Key Takeaways
- 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 can sustainably boost crop yields by 10% to 60% while reducing fertilizer dependency.
- Applying biochar to soil significantly sequesters carbon and reduces greenhouse gas (GHG) emissions from agriculture, helping achieve carbon neutrality goals.
- It acts as a powerful 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, improving water retention , nutrient availability, and enhancing beneficial microbial activity.
- The technology supports a circular bio-economy by converting agricultural and organic wastes, which often cause pollution, into a valuable soil input.
- Widespread adoption requires addressing high production costs and implementing policies like carbon credit systems and decentralized production methods.
Agriculture today is grappling with declining productivity, resource degradation, and the increasing pressures of climate change. This intricate problem is aggravated by imbalanced and intensive fertilizer use, which leads to low nutrient use efficiencyNutrient use efficiency refers to how effectively plants can take up and utilize nutrients from the soil. Biochar can improve nutrient use efficiency by enhancing nutrient availability and retention in the soil. More (NUE) and environmental contamination. In a comprehensive review published in the Indian Journal of Fertilisers, Samarendra Hazarika, Niraj Biswakarma, Rahul Saikia, and Balusamy Arumugam position biochar as a sustainable soil amendment and alternative fertilizer crucial for fostering climate-resilient agriculture.
Biochar’s influence on soil health is multifaceted. Physically, its high porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More reduces bulk density and improves hydraulic conductivity, which in turn enhances aeration, water infiltration, and root growth. The material also helps to form stable soil aggregates by interacting with soil organic matter (SOM) and microbial networks. Chemically, biochar acts as a liming agent, raising soil 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 to reduce aluminum toxicity, which is particularly useful in acidic soils. Crucially, it boosts the soil’s cation exchange capacity (CEC) and enhances nutrient retention. Biochar is shown to reduce nitrogen (N) leachingLeaching is the process where nutrients are dissolved and carried away from the soil by water. This can lead to nutrient depletion and environmental pollution. Biochar can help reduce leaching by improving nutrient retention in the soil. More and increase the availability of phosphorus (P) and potassium (K). These chemical and physical improvements collectively contribute to a higher Fertilizer Recovery Value (FRV), meaning more of the applied fertilizer actually becomes available to the crops, generating cost savings and promoting sustainable agricultural intensification. Biologically, biochar supports a favorable microenvironment for beneficial microbes and mycorrhizal fungiThese are friendly fungi that form a partnership with plant roots. They act like an extension of the root system, helping plants access water and nutrients more effectively. Biochar can create a cozy habitat for these helpful fungi, boosting their growth and improving plant health. More, which are essential for nutrient cycling, and can stimulate biological N-fixation by up to 63%.
The ability of biochar to sequester carbon and reduce pollution is equally significant. Crop residue burning is a major issue in Indian agriculture, causing the loss of SOM and essential nutrients, besides posing serious health and air quality risks. India generates approximately 500 million tonnes (Mt) of crop residues annually, with 92 Mt burned in situ. By converting this waste 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 into stable, aromatic biochar through 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, otherwise labile C is transformed into a recalcitrant form and retained in soils, making it an effective C sink. Soil is the largest terrestrial C reservoir, and biochar application is an eco-friendly practice with the potential to remove 1.0–1.8 Pg CO2-C equivalent of greenhouse gases (GHGs)Greenhouse gases (GHGs) are gases in the atmosphere that trap heat, contributing to the warming of the planet. Carbon dioxide, methane, and nitrous oxide are examples of greenhouse gases. Biochar helps to mitigate the emission of GHGs through various mechanisms. More per year, contributing significantly to climate mitigation efforts. Furthermore, biochar exhibits a strong adsorption capacity due to its high surface area and porous structure, effectively reducing the bioavailability and leaching of heavy metals (like lead, cadmium, and arsenic) and removing nitrate, phosphate, and organic pollutants.
The impact on agricultural productivity is substantial; meta-analyses suggest that biochar application can enhance the system productivity of different crops by 16.0% , with various studies reporting crop yield increases ranging from 10.2% to 60%. This improved yield, along with reduced fertilizer requirements due to enhanced NUE, strengthens local food systems and supports rural livelihoods, especially in resource-limited regions.
Despite its potential, widespread adoption of biochar faces several hurdles. Production costs are high, particularly for small-scale farmers, requiring significant capital investment in advanced pyrolysis systems and specialized equipment. 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 variability and the risk of contamination (e.g., from sewage sludge) also pose safety and quality challenges. To overcome these challenges, future efforts need to focus on developing standardized production protocols and certification systems, exploring decentralized and low-cost production methods like simple kilns and retort systems. Integrating biochar systems with renewable energy units (coupled technologies) could enhance energy efficiency and make production self-sustaining. Policy support, such as carbon credit mechanisms and green certification programs, and long-term field trials are essential to incentivize adoption and fully realize biochar’s promise for a sustainable, resilient, and climate-friendly agricultural future.
Source: Hazarika, S., Biswakarma, N., Saikia, R., & Arumugam, B. (2025). Biochar as an Alternative Fertiliser for a Green Future. Indian Journal of Fertilisers, 21(12), 1-12.
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