Transforming livestock and crop by-products into resources: life cycle assessment strategies for informed decision-making

Achieving the Paris Agreement targets requires transforming agriculture from a major greenhouse gas (GHG) emitter into a circular, climate-smart system. This review synthesises current evidence on livestock and crop waste valorisation using Life Cycle Assessment (LCA), exhibiting how technological choices shape environmental performance.

A systematic review was conducted, following PRISMA guidelines, based on 97 peer-reviewed articles published from 2009 to 2024. Key studies were selected using specific LCA keywords, focusing on agro-waste valorisation processes and their comparison to traditional waste management.

Hybrid systems, especially anaerobic digestion (AD) combined with pyrolysis, deliver the highest sustainability gains through synergistic energy recovery, nutrient recycling, and carbon sequestration, with overall GHG mitigation reflecting the cumulative effects of avoided emissions, renewable energy substitution, and stabilised biochar carbon. While AD alone remains the most mature and regionally adaptable option, often achieving more than 60% GHG reductions relative to conventional manure management.

Effective policy integration requires standardised LCA methods, regional datasets, and incentives for multifunctional resource recovery to promote circular bioeconomy strategies.