A systematic review published in BiomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More Conversion and Biorefinery by Dandara Paula da Silva Guimarães, Angélica de Cássia Oliveira Carneiro, João Gilberto Meza Ucella Filho, Emanoele Lima Abreu, Evanderson Luis Capelete Evangelista, Fillipe Tamiozzo Pereira Torres, and Gabrielle Fialho Abranches examined the trajectory of scientific research focused on biochar derived from agricultural and forestry residues. The authors combined bibliometric mapping of thousands of indexed articles published over a decade with a critical quantitative synthesis of experimental findings and industrial implementation studies. Their analysis traced the growth of global research activity, mapped evolving thematic priorities, and quantified how thermal processing choices influence the physical, chemical, and energy characteristics of the resulting biochar materials.

The bibliometric assessment demonstrated a compound annual growth rate exceeding twenty percent in annual publication output. Scientific production surged from around fifty articles annually at the start of the study period to several hundred per year by its conclusion, driven heavily by international research contributions concentrated across major agricultural nations. Co-citation networks and keyword mapping revealed an intellectual structure anchored around thermochemical processing, physicochemical characterization, soil amendmentA soil amendment is any material added to the soil to enhance its physical or chemical properties, improving its suitability for plant growth. Biochar is considered a soil amendment as it can improve soil structure, water retention, nutrient availability, and microbial activity.   More functions, and environmental remediation pathways. While traditional agronomic and pollutant sorption topics maintained strong continuity throughout the decade, newer research frontiers rapidly emerged in later years, particularly concerning anaerobic digestion, waste valorization strategies, and specialized carbon materials.

Agricultural and agro-industrial waste streams represented the vast majority of all evaluated feedstocks, with cereal crop residues such as rice husk and straw, sugarcane bagasse, maize residues, and wood sawdust appearing most frequently in experimental trials. PyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More served as the primary conversion technology across the literature, far outstripping alternative thermal methods such as gasificationGasification is a high-temperature, thermochemical process that converts carbon-based materials into a gaseous fuel called syngas and solid by-products. It takes place in an oxygen-deficient environment at temperatures typically above 750°C. Unlike combustion, which fully burns material to produce heat and carbon dioxide (CO2​), gasification More, hydrothermal carbonization, and torrefaction. Among studies specifying precise processing regimes, slow pyrolysis proved to be the most widely adopted method for solid biochar generation. However, a significant portion of published literature described thermal conversion using only generic terminology, omitting detailed descriptions of reactor configurations or exact thermal environments.

Quantitative synthesis of experimental data revealed clear within-study trends regarding the impact of thermal severity on product yields and chemical composition. Across comparable experimental setups, increasing processing temperatures systematically reduced total gravimetric biochar yields while lowering volatile matterVolatile matter refers to the organic compounds that are released as gases during the pyrolysis process. These compounds can include methane, hydrogen, and carbon monoxide, which can be captured and used as fuel or further processed into other valuable products.   More contents. Conversely, higher thermal conditions concentrated mineral fractions and fixed carbon, leading to elevated ashAsh is the non-combustible inorganic residue that remains after organic matter, like wood or biomass, is completely burned. It consists mainly of minerals and is different from biochar, which is produced through incomplete combustion.   Ash Ash is the residue that remains after the complete More contents and higher carbon percentages. Elemental analysis confirmed progressive devolatilization at higher temperatures, marked by declining hydrogen and oxygen contents that produced lower atomic ratios indicative of enhanced aromatic condensation, chemical stability, and recalcitrance. Physical properties followed similar trajectories, as higher temperatures elevated pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More levels and expanded specific surface area through greater pore network development.

Despite these clear property trends, the authors uncovered widespread underreporting of secondary operating parameters across the scientific literature. While production temperatures were explicitly documented in a majority of studies, critical variables including vapor and solid residence times, heating rates, system atmospheres, and reactor configurations were recorded in only a small fraction of published research. Because these parameters jointly dictate heat transfer dynamics, devolatilization extent, and secondary reactions, their frequent omission restricts direct comparisons between independent studies and hinders process optimization.

Moving beyond laboratory characterization, the review highlighted significant fragmentation in research addressing large-scale deployment and commercial adoption. Only a minor fraction of the literature evaluated real-world implementation factors such as system logistics, techno-economic feasibility, life cycle environmental impacts, operational safety, or efficiency metrics. Most implementation studies analyzed these dimensions in isolation rather than through multi-criteria frameworks. Furthermore, technical evidence regarding operational safety risks—including dust explosion hazards, self-heating behavior during bulk storage, and long-term handling protocols—remained sparse. The authors concluded that bridging the gap between experimental biochar research and scalable industrial deployment will require holistic assessment models that integrate supply chain logistics, economic viability, regulatory standardization, and process safety alongside material performance.

Source: Guimarães, D. P. D. S., Carneiro, A. D. C. O., Ucella Filho, J. G. M., Abreu, E. L., Evangelista, E. L. C., Torres, F. T. P., & Abranches, G. F. (2026). Biochar from agricultural and forestry residues: research trends, technical evidence, and scale-up challenges. Biomass Conversion and Biorefinery, 16, 363.