A methodology to guide the conceptualization of a farm system : application to the transition of vineyards to agro-ecological farming

International audience; To assist the analysis, assessment and design of agro-ecological cropping systems a conceptualization at farm level is required. This Farm System (FS) is an integrative scale to assess multicriteria performances of cropping systems and their organization in space. We proposed a methodology to guide the conceptualization of an issue (here related to the agro-ecological transition) into a farm system. The output is a conceptual model aimed at sharing knowledge from various sources, organizing a set of indicators for assessing or implementing a numerical model. We have adapted to the FS the method proposed by Lamanda et al., 2012 on the agrosystem at field scale to guide the conceptualization of an issue into an Agrosystem. The conceptualization is based on structure-function analysis that is to say the relations in time and space between the components of the system (nature and organization), the processes (biophysical, technical, socio-economic) and the performances. The originality of the concept of activity to decompose with parcimony the FS. An activity is defined by a type of agricultural product and the technical , biophysical, financial and labor input used for it. Activities are performedon all fields of the "farm territory" (i.e. all pieces of land, including ecological infrastructures included by the farmer in the farm activities). The final product of the methodology is a conceptual model of the FS for the issue to be addressed. The approach has been tested on case studies of agro-ecological vineyard farms. We showed that the methodology to guide conceptualization was appropriate to identify activities with parsimony and at the crossroad of different disciplines. The conceptual model obtained was used to define and calculate a set of indicators of FS performances. In the case study of a farm in conversion to organic farming, four activities in conventional farming and four in organic farming were identified whereas the vineyard regrouped 19 plots. Each activity was qualified by labor requirements and its cost at different periods of the year. We also tested its relevance for life cycle assessment and economic analysis of grape production. Finally we tested the approach to assess strategic decisions related to production factors during transition towards agro-ecological farming. The conceptual model was used to derive a bioeconomic model of the FS based on linear programming and optimization. The methodology of conceptualization of an issue into a Farm System was developed and tested on vineyards farms which are particulary complex in term of combination of activities and fields. The methodology demonstrated its use for sharing knowledge between different disciplines, integrating various results of a project and implementing numerical model for scenario analysis. It provides an operational way to integrate the biophysical, technical and socio-economic dimensions needed to design and manage the agro-ecological transition of farms.