Closing the food waste loop: Analysis of the agronomic performance and potential of food waste disposal products

The recycling of urban food waste (FW) is of great importance to the sustainable and low-carbon urban development. Focusing on the solid residues of FW aerobic composting and anaerobic digestion, this study selects three FW disposal products (FWDPs) and compares their nutrient compositions with the main traditional organic fertilizers in China through a literature review; carries out a seven-season field experiment with 30% of the nitrogen in FWDPs substituted for equal chemical nitrogen to explore the impacts on vegetable yields; and uses a field questionnaire to investigate farmers' awareness of FWDPs. FW aerobic compost and FW digestate solid residue can significantly increase seven-season total yields by 21.5% and 17.2% respectively compared with conventional chemical fertilizer alone, and maintain the same yield level with conventional combined application of chicken manure and chemical fertilizer, proved to be effective on crop yield as organic fertilizers. The case study of Xiamen indicates that FWDPs have great potential to produce organic fertilizers and reduce the application amount of pure chemical fertilizers by 5.6% under current conditions, where around one-third of restaurant FW is disposed of using anaerobic digestion technologies. Measures like formulating supportive regulations, expanding government propaganda, and producing qualified and cost-effective commercial organic fertilizers with FWDPs will improve farmers’ knowledge and acceptance of FWDPs. • Food waste aerobic compost and digestate have good fertilizer effect as fertilizers. • Food waste digestate biochar used at low rate is beneficial to crop growth. • Most farmers are interested in using food waste disposal products despite lack of knowledge.