Yam (Dioscorea spp.) is a tuber crop grown for food security, income generation, and traditional medicine. This crop has a high cultural value for some of the groups growing it. Most of the production comes from West Africa where the increased demand has been covered by enlarging cultivated surfaces while the mean yield remained around 10 t tuber ha−1. In West Africa, yam is traditionally cultivated without input as the first crop after a long-term fallow as it is considered to require a high soil fertility. African soils, however, are being more and more degraded. The aims of this review were to show the importance of soil fertility for yam, discuss barriers that might limit the adoption of integrated soil fertility management (ISFM) in yam-based systems in West Africa, present the concept of innovation platforms (IPs) as a tool to foster collaboration between actors for designing innovations in yam-based systems and provide recommendations for future research. This review shows that the development of sustainable, feasible, and acceptable soil management innovations for yam requires research to be conducted in interdisciplinary teams including natural and social sciences and in a transdisciplinary manner involving relevant actors from the problem definition, to the co-design of soil management innovations, the evaluation of research results, their communication and their implementation. Finally, this research should be conducted in diverse biophysical and socio-economic settings to develop generic rules on soil/plant relationships in yam as affected by soil management and on how to adjust the innovation supply to specific contexts.

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Yam (Dioscorea sp.) is an understudied tuber crop despite its importance for food security, income generation, culture, and health in West Africa. Traditional yam cropping practices in West Africa deliver low yields and lead to environmental degradation. In the context of a ‘research for development’ project, we developed and implemented a participatory and transdisciplinary research approach as a means to derive more sustainable yam production practices. We identified and studied different soil and plant management technologies adapted to varying biophysical and socio-economic contexts. For this purpose, we established innovation platforms (IPs) in four yam growing regions of West Africa, to validate the new technologies and to promote their adoption. These co-developed technologies were set up and tested first in researcher-managed plots before doing the same in farmer-managed plots. The new technologies resulted in a significant increase in yam productivity compared to conventional practices. The results discussed in the IPs gained interest from regional stakeholders and were shared through the media at local and national levels. Overall, this development-focused research approach showcases the relevance of purposeful stakeholder involvement to improve agricultural research outcomes.

Soil fertility decline and high N demand during plant growth are cited as main causes of low yield in yam (Dioscorea spp.). As information regarding fertilizer N use in yam is lacking, a field experiment was undertaken in 2006 and repeated in 2007 in central Côte d'Ivoire using 15N (15NH415NO3) labeled fertilizers to monitor N uptake and fertilizer use efficiency in D. alata. The 15N‐labeled fertilizer was added in two splits (at 90 and 130 d after planting) for a target tuber yield of 40 Mg fresh tuber ha−1. The application of mineral fertilizers increased total biomass production and tuber yield as well as N uptake from native soil organic matter. The recovery of 15N‐labeled fertilizer applied at 90 and 130 d after planting was not significantly different but the year affected 15N recovery by the plant. The maximum 15N recoveries calculated from the sum of the 15N recovery measured at both application dates were 46 and 23% in 2006 and 2007, respectively. Leaf dry matter and leaf N uptake were higher in 2006 than in 2007, but tuber dry matter was not different between years at the final harvest. Up to 170 kg N ha−1 was returned to the soil through the fallen shoots, indicating an important recycling of N for soil fertility replenishment. Thus, crop succession or intercropping are encouraged in a yam cropping system. Our results also show that the application of mineral fertilizers had a strong “priming effect” on the native soil N in both years.