The article deals with the contribution of agriculture to the development of periurban spaces led by towns. It is based on the comparison of two pieces of research, the first done during a PhD in the region of Lille in 1999, and the second done during a scientific program about sustainable urban development in the region of Tours in 2007. The comparison reveals the importance of land availability and the convergence of images of the role of farms. The article explains the reticence of farmers to get involved in local planning policies that appear to be discriminatory and ends with the interest of land scarcity as a tool to implement a multifunctional farm.