Valorization of paddy straw through fermented organic manure: a circular economy approach for low carbon agriculture

Crop residue burning, particularly of paddy straw, is a prevalent agricultural practice in India that significantly contributes to air pollution, greenhouse gas emissions, and soil degradation, leading to severe environmental and health consequences. This practice depletes essential soil nutrients and microbial activity, despite India being the world’s second-largest agro-based economy with vast agricultural waste generation. Concurrently, India faces substantial energy import dependency and growing fossil fuel demand, exacerbating climate change. This review proposes a circular economy approach by valorizing paddy straw into compressed bio-gas (CBG) and fermented organic manure (FOM). CBG offers a renewable energy alternative, reducing reliance on fossil fuels, while the nutrient-rich digestate by-product is converted into FOM, enhancing soil health and reducing the need for chemical fertilizers. The novelty of this work lies in presenting an integrated dual-valorization model that links bioenergy generation and nutrient recycling, quantitatively connecting CBG production with nutrient recovery. It offers a circular bio-economy assessment tailored to India, evaluating emission reductions and demonstrating how the CBG–FOM system enables sustainable, low-carbon agricultural development.