A socio-economic analysis of the farms in four villages of the Dikodougou region (North of Cote d'Ivoire) reviews two debates about the evolution of the farming systems in sub-Saharan Africa. Firstly, the two opposing views in the controversy "Boserup versus Malthus" are complements rather than opposites. In a first phase, demographic pressure causes Malthusian mechanisms (proliferation of weeds, deterioration of the bio-physical environment, of global fertility and of the profitability of the traditional production system) generating favourable conditions for the adoption of ox-drawn farming. In a second phase, the alternation of the production system illustrates well the Boserupian response to a situation where the traditional system is not adapted to the new socio-economic conditions. Secondly, the economic analysis proposes to review the debate "competition versus complementarity" between cotton and food crops. The competition thesis seems only valid for not mechanised farms, where cotton competes with food crops for labour. However, the second phase of the evolution of the production systems (utilisation of pesticides and fertilisers, substitution of manual farming by ox-drawn farming) is possible thanks to the favourable conditions (access to pesticides, fertilisers, credit and know-how) generated by the CIDT (Compagnie Ivoirienne de Developpement des Textiles).