Reducing pesticide use has become a goal shared by several European countries and a major issue in public policies due to the negative impacts of pesticides on the environment and on human health. However, since most of the agri-food sector relies on pesticides in these countries, substantially reducing pesticide use is a complex issue. To overcome this situation, we argue that agricultural research has a major role to play and must adopt a pesticide-free paradigm to expect a deep impact on pesticide use. In this article, we explain why this new paradigm is needed and outline research fronts that it will help address. These research fronts are related to five strategies: (1) redesigning cropping systems to enhance prophylaxis, (2) diversifying biocontrol strategies and associated business models, (3) broadening the scope of plant breeding to include functional biodiversity and evolutionary ecology concepts, (4) setting new goals for agricultural machinery and digital technologies, and (5) supporting development of public policies and private initiatives for the transition toward pesticide-free agri-food systems. The corresponding research activities must be managed conjointly to develop systemic and coupled innovations, which are essential for reducing pesticide use significantly. We therefore provide examples of cross-cutting objectives that combine these fronts while also highlighting the need for interdisciplinary research projects. By doing so, we provide an overall orientation for research to achieve sustainable agriculture.

Agroecology represents a pertinent option to improve the sustainability of agriculture. To promote its application, agroecological concepts should be taught to students and professionals in the agricultural sector. However, most agricultural courses are not adapted to teach these concepts due to little interactivity or interdisciplinarity, and a lack of a systems approach to farm management. Serious games help to fill these gaps by simulating complex models in which players can learn by doing. We thus developed a serious computer game, called SEGAE (SErious Game for AgroEcology learning), which represents a mixed crop-livestock farm and assesses impacts of farming practices on indicators related to environmental, economic, and social sustainability. Its pedagogical interest was evaluated through two types of surveys given to university students who played the game during a one-week workshop: A knowledge survey on agroecology, and a feedback survey based on flow theory. Results showed that students increased their knowledge of agroecology significantly, particularly those who had had little knowledge of crop production. More than 86% of the students enjoyed the game, appreciating its interaction and feedback. Thus, SEGAE is an interesting tool to help students acquire knowledge of agroecology in a fun way by facilitating interdisciplinary and collaborative learning.

Crop diversification is one of the main mechanisms identified for developing a more sustainable agriculture. Legumes are interesting diversifying crops to add to crop rotations because of their many positive impacts on agronomic systems. Nonetheless, production of these crops remains relatively low in Europe, in part because of socio-economic factors. The objective of this study was to analyze how the economic attractiveness of legumes may be influenced by two factors: opportunity costs and transaction costs. The method is divided into three steps. First, we built a database of opportunity costs of legumes from a literature review. Second, we qualitatively characterized transaction costs associated with exchange of legumes between producers and collectors. Third, we qualitatively analyzed if contracts currently offered in western France decreased transaction costs. For comparison, transaction costs of linseed were also studied. Our results indicate that legumes are economically attractive at the rotation scale due to zero or negative opportunity costs, but that their transaction costs are high. The contracts studied do not decrease these transaction costs sufficiently, in particular because uncertainties in price remain high in half of these contracts. Downstream differentiation seems necessary to decrease transaction costs by creating added value along the entire agro-food chain.

Legumes, which currently show low production levels in the European Union, can reduce negative environmental externalities of agricultural systems by lowering nitrogen (N) fertilization and increasing protein self-sufficiency. This has led to the introduction of coupled support in France, in contrast to Germany. However, the German implementation of the Nitrates Directive is more favorable for legumes. Our study assesses economic and environmental impacts of these two policies affecting legume production. We employ the bio-economic model FarmDyn, representing French and German dairy farms. The results suggest that relatively low levels of coupled support can lead to modest increases in legume production, but that more substantial changes require considerable subsidies. Allowing the French farm to apply manure on legumes, as is already possible in Germany, fosters legume production while considerably reducing the use of synthetic N fertilizer and imported protein-rich feed. However, environmental benefits are limited.

Cette thèse de doctorat porte sur les complémentarités culture-élevage permises par les légumineuses, dans la région de l'Ouest de la France. Une évaluation économique et environnementale de ces complémentarités est réalisée depuis l’échelle de l’exploitation agricole jusqu’à celle de la région.Le principal apport de cette thèse est l’élaboration d’un modèle bioéconomique SYNERGY qui modélise les échanges locaux de cultures (dont les légumineuses) et d’effluents entre des exploitations de grandes cultures et des exploitations d'élevage. Ce modèle prend en compte l’effet précédent des légumineuses et comprend des rations alternatives avec ces cultures riches en protéines. Les principaux résultats de simulation montrent que les aides couplées aux légumineuses accroissent leurproduction mais n’engendrent pas une meilleure valorisation des complémentarités techniques. Un moyen d’accroître l'utilisation de légumineuses en alimentation animale est de labelliser les produits animaux sans OGM. Cependant, les échanges locaux simulés restant faibles, les légumineuses sont en grande partie importées de l’extérieur de la région. Ainsi, les résultats économiques et environnementaux ne sont pas améliorés à l’échelle régionale et l'autonomie en protéines diminue. Enfin, à l’échelle des filières, nous montrons que les échanges de légumineuses engendrent des coûts de transaction élevés, peu réduits par les contrats existants. Le développement de marchés valorisant les ressources locales pourrait encourager la culture de légumineuses.