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Biochar is known to decrease the soil acidity and in turn enhance the plant growth by increasing soil fertility. Major objective of the present work was to understand the effect of biochar treatment on alleviation of soil aluminium (Al) toxicity and its role in enhancing plant growth parameters. Soil incubation study was conducted to understand the effect of biochar (Eucalyptus wood, bamboo, and rice husk) on soil pH, soluble and exchangeable Al in soil with and without Al addition. Another independent pot experiment with rice crop (Oryza sativa L. var. Anagha) was carried out for 120 days to examine the effect of biochars on soil properties and growth parameters of rice plants. Wood biochar application to soil at 20 t ha −1 was found to be highly consistent in decreasing soil acidity and reducing soluble and exchangeable Al under both studies. We conclude that wood biochar at higher dose performed better in reducing soluble and exchangeable Al in comparison to other biochars indicating its higher ameliorating capacity. However, rice husk biochar was effective under Al untreated soil, indicating the role of Si-rich biochars in enhancing plant growth. Soil acidity in many parts of the world poses a significant challenge to crop productivity. Around 30% of the total land area in the world and more than 50% of the world's potentially arable area fall under acidic soils 1-3. Approximately 30% of arable land in India are acidic in nature, resulting in low crop yield 3. Acid soils have low pH values (< 5.5 or 6) and are usually associated with the severe aluminium (Al) toxicity to plants. Aluminium is mainly in the form of insoluble silicate or oxide in neutral soils (pH = 6.5-7.5). However, low soil pH (< 5) leads to the solubilization of Al, primarily to the phytotoxic form of Al 3+ in soil solution 4,5. Aluminium toxicity has been reported to cause direct inhibition of root elongation and further interfere with uptake of plant nutrients 6,7. Aluminium toxicity can therefore be considered a primary limiting factor in acid soils for plant growth and development. Consequently, focusing on worldwide acid soil remediation is crucial to enhance crop yield and thus alleviating world hunger. Liming has been the prominent approach for amending acid soil. However, biochar application as soil amendment has been receiving lot of attention, for many reasons such as neutralizing acidity in soil, creating a carbon (C) sink to mitigate global warming, increasing soil water holding capacity, reducing greenhouse gas emissions and stabilizing mobile heavy metals, pesticides and other organic pollutants in soil 8-12. Biochar is carbon rich material obtained by pyrolysis of biomass with little or no oxygen 13. Pyrolysis of plant biomass normally results highly alkaline biochar 13-15. However, alkalinity varies with respect to feedstock properties used for the biochar production. Greater the alkalinity of biochar, greater is the reduction in acidity 16. Addition of biochar to nutrient poor soil has been reported to enhance nutrient avail...

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