Résumé
The oases of Biskra (Algeria) are famous for their date palms, which constitute their main and long-established crop. In the middle of the 1980s, greenhouses started to appear in this region, thus creating new agrarian dynamics. These dynamics are related to arrangements of different actors (owners, lessees, sharecroppers and employees) pooling their production factors (land, water, labour, capital). The aim of the present study was to explain the development of these dynamics. We analysed the functioning of farm holdings through 77 surveys with the different actors in the municipality of El Ghrouss in the region of Biskra. We show that there can be two logics on the same plot, that of the lessee or sharecropper and that of the owner, with two distinct ambitions: social ascent by accumulating production factors through greenhouse horticulture, and guaranteed retirement by cultivating perennial crops (date palms). The combined energy and action of these actors are at the basis of agrarian dynamics in El Ghrouss, leading to the very expansion of the oases and upward social mobility.