Agricultural specialization is linked with negative environmental impact. The SYNERGY bio-economic model studies promising levers to limit these impacts: expand of legumes production and exchanges of crops and manure between farms. SYNERGY is a regional model that includes specialized farm types and models exchanges of crops (including legumes) and manure between them. To build this model, a large variety of data were collected. The aim of this paper is to present these data and specify their sources. The data implemented in SYNERGY were secondary data collected from a variety of sources or primary data generated thanks to different tools. It encompasses several domains (crop, livestock, feed, fertilization), and several scales, from national data (France), to local data (administrative regions). The data set presents three specific features. First, it includes data on feed costs that are differentiated according to their origin. Secondly, it includes detailed data on legumes, from their production to their use in feed. Thirdly, it includes data to calculate two environmental indicators on nitrogen efficiency and nitrogen losses. Thus, the data set of the SYNERGY model represents a valuable collection of agronomic, economic and environmental data to develop further research on the production of legumes, the different feeding strategies and their related environmental and economic impacts of agroecosystems.