The article studies the politics of expertise and the co-production of sociotechnical imaginaries, expertise identities and public policies in agriculture and the use of fertilisers in Greece between the years 1945 and 2000. By applying the concept of the co-productionist idiom, the processes of appropriation will be studied and dynamic processes in postwar Greece are demonstrated. The study argues that experts functioned not only as mediators but as promoters and shapers of sociotechnical imaginaries in Greece, and that they directed specific policies in promoting or controlling the use of fertilisers: particularly nitrogen (N) fertilisers. Until 1990, experts had the power and the authority to politically and socially legitimise the use of intense fertilisation. In the years since 1990, the experts’ role was configured by transnational political pressures from the European Union that shaped the experts’ consensus on the harmful effects of agriculture malpractice and the overuse of nitrogen fertilisers. Yet still while an environmentally friendly agriculture paradigm was sought the dominant public discourse promoted by experts in Greece still prioritised accuracy and rational use.