Management of Lignin Rich Crop Residue for Soil Health and Sustainability

Soil health underpins terrestrial ecosystem sustainability and global food security, yet one-third of the world’s soils are already degraded, with projections of up to 90% degradation by 2050. Sustainable management of lignin-rich lignocellulosic biomass, produced in vast quantities as crop residues and industrial by-products, offers significant opportunities for improving soil fertility and reducing environmental impacts. In-situ management strategies such as mulching, straw incorporation, composting, biochar application, and microbial inoculants (e.g., Pusa Decomposer) enhance soil organic matter, nutrient availability and water retention while mitigating greenhouse gas emissions. Ex-situ approaches involve lignin extraction from black liquor and other pulping processes, enabling its conversion into value-added products. These include lignin nanoparticles for controlled- release agrochemicals, carbon fibers, polyurethanes, biofuels and aromatic compounds with diverse industrial applications. Beyond its agronomic and industrial potential, lignin utilization contributes to climate change mitigation by reducing fossil fuel dependency and lowering greenhouse gas emissions. This review synthesizes current knowledge on the management and valorization of lignin-rich residues, highlighting their role in sustainable soil management, circular bioeconomy and climate resilience, while identifying research needs for unlocking their full potential.