Africa is rich in both natural and human resources, yet nearly 200 million of its people are undernourished because of inadequate food supplies. Comprehensive strategies are needed across the continent to harness the power of science and technology (S&T) in ways that boost agricultural productivity, profitability, and sustainability -- ultimately ensuring that all Africans have access to enough safe and nutritious food to meet their dietary needs. This report addresses the question of how science and technology can be mobilized to make that promise a reality.
In the above sections, emphasis was placed on productivity increase at the field level, in both specialized systems and diversified cropping. Farms in many African regions are complex units that combine their activities over time and space to maximize food security and provide for other needs (Lhoste and Richard, 1993; Rabot, 1990; Sissoke, 1998). Opportunities for off-farm earnings also strongly influence the livelihoods of farming families. Optimization of natural resources management also needs addressing at the spatial scale, and is also influenced by off-farm activities. The adoption rate of many technology options derived from past research has been disappointing, possibly because the technologies are assessed at the crop or livestock activity level only, and this may not match the complex and multiple goals of a farm household.
In general, activities are organized such that a concentration of soil fertility occurs nearer to the farm house, indicating priority decisions made by the farmers. This phenomenon is well known and has been extensively described in the past (Prudencio, 1993; Ruthenberg, 1980). Little is however known about the way these gradients affect resource use efficiency and the way that management reinforces rather than decreases the gradient. Box 4.15 describes one attempt to better understand nutrient flows at the farm and village level. Recent work tries to explore farm-scale dynamics in terms of trade-offs at farm scale between spatial allocation of resources and temporal trade-offs between short-term yields and long-term sustainability (Giller, 2002; Tittonell, 2003).
Practical tools for nutmon farm analysis comprise a toolbox, consisting of questionnaires, data entry and data analysis facilities, and facilities to present the results of the analysis in a way understandable for farmers (Vlaming et al., 2001). The nutmon approach is helping research and development projects to address soil fertility management in situations of both nutrient depletion and nutrient accumulation. Currently the nutmon Toolbox is being applied in Burkina Faso, China, Ethiopia, Ghana, Indonesia, Kenya, Mali, Thailand, Uganda and Vietnam (Van Den Bosch et al., 2001).
Most African crop and animal production is practiced under low-input agricultural systems, often because of low accessibility to external inputs, low economic returns from inputs and market risks. Many have tried to increase the productivity of these systems with or without limited external inputs. The chances for substantial improvement with low external inputs are very low, and it would be unwise to promote such low external input systems. The niche markets for some organic products in the Western world may be profitable for a limited group of farmers to generate income, but their potential contribution to increased food security is very limited.
In search of increased productivity in sorghum, Ouedrago and colleagues (2001) applied up to 10 tonnes of compost in their experimental fields. Sorghum yields tripled compared to zero application rates - up to 10 tonnes per hectare. Farmers were aware of the role of compost in sustaining yield and improving soil quality. However, the lack of equipment and animals to generate enough organic material for making compost, uncertain land tenure and the intensive labour required for making compost appear to be major constraints for the adoption of compost technology. Increasing phosphorus levels in the soil and the contribution of N2-fixing species in the cropping systems would contribute to crop yield increase when large volumes of compost are not available.