Sustainable agriculture develops itself as a new paradigm that shatters the routinized knowledge mastered by producers. It encompasses a whole set of activities related to the cultivated plots but also to their environnement, even to the delivery of services to clients. New activities require new skills such as observation, anticipation, diagnosis ability. It summons also new domains of knowledge such as pest epidemiology ou weed ecophysiology. Moreover, information and technical references are scarce at national level as well as at the local level. Hence, relational skills appear as chore competences to implement cognitive strategies and carry out learning processes by connecting with complementary sources of knowledge that is to say relevant actors, according to the learning objectives. Nevertheless, integration skills are needed when it comes to the implementation of a combination of different knowledge. Then the paper presents a twofold approach to the learning processes ; i) to build a typology based on the learning practices and the questions raised by farmers and ii) to identify experts through advices network analysis. Results show that categories such as leaders or pionneers do not fit with the complexity of the processes, highlight the possible complementarity between individual situations and address the usual development-oriented typologies.