Biochar in South America: A systematic review of production potential, feedstock availability, and soil amelioration in neotropical agro-ecosystems

Inspired by the fertile Terra Preta de Índios of the Amazon, biochar has emerged as a strategic solution for soil degradation and waste management in South America. This study presents a systematic review of the state-of-the-art regarding biochar production technologies, feedstock availability, and agronomic effects on South American soils, with a specific focus on the differentiation between tropical and temperate soil responses. A comprehensive analysis of literature from the last decade was conducted, categorizing production methods and edaphic interactions across the region. Results indicate that Brazil leads regional research, capitalizing on abundant forestry and sugarcane residues—key feedstocks for the biofuels industry—followed by emerging studies in Colombia and Ecuador. The review reveals that biochar application in South America is particularly effective in acidic, highly weathered soils (Ferralsols). These neotropical agro-ecosystems demonstrate significant improvements in pH buffering (liming effect), cation exchange capacity (CEC), and water retention that surpass results often observed in temperate European soils. Furthermore, while high-tech engineered biochars are emerging, low-tech slow pyrolysis remains the dominant production method in the region, favoring high carbon recalcitrance and potential for carbon credits. In the context of the global energy transition, biochar represents a viable circular economy tool for South America, converting agro-forestry liabilities into assets that enhance soil health and sequester carbon. This review concludes that integrating biochar production within the bioenergy framework allows for a dual-benefit approach: sustainable biomass utilization and long-term carbon sequestration, provided that production parameters are standardized for industrial scaling.