Rediscovering circularity in productive urban landscapes

The recycling of urban green waste generated from urban forests is important in enhancing urban circularity; however, most green waste remains underutilized. An effective way to recycle green waste is composting. Recent studies show the effectiveness of decentralized composting in home and community gardens; however, little is yet known about linkage to commercial urban agriculture, which could play a critical role in urban food supply. This study aims to investigate the community-scale composting system of green waste integrated into commercial farming, using Tokyo as a case study where urban and agricultural land uses are mixed historically. We conducted mailed questionnaire surveys and in-person semi-structured interviews with urban farmers. The results revealed that approximately one-third of professional urban farmers still produced compost from green waste, especially leaf litters, to improve soil quality. They have adapted urbanization by expanding leaf litter sources beyond their own woodlands to various neighboring urban forests within a few kilometers, including parks, schools, and shrines. Although urbanization has drastically changed the tangible landscape, urban farmers have handed down the intangible system for hundreds of years by retrofitting their system. While the system can contribute to reducing green waste and enhancing urban circularity, urban farmers are motivated by economic reasons rather than such environmental reasons. In cities that encompass productive urban landscapes, decentralized composting systems work effectively in commercial urban agriculture due to its geographic proximity of waste supply and demand sites. This study suggests the potential benefits of having urban farms in cities abundant in underutilized organic wastes. Further research is needed on how to scale up waste recycling through urban agriculture to foster urban circularity and sustainability.