Synergistic pathways to a circular bionutrient economy

Bionutrient circularity can increase food system sustainability. Global food production currently depends substantially on synthetic fertilizers, while massive volumes of crop residues, food scraps, and excreta are undervalued and mismanaged, contributing to environmental degradation and climate change. Transforming these organic underutilized resources through combinations of physiochemical, biological, and thermochemical processes can improve public hygiene while keeping carbon and nutrients within the food system. By redirecting both organic matter and nutrients to soils, bionutrient circularity can offset fertilizer and energy costs. Meanwhile, circular feeds can enable livestock sectors to grow without increasing land demands for crop production, much of which is currently fed to livestock. Synergistic integration of transformation processes and resource recovery pathways will unlock substantial economic and environmental benefits. Realizing the potential of a circular bionutrient economy, however, will require robust management of contaminants, navigation of context-dependent tradeoffs, and integration of sociocultural, technical, operational and regulatory innovation processes. Multiple transformation processes can be utilized to convert organic underutilized resources into products and ecosystem services in a circular bionutrient economy. Synergies among these processes can lead to viable pathways for reducing waste, keeping nutrients in circulation and regenerating nature by enhancing soil health, offsetting the greenhouse gas emissions associated with synthetic nitrogen production and use, alleviating pressure on land, fisheries (current sources of nutrients for animal feeds) and finite stocks of phosphorus, and reducing nutrient pollution. • Recycling nutrients and carbon from by-products to the food system can reduce pollution. • Biological, thermal, and physical transformation processes can be synergistic. • Biochar enhances many biological transformations. • Social, entrepreneurial and policy shifts are needed to support bionutrient circularity.