CLASSIFYING, MONITORING AND IMPROVING SOIL NUTRIENT STACKS AND FLOWS IN AFRICAN AGRICULTURE

Nutrient stocks and budgets (positive minus negative flows) are quanti fiable indicators of sustainability, and are applied in this paper to classify agro-ecosystems. Earlier work revealed that most agricultural systems in sub-Saharan Africa (SSA) can be labelled nonsustainable du e to low nutrient stocks and negative nutrient budgets. To increase pr oduction and build sustainable agro-ecosystems in SSA, technologies th at rank under ''integrated nutrient management'' (INM) should be adopt ed, to save nutrients from being lost, and to add new nutrient supplie s to the system. An account is given of the socioeconomic factors at n ational and farm level, the interplay of which determines the actual a doption rate of INM. Based on an overview of what we do know and what we don't know, an INM research agenda is proposed that is based on the knowledge gaps.