Termed as an 'extravagant' or 'irrational' crop with high labour inputs, significant transport costs, demanding soils requirements and costly seed production, yam has been doomed to disappear in a world dominated by the so-called 'superfoods' (maize, rice and wheat) and, more often than not, has been relegated to the margins in agricultural policies and research efforts. Even though it has generally reached high prices in urban markets, cultural attachment and restricted opportunities have been usually argued as the only reasons to keep rural farmers growing a crop whose profits seemed elusive for them because of an information asymmetry that benefitted mainly traders. Nevertheless, farmers in Ghana have led a spectacular increase in yields and production, especially from the 1980s, to the point that yam is currently the most important crop in value in this country.

This paper analyses this apparent contradiction examining from a historical point of view the changes in the Ghanaian marketing system and their effects on production, with a special focus on the role of the farmers in these changes. From a trader- to a farmer-dominated system, yam marketing in Ghana is currently a very competitive and vibrant market characterised by a quick flow of information, complex arrangements between the actors involved - including the complete blurring of their roles -, the opening of numerous producers' markets, and multiple financial and contract agreements to ensure production and supply to a market that, nonetheless, remains complex and puzzling for all its participants.

Conventional approaches to agricultural development in Africa underplay the potential of local initiatives and the gradual successes achieved by smallholder farmers.　 Marshy areas were marginally used in the research site about half a century ago. Although without any external assistance, Nigerian farmers have been able to mobilize local resources and gradually expand indigenous irrigation and scale of cash crops farming on lowlands. They have also gradually incorporated yams, a high valued exotic crop, into their upland farming system and dietary habit. The study examines the reciprocal natural resource use relationship between the farmers and the pastoralists. Findings suggest that pastoral groups in the research site have different strategies to maintain social ties with agricultural villages through the adoption of corralling contract. Pastoralists in the research site have developed their local agricultural initiative, which is the indigenous herding practice. By flexibly adjusting herding activities in accordance to subsequent changes in natural and human environments, Nigerian pastoralists are able to utilize the limited resources available in every time and space niche. The study on the farmers and the pastoralists in Nigeria demonstrates how rural communities have developed local agricultural initiatives to diversify their production system and to secure their natural resources need. African peasants are often assumed to be irresponsive to new innovation and reluctant to change, but through the evidences obtained by fieldwork, they are proven to be capable of generating indigenous solutions in response to gradual changes in the natural and human environments.