Soil nutrient balances: what use for policy?

Abstract

This paper reviews the application of the nutrient budget and balance approach from a range of settings and scales in Africa. The paper asks: can such analyses help in the design of effective policy which supports improved soil fertility management by Africa's small-holder farmers? Through the examination of existing studies, the paper highlights some of the difficulties with nutrient budget analyses, including potential problems with a snapshot approach when trying to understand longer term dynamic processes; the danger of extrapolation to wider scales from limited locale-specific data sets; the challenges of understanding diversity, complexity and uncertainty within small-holder farming systems; and the importance of insights into the many socio-economic and institutional factors which influence decision-making at farm level and so mediate the processes of environmental change. The paper concludes by recognising the potential contribution of nutrient budget analyses to the policy process, but suggests caution over uncritical use; particularly the employment of aggregate studies to diagnose generalised problems and suggest blanket solutions. The paper also highlights how nutrient budget analyses can be used as simple devices to encourage debate and dialogue among farmers, technical scientists and policy actors in a participatory process of negotiating interventions or policies for tackling issues of agricultural sustainability in Africa.