In a recent review published in the journal Environments, authors Stavroula Dimitriadou, Ekavi Aikaterini Isari, Eleni Grilla, Petros Kokkinos, and Ioannis K. Kalavrouziotis explore the multifunctional role 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 in revitalizing degraded soils. They highlight how this carbonaceous material, derived from 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 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, is emerging as a critical tool for soil enhancement, climate change mitigation, and sustainable agriculture. The review synthesizes the latest findings on biochar’s impact on soil health, addressing its physicochemical properties, effects on soil biota, and its potential in remediating problematic soils across Europe and the globe.

Soil degradation is a pressing global issue, with one-third of the world’s soil already degenerated due to a range of factors including erosion, salinization, and pollution from heavy metals and chemicals. This degradation is compounded by the excessive use of chemical fertilizers, which worsens soil health and leads to nutrient imbalances. In Europe, for example, 62% of the soil is considered degraded, and 89% of agricultural land has unhealthy soil, underscoring the urgent need for sustainable soil management strategies. Biochar offers a promising solution by improving soil quality and enhancing its resilience. Biochar’s effectiveness stems from its unique physicochemical properties, which are largely determined by the biomass 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 and the pyrolysis temperature used in its production. For instance, biochar from plant residues often has high 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 alkalinity, making it suitable for neutralizing acidic or heavy metal-contaminated soils. In contrast, biochar from livestock manure contains more functional groups, enhancing its sorption capacity. The review notes a striking example: biochar from corn straw and waterweeds can produce very high cation exchange capacity (CEC) values, up to 210 cmol kg⁻¹ and 509 cmol kg⁻¹, respectively, which are crucial for nutrient retention in degraded soils.

Once in the soil, biochar undergoes a three-stage transformation process—dissolution, reactive surface development, and aging—which allows it to provide long-term benefits. Its porous structure, with a high specific surface area, increases water-holding capacity and creates ideal microhabitats for soil microbiota. For sandy soils, biochar application significantly improves water retention, increasing plant-available water by 33% to 45%. This effect is less pronounced in fine soils, where the increase is only 9% to 14%. This highlights the importance of tailoring biochar application to specific soil types.

Biochar also excels at remediating heavy metal-contaminated soils. Its high CEC and functional groups allow it to effectively immobilize cationic contaminants like cadmium, zinc, and lead, reducing their bioavailability and uptake by plants. A study on contaminated soil showed that sunflower shell biochar reduced cadmium and zinc uptake by over 64% and 94%, respectively. The review also explores the use of sewage sludge biochar (SSB), a potential slow-release fertilizer rich in phosphorus (P). Studies show that SSB can increase available P content in medium- to fine-textured soils by a remarkable 324%, leading to a crop productivity increase of over 50% for maize and wheat compared to unamended controls.

Beyond its physical and chemical benefits, biochar plays a key role in biological processes. It stimulates microbial activity and enzyme diversity, fosters a more active microbial community, and neutralizes acidic soils. The review notes that aged biochar can persist for hundreds to thousands of years, continuing to support soil microbial activity and promoting ecosystem stability and diversity.

While the benefits are clear, the review emphasizes that robust, long-term field-based research is essential to validate these findings and support the development of targeted and sustainable biochar applications. The current literature is dominated by short-term, lab-scale studies, which raises uncertainty about long-term effects. As a multifunctional material with the potential to address numerous agricultural challenges, biochar’s widespread adoption requires a careful, evidence-based approach that aligns its properties with specific soil needs and environmental goals.

SOURCE: Dimitriadou, S., Isari, E. A., Grilla, E., Kokkinos, P., & Kalavrouziotis, I. K. (2025). Revitalizing Degraded Soils: The Role of Biochar in Enhancing Soil Health and Productivity. Environments, 12(9), 324.