This paper develops a spatial general equilibrium analysis of an agri-environmental policy in a suburban context. We present a static monocentric model of an open city where agricultural bid-rents and agricultural amenities vary endogenously in space. Amenities are valued by households and are thus a factor of urban decentralisation. This leads us to focus on the spatial effects of agri-environmental policies promoting amenities. The model characterises a suburban mixed land-use area where households and farmers share space. We provide theoretical evidence that agri-environmental policies are not adopted uniformly by farmers and that they impact on several city features. We highlight that the funding of an agri-environmental policy through household income taxation can modify urbanisation patterns. We also discuss its distributional aspects.