Invasive plants as sustainable biochar feedstocks: Production, applications, and environmental implications

Introduction

Invasive plants are non-native species that spread rapidly into new environments, threatening local ecosystems, native plants, the economy, or human health (Weber, 2017). They often grow quickly and produce numerous seeds that accumulate in the soil (Marchante et al., 2010) or spread vegetatively (You et al., 2016). Typically, these plants lack natural predators in new locations, increasing competition with native species for light, water, and nutrients. Consequently, invasive alien plants (IAPs) represent one of the most significant ecological challenges globally, threatening biodiversity, ecosystem functioning, and human health (Klavins et al., 2024). Their exceptional environmental tolerance, rapid reproduction, and spreading capabilities have led to their proliferation across diverse ecosystems, causing substantial economic and ecological damage (Feng et al., 2021;Yang et al., 2022). Managing and eradicating IAPs, while essential, generates substantial biomass waste that poses additional disposal challenges and incurs considerable costs (Ceriani et al., 2024) [63, 41, 68, 32, 14, 65, 7] . This dual challenge-controlling invasions while managing waste biomass has prompted researchers to explore sustainable valorization pathways that can transform this ecological liability into a resource. Biochar, a carbon-rich material produced by pyrolyzing organic biomass under oxygen-limited conditions, has emerged as a promising solution for converting IAP biomass into value-added products (Feng et al., 2021;Yang et al., 2022). Pyrolysis not only enables the safe disposal of invasive plants but also produces a versatile material with applications in agriculture, environmental remediation, and energy production (Ahmed et al., 2020;Lian et al., 2020). Biochar characteristics including porous structure, high surface area, functional groups, and carbon stability depend on feedstock type and pyrolysis conditions, particularly temperature (Reza et al., 2020;Li et al., 2023). This variability enables the production of biochar tailored for specific applications, from soil amendment and carbon sequestration to wastewater treatment and heavy metal adsorption (Wang et al., 2021;Ghosh and Maiti, 2021). The global imperative to achieve net-zero emissions and transition toward circular economies has further intensified interest in utilizing IAP biomass as a renewable resource (de Almeida Moreira et al., 2025). Beyond biochar production, IAP biomass shows potential for bioenergy generation, pellet production, and extraction of bioactive compounds (Klavinš et al., 2024). However, realizing this potential requires addressing challenges related to cost management, transportation logistics, and regulatory frameworks (Rawat et al., 2024). This systematic literature review comprehensively synthesizes current knowledge on the utilization of invasive plant biomass, with particular emphasis on biochar production and its diverse applications, to identify research trends, knowledge gaps, and future directions for sustainable management of IAPs [10, 14, 65, 2, 35, 49, 34, 58, 20, 10, 32, 48] .

Methodology:

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to ensure transparency and reproducibility. A comprehensive literature search was conducted across four major electronic databases: Google Scholar, PubMed, Scopus, and Web of Science. The search strategy employed a combination of keywords and Boolean operators including: ("invasive plants" OR "invasive alien species" OR "invasive weeds") AND ("biochar" OR "pyrolysis" OR "biocarbon") AND ("soil amendment" OR "heavy metal adsorption" OR "wastewater treatment" OR "carbon sequestration" OR "agricultural productivity" OR "environmental remediation"). Studies published between January 2013 and June 2026 were considered for inclusion. The search was limited to peer-reviewed journal articles, review papers, and conference proceedings published in English. Additional records were identified through manual screening of reference lists of included studies and relevant review articles to ensure comprehensive coverage of the literature. Studies were included if they (i) investigated biochar production from invasive plant species; (ii) evaluated biochar applications in agriculture, environmental remediation, or carbon sequestration; (iii) reported original experimental data or comprehensive reviews; and (iv) provided sufficient methodological details for data extraction. Studies were excluded if they (i) focused on non-invasive plant species; (ii) did not involve biochar production or application; (iii) were non-peer-reviewed publications such as book chapters, editorials, or conference abstracts without full-text availability; or (iv) were duplicate publications. After initial screening of titles and abstracts, we assessed full-text articles for eligibility. A total of 70 relevant studies were included in this systematic review. Data extraction focused on: (i) biochar production parameters (feedstock type, pyrolysis temperature, residence time, yield); (ii) biochar physicochemical characteristics (pH, surface area, carbon content, functional groups); (iii) application areas (agriculture, environmental remediation, carbon sequestration, emerging applications); and (iv) reported outcomes and mechanisms.

Results and Synthesis

Biochar Production from Invasive Plants

The production of biochar from invasive plant species has been extensively investigated across diverse feedstocks and pyrolysis conditions. Liao et al. (2013) (2023) studied co-pyrolysis of pig manure and Japanese knotweed at different mixture ratios (3:1, 1:1, 1:3) and temperatures (400-700 °C), finding that co-pyrolysis increased fixed carbon contents by nearly 1.5 folds compared with manure-derived biochar alone, significantly reducing heavy metals and transforming Cu and Zn into more stable forms. The combined feedstock biochar P1J1 generated at 600 °C was most effective in reducing environmental risk of heavy metal leaching while retaining most nutrients (P, Ca, Mg, and K). Jiang et al. (2025) employed machine learning using deep neural networks and LightGBM to predict biochar specific surface area based on plant characterization information, finding that plant organ information enhanced model performance with pyrolysis temperature identified as a key feature. The DNN model achieved R² improvement from 0.897 to 0.917 after incorporating plant organ characteristics. Tshikovhi et al. (2024) investigated biochar from water hyacinth synthesized via controlled pyrolysis (300-700 °C), with biochar at 500 °C (WHB500) exhibiting highest adsorption capacity attributed to high porosity and optimal carbon content (73.1%). FTIR analysis showed structural changes in functional groups (aliphatic C-H and carbonyl C=O), with WHB700 showing enhanced adsorption due to strong alkaline amine peaks. Overall adsorption efficiency followed the order WHB500 > WHB700 > WHB300 > Raw WH [37, 2, 49, 35, 58, 38, 46, 27, 54] .

Agricultural Applications and Soil Improvement

Biochar derived from invasive plants has shown considerable promise for enhancing agricultural productivity and soil health. Fartyal et al. (2025) evaluated biochar from Ageratina adenophora, Lantana camara, and Parthenium hysterophorus applied at four rates (1, 3, 5, 7 g kg⁻¹ soil) to Lens culinaris crops, finding that P. hysterophorus-derived biochar outperformed others, though biochar application inhibited seed germination rates while stimulating growth parameters including shoot length, total plant length, shoot volume, total biomass, root moisture content, and seed vigour index. The study concluded that feedstock type significantly influences biochar characteristics and nutrient content. Khatri et al. (2025) reported that A. adenophora biochar produced at 500 °C increased germination rates, while 350 °C biochar at lower application rates (1 g/kg) yielded optimal growth and productivity in wheat, with interactive effects of temperature and application rate showing significant effects on germination rate, length, and biomass of roots in the initial growth period. Choudhary et al. (2023) demonstrated that Lantana camara biochar (10 t/ha) combined with 75% recommended fertilizer increased oat fodder yield by ~8% and crude protein by ~6%, decreased acid detergent fibre and neutral detergent fibre by 5.70% and 6.04%, and significantly improved soil microbial populations including bacteria (7.33 × 10⁸ CFU/g soil), alkaline phosphatase activity (19.56 μg pNP/g soil/h), microbial biomass carbon (156.67 μg/g soil), and dehydrogenase activity (12.59 μg TPF/g/24 h). Agbeshie et al. (2025) conducted a three-season field experiment in Ghana, finding that invasive aquatic plant biochar increased persistent soil organic carbon pools by 36-50% through greater accumulation of mineral-associated organic carbon, with the largest bulk soil organic carbon stock of 25.52 t ha⁻¹ observed at 0-15 cm depth. The B5 treatment increased particulate organic carbon and soil microbial biomass carbon concentrations by up to 300%. Leaf chlorophyll content, NPK uptake, and grain yield were significantly enhanced by amendments C4, C2, and B2.5 + C2, with value-cost ratios exceeding 2 indicating profitability. Li et al. (2023) compared biochar from invasive plants (Blackjack, Wedelia, and Bitter Vine) with liming for acid rainaffected soils (pH 4.5 and 2.5), showing that biochar maintained neutral soil pH (6.5-7) while liming alkalinized soil pH to 9.5. Biochar caused fourfold increases in available N and P compared to liming, while liming decreased available soil N, P, and K by 36.3%. BJ-biochar increased soil available P and K, while BV-biochar maximized soil available N. Biochar caused balanced increments in Ca²⁺ by threefold, cation exchange capacity by 45%, urease activity by 16%, and fungal diversity by 10%, while having slight reduction in bacterial diversity by 2.5%. The study strongly recommended biochar from invasive plants instead of lime for sustainable improvements in soil properties under acid rain. Wang et al. (2024 -Wang S.) investigated Solidago canadensis L. biochar to control bacterial wilt in tomato, finding that application significantly reduced Ralstonia solanacearum abundance (16.8-32.9%) and wilt disease index (14.0-49.2%) while promoting tomato growth. The biochar treatment increased soil organic carbon, nutrient availability, soil chitinase, and sucrase activities under pathogen inoculation, and significantly increased relative abundance of beneficial organisms including Bacillus and Sphingomonas. Karim et al. (2025) evaluated Acacia auriculiformis wood-waste biochar on germination and early growth of five major crops (rice, wheat, chili, eggplant, tomato) in Bangladesh, finding significant (p<0.001) increase in germination with higher biochar application rates. In Capsicum annuum the 15 t/ha treatment resulted in 96% increase in germination compared to control (43.3% vs 85.1%). The linear mixed-effects model showed significant effect of biochar treatment on germination (F = 57.33, p<0.001) and significant interaction with crop type (F = 15.84, p<0.001). Shamim et al. (2018) assessed impact of biochar from Albizia saman, Neolamarckia cadamba, and Albizia richardiana on paddy germination and early growth, finding that 15 t/ha of Raintree biochar significantly increased root length, while 15 t/ha of Chambul biochar showed strongly significant (p<0.001) increase of NPK compared to control. Luo et al. (2019) investigated co-application of poplar-derived wood vinegar and biochar on pepper and tomato, finding that wood vinegar promoted root and shoot lengths at low concentrations (0.002% and 0.02%), while co-application significantly increased root length, surface area, and volume of tomato by 98.0%, 66.7%, and 83.1% respectively, attributed to enhanced nutrient availability and slow-released active acid and phenol components adsorbed by biochar [13, 31, 9, 1, 34, 60, 29, 50, 40] . Fornes et al. (2025) evaluated raw biochar, nitrogen-enriched biochar, and urea on tomato cultivation, finding that raw biochar stimulated seed germination and early radicle growth possibly due to karrikins detected (0.039 and 0.044 mg kg⁻¹), while nitrogen-enriched biochar showed positive impact on plant growth and yield without releasing high ammonium or negatively affecting seed germination. Dziosa and Makowska (2025) investigated biochar from Chlorella sp. algae as seed growth stimulant for radish, finding average germination time of 1.12 for treated samples vs 1.87 for control, germination energy of 93% vs 88%, and germination capacity of 97% vs 92%. Gasco et al. (2016) reported seed germination and plant development for three biochars (wood, paper sludge plus wheat husks, sewage sludge) on five higher plant species, finding that seed germination was generally not affected except for inhibition caused by wood biochar and paper sludge biochar on lettuce, with results significant for advancing understanding of biochar impacts on vegetative growth. Zhang et al. (2022) provided extensive overview on biocharbased seed coating, discussing promotion of seed germination and stand establishment, improvement of plant growth and nutrition, suitable carriers for microbial inoculants, and increase in herbicide selectivity. Tan et al. (2025) investigated biocharbased pelletized seed for late-sown rapeseed with functional agents including 6-benzylaminopurine, abscisic acid, salicylic acid, and trehalose, finding that Tre1 treatment increased yield by 9.75% in 2021-2022 and 5.88% in 2022-2023. The pelletizing treatments significantly improved emergence and germination, increased osmoregulatory capacity and enzymatic antioxidant capacity, and reduced membrane lipid damage and reactive oxygen species damage during overwintering. Redundancy analysis revealed late-sown rapeseed yield was significantly and positively correlated with relative growth rate and cold resistance of seedlings. Amoroso et al. (2025) evaluated biochar-enriched coatings incorporating olive pomace, buffalo digestate, and microbial consortia for four crops, finding that biochar-based coatings mitigated phytotoxic effects of ammonia, salts, and polyphenols, enhancing germination and root elongation. Trichoderma harzianum addition further improved seedling establishment with increases exceeding 100% compared to control. Field trials confirmed biochar-T. harzianum combinations improved both shoot and root biomass, particularly in Lactuca sativa and Solanum lycopersicum. Huang and Gu (2019) reviewed effects of biochar on container substrate properties and plant growth, finding that 77.3% of studies found certain percentages of biochar addition promoted plant growth, while 50% revealed plant growth decreased due to certain percentages. The review cautioned about toxic substances (heavy metals, polycyclic aromatic hydrocarbons, dioxin) in biochars and emphasized caution when selecting feedstocks and production conditions. Frenkel et al. (2017) reviewed biochar influence on plant disease, revealing that lower concentrations (≤1%) often suppressed diseases while higher concentrations (≥3%) were mostly ineffective or induced disease, recommending standardization of feedstocks and concentrations for consistent and reproducible effects. Poveda et al. (2021) presented comprehensive review of pathogensuppressive effects of biochar, describing modification of root exudates, soil properties, nutrient availability, induction of systemic plant defenses, activation of stress-hormone responses, and changes in active oxygen species. The review highlighted biochar's potential for controlling root or foliar fungal pathogens, nematodes, and insect pests through changes in soil microbial community diversity, release of nematicidal compounds, and induction of plant defenses [15, 12, 17, 69, 53, 3, 25, 16, 45] . Murtaza et al. (2023) reviewed biochar-soil-plant interactions for sustainable agriculture under changing climate, highlighting role in transforming soil physicochemical and biological properties, improving seed germination and seedling growth, altering crop physiological attributes, enhancing crop resistance against biotic and abiotic stresses, improving crop productivity, curtailing GHGs, and controlling nutrient leaching losses. Wang et al. (2019) conducted meta-analysis on co-composted biochar (COMBI) effect on plant productivity, finding application rates of <20 t/ha and >30 t/ha significantly increased plant productivity by 48.3% and 15.7% respectively, with greatest increase at acidic soil pH (4-5), and cereal grasses yielding significantly higher grain yields (39.7%). Liu et al. (2018) reviewed migration and transformation mechanisms of nutrient elements (N, P, K) within biochar in straw-biochar-soil-plant systems, noting that pyrolysis conditions vital in regulating nutrient characteristics, with appropriate conditions (400 °C in CO₂ atmosphere) reducing migration of nutrients to liquid and gaseous products and increasing retention rate of nutrient elements (biochar-N: 64.94%; biochar-P: 100%; biochar-K: 100%) [42, 62, 39] .

Environmental Remediation: Heavy Metals and Organic Pollutants:

The adsorption capacity of invasive plant-derived biochars for heavy metals and organic contaminants has received substantial research attention. Wang et al. (2021) reported that biochars pyrolyzed at 500 and 700 °C exhibited high metal adsorption capacity, with BBC500 (Bidens pilosa) and MBC500 (Mikania micrantha) showing equilibrium adsorption capacities of 38.10 and 38.02 mg•g⁻¹ for Cd²⁺ and 20.01 and 20.10 mg•g⁻¹ for Cu²⁺. The Langmuir model fit IBC500, MBC500, and LBC500 better than the Freundlich model, while the opposite was true for BBC500 and PBC500, suggesting monolayer adsorption for some and chemical adsorption for others. Wang et al. (2024 -Wang X.) demonstrated that biochar mixtures from multiple invasive species improved Cd-contaminated soil remediation, with effects increasing with species richness (from ~22% to ~38% reduction in Cd bioavailability). Biochar application significantly increased both the concentration (~126%) and pool size (~59%) of Cd in roots of native plant communities, although it significantly decreased biomass (~25%). The study identified a novel biodiversity-mediated ecosystem service using multiple invasive plant species for biochar production. Yang et al. (2024) developed Mikania micrantha biochar for bacterial immobilization and adsorption of contaminants, embedding Proteus terrae ZQo2-MB within polyvinyl alcohol-sodium alginate gel to create biochar-modified bacterial microspheres. Taking chlorothalonil as example, field experiments demonstrated removal efficiency of 59.8% by the third day, while improving richness and diversity of soil bacteria and enhancing microbial community structure by the seventh day. The study validated the adsorption capacity of MB, the biofilm growth-promoting ability of BBM, and the CHT mineralisation ability of strain ZQo2 as a joint mechanism. Li et al. (2020 -Li S.) functionalized invasive plant-derived biochar with CaAl-LDH at five mass ratios for Eu(III) adsorption, finding that sorption affinities were strongly affected by solution pH, contact time, temperature, and mass ratio. The CaAl-LDH/IPB composite with high ratio of IPB had higher sorption capacity due to larger porosity. Three mechanisms-ion exchange between Al and Eu ions, surface complexation with carboxyl-and oxygen-containing functional groups, and precipitation were involved, with dominant mechanism differing with mass ratio. In composites with more IPB, both ion exchange and surface complexes dominated, while in high LDH composites, ion exchange dominated. Poonia accumulation in plants. Results showed average decreases of 38%, 39%, 25%, and 17% in accumulation of Cd, Pb, Cu, and Zn respectively. Manure-derived biochar was most effective for reducing Cd and Pb concentrations, and biochar with high pH and high application rates resulted in greater decreases in plant heavy metal uptake. Zhao et al. (2025) used hierarchical metaanalysis of 237 datasets from 59 studies to evaluate coapplication of biochar and plant growth-promoting bacteria, finding combined treatment increased root and shoot biomass by 84% and 116% respectively, while reducing heavy metal concentrations in roots (33%), shoots (45%), and soil (44%). The biochar and Pseudomonas combination exhibited optimal biomass enhancement, while Proteobacteria and biochar consortium had most significant effect on decreasing heavy metal content in plant and soil [58, 61, 66, 33, 44, 43, 8, 70] . Wang et al. (2023) characterized heavy metal and antibiotics contamination in Pearl River water and sediment samples, finding that heavy metals and antibiotics increased toward downstream region of Pearl River Delta. Invasive plant-derived biochars showed high antibiotic removal capacity but failed to reduce most water heavy metals since these invasive plants are potential heavy metal hyperaccumulators. Su et al. (2025) explored nanosilica modification of biochar from terrestrial (Sonchus oleraceus L.) and aquatic (Myriophyllum verticillatum L.) invasive plants for mitigating heavy metal stress in Allium hookeri. Silicon modification increased silicon mass fraction by 9.10% and 4.67% respectively. Terrestrial Si-KBC significantly increased chlorophyll A, chlorophyll B, and chlorophyll T compared to aquatic Si-HBC. Si-HBC was most suitable for yellow soil contaminated by Cd, Cu, and Pb, while HBC was best suited for remediation of Fe and Zn contaminated brown soil. Rajapaksha et al. (2014) investigated burcucumber biochar (BBC700) for sulfamethazine uptake by lettuce, finding that with 5% BBC700, uptake was reduced by 86% in soil spiked with 5 mg kg⁻¹ SMT compared to control, with 63% reduction observed in soil spiked with 50 mg kg⁻¹ SMT. Vithanage et al. (2014) examined sorption and transport of sulfamethazine in agricultural soils amended with burcucumber biochar produced at 300 and 700 °C, finding that biochar-700 had high degree of SMZ retention, achieving up to 89% and 82% increase in SMZ retention in sandy loam and loamy sand soils respectively. Mechanisms included π-π electron donor-acceptor interaction and electrostatic cation exchange at pH 3, while cation exchange was main mechanism at pH 5 and 7 [52, 47, 57] . Dong et al. (2024) [11] reviewed application of invasive plantderived biochar in controlling plant invasion by removing its own allelochemicals, noting that research on biochar prepared by invasive plants to adsorb their own allelochemicals is still scarce, which may limit application in invasion prevention and control. Kamyab et al. (2025) [28] examined biochar as carrier for plant growth-promoting bacteria in phytoremediation of pesticides, highlighting biochar's suitability due to porous structure, surface chemistry, and ability to create microbial habitats, with interactions between biochar, PGPB, and plants enhancing phytoremediation efficiency. Hasnain et al. (2026) [24] comprehensively reviewed adverse biochar effects including contaminants (persistent free radicals, metal cyanides) posing risks like phytotoxicity, cytotoxicity, and neurotoxicity, emphasizing significance of designing pyrolysis units that ensure separation of pyrolysis liquids from solids, minimizing organic contaminant condensation, and reducing PTE levels through co-pyrolysis and higher pyrolysis temperatures.

Carbon Sequestration and Climate Change Mitigation

The potential of invasive plant-derived biochar for carbon sequestration has been explored in multiple contexts. Ceriani et al. (2024) carried out in-depth characterization of biochar produced at 550 °C from 10 widespread IAPS (five woody and five herbaceous) in the central-southern Alps region. IAPSderived biochars exhibited relevant properties in different fields, with coordinated variation and trade-offs from biochars with high stability to biochars with high soil amendment potential (PC1), while soil remediation potential represented independent axis of variation (PC2). Herbaceous IAPS were more suitable for soil amendment due to greater pH, macronutrient content, and macropore area, while woody IAPS showed greater surface area, smaller pores, and higher lead adsorption potentials from aqueous solutions, with higher fixed carbon content indicating higher carbon stability preferable for carbon sequestration. Ghosh and Maiti (2023) applied invasive weed biochar at 10 t/ha and 20 t/ha to 8-year-old reclaimed mine spoil, finding that BC20 significantly improved moisture content (+27%), available-N (+3%), exchangeable-K (+15%), and cation exchange capacity (+35%). Geometric mean of enzymatic activities index increased in BC10 (8) and BC20 (10.2) compared to control (5.8). BC20 had significantly high recalcitrant carbon, total carbon stock increased by 13% and 91% at BC10 and BC20 respectively, and CO₂ sequestered increased by 13% at BC10 and 91% at BC20. In-situ production and surface application of biochar at 20 t/ha cost 239 USD/ha. Ghosh and Maiti (2021) conducted 6-month incubation study on effect of biochar amendment (2% and 3%) on mine spoil enzymatic activities, finding significant improvement in dehydrogenase (83%) and cellulase activity (78%) at 3% amendment. Geometric mean of enzymatic activities increased from 1.87 in control to 4.51 at 2% and 3.25 at 3%. Mine spoil physio-chemical properties such as soil organic carbon (65%), cation exchange capacity (54%), bulk density (25%), and water holding capacity (19%) improved significantly. Biochar amendment reduced CO₂ flux at 2% (2.85 μmol CO₂ m⁻² s⁻¹) and 3% (2.60 μmol CO₂ m⁻² s⁻¹) compared to control (4.92 μmol CO₂ m⁻² s⁻¹). Cost of biochar production and application in pit plantation during reclamation estimated at 844 USD t ha⁻¹. Simmons et al. (2021) examined clearing invasive native scrub in southern Australian rangelands and pyrolysing residues to produce biochar, assuming syngas used for electricity generation and biochar applied to soils for wheat production. The pyrolysis scenario provided mitigation benefits from reduced N₂O emissions from fertiliser use and reduction in lime use to ameliorate soil acidity. Yin et al. (2024) explored effects of invasive-plant biochar on established invaded plant communities in Tianjin coastal saline-alkaline wetland, adding biochar derived from Amaranthus palmeri and Spartina alterniflora at 0%, 1%, 3%, and 5% addition rates. Biochar addition significantly decreased performance measures of invaded plant community, with decrease in abundance of A. palmeri and increase in native plants. S. alterniflora biochar exhibited more pronounced effect compared to A. palmeri biochar. At 5% addition rate, A. palmeri and S. alterniflora biochar had contrasting effects on complexity of interspecific relationships within plant community. Phylogenetic β-diversities were significantly correlated with biochar addition rate and stochastic processes primarily governed plant community assembly [7, 21, 20, 51, 67] . Feng et al. (2021) reviewed current research status of invasive plants, focusing on potential for biochar productions and applications, noting that invasive plant-derived biochar showed significant differences in structure, composition, and adsorption performance compared to traditional biochar. Yang et al. (2022) summarized progress of preparing and using invasive plant biochar, including production, modification, merits and demerits, application in improving soil quality, adsorption of pollutants, application in energy storage, and climate change mitigation potential. Viswanathan et al. (2023) investigated agronomic properties of biochars derived from selected invasive wetland weeds and effect on soil organic carbon dynamics and stability of tropical Ultisol soil. Agbeshie et al. (2025) suggested that biochar from IAP serves as climate-smart technology offering potential to increase crop productivity and contribute to "recarbonizing global soils" initiative for sustainable agroecosystems. Carson et al. (2018) assessed Laurentian Great Lakes coastal wetlands, finding that three invasive plants dominated 76,825 ha (36%) of approximately 212,000 ha of wetlands. A single growing season's biomass of these invasive plants was estimated at 659,545 metric tons, containing 10,805 and 1,144 metric tons of nitrogen and phosphorus respectively. One-time harvest and utilization for energy would provide gross equivalent of 1.8 million barrels of oil if combusted, or 0.9 million barrels of oil if converted to biogas. de Almeida Moreira et al. (2025) examined conversion of invasive environmental weeds into market-grade pellets, finding that non-woody species such as Brazilian Nightshade and Climbing Asparagus produced durable pellets (97-98%) with high energy density (up to 3.9 GJ/m³) and low ash (<5.1%). Response surface modelling revealed optimal pelletizing parameters, while principal component analysis underscored lignin content, ash chemistry, and particle size distribution as factors influencing pellet performance [56, 1, 6, 10] .

Emerging Applications and Future Directions

Recent research has expanded the application domains of invasive plant-derived biochar. GuhaRay et al. (2019) investigated Prosopis juliflora biochar for stabilizing expansive black cotton soil at 5% and 10% w/w, reporting increased shear strength and California bearing ratio while decreasing free swell index. Microstructural (XRD, FTIR, SEM, EDX) and physicochemical (CEC, pH, specific gravity) as well as geotechnical characterizations (consistency limits, free swell, permeability, CBR, shear strength) were carried out, revealing that biochar-amended soils possess excellent geotechnical properties for stabilizing expansive soils. Kasak et al. (2018) assessed effect of wood-derived biochar amendment (10% v/v) on purification efficiency of pretreated municipal wastewater in planted (Typha latifolia) horizontal subsurface flow constructed wetlands filled with lightweight expanded clay aggregates. Biochar addition significantly increased plant biomass production (aboveground 1.9-fold, belowground 1.5-fold) and enhanced wastewater treatment efficiency. Efficiencies of TN and TP removal were highest in LBP filters (20.0% and 22.5%), followed by LP (13.7% and 16.2%) and LB (9.5% and 15.6%). More N and P were incorporated into plant biomass from wastewater in presence of biochar. Jayathilake et al. (2024) evaluated potential utilization of biochar as efficient filter medium made by invasive aquatic plants Salvinia spp. and Eichhornia spp. for treating rubber-manufactured wastewater. OH stretching (3,550-3,200 cm⁻¹), C=C aromatic stretching (1400-1660 cm⁻¹), and Phenol-O-H bending (1,300-1,400 cm⁻¹) were recorded in all biochar samples. Filter unit incorporated with activated Eichhornia spp. gave best treatment efficiency, with activated biochar-incorporated filters showing no mortalities in toxicity assay, suggesting green approach using invasive aquatic plants for sustainable wastewater treatment. Cai et al. (2024) investigated effects of biochar from water hyacinth on soil erosion under varying compaction and slope conditions using flume tests. Biochar addition reduced soil erosion by 10-69% and improved rainwater storage by 20-59%, with 5% biochar amendment achieving best efficiency due to enhanced formation of water-stable macroaggregates. Biochar content was most important factor for water retention (33% contribution) and erosion reduction (40% contribution). The study broadened understanding of water erosion and hydrologic responses under biochar influence and provided sustainable perspective for hydrologic management practice. Liang et al. (2026) systematically explored key advances in multifunctional capacity of biochar-based slow-release fertilizers, structured around four interconnected pillars: environmental intelligence and responsive nutrient management, closed-loop nutrient cycling, carbon-fertilizer synergy, and rhizosphere microregulation. The review assessed underlying nutrient release mechanisms, effects on soil characteristics and plant physiology, economic evaluations, and outlined challenges and prospective research directions for incorporating BSRFs into precision agriculture frameworks. Ghorbani et al. (2025) investigated combined effects of pyrolysis temperature (350 and 450 °C) and post-production hydrogen peroxide oxidation on soil nutrient dynamics and plant performance using wheat straw and wood residue biochars. Pristine biochars increased soil pH from 6.82 to 8.73-9.12 and EC from 2.15 to 3.06-4.71 dS m⁻¹, while oxidized biochars decreased soil pH to 5.62-5.93 due to introduction of oxygen-containing functional groups. All biochars reduced NO₃⁻-N, NH₄⁺-N, and PO₄³⁻-P leaching, with most pronounced reductions in oxidized wheat straw biochar at 450 °C (O-BWS450). Fava bean plants grown in O-BWS450amended soil achieved greatest N (6.71%) and P (3.89%) uptake, significantly higher than control [22, 30, 26, 22, 36, 19] . Ghani et al. (2026) investigated pyrolysis temperaturedependent biochar strategy for improving nutrient retention by integrating urea with biochar produced at 300, 500, and 700 °C using water spinach. IB500 (biochar at 500 °C impregnated with urea) was most effective, improving CEC and availability of Ca²⁺, Mg²⁺, and K⁺ while increasing microbial biomass carbon and nitrogen. IB500 resulted in 56% increase in root length, 81% increase in surface area, 91% increase in root tip formation, 33% increase in leaf number, 59% increase in leaf area index, 44% increase in chlorophyll content, 12% higher photosynthetic rate, 13% increase in stomatal conductance, and 79% increase in nitrogen uptake. Vega et al. (2025) The study implied that for competitive biomass-toenergy conversion, cost management particularly for transportation and significant regulatory incentives are essential, along with effective policy instruments promoting innovative systems and knowledge generation [18, 55, 64, 4, 23, 48] .

Discussion

Research Trends and Synthesis

Analysis of the reviewed literature reveals several discernible research trends. First, studies have progressively shifted from characterizing biochar properties to optimizing production parameters for specific applications, with pyrolysis temperature consistently identified as the most critical factor influencing biochar characteristics (Ahmed et [2, 49, 35, 58, 38, 18, 7, 46, 61, 30, 22, 36, 19, 54, 5, 66, 60, 45, 70, 16, 27, 8, 62, 70, 24, 25, 17] .

Knowledge Gaps and Future Directions

Despite significant progress, several knowledge gaps remain. The long-term field performance of IAP-derived biochar across diverse environmental conditions requires further investigation. The economic feasibility and scalability of production need comprehensive assessment, including cost-benefit analysis across different contexts. Standardization of biochar properties and quality control measures remains insufficient. Potential ecotoxicological risks, particularly persistent free radicals and heavy-metal accumulation in food chains, require systematic evaluation. Regulatory frameworks for biochar application and IAP management need to be developed and harmonised. Integrating invasive plant management with biochar production offers a promising circular-economy approach that addresses ecological restoration, waste valorisation, and sustainable agriculture. Future research should focus on developing tailored biochar products for specific applications, optimising production parameters for maximum efficiency, assessing long-term environmental impacts, and establishing regulatory frameworks to facilitate commercialisation. Combining IAP management with biochar production represents a win-win strategy that addresses both ecological restoration and sustainable resource utilisation.

Conclusions

This systematic review synthesizes current knowledge on invasive plant-derived biochar production and applications across 70 studies identified from Google Scholar, PubMed, Scopus, and Web of Science. Pyrolysis temperature emerges as the most critical factor influencing biochar characteristics, with temperatures ranging from 300-700 °C producing biochars with varied properties suitable for different applications. Agricultural applications demonstrate enhanced crop productivity, soil health, and disease suppression. Environmental remediation applications show significant potential for heavy metal adsorption, organic pollutant removal, and wastewater treatment. Carbon sequestration studies confirm biochar's climate change mitigation potential. Emerging applications in geotechnical engineering, constructed wetlands, and slow-release fertilizers expand the utility of IAP-derived biochar. Risk assessment studies identify potential contaminants requiring mitigation strategies. The integration of invasive plant management with biochar production offers a promising circular economy approach that simultaneously addresses ecological restoration, waste valorization, and sustainable agriculture. Future research should focus on long-term field performance, economic feasibility, standardization, ecotoxicological risks, and regulatory frameworks to facilitate widespread adoption.

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