A growing number of activities formerly undertaken off-farm are now carried out on-farm, including product processing, agronomic experimentation or animal slaughter. This also applies to the production of certain agricultural inputs, including micro-organisms used as alternatives to chemical inputs in plant nutrition and health. Based on a case study in Brazil, this article analyses the mechanisms behind this shift in the production of inputs, particularly the way it challenges the boundaries that usually delimit the skills and activities of farmers, agri-supply companies and agricultural research. It highlights the boundary work they undertook to extend or, on the contrary, to preserve their prerogatives and competences. Economic, political and epistemic issues are at stake around these boundaries and their movements, and the stakeholders involved defend contrasted positions. The results show that the shift of certain activities towards the farm, which is often seen as an important lever in agroecological transitions, is a complex process and can cause major tensions among stakeholders. Il also shows that, despite these movements, the on-farm production of nature-based solutions and bio-based technologies like microorganisms only partially call the organisation and trajectory of agro-industrial systems into question. In conclusion, the article calls for reflection on the role of agri-supply companies in the transformation of agricultural technological systems. It also calls for research into the control of the technologies produced on farm, and into the ways in which the State can transform existing systems.