Effective solutions for integrating development of agriculture and conservation of biodiversity at a landscape scale remain to be identified. This article presents a case study on an intensively farmed French cereal plain, where the reintroduction of grasslands has been proposed to protect the Little Bustard, a threatened European bird species. Although this solution may seem trivial at first glance, we analyze the design reasoning from which it resulted in order to highlight the innovative paths it opened. We apply C-K theory, a design theory that distinguishes concepts (i.e., unknown proposals) from knowledge. Our analysis reveals the links between the production of scientific knowledge and the generation of various solutions. It also highlights that specifying the ecological functions of grasslands facilitates their management. In the cereal plain, some of these functions give grasslands the status of common goods. This consideration opens new possibilities for managing agricultural landscapes in a way that reconcile agriculture and conservation.