Integrated soil fertility management in Sub-Saharan Africa: principles and practice
Traditional farming systems in sub-Saharan Africa depend primarily on mining soil nutrients. The African Green Revolution aims at intensifying agriculture through dissemination of Integrated Soil Fertility Management (ISFM). In this paper we develop a robust and operational definition of ISFM, based on detailed knowledge of African farming systems and their inherent variability and of optimal use of nutrients. We define ISFM as ‘A set of soil fertility management practices that necessarily include the use of fertilizer, organic inputs, and improved germplasm combined with the knowledge on how to adapt these practices to local conditions, aiming at maximizing agronomic use efficiency of the applied nutrients and improving crop productivity. All inputs need to be managed following sound agronomic principles.’ First, the focus on maximal agronomic use efficiency is justified. Secondly, the application of the various ISFM principles and their impact on the agronomic efficiency of applied inputs is illustrated for specific African farming systems with high potential for adoption. Such cropping systems include sorghum and millet based systems in the Sahel, legume-maize systems in the savanna, and cassava-based systems in the humid forest areas. Finally, the conditions that enable the adoption of ISFM technologies are discussed, including profitable access to markets, appropriate extension methods, and a favorable policy environment.