In 2050, agriculture will have to feed 70 million inhabitants in France, to provide part of energy and materials, while preserving soil fertility, water quality, biodiversity and contributing to reduce the greenhouse gases. Given these challenges, the current dominant agricultural systems seem to reach their limits and pose environmental, social and economic problems. To search alternatives and to evaluate how new modes of development and use of the natural resources are able fulfill these objectives, a citizen approach, called Afterres2050, has been engaged by Solagro NGO, with the support of the Charles Léopold Mayer foundation. Afterres2050 consists in building a global physical model connecting the future needs and the available resources, expressed as the surface of territory. The results are evaluated with multiple indicators. By an iterative approach, it identifies scenario that seems to satisfy the most of the objectives. They were presented and discussed at meetings open to non-expert publics in order to identify limits of the scenario and improvements. Afterres2050 is one of the most comprehensive scenario, it integrates the largest number of factors and of indicators of the functioning of the agricultural and forest systems to the national scale. It arouses an increasing interest of the political authorities, but also of the citizen and consumer organizations, and representatives of economic sectors. With 50% organic farming and 50% of integrated agriculture, i.e. with a moderate use of the chemical intrans, it is possible to feed France in 2050, while answering partly some of the environmental issues. But this is only possible with really different plates and landscapes. The diet will have to contain more cereals, fruit and vegetables, and much less meat, sugar and milk, in agreement with the dietetic recommendations. The grounds will have to never be uncovered and the plots will have to be arranged to carry up to 6 productions (cereals, green manures, fruits, wood, animals) in agreement with the agro-ecological principles. Number of livestock will be strongly reduced, to limit greenhouse gases, the imports of food, fodder crops and nevertheless to maintain the spaces dedicated to grasslands.These changes would result in releasing 5 to 8 million hectares of land, likely to satisfy with other needs, like the production of biomass for energy, green chemistry or building materials. Nevertheless, whatever the scenario, it appears that agriculture and the forest can contribute to reduce the emissions of greenhouse effect gas only by a factor of 2, whereas the global objectives are to divide them by 4. The continuation of the Afterres2050 approach involves a territorial variation, at the request of regional governance bodies, by the search for new indicators, in particular related on the improvement of health by better food and the evaluation of the adaptive capacities of the systems considered, and finally in the evaluation of the social and economic implications of the transitions necessary to move towards the realization of this scenario.These evolutions are conducted with the support of agro-ecological research and the involvement of the multiple actors concerned, according to various original methods.