This publication is the introductory chapter of the book, Nutrients on the move: Soil fertility dynamics in African farming systems; it summarizes the main findings of soil fertility case studies in six African countries. Key biophysical and socioeconomic constraints on production by smallholder farmers and the possibilities for improving agricultural productivity in Africa are highlighted. The case studies seek to find what is actually happening at farm and field level, how soil fertility management varies between different fields, farmers and locations, and what are the implications for interventions aimed at improving soil fertility management.