In a comprehensive review published in Frontiers in Sustainable Food Systems, Sazada Siddiqui explores the multifaceted environmental potential of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, detailing its production, diverse applications, and inherent limitations. The article, “Unlocking the environmental potential of biochar: production, applications, and limitations,” highlights biochar’s role in addressing critical global challenges like soil degradation and climate change.

Soil degradation, driven by factors such as prolonged cultivation, acidification, erosion, and the overuse of chemical fertilizers, poses a severe threat to global food security. The Green Revolution, while boosting crop yields, inadvertently contributed to a decline in soil fertility and quality. Biochar, a renewable and carbon-rich material produced through the 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 of 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 under limited oxygen, emerges as a promising solution. It is characterized by high specific surface area, low bulk density, and strong adsorption capacity, making it a valuable tool for soil fertility management, crop yield improvement, and greenhouse gas emission reduction.

Biochar improves soil fertility through various mechanisms. It enhances soil structure by promoting aggregation and water retention. When mixed with ammonium, nitrate, and phosphate, it acts as a slow-release fertilizer. Studies indicate that biochar can increase crop productivity by an average of 10% , and when combined with inorganic or organic fertilizers, it further boosts yields, especially in tropical soils. For instance, rice husk biochar increased maize/soybean yields by 10-40%, and cow manure biochar boosted radish yields by 150%. In another case, waste wood biochar increased maize yield by 88.9% with a dosage of 30 tonnes per hectare. This yield enhancement is particularly noticeable in degraded, acidic, or nutrient-poor soils, where biochar improves 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, cation exchange capacity (CEC), and water retention. However, its benefits may be limited or even negative in nutrient-rich or well-structured soils, sometimes causing nutrient imbalances.

Beyond its agricultural benefits, biochar offers significant environmental advantages. It is recognized as a crucial tool for carbon sequestration, capable of persisting in soil for centuries. A 250-hectare farm, for example, could sequester around 1900 metric tonnes of CO2​ per year. The International Biochar Initiative (IBI) suggests that biochar could reduce global warming by absorbing approximately 3.67 gigatonnes of CO2​ annually. Furthermore, biochar plays a vital role in reducing greenhouse gas emissions, particularly nitrous oxide (N2​O) and methane (CH4​), which are potent global warming gases. Biochar can sequester about 12% of GHGs from soils. Its large surface area provides numerous sites for GHG adsorption, and its alkalinity can accelerate the microbial reduction of nitrous oxide to nitrogen.

Biochar also excels in mitigating persistent organic pollutants (POPs) and toxic metals in soil. Its porous structure, high surface area, aromatic character, and abundance of polar functional groups enable it to adsorb various organic compounds like pesticides and polycyclic aromatic hydrocarbons (PAHs). While high-temperature biochar can sometimes hinder POP biodegradation by reducing microbial accessibility, low-temperature biochars have been shown to promote it. For toxic metal remediation, biochar effectively immobilizes heavy metals such as Cd, Pb, Cr, Cu, and Zn, reducing their accumulation in plants. For example, biochar produced at 700∘C was effective in reducing Zn and Pb mobility by 100% in acidic environments.

The potential for biochar production is substantial, especially in developing countries. India, for instance, generates approximately 500-550 million metric tonnes of crop residue annually, with major contributions from wheat, paddy, sugar cane, and maize. Utilizing even 1% of this residue for biochar production with modern instruments could generate about 1,300 metric tonnes of bio-oil and 900 metric tonnes of biogas. Similarly, East Africa’s maize cultivation produces around 33.3 million metric tonnes of crop residues annually, representing a significant feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More for biochar.

Despite its numerous benefits, biochar application has limitations. Its effects are soil-specific; while highly beneficial in sandy soils with poor water retention, it may offer minimal or even negative effects in clayey or nutrient-rich soils. Biochar can also release organic pollutants if feedstock contains them or if pyrolysis is incomplete. Furthermore, biochar can absorb essential nutrients like nitrogen and iron, potentially hindering plant development. High-temperature biochars, while effective in some aspects, can increase 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 content and may have negative effects on plants.

To harness biochar’s full potential, especially in developing countries, a multi-faceted approach is needed. This includes investing in research to enhance production efficiency and cost-effectiveness, promoting farmer education, integrating biochar production into existing waste management systems, and fostering collaboration among researchers, farmers, and policymakers. Encouraging low-cost, on-site pyrolysis technologies and community-based models can facilitate its adoption by smallholder farmers, ultimately contributing to sustainable agriculture and climate change mitigation.

Source: Siddiqui, S. (2025). Unlocking the environmental potential of biochar: production, applications, and limitations. Frontiers in Sustainable Food Systems, 9, 1569941.