Spatial diffusion of efficient irrigation systems: a study of São Paulo, Brazil*

Finding ways to stimulate the diffusion of water-saving irrigation systems is essential to mitigate the negative impacts of climate change on water supply. We analyse the spatial diffusion of more efficient irrigation strategies in São Paulo, Brazil, comparing the two most common irrigation technologies: conventional sprinkler irrigation and the localised irrigation. We use longitudinal municipal-level information for 2006 and 2017 and test different spatial panel models' specifications, representing different hypotheses about technological transfer channels. Our results highlight how the diffusion of water-saving irrigation systems (localised irrigation) in one municipality is strongly influenced by the diffusion in neighbouring municipalities. Membership in cooperatives or farmers' associations plays a significant role in this technological transfer. On the other hand, the diffusion of less efficient systems (sprinkler irrigation) depends fundamentally on the local availability of water and unobservable factors in the neighbourhood. The discussion highlights how easing knowledge transmission may contribute to the diffusion of more sustainable agriculture practices.