Adaptation of yam (Dioscorea spp.) cultivation to changing environment and economic constraints in Benin, West Africa

The Republic of Benin is a very important and dynamic yam producer in West Africa. During the past 30 years the country's yam output was multiplied by more than 3 that represents an annual increase rate of 3.75%. The traditional yam cultivation is based on slash and burn practices but now cropping techniques are evolving for many reasons. In order to understand and to assess farmers' yam production strategies, a study of yam based farming systems was carried out in the Borgou region which can be considered as the core of Benin's yam belt. 60 farmers have been followed up in detail (including yield measurement) during three cropping years and in addition 300 others farmers were interviewed more rapidly. The comparison between different groups of yam growers as yam chip oriented producers, sedentarized Fulani shepherd recently involved in agriculture or cotton oriented farmers, allow to understand the different strategies used for yam cultivation. In particular the management of the different genetic resources according to various constraints, such as fallow shortening or market demand allow the understanding of how farmers adapt themselves to external changes. (Resume d'auteur)