Jun 2026· Sains Malaysiana· Vol 55, pp. 1088-1099· 0 citations
Abstract
The growing world population has increased the demand for food to meet global needs, which contributed to the growth and vibrancy of the agricultural sector. There is an urgent need for soil treatment to restore healthy soil conditions due to extensive and unregulated agricultural activities that have degraded soil fertility, resulting in reduced crop yields. Sludge from a municipal wastewater treatment plant is potentially used in biochar production. Thus, the combination of biochar with plant growth-promoting bacteria offers an ecologically friendly alternative for improving soil health and agricultural output. ICP-MS and Brunauer–Emmett–Teller (BET) analysis were used to determine the quality of the developed biochar. An indigenous Pseudomonas sp. isolate, RA21, was mixed with biochar and used as a soil conditioner to promote chili plant growth. Plant height, leaf size, and stem diameter were measured to compare treated and untreated plants. ICP-MS analysis indicates that zinc and iron were the dominant metals present in all samples. BET analysis shows that approximately 70% of the biochar pore volume is composed of mesopores. The Fe and Zn nutrients in biochar serve as nutrient sources for plant uptake, while the high proportion of mesopores provides sites for bacterial colonization and enhances adsorption capacity. The application of a soil conditioner resulted in greater plant growth variables such as height, leaf size, and stem diameter when compared to the control group, and was equivalent to commercial fertiliser. Using soil conditioner resulted in more leaf area (651 cm²) in chilli plants compared to those treated with commercial fertiliser (629 cm²). Biochar, in particular, serves as a transporter for bacteria, allowing for optimal growth and activity while also providing nutrients that promote healthy plant development. The combination of sludge-derived biochar with the indigenous Pseudomonas sp. strain RA21 has shown encouraging results as a soil conditioner by increasing nutrient availability, allowing for the value-added use of municipal sludge within a circular economy framework.
This study evaluated the effects of sewage sludge composted (SSC, mixed with sugarcane bagasse at 1:1 ratio) and microbial biopromoters on soil fertility and early growth of Astronium fraxinifolium, a native tree with high recovery potential in the Brazilian Cerrado. In a randomized block design (2 × 4 factorial), treatments consisted of two SSC levels (with and without 23 g pot⁻¹ of chemically characterized, environmentally safe compost) and four inoculation treatments (control; Bacillus subtilis - BS; Rhizophagus clarus - RhC; and BS + RhC) with five replicates in 6-L pots. After 150 days, growth, root morphology, gas exchange, and soil properties were evaluated. SSC improved soil fertility (reduced aluminum, increased P, sum of bases, base saturation, and essential micronutrients Fe, Mn, Zn) without inducing heavy metal toxicity, increasing plant height. The SSC + RhC interaction significantly promoted shoot and root biomass, stem diameter, and root surface area/volume. Seedling Quality Index (SQI) was highest under SSC + RhC and SSC + BS. Furthermore, SSC and inoculants significantly enhanced gas exchange parameters, translating into substantially higher photosynthetic performance. Overall, combining this specific SSC rate with biopromoters, particularly Rh. clarus, effectively improved soil chemical properties and seedling vigor. While limited to nursery conditions, these findings demonstrate that this approach successfully promotes high-quality seedlings, establishing a promising baseline for future long-term field validation and dose-response trials in degraded lands.
P. Silva, Adrielle Rodrigues Prates, D. M. Fernandes et al.· New forests· 0 citations
Soil degradation is a major concern, causing a decline in crop productivity and making sustainable agricultural practices essential for humankind. Biochar and plant growth-promoting bacteria (PGPB) are currently applied as affordable and environmentally safe alternatives. Biochar, a porous, carbon-rich by-product of biomass pyrolysis, was applied at 3 % (w/w) alone (control) and in combination with microbial inoculants, including a bacterial consortium. A 15-day pot experiment was conducted under controlled conditions to evaluate the effects of biochar and plant growth-promoting bacteria (PGPB) on plant growth. This study investigates the effects of biochar and PGPB (three Pseudomonas spp. and one Diaphorobacter spp.) on rice (Oryza sativa L.) and mustard (Brassica juncea L.) when applied individually and in combination. The results were evaluated based on plant growth-promoting criteria namely root and shoot length and chlorophyll content. It was observed that biochar had a positive impact on plant growth parameters when applied individually, however in combination with bacterial inoculants, the results were significantly improved. The consortium treatment showed higher values for root length, shoot length and chlorophyll content compared with individual treatments. This study highlights the major scope and potential of utilising plant growth promoting bacteria and biochar to achieve sustainable increases in plant growth and yield. However, some treatments showed variability in results, which could be attributed to the compatibility between biochar and microbial inoculants. This underscores the need for further optimisation studies on the interaction between biochar and bacterial inoculants.
D. Ruchi, S. Sunita, G. Arpita et al.· Plant Science Today· 0 citations
Introduction Understanding the effects of different soil amendments on bacterial community structure and diversity in acidic rubber plantation soils is essential for biological remediation and the targeted restoration of these degraded systems. Methods In this study, a 2.5-year long field experiment was conducted in a second-generation 25-year-old rubber plantation at Dongfeng Farm in Jinghong City, southern Yunan, China. The experiment included five fertilization treatments: (1) unfertilized control (CK), (2) microbial fertilizer (T1), (3) biochar-based fertilizer (T2), (4) tobacco ash and oil cake organic fertilizer (T3), and (5) bio-organic fertilizer combined with polyacrylamide (T4). Soil samples were collected from the 0–20 cm layer in October 2022, and bacterial communities were analyzed using Illumina MiSeq high-throughput sequencing. Key environmental drivers were identified by integrating sequencing data with soil physicochemical properties. Results The application of soil fertilizers significantly altered the tested soil physicochemical properties and bacterial community composition. Compared with CK, T1 and T4 increased soil pH. T2 and T3 significantly enhanced soil organic matter, available phosphorus, and total nitrogen. In addition, T2 specifically increased exchangeable Ca2+ and Mg2+ concentrations and elevated the Chao1 richness index. Both T2 and T3 enriched beneficial taxa, including Proteobacteria and BradyRhizobium, while principal coordinate analysis (PCoA) revealed distinct shifts in bacterial community structure. The T4 treatment resulted in the most complex bacterial co-occurrence network. Mantel tests identified organic matter, total nitrogen, available phosphorus, and available nitrogen as the primary drivers of bacterial diversity. Further analysis using structural equation modeling indicates that soil conditioners alter bacterial community structure and diversity by influencing soil fertility and pH. Discussion Collectively, these findings demonstrate that organic matter, total nitrogen, available phosphorus, and available nitrogen serve as key environmental factors shaping bacterial community structure and diversity in acidic rubber plantation soils. Organic fertilizers and biochar have proven highly effective in enhancing soil fertility and buffering capacity, while significantly increasing the abundance of dominant bacterial taxa. Therefore, organic and biochar-based amendments should be prioritized as effective and sustainable strategies for restoring soil health and promoting continuous soil quality improvement in acidified rubber plantations.
Jifen Yang, Xiaoling Shi, Shunjun Geng et al.· Frontiers in Microbiology· 0 citations
Sandy soils are widely distributed in Egypt and are characterized by poor physical properties and a limited capacity to retain irrigation water and nutrients, which severely constrains agricultural productivity. Addressing these limitations has become increasingly critical to ensure sustainable crop production under arid and semi-arid conditions. Therefore, this study aimed to evaluate the effectiveness of biochar as a soil amendment for improving growth performance, yield, nutrient accumulation, photosynthetic pigments, and essential oil production of Mentha spicata cultivated under sandy soil conditions over two successive seasons (2024–2025). The field experiment consisted of four treatments: untreated control, NPK at 5 g L-1, biochar at 12.5 ton ha-1, and combined NPK (5 g L-1) and biochar (12.5 ton ha-1). The results showed that biochar application, either alone or in combination with mineral fertilizer, significantly improved all vegetative growth parameters, fresh and dry herbage yields, essential oil percentage and yield, leaf macronutrient content (N, P, and K), and chlorophyll b concentration. Biochar applied alone consistently outperformed mineral fertilizer alone, while the combined biochar–NPK treatment produced the highest values for all measured traits, with improvements exceeding the additive effects of individual applications. These enhancements were closely associated with increased nutrient accumulation and improved nutrient use efficiency, reflecting the ability of biochar to retain nutrients, reduce leaching losses, and synchronize nutrient availability with plant demand. The synergistic interaction between biochar and mineral fertilization highlights the potential of biochar as a sustainable soil amendment for improving productivity, quality, and resource-use efficiency of mint grown in low-fertility sandy soils.
Y. Soliman, W. Soliman· Scientific Reports· 0 citations
Soil salinization has become a major constraint on sustainable agricultural development and the improvement of crop productivity. However, the effects of biochar combined with different organic amendments on the microbial ecology of saline–alkaline soils and crop performance remain insufficiently understood. This study evaluated the effects of different amendment strategies, including sole applications of fulvic acid (FA), organic fertilizer (OF), and biochar (BC), as well as their combinations. Soil bacterial community composition, richness, and diversity, oat agronomic traits, hay yield, and forage quality indicators were assessed. Spearman correlation analysis and the Mantel test were employed to examine the relationships among soil physicochemical properties, microbial communities, and crop performance. Combined applications exerted stronger effects on modulating soil bacterial community composition than sole applications, while FA, BC, or their combinations significantly enhanced bacterial richness and diversity. Crop responses exhibited distinct functional differentiation among combined treatments. The biochar combined with fulvic acid (BC + FA) treatment showed the greatest potential for promoting oat growth and increasing yield, with plant height and stem diameter reaching 99.20 cm and 3.99 mm, respectively, and hay yield increasing by 48.5% compared with the control treatment. In contrast, the biochar combined with organic fertilizer (BC + OF) treatment significantly increased crude protein content (CP) and reduced acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents, indicating improved forage quality. Although the crude fat content was numerically higher under BC + OF, no significant differences were observed among treatments. Correlation analyses further revealed that changes in soil physicochemical properties were associated with variations in several dominant bacterial genera, which were correlated with oat agronomic traits and forage quality indicators. Overall, the combined application of biochar with fulvic acid or organic fertilizer improved saline-alkaline soil microbial characteristics and showed potential for enhancing forage oat yield and quality, with BC + FA primarily improving yield production and BC + OF mainly enhancing forage quality.
Teng Wang, Zhen Li, Shilan Shao et al.· Land· 0 citations
Sewage sludge is widely explored as an organic nutrient source, but its ecological effects on soil microbial communities remain context dependent. This study evaluated the effects of sewage sludge and NPK fertilizers on soil microbial populations associated with kale (Brassica oleracea L. cv. ‘GM Dari’) and spinach (Spinacia oleracea L. cv. ‘Shalimar Green’). A two-season field experiment (rabi and kharif) was conducted at the Experimental Farm, Wadura Campus, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, using a randomized complete block design with nine treatment combinations and three replications. Results showed that sewage sludge amendments significantly increased the abundance and diversity of soil microorganisms compared to control and solely chemical fertilizer treatments. Rhizospheric soils of kale and spinach contained Flavobacterium, Bacillus, and Alcaligenes species, while fungal genera such as Aspergillus, Trichoderma, Mucor, and Paecilomyces were predominant in sludge-amended soils. The highest bacterial counts (39.30 × 10x CFU g-1 for kale and 39.25 × 10x CFU g-1 for spinach) and fungal counts (16.70 × 10t CFU g-1 for kale and 16.39 × 10t CFU g-1 for spinach) were recorded under 100% sewage sludge, followed closely by the combined treatment of 75% sludge + 25% NPK, whereas the control plots exhibited the lowest microbial abundance. The findings demonstrate that sewage sludge effectively enhances soil microbial activity and diversity, improving soil biological fertility. Partial substitution of mineral fertilizers with sludge (75% sludge + 25% NPK) appears optimal for maintaining microbial health and supporting sustainable vegetable production in the Kashmir Valley.
Sabia Zafar, K. Hussain, Sameer Farooq et al.· Journal of the Indian Societ...· 0 citations