Sustainable intensification of smallholder farming is a serious option for satisfying 2050 global cereal requirements and alleviating persistent poverty. That option seems far off for Sub-Sahara Africa (SSA) where technology-driven productivity growth has largely failed. The article revisits this issue from a number of angles: current approaches to enlisting SSA smallholders in agricultural development; the history of the phenomenal productivity growth in the USA, The Netherlands and Green Revolution Asia; and the current framework conditions for SSA productivity growth.

This paper takes the viewpoint of a social scientist and looks at agricultural scientists' pathways for science impact. Awareness of these pathways is increasingly becoming part and parcel of the professionalism of the agricultural scientist, now that the pressure is on to mobilize smallholders and their productive resources for (global) food security and for reducing persistent rural poverty. Significant new thinking about pathways is emerging and it is useful to present some of this, even if it is not cut-and-dried.

Innovation is often presented as one of the main catalysts for more sustainable and inclusive development. In the agricultural and food sectors, innovation is characterized not only by specificities arising from its relationship to nature, but also from the wide diversity of its stakeholders, ranging from farmers to consumers, and including intermediaries such as the research community and advisory services. Innovation emerges from interactions between these actors, who mobilize resources and produce knowledge in collaborative mechanisms in orderto generate changes.

This article examines how research on the agriculture and agrifood systems mobilizes the concept of Innovation System (IS). A literature review on the IS provides an analytical framework for determining its theoretical frame of reference, its area of application and its uses.