Résumé
Most sorghum growers either produce their own seed or obtain it through exchange. They seldom use seed delivered by formal seed systems. The reason is that seed exchange strengthens traditional solidarity networks which are the basis for collective risk management in the case of precarious cropping conditions. Our study aimed at characterizing the seed exchange system in sorghum; and verifying if frequency or modalities could be modified in a village where farmers are used to making money from cotton growing. it was carried out in 2004 and 2005, in five villages in Burkina Faso. Farmers were sampled according to the "snowball" method. The results show that farmers usually buy and sell small quantities of seed when their harvests are sufficient. In general, seeds are given for free and according to traditional rules. People exchange more with people who are close to them geographicaly or socially, and such exchanges mostly take place within villages, ethnic groups, or families. However, such rules are not exclusive, and exchanges also happen among people who are unrelated or from remote villages. In 2005, the comparison between two villages, one growing cotton (Siby) and the other not (Tiogo), showed that the cotton producers behaved like the others. They exchange as many seeds and in the same way. Cotton does not seem to modify the traditional exchange network. Gift and intra-ethnic exchanges remain frequent and trade exchanges do not increase. On the other hand, the social organization generated by cotton production eased the development of new exchanges, among friends, while in the non-cotton producing village, the exchanges were essentially kept within the family. By growing cotton, farmers create a source of income and an access to an alternative and individual mode of risk management. While integrating new members into their exchanges, they also remain involved in the traditional system.