Résumé :

The principles of agroecology and those of irrigated agriculture are often considered to be contradictory, although science and innovation have made numerous efforts in technological improvements to limit the impact of irrigated agriculture on the environment. In particular, drip irrigation is often presented as a "green" solution because of its good theoretical performance. The development of drip irrigation has thus been promoted and encouraged by many public policies, particularly in the Southern Mediterranean. However, these optimistic efficiencies are often obtained in experimental conditions, and performances in real field conditions may substantially differ. The main challenges of this technology are the improvement of performances and its resulting food productivity while reducing its environmental impacts, in particular on water and nitrogen resources. Studies focusing on agroecology as a potential solution to overcome these issues are rare, especially in the arid and semi-arid irrigated areas of the Southern Mediterranean. The aim of this thesis is to analyze the agroecological performance of drip-fed market gardening in Central Tunisia (Merguellil plain). To this end, several complementary approaches are used, including surveys and observation of technical management routes (TMRs), their modelling using a crop model dedicated to fertigation scheduling (Optirrig model) and their assessment in both qualitative and quantitative manners. The study showed the existence of a wide diversity of TMRs within the panel of farmers studied. Although farmers do not design their technical management routes with an agroecological perspective, they often combine heterogeneous practices from this point of view, including environmentally virtuous practices. When the focus is on fertigation practices, the results show great potential for water and nitrogen savings combined with high yield gain potentials. Finally, the joint improvement of both irrigation management and cropping systems (through agroecological practices) would improve the performance of these market gardening systems, according to the environmental and economic components of sustainability. This thesis opens the way to broad prospects for improving the current performances of drip-irrigated agriculture, in order to combine environmental protection and agricultural production and initiate the agroecological transition of these systems.