Search Results (1,099)

Soil erosion is a critical issue on the Loess Plateau due to weak soil and intense summer rainfall. Plant roots provide essential soil stabilization. A split-plot field experiment was conducted in Liulin County, Shanxi Province, to evaluate the effects of biodegradable mulch and organic amendments on maize root development and soil stabilization. The main plots included no mulch (N) and biodegradable mulch (M). The subplots comprised five treatments: control (CK, no amendment), peat (PT), biochar (BC), fermented pig manure (PM), and corn stover (CS). Correlation and principal component analyses were used to elucidate the underlying mechanisms. The results showed that organic amendments were the primary factor influencing the root and soil properties. Peat and biochar significantly raised the root surface area density (RSAD, p < 0.05) and root–soil composite cohesion (with increases of 122.56% and 109.06% for NPT and NBC compared to NCK, respectively). Biodegradable mulch, and its interaction with the organic amendments, had no statistically significant effect on either the root–soil composite cohesion or root system parameters. The strong positive correlations of cohesion with the root length density (RLD, r = 0.80) and root volume density (RVD, r = 0.81) highlight that root occupancy is the key mechanism for enhanced shear resistance. Therefore, biochar is recommended for its effectiveness in enhancing soil retention and its potential co-benefits for carbon sequestration. This study provides a technical reference for sustainable agriculture on the Loess Plateau, while also acknowledging the need for further research on long-term carbon dynamics. Full article

Sustainable management of vineyard residues through biochar production requires balancing carbon stability with agronomically relevant nutrient functionality. Pyrolysis temperature controls this trade-off by affecting carbon condensation and micronutrient availability. This study aimed to determine how pyrolysis temperatures (300 and 600 °C) govern this trade-off in vineyard-trimming biochars. The motivation focuses on optimizing carbon storage while maintaining micronutrient availability. Biochars were produced by slow pyrolysis at 300 and 600 °C for 1 h and characterized using proximate and elemental analyses, total macro- and micronutrient determination, and DTPA extraction to evaluate potentially bioavailable trace elements. The results showed that increasing temperature from 300 to 600 °C reduced yield (45.15 to 32.30%) and volatile matter (40.33 to 16.50%), while increasing fixed carbon from 55.37 to 77.33% and total carbon from 66.49 to 77.89%. Atomic ratios (H/C: 0.67 to 0.31; O/C: 0.32 to 0.18) confirmed enhanced carbon condensation at 600 °C. Regarding nutrients, although total Mn, Fe, Cu, and Zn concentrations declined at higher temperatures, their potentially bioavailable fractions (operationally defined as extractable with the chelating agent DTPA showed element-specific redistribution; Fe, Cu, and Zn extractability increased, while Mn decreased. These findings reveal a temperature-driven trade-off between carbon sequestration and micronutrient release. Full article

Soil amendments are widely promoted to improve turfgrass performance and soil properties in suboptimal soil; however, their effectiveness under field-managed conditions remains unclear. Two concurrent field experiments (i.e., turfgrass and soil and reduced nitrogen) were conducted from August 2022 to November 2023 in Gainesville, FL, using a randomized complete block design to evaluate organic and biological amendments under standard and reduced nitrogen (N) fertilization. In the turfgrass and soil portion, treatments included granular humic + fertilizer, liquid humic + fertilizer, biochar + fertilizer, microbial inoculant + fertilizer, compost, natural fertilizer, fertilizer, and a non-treated control. In the reduced N experiment, fertilizer rates for all amendment combinations and the natural fertilizer were applied at 50% (12.2 kg N ha⁻¹), while the full-rate fertilizer (24.4 kg N ha⁻¹) and non-treated control were included for comparison. Treatments were applied to St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) and zoysiagrass (Zoysia spp. Willd.) established on a sand-based root zone. Turfgrass performance was assessed using visual quality, normalized difference vegetation index, and percent green via digital image analysis. Soil properties were evaluated using physical, chemical, and biological parameters. Treatment responses varied by amendment type and N rate. All treatments improved turfgrass performance relative to the non-treated control, with compost producing the greatest improvements in turfgrass quality and soil properties, including organic matter, pH, and plant-available P, K, and Fe. Humic substances, biochar, and microbial inoculants primarily increased potentially mineralizable N but provided limited improvements in turfgrass performance compared with fertilizer alone. Nitrogen rate was the primary determinant of turfgrass performance, with full N treatments producing the highest quality. Although reduced N treatments improved turfgrass quality relative to the control, amendment additions did not consistently enhance turfgrass performance under reduced N conditions. Full article

In recent years, microplastics (MPs) pollution in agricultural soils has increased markedly, largely due to the improper management of plastic mulch films used to improve crop growing conditions. In this context, the present study evaluated the use of biochar (BC) as a soil amendment for mulch-derived MPs-contaminated soils in a radish (Raphanus sativus L.) crop under greenhouse conditions. A pot experiment was established in soils contaminated with MPs (0.5% w/w) and amended with four BC rates (w/w): 0% (Control), 1% (BC1), 3% (BC3), and 5% (BC5). Soil physicochemical indicators were assessed, together with germination, leaf, and radish bulb growth parameters. The experiment was conducted under greenhouse conditions until the radishes reached commercial maturity. Most of the soil’s physicochemical indicators, such as hydrogen potential (pH), electrical conductivity (EC), water holding capacity (WHC), total organic carbon (TOC), organic matter (OM), total nitrogen (TN), ammonium (N–NH₄⁺) and nitrates (N–NO₃⁻), showed significant differences between treatments (p < 0.05), with the exception of the carbon-nitrogen ratio (C/N), which did not vary significantly (p ≥ 0.05). No significant differences were observed among treatments (p ≥ 0.05) for germination indicators. For leaf traits, dry biomass was significantly lower in BC1 than in the other treatments (p < 0.05). For radish bulb traits, fresh weight was significantly higher in BC3 (p < 0.05) compared with the other treatments. Similarly, total plant fresh weight showed significant differences among treatments, with BC3 exhibiting the highest value (p < 0.05). Overall, the BC3 treatment provided the greatest improvement in radish development in MPs-contaminated soil. However, further research involving different types of MPs, BCs, or other crop species is needed to more comprehensively assess the impact of BC on agricultural soils contaminated with MPs. Full article

Drought reduces soil moisture and impairs root function, posing a significant threat to rice production in arid regions. The influence of soil amendments on early rice root development under semi-dry cultivation remains insufficiently characterized, especially when assessed using non-destructive rhizotron techniques. This study employed a scanner-based rhizotron system to evaluate early root responses of rice seedlings to six amendments under semi-dry irrigation: vermicompost and peat moss, spirulina powder, gypsum, rice husk biochar, zeolite, and an unamended control. The vermicompost plus peat moss (VC+PM) treatment demonstrated the highest water-holding capacity (26%), root projected area (9.60 cm² plant⁻¹), and root surface area (84.79 cm² plant⁻¹). VC+PM also promoted extensive lateral branching (233 secondary and 1709 tertiary roots) and the greatest total lateral root length (363.09 cm plant⁻¹), resulting in superior biomass (shoot: 140.00 mg plant⁻¹; root: 56.70 mg plant⁻¹) and the lowest root-to-shoot ratio (0.90). These improvements are attributed to the enhanced moisture retention of peat moss and the nutrient and phytohormone contributions of vermicompost. In contrast, rice husk biochar exhibited the lowest water-holding capacity (14%), while other amendments produced moderate or limited effects. The results establish a direct relationship between improved soil water retention and early-stage drought-avoidant root development. The combination of VC and PM emerges as a promising approach to enhance root plasticity and seedling establishment in water-saving rice systems. As this study was conducted under controlled rhizotron conditions and limited to the seedling stage (20 days after sowing), future research should prioritize multi-season field trials to assess yield translation and economic feasibility assessments to support farmer adoption. Full article

The transition towards circular economy is now a key strategy to address the environmental issues we are facing. Within this framework, biochar, a carbon-rich material derived from residual agricultural pyrolysis, can represent a sustainable and circular solution. This paper aims at evaluating the possibility of implementing a local biochar-production system as part of an economic and social strategy of the redevelopment of an abandoned rural site, Borgo di Perolla, in Tuscany, Italy. A cost–benefits analysis (CBA) was conducted to evaluate the economic feasibility of three different scenarios of production and strategies: Scenario 1 considers revenues solely from the production and sale of biochar and wood vinegar; Scenario 2 additionally includes potential income from the sale of voluntary carbon credits; and Scenario 3 incorporates biochar credits within the European Union Emission Trading System (EU ETS). For each scenario, three indicators were calculated: Net-Present Value (NPV), Internal Rate of Return (IRR), and Breakeven point (BEP). The most evident result that emerged is that the sale of biochar and its by-products alone is not sufficient to ensure the project’s economic sustainability, mainly due to high production costs. Only through carbon-credit-trading markets biochar becomes not only an environmentally strategic tool but also an economically rewarding one. In this sense, market infrastructures, such as the ETS, are essential for the dissemination of circular models, like biochar, that generate both environmental and economic benefits. Previous studies on biochar have largely focused on its application and associated benefits, while cost–benefit analyses have primarily examined its economic feasibility through the commercialization of biochar as a soil amendment, particularly within the United States context. The present work contributes to this literature in three main ways. First, it provides a site-specific and replicable CBA framework applied to a real territorial regeneration project (Borgo di Perolla), grounded in primary data collected through field surveys, stakeholder interviews, and expert validation. Second, the study explicitly compares multiple market-access scenarios within the same analytical framework, ranging from biochar-only sales to voluntary carbon markets, allowing for a clear identification of the economic thresholds at which biochar becomes financially sustainable. Third, and most importantly, the main contribution of this work lies in the explicit modeling of biochar integration into the EU Emissions Trading System. This paper extends the analysis to a regulated carbon market scenario, assuming the recognition of biochar-based carbon removals within the EU ETS framework. From a methodological perspective, the study quantitatively assesses how ETS price dynamics affect the profitability, internal rate of return, and break-even point of a biochar project over a long-term horizon. From a policy perspective, the analysis anticipates recent regulatory developments, such as the EU Regulation 2024/3012, on establishing a Union certification framework for permanent carbon removals, carbon farming, and carbon storage in products, by showing how biochar could function as a fully market-integrated climate technology. Full article

The undegradable characteristics of heavy metals on environmental quality have become a serious human health concern. A study was conducted in a potato field to investigate the impact of soil amended with animal manure or biochar on the transport of toxic heavy metals and nitrates to runoff and seepage water. The soil in 18 field plots was separated, and each of 3 plots was mixed with biochar, chicken manure, vermicompost, sewage sludge, or cow manure, with 3 plots used as the control. Following a natural rainfall event, the impact of soil treatments on the runoff and infiltration water volume was monitored. Runoff water from the soil amended with biochar exhibited 10.6 L plot⁻¹, whereas cow manure exhibited 4.1 L plot⁻¹, indicating about 61% reduction in runoff water volume. The vermicompost-amended soil increased the seepage water volume from 1.6 L plot⁻¹ in the control treatment to 4.4 L plot⁻¹, indicating a 175% increase in percolating water, a desirable attribute to direct rainfall water towards the plant roots. The concentrations of Pb, Cd, Ni, Mn, Cr, Mg, Cu, and K in infiltration water were greater in runoff sediments, highlighting the need for runoff sediment remediation technology. Full article

In agriculture, soil amendments like compost, manure, superabsorbent polymers (SAP) and biochar (BC) are already in use to mitigate the effects of water shortage and to obtain a higher yield and survivability. The present study focuses on the impact of BC and SAP under moderate and reduced soil water content (SWC) on the physiological and biochemical response of Chenopodium quinoa Willd. (cv. UDEC-5), a naturally drought-resistant and strategic crop in arid regions, with the aim of further improving its resilience and biomass production. Plants were grown in the presence or absence (control) of SAP (1% or 0.1% g/100 g SAP) or BC (3% g/100 g BC) by taking into account the smallest possible amount of irrigation necessary for optimal growth of the control. Sixty-five days after sowing, the reduced watering approaches started. The irrigation amount was reduced slowly until plants without any amendment showed a significant reduction in CO₂/H₂O gas exchange and further significant changes in 23 morphological, physiological and biochemical symptoms of water shortage. Each amendment already caused individual plant response in wet conditions: The soil amendments of SAP (1% and 0.1%) and BC had no significant effect on biomass production but caused changes in PS I (portion of oxidized and open centers in PS I), the C/N ratio and N content. The addition of SAP (0.1% and 1%) led to a decrease in gH⁺, ECStmAu ^× gH⁺, R_D, R_L, the C_i/C_atm ratio and ETR/A_gross ratio and to an increase in water use efficiency (WUE), especially in the 0.1% SAP treatment. In moderate conditions, 0.1% SAP and 3% BC caused a significant increase in both the LOP and C/N ratio. In the moderate treatments, the application of 0.1% SAP promoted an increased A_net, while 3% BC promoted a significant reduction in malondialdehyde (MDA). The results of the present quinoa experiment indicate the drought avoidance mechanism of the control under low SWC. The reduced transpiration led to increased WUE due to the efficient use of the substomatal CO₂ reservoir under low C_s and low E. It could also be confirmed that quinoa plants balanced low soil water potential by the accumulation of compatible solutes to lower the LWP and LOP. Drought led, especially in leaves in the 1% SAP treatment, to significant reductions in CO₂/H₂O gas exchange (A_net, R_D), decreases in Y (II) and ETR in PS II, and an increase in the ETR/A ratio and over-reduced centers in PS I, pointing to an increased appearance of reactive oxygen species (ROS) in the chloroplasts. The latter change was indicated by higher levels of lipid peroxidation (MDA). It could be shown that the response of the test species Chenopodium quinoa to the addition of BC and SAP proved to be highly adaptable. The plant reacted in a very coordinated and specific way to both the danger of oversupply of SAP soil amendments under water shortage conditions and an effective adaptation to a limited water supply with 3% BC and 0.1% SAP by increasing WUE and proline content. However, BC also had a mitigating effect on the level of reactive oxygen species (ROS). It can be assumed that this effect is based on a more plant-compatible, less one-sided ion composition of BC. The results presented indicate that SAP and BC can have an impact on the water and nutrient accessibility for plants. Therefore, optimal biomass production and plant response can only be reached if plant soil interactions and competition between SAP, BC and the plant roots are taken into account when planning for climate-resilient, water-saving agriculture. Full article

Soil salinization is a major constraint on global crop production. While organic amendments are used in mildly saline soils, their seasonal effects require further study. This research applied biochar (BC) and humic acid (HA) annually in 2022 and 2023 separately, with an unamended control (CK), to assess impacts on soil quality and wheat yield. BC significantly reduced soil salt content by 28.1% and 17.5% in 2022 and 2023 at a rate of 7.5 Mg·ha⁻¹, while increasing organic matter and total phosphorus. In contrast, HA lowered soil pH by 3.1% in 2022 and enhanced available nitrogen, potassium, and phosphorus. Both BC and HA increased alkaline phosphatase activity by 7.6% and 6.9% in 2023, respectively. Notably, grain yield showed no direct link to soil nutrients but was positively correlated with phosphatase activity in 2023. Consequently, BC did not improve the soil quality index but raised grain yield by 12.9% and 20.7% over two years, primarily via increased 1000-grain weight. In contrast, HA both improved the soil quality index by 16.1% in 2023 and increased grain yield by 17.2%, driven by enhanced aboveground biomass. In conclusion, soil chemical properties and crop productivity were decoupled in these mildly saline–alkaline soils, highlighting the potential for site-specific application of organic amendments. Full article

To address freshwater scarcity in agriculture, the use of brackish and reclaimed water for alternate irrigation has emerged as a viable alternative. This study evaluated four biochars (rice husk, peanut shell, rice straw, and wheat straw, applied at 2%) and three silicon fertilizers (Lang-Si (S1), Nayou-Si (S2), and sodium metasilicate pentahydrate (S3)) as amendments for sandy loam soil (Lang-Si, Nayou-Si, foliar spray at 1000× dilution; sodium metasilicate pentahydrate, foliar spray at 150 mg∙L⁻¹). Their effects on soil salinity, physicochemical properties, and microbial community structure were assessed under alternate irrigation with brackish and reclaimed water. Alternate irrigation reduced soil electrical conductivity and increased total phosphorus (TP) content compared to single-source irrigation. The effects of amendments varied by type. Biochars improved soil fertility and reduced salinity: peanut shell biochar decreased EC by 15.5%; rice husk biochar increased total nitrogen (TN), TP, and organic matter (OM) by 11.8%, 8.2%, and 10.1%, respectively; and wheat straw biochar elevated subsurface soil TN and OM by 14.1% and 40.0%. Straw-derived biochars and sodium metasilicate pentahydrate maintained higher bacterial α-diversity (Shannon index ≥ 6.67). These effects corresponded with the nutrient adsorption capacity of biochars and the ionic stress alleviation by soluble silicon. The correlation analysis identified OM, TN, TP, and EC as the key drivers shifting the microbial community. Straw-derived biochars and sodium metasilicate pentahydrate are suitable amendments for alternate irrigation systems. These materials balance salinity control, fertility improvement, and microbial conservation, offering practical options for sustainable use of brackish and reclaimed water in agriculture. Full article

In this research, the effects of organic amendments and planting methods on the grain yields, enzyme activity, soil quality, and the structures of fungal populations in the rhizosphere of rice were evaluated. In comparison to the control group with direct seeding, the transplanting method resulted in a 23.5% higher grain yield. Furthermore, rice straw addition significantly improved fungal diversity indices (i.e., Chao1, ACE, Shannon, and Simpson). Dissimilarity distances and principal coordinate analysis revealed substantial variations in the compositions of root-associated fungal communities across the experimental groups with different planting methods. When the transplanting method was used, the Ascomycota, Basidiomycota, Chytridiomycota, Olpidiomycota, Aphelidiomycota, Monoblepharomycota, and Calcarisporiellomycota phyla became dominant. Biochar and rice straw applications caused substantial increases in the abundance of the Ascomycota, Basidiomycota, Chytridiomycota, Rozellomycota, Mucoromycota, Olpidiomycota, Aphelidiomycota, and Gammaproteobacteria phyla. Changes in enzyme activity and the physicochemical properties of the soil were also observed across the treatment groups with different planting methods and organic amendments. Direct seeding enhanced cellulase activity, microbial biomass carbon and nitrogen, available nitrogen, available potassium, nitrate nitrogen, and ammonium nitrogen, whereas transplanting boosted the activity of sucrase and urease enzymes. Rice straw application enhanced cellulase activity and the concentrations of available nitrogen, available phosphorus, nitrate nitrogen, and ammonium nitrogen in the soil. Biochar addition resulted in increased urease activity, microbial biomass carbon and nitrogen, soil pH, and available potassium. The Ascomycota abundance and grain yield exhibited a positive connection, while unclassified_Fungi exhibited negative correlations with the soil pH, organic carbon, available phosphorus, grain yield, and activity of sucrase and urease. Mortierellomycota was positively correlated with microbial biomass nitrogen and nitrate nitrogen. Overall, both the organic additives and planting methods influenced the soil properties, enzyme activity, rhizosphere fungal populations, and grain yield. These results provide new insights and a theoretical basis for studying the changes in soil fungal diversity and richness with different planting methods and organic amendments in Northeastern China. Full article

Soil salinization remains a major global challenge, and rice cultivation has been widely practiced in saline–alkali soils of the black soil region in Northeast China as an effective strategy for soil improvement. However, this practice is often slow to produce benefits and is prone to secondary salinization, limiting rapid gains in soil fertility and crop productivity. To address these limitations, this study evaluated the effects of four soil amendment strategies (microbial inoculant, organic fertilizer, biochar, and their combined application) on bacterial and fungal communities, as assessed by high-throughput sequencing of the 16S rRNA gene and the ITS region, respectively. The application of microbial inoculants significantly increased bacterial diversity and richness, while all amendment treatments promoted the enrichment of key microbial groups. Organic inputs strongly influenced microbial community assembly, with microbial inoculant and combined treatments shifting assembly toward more deterministic processes. In addition, the amendments altered microbial interaction networks, leading to widespread cooperative relationships dominated by positive associations and strong interactions across taxonomic groups. Notably, the combined treatment reshaped bacterial functional profiles and reduced the predicted abundance of pathogenic fungi. Overall, these results demonstrate that organic amelioration strategies can improve the ecological functioning of saline–alkali soils by regulating microbial community assembly and interactions. This study provides a robust theoretical framework and scalable practical solutions for the integrated management and sustainable development of saline–alkali agriculture. Full article

Nutrients recovered from municipal and dairy wastewaters in a bioelectrochemical system constructed with terracotta and biochar were used in different soil amendments. These amendments included addition of terracotta (TS), biochar (BS), terracotta and biochar nutrient-rich mixtures from bioelectrochemical systems, DWW (dairy wastewater), and SWW (synthetic wastewater), respectively. Corn growth affected by these amendments was compared with control, termed straight soil (SS). The first experimental setup consisted of 60 plants, four replications per group, and nutrient loadings (0%, 50%, and 100% Hoagland Nutrient Solution, HNS) in the fall season. After harvesting, the plants and soil were analyzed for agro-physical characteristics by various methods. At the 100% nutrient treatment, the TS soil had the best yielding plants. Overall, plants grown in DWW and SWW soil amendments with 0% and 50% nutrient treatments had the best results in plant height, total plant dry weight, the average number of leaves per plant, leaf surface area, shoot dry weight, root/shoot ratio, root surface area, and NBI when compared to the control group. Another test was carried out with 80 corn plants grown using five different soil mediums and using four different nutrient treatments in the spring season. Twenty of the plants were put through a simulated drought to evaluate drought resistance (as measured by plant growth) in different soil amendments. In this test, the SWW soil amendment had a negative effect at 0% HNS and in warm weather. The SWW soil medium had large retention in soil moisture, which had a negative growth effect. It is recommended that the irrigation be monitored closely when applying the SWW soil amendment to avoid overwatering. This research provides critical insights into nutrient reuse in crop production. Full article

Soil contamination by per- and polyfluoroalkyl substances (PFAS) represents a pressing environmental and public health concern due to the exceptional persistence of carbon–fluorine bonds, which prevent natural attenuation and limit the effectiveness of conventional remediation. Agricultural and industrial soils serve as long-term sinks for PFAS, continuously releasing these pollutants into groundwater and facilitating their transfer through the food chain. Conventional chemical and physical remediation methods are often costly, energy-intensive, and yield incomplete removal, underscoring the need for sustainable and biologically driven alternatives. Microbial consortia have emerged as a promising solution due to their metabolic complementarities, cross-feeding interactions, and ecological resilience, which together enable PFAS transformation and partial defluorination under complex soil and subsurface conditions. Key enzymes such as oxygenases, reductive dehalogenases, and hydrolases are often operating within co-metabolic networks, which play central roles in these processes. Advances in metagenomics, CRISPR-based functional screening, and metabolic modelling are rapidly uncovering novel PFAS-degrading microbes and pathways. Integration of machine learning with multi-omics and environmental datasets further enables the prediction of degradation mechanisms, identification of keystone degraders, and rational design of synthetic consortia. Emerging sustainable strategies, including biochar- and nutrient-amended soil microcosms, plant–microbe partnerships for coupled soil–groundwater phytoremediation, and bioelectrochemical systems that offer new avenues for enhancing PFAS biodegradation in situ. This review synthesises recent research progress and provides critical perspectives on the mechanistic, ecological, and engineering dimensions of PFAS bioremediation, proposing an integrated conceptual framework linking microbial consortia dynamics, enzymatic pathways, and environmental engineering interventions to guide scalable field applications and sustainable management of PFAS-contaminated soil–groundwater ecosystems. Full article

Ultramafic soils, particularly those affected by mining, often contain toxic nickel (Ni) levels that hinder plant growth and ecosystem recovery. This study assessed engineered biochar–nanocomposite amendments to improve vetiver (Chrysopogon zizanioides) growth, biomass, and Ni phytoextraction in Ni-rich ultramafic soils from Santa Cruz, Zambales, the Philippines. Seven samples were tested: T₁—control (no application); T₂—biochar; T₃—nanocomposite; T₄—biochar + nano-silica; T₅—biochar + nano-calcium; T₆—biochar + nano-chitosan; and T₇—biochar + nanocomposite. Biochar combined with nano-silica (T4) significantly enhanced vetiver growth, producing the highest root, shoot, and total biomass (469.97 g plant⁻¹), indicating improved plant tolerance under Ni stress. The highest shoot Ni concentration (24.52 mg kg⁻¹) and translocation factor (0.56) were observed in the biochar + nano-chitosan treatment (T6), suggesting increased Ni bioavailability and uptake. However, translocation factor values remained below unity across all treatments, indicating limited Ni transfer from roots to shoots and a dominant phytostabilization behavior. Overall, nano-silica-engineered + biochar primarily enhanced biomass production, while nano-chitosan influenced Ni uptake dynamics, highlighting the potential of engineered biochar–nanomaterial amendments for sustainable rehabilitation of Ni-contaminated ultramafic soils. Full article