Fermented Organic Manure from Compressed Biogas Systems: Linking Bioenergy, Nutrient Recycling Towards Circular Economy and Sustainable Agriculture

Abstract

Increasing dependence on chemical fertilizers and poor crop residue management in the Indo-Gangetic Plains has contributed to declining soil health, soil organic carbon and environmental pollution. Compressed biogas (CBG) plants offer a circular economy solution by converting agricultural residues and organic wastes into renewable energy while generating nutrient-rich anaerobic digestate which can be processed into fermented organic manure (FOM) biofertilizer enriched with nutrients, beneficial microorganisms and bioactive compounds that supports sustainable crop production. This review examines the production, characteristics and agronomic potential of FOM derived from CBG systems, with emphasis on nutrient recycling, crop residue management and circular agriculture with emphasis on opportunities for large-scale FOM production in the Indo-Gangetic Plains through expanding CBG infrastructure. It focusses on improving resource-use efficiency, reducing environmental pollution and enhancing farm sustainability. However, challenges such as limited standardization, low farmer awareness, competition from subsidized fertilizers and weak supply chains continue to hinder adoption. Addressing these constraints through supportive policies, quality standards and extension efforts is essential for wider utilization of FOM in sustainable agriculture.