Despite a 100% increase in the rural population every 18 years, the Lake Alaotra region is still an important area of immigration. Land occupation is saturated in the irrigable lowlands (well irrigated rice growing areas, rice fields with poor water management, and rainfed lowlands with access to groundwater resources in the dry season, known as "baiboho"). As a consequence expansion, in terms of new cultivated lands, occurs on uplands ("tanety") surrounding lake plain. The diversity of soils, their fragility - with signs of erosion such as "lavaka " (areas of hill collapse) - intense deforestation in the valley lowlands and at the bottom of hills, and extensive cattle rearing initially based on common land have generated a huge diversity of landscapes and land uses. Given this broad range of situations, development projects need to propose varied and locally adapted technical systems, and especially cropping systems generating regular and sustainable yields (based on risk reduction), soil protection from erosion and from roaming cattle culminating in a renegotiation of agriculture-livestock relations. To that end, Direct-Seeding Mulch-based Cropping Systems (DMC systems), introduced and disseminated by the BVLac project since 2003, seem promising. Monitoring of hundreds of plots, supervised by BRL led to the creation of a reliable database containing the results actually observed in BRL farmers' fields. Combined with a 'farm approach', taking into account farmer strategies and the constraints associated with the whole range of agricultural activities, use of this database provides a clearer understanding of local innovation processes related to this important change in paradigm for producers. Indeed, the novel techniques of agro-ecology call for a halt to ploughing or tilling operations, and the combination of plants which are sometimes unproductive but which generate positive externalities within the system. Moreover, these techniques go hand in hand with a certai