Cet article explore la circularité des filières de matières organiques à Nkayi, une ville intermédiaire du Congo, marquée par de forts enjeux en matière de services essentiels et de souveraineté alimentaire. A partir d’entretiens et d’observations menés dans le cadre d’une démarche de recherche-action, il aborde l’articulation entre gestion des déchets et agricultures urbaines, dans un contexte spécifique d’Aide Publique au Développement. L’enquête qualitative révèle la coexistence de plusieurs filières de matières organiques : la filière institutionnelle de déchets ménagers et assimilés, appuyée par un projet dit de développement, et des filières informelles de matières organiques, identifiées à partir des pratiques agricoles intra et périurbaines. Celles-ci sont traversées par diverses tensions socio-territoriales, politiques et économiques. Entre circularités quotidiennes et promues, les pratiques de fertilisation interrogent la place des déchets urbains dans le bouclage des flux, notamment à travers l’introduction du compost comme produit marchand. L’analyse de circulations de matières, de rapports de pouvoir et de pratiques donne à voir le métabolisme urbain de Nkayi, et invite à penser la filière dans une perspective d’écologie politique et territoriale.

This article explores circularity in organic matter chains. Public waste management services and urban agriculture aim to recover organic resources, each guided by distinct logics and purposes : waste valorization and soil fertilization. This raises the question of how these chains are socio-territorially articulated within urban and periurban spaces. This work draws on waste studies, urban political ecology and socio-anthropology of development, extending these frameworks to an intermediate city in the Republic of Congo. The case study focuses on Nkayi, which faces significant challenges related to essential services and food sovereignty. Through a qualitative approach to urban metabolism, the article analyzes the political dimension of material flows, actor relations, and everyday fertilization practices. The findings reveal the coexistence of multiple organic matter chains, marked by social, political, and economic tensions. The institutional chain of household and similar waste was supported by an NGO-led development project, aimed at source separation and composting. Facing socio-technical adaptation challenges and conflicts over service governance, the chain struggles to valorize these flows and link them to intra and peri-urban agricultural spaces. This difficulty in achieving circularity becomes even more evident when examined through the everyday practices of urban farmers. These farmers maintain informal chains of manure, wood residues or plant matter through adaptive socio-spatial arrangements in the face of instability and competition over resource access. Between everyday and institutionally promoted circularities, fertilization practices raise questions about the role of urban waste in closing loops, particularly with the introduction of compost as a marketable product. This analysis sheds light on Nkayi’s urban metabolism of organic matter. It calls for rethinking waste-resource chains through the lens of political and territorial ecology in Central African intermediate cities, attentive to power relations, practices, inequalities, and the challenges of public action supported by development aid.