Sep 2026· Journal of Ecological Engineering· Vol 27, pp. 75-87· 0 citations· 34 references
Abstract
Wastewater containing heavy metals can lead to soil and crop accumulation, thus posing a risk to the environment. Biochar, being a rich carbon-containing organic fertilizer, can reduce these adverse impacts by increasing soil fertility. This study was conducted to assess the biochar-treated wastewater for beetroot cultivation using Beta vulgaris L. at three locations in Faisalabad, namely, Directorate of Farms UAF, Uchkera Farm, and Satyana Farm, Faisalabad, using an RCBD factorial design with three wastewater treatments, namely, UAF sewage, Madhuana, and Paharang drains. As a result, pigments increased (Chl a/b 25%, carotenoids 25%), and physiological charac - teristics improved (RWC 25%, electrolyte leakage -20%). The elevated levels of heavy metals were lowered by biochar. Heavy metal buildup in beets was significantly enhanced by wastewater irrigation, but most metals were successfully reduced by applying biochar, improving crop safety and lowering environmental risk. In general, 2024 performed better than 2023. While biochar further improves performance and reduces the dangers of heavy metals, wastewater irrigation increases beetroot growth, yield, and stress tolerance, encouraging safer and more sustainable crop production.
Declining soil fertility resulting from continuous cultivation, nutrient depletion and dependence on inorganic fertilizers poses a major challenge to sustainable crop production in Nigeria. Woody plant ashes offer a low-cost and environmentally sustainable alternative soil amendment owing to their rich mineral composition. This study evaluated the nutrient composition, heavy metal characteristics and transfer potential of ashes derived from Azadirachta indica, Eucalyptus globulus and Prosopis africana applied to nutrient-deficient soil cultivated with Abelmoschus esculentus under controlled screen-house conditions. Surface soil (0–15 cm) collected from the experimental farm of Hussaini Adamu Federal Polytechnic, Kazaure, Nigeria, was amended with the three wood ashes at application rates of 0, 0.5, 1.0 and 1.5 kg per 5 kg soil. The ashes were characterized for essential macronutrients (N, P, K, Ca, Mg and S) and selected heavy metals using standard analytical procedures. Heavy metal concentrations in harvested okra samples were determined, while transfer factors and correlation analysis were employed to evaluate metal mobility and nutrient–metal relationships. Potassium was the predominant nutrient in all ash types, with nutrient availability following the order K > Mg > S > P > Ca > N for A. indica and E. globulus, and K > S > Mg > P > Ca > N for P. africana. Metal uptake followed the trend Pb > Cr > Cu > Cd. Prosopis africana recorded the highest Cu transfer factor (2.016), whereas A. indica consistently exhibited higher transfer values for most metals. Significant nutrient associations included a strong negative correlation between Ca and Mg (r = −0.995) and positive correlations between Ca and N (r = 0.977) and S (r = 0.891). The findings demonstrate the potential of woody plant ashes as sustainable nutrient-rich soil amendment materials.
S. A. Abdallah, David F. Chinemerem, M. Ibrahim et al.· HAFED POLY Journal of Scienc...· 0 citations
Lead (Pb) contamination in agricultural soils threatens rice production by reducing plant growth and increasing the risk of heavy-metal accumulation in edible tissues. Biochar has emerged as a sustainable soil amendment capable of immobilizing heavy metals while improving soil properties. This study evaluated the comparative effectiveness of rice-husk biochar and corn-residue biochar applied at rates of 0%, 10%, and 20% in reducing Pb availability and enhancing the early growth of upland rice (Oryza sativa L.). A factorial completely randomized design with three replications was employed under controlled pot conditions. Soil pH, residual Pb concentration, rice growth parameters, biomass production, root development, and Pb accumulation in plant tissues were measured and analyzed using analysis of variance followed by Duncan's Multiple Range Test at the 5% significance level. Biochar application significantly reduced soil Pb concentration, with the 20% application rate decreasing Pb by approximately 23% compared with the untreated control. A parallel reduction in Pb accumulation was observed in rice tissues, indicating lower Pb bioavailability. Root length increased markedly from 6.35 cm in the control to 16.50 cm at the highest biochar rate, while shoot length also improved significantly. Corn-residue biochar generally promoted greater root development and biomass production than rice-husk biochar, likely because of its higher concentrations of exchangeable potassium, calcium, and magnesium. Although soil pH increased following biochar application, the differences were not statistically significant, suggesting that Pb immobilization resulted primarily from adsorption, ion exchange, surface complexation, and mineral precipitation rather than pH modification alone. Overall, biochar application rate exerted a stronger influence on Pb immobilization than feedstock type, whereas biochar feedstock more strongly affected plant growth. These findings demonstrate that agricultural-residue biochars represent promising, low-cost amendments for mitigating Pb contamination and improving early rice establishment, although long-term field validation is required before practical recommendations can be made.
Syarifa Mayly, Ida Zulfida, Dora Silvia Dewi et al.· Jurnal Al Ulum LPPM Universi...· 0 citations
It is suggested that Bacillus strains possess PGP properties under metal stress conditions, indicating their potential for application in the remediation of metal-contaminated soils and enhancement of plant growth.
Aisha Bibi, S. Alam, Alia Naz et al.· Plant and Soil· 0 citations
The reuse of polluted drainage water for irrigation is increasingly unavoidable in arid and semi-arid regions, yet it poses serious risks due to the accumulation of toxic heavy metals in soils and crops. Although biochar and plant growth-promoting rhizobacteria (PGPR) have individually shown potential to alleviate metal stress, field-scale evidence elucidating their synergistic and mechanistic effects under realistic, combined soil- and irrigation-derived contamination remains limited. This study addresses this gap by evaluating the effectiveness of PGPR-enriched biochar in mitigating lead (Pb), cadmium (Cd), and nickel (Ni) stress in canola (Brassica napus L.) grown under open-field conditions. A naturally contaminated clay soil was continuously irrigated with polluted drainage water from the Kitchener drain (Egypt), creating chronic heavy metal stress. Biochar was applied at 5 and 10 ton ha⁻¹, alone or enriched with defined PGPR consortia composed of Bacillus circulans NCAIM B.02324, Azospirillum brasiliense SARS 1001, and Pseudomonas koreensis MG209738, applied via seed inoculation. The combined application of 10 ton ha⁻¹ biochar with the three-strain consortium (10BC+PGPR3) produced the strongest responses. This treatment (10BC+PGPR3) significantly enhanced soil microbial respiration and key enzyme activities, indicating improved soil biological functioning, while reducing extractable Pb, Cd, and Ni by 55–65% relative to the untreated control. These soil-level improvements translated into marked reductions in metal uptake and translocation to shoots and seeds, alongside enhanced plant water status, membrane stability, and oxidative stress tolerance. Consequently, seed yield and oil content increased by ~ 60% and ~ 90%, respectively. Overall, this study demonstrates that PGPR-enriched biochar acts through coupled soil biochemical and plant physiological mechanisms to immobilize heavy metals and restore crop productivity under real contaminated irrigation scenarios. The findings provide robust field-based evidence supporting this integrated strategy as a practical and sustainable solution for improving soil health, crop performance, and food safety in heavy metal-affected agroecosystems.
T. Alshaal, Khadiga Alharbi, Alaa El-Dein Omara et al.· BMC Plant Biology· 0 citations
Wastewater sludge can improve soil fertility and support resource recycling, but potential heavy metal accumulation limits its agricultural application. In this study, we evaluated the effects of anaerobically digested wastewater sludge, applied alone or in combination with the purple non-sulfur bacterium (Rhodopseudomonas palustris), on two green manure crops, Sesbania cannabina and Glycine max. A 90-day pot experiment was conducted with five treatments: control, sludge at 10 and 20 t/ha, and each sludge level combined with R. palustris. Soil physicochemical properties, plant biomass production, and heavy metal concentrations in soil and plant tissues were analyzed. Sludge application increased soil total carbon, total nitrogen, and available phosphorus, while co-application with R. palustris further enhanced phosphorus availability. The greatest biomass production response was observed in G. max under 20 t/ha sludge plus R. palustris, with a 78% increase after 90 days. However, heavy metal concentrations and plant uptake generally increased with sludge dosage, particularly for Ni and Cr. These results indicate that sludge–PNSB application may improve soil fertility and biomass production, but heavy metal risks require careful evaluation.
Ping-Yuan Yang, Chun-Han Ko, Bo-Xiang Lee et al.· Agronomy· 0 citations
Heavy metal contamination, particularly cadmium (Cd), can arise from the use of organic fertilizers derived from urban waste. Cd is highly toxic and mobile, posing serious health risks when accumulated in edible crops such as lettuce. This study aimed to evaluate the potential of rice husk biochar (RHB) and silica fertilizer to mitigate Cd stress on lettuce growth. The research employed a factorial Completely Randomized Design with two factors: biochar dose (0, 15, 30, 45 tons/ha) and silica dose (0, 3, 6 g per 3 kg soil per polybag). Soil was spiked with 15 ppm Cd. Parameters measured included plant height, leaf number, fresh weight, soil Cd, and plant Cd. Data were analyzed using ANOVA and LSD test at 5%. Results showed that biochar significantly affected plant height and leaf number (P<0.01), with 45 tons/ha producing the tallest plants (19.81 cm) and most leaves (18.56 leaves), while reducing plant Cd to 0.47 ppm. The combination of P3S1 (45 tons/ha biochar + 3 g/3 kg silica) resulted in the lowest soil Cd (1.16 ppm) and plant Cd (0.32 ppm). Regression analysis showed a weak correlation (R² = 22.74%) between soil and plant Cd. Although the interaction between biochar and silica was not statistically significant (P > 0.05), the main effect of biochar significantly reduced plant Cd concentration (P < 0.05), with the highest dose (45 tons/ha) producing the lowest plant Cd (0.47 ppm). The treatment combination P3S1 (45 tons/ha biochar + 3 g/3 kg silica) numerically produced the lowest soil Cd (1.16 ppm) and plant Cd (0.32 ppm), but did not show synergistic interaction.
Diny Evitasari, Moch. Arifin, M. Maroeto· Jurnal Teknik Pertanian Lamp...· 0 citations
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