In sub-Saharan Africa much attention has been focused on the quantification and estimation of nutrients entering and leaving agricultural systems, the balance showing whether the agricultural system is a net gainer or loser of soil fertility.
The FAO Land and Water Development Division is concerned with the development of technology, strategy and policy, and with the provision of advisory and technical services to FAO Members. Its programmes include activities related to the enhancement of soil fertility and land productivity for food production; land degradation assessment in drylands (LADA) and compilation of scaling subnational land-use databases are core elements.
Soil nutrient balance models quantify the flows of nutrient inputs and outputs for systems ranging from a microlevel experiment to the global level. To date, most studies of such systems have focused on either the microlevel or the macrolevel. They have provided useful data and findings for decision-makers operating at the national and international level and for researchers and individual farmers in limited realities. Their contribution to the body of knowledge should not be underestimated. However, they have tended to ignore an intermediate level that is important to broader groups of farmers, stakeholders, policy-makers and planners operating at the level of a province, district, agro-ecological zone or agro-economic system (e.g. a cotton-based farming system). This intermediate level is termed the mesolevel.
In African countries such as Ghana, Kenya and Mali, the mesolevel is the level where facilitation of production can take place and where a developing private sector can invest in a commodity or production system. It also provides a useful entry point for policy-makers at subnational level.
