The Challenge of Improving Soil Fertility in Yam Cropping Systems of West Africa

Abstract

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.

A review of root, tuber and banana crops in developing countries: past, present and future

“…In West Africa, yam serves as a rural staple and source of cash income, an urban secondary food, a source of foreign exchange and an important component in traditional cultural/ceremonial activities that sets it apart from other commodities (Nweke, 2016; Frossard et al ., 2017). Elsewhere in SSA, yam is more of a food security crop and is reportedly used in traditional medicine (Asiedu & Sartie, 2010).…”

Evaluation of Image-Based Phenotyping Methods for Measuring Water Yam (<em>Dioscorea alata</em> L.) Growth and Nitrogen Nutritional Status under Greenhouse and Field Conditions

“…Indeed, given the high diversity of yam cropping systems [1] there is no one suits all solution [4,6].…”

“…Appropriate site-specific innovations need to be designed, tested, and validated with local stakeholders [6]. If this is done, there is a chance that farmers will adopt innovations and sustainably improve yam productivity in their fields [4].…”

“…West Africa produces more than 90% of the world tuber production over 8.5 million of hectares [1]. The increase in yam tuber production observed in West Africa during the last 60 years was made possible by an increase in cultivated surfaces and not by an increase in tuber yields [4]. The average tuber production in West Africa remains low (around 10 t fresh tuber ha -1 ) compared to 50 t fresh tuber ha -1 that can be produced under well-managed conditions [5].…”

“…Yams are traditionally planted by small holders in slash and burn systems following either long or short-term fallows without any external inputs, with low quality planting material and at low planting density. Low soil fertility, bad planting material, high pest, and disease pressure, and decreasing and erratic rainfall distribution are major yield limiting factors [1,4,6]. As population is still growing at a fast pace in West Africa, yam tuber demand will probably further increase.…”