importance. This field study evaluated the effects of Se nanoparticle application at different growth stages on crop yield, Se accumulation, and Se speciation. Se NPs application at the jointing stage significantly increased grain yield (up to 10.2 % in rice, 8.4 % in wheat) and Se concentration (9.7-fold in rice, 21-fold in wheat). Rice showed higher Se uptake efficiency, while wheat exhibited greater translocation of Se from leaves to grains. Notably, Se NPs were absent from grains in both rice and wheat, ensuring food safety. Selenomethionine was the dominant Se species in both grains (>62 %), unaffected by fertilization timing. Delayed fertilization increased Se retention in the wheat inner fraction, enhancing Se recovery during flour processing. These findings offer practical guidance for optimizing Se biofortification strategies to improve grain Se content and nutritional quality.

Heavy metal pollution in soil is a significant challenge around the world, particularly cadmium (Cd) contamination. In situ phytoextraction and remediation technology, particularly focusing on Cd hyperaccumulator plants, has proven to be an effective method for cleaning Cd-contaminated agricultural lands. However, this strategy is often hindered by a long remediation cycle and low efficiency. To address these limitations, assisted phytoextraction has been proposed as a remediation strategy based on the modification of certain traits of plants or the use of different materials to enhance plant growth and increase metal absorption or bioavailability, ultimately aiming to improve the remediation efficiency of Cd hyperaccumulators. To thoroughly understand the progress of Cd hyperaccumulators in remediating Cd-polluted soils, this review article discusses the germplasm resources and assisted phytoextraction strategies for these plants, including microbial, agronomic measure, chelate, nanotechnology, and CO2-assisted phytoextraction, as well as integrated approaches. This review paper critically evaluates and analyzes the numerous approaches and the remediation potential of Cd hyperaccumulators and highlights current challenges and future research directions in this field. The goal is to provide a theoretical framework for the further development and application of Cd pollution remediation technologies in agricultural soils.

The co-fertilization of nitrogen (N) and zinc (Zn) offers significant advantages in improving the growth and development of tea plants (Camellia sinensis L). However, the corresponding responses of rhizosphere microecology remain unclear. In this study, a pot experiment was performed to investigate the effects of N-Zn co-fertilization on rhizosphere soil's N availability, the rhizobacterial community and the metabolism of tea plants. N-Zn co-fertilization significantly increased the soil total of N, NH4+-N and NO3--N contents. 16S rRNA sequencing found that N-Zn co-fertilization recruited rhizobacteria associated with N cycling and Zn activation, including Proteobacteria, Acidobacteriota and Gemmatimonadota, resulting in complex rhizobacterial networks. Metabolomics analysis indicated obvious interferences in the metabolisms of lipids, amino acids and cofactors and vitamins after fertilization. PLS-PM analysis suggested that fertilization had both direct and indirect influences on the rhizobacterial community and differential metabolites. RDA models identified pH (R2 = 0.734, p < 0.01; R2 = 0.808, p < 0.01) and total N (R2 = 0.633, p < 0.05; R2 = 0.608, p < 0.01) as dominant factors influencing both the rhizobacterial community and differential metabolites. Finally, network analysis found significant associations between rhizobacteria related to N cycling and Zn mobilization and metabolic processes involved in N metabolism and responses to Zn stress. These findings underscored that appropriate N-Zn co-fertilization is crucial for the rhizosphere soil's N availability and the microenvironment of tea plants.

Converting waste into catalysts is a sustainable approach for wastewater treatment and resource management. Here, heavy metals-enriched hyperaccumulator (Sedum alfredii) residues were utilized to prepare various functional biochars through hydrothermal carbonization (HTC) pretreatment followed by pyrolysis. The catalytic performance of these biochars for the removal of azo dye acid orange 7 (AO7) was evaluated in conjunction with activated peroxymonosulfate (PMS). The results depicted that functionalized biochar (SAHC200-8)/PMS system achieved 99.7 % removal of AO7 (50 mg L-1) within 30 min, compared to the pristine biochar (SABC-8)/PMS system (10 %), depicting the apparent rate constant (Kobs) of 0.1333 min-1. Despite the presence of multiple reactive oxygen species (ROSs) in the reaction solution, the relative contribution of nonradical electron transfer was quantified to be the largest (RET=86.56 %). In addition, the quantitative evaluation using the life cycle assessment (LCA) revealed that the SAHC200-8/PMS system exhibits superior environmental performance compared to the conventional biochar/PMS system. This study highlights that HTC, as a pretreatment method, significantly enhances the electron transfer capacity of biochar by promoting the development of graphitic structures. This approach not only boosts catalyst performance but also offers a sustainable method for waste utilization, contributing to effective environmental remediation and pollution reduction.