Yaalon in Correspondence (Nature 405, 993; 2000) refers to my earlier Correspondence in which I argued that local farmers could feed Africa if they were given the chance (Nature 404, 431; 2000).
I agree with Yaalon that available data on land resources are not always reliable. Their accuracy depends on data provided by national authorities. The UN Food and Agriculture Organization, which collects and publishes this material, is the only source for this worldwide information and is not to blame for any inaccuracies.
The comparatively low agricultural production in Africa today is not due to population pressure, the subsequent shortening of the fallow period and the depletion of soil nutrient status, as is generally believed. As I pointed out, there is a growing shortage of labour in rural areas as people migrate to the cities, and hence a reduction in cultivated acreage.
Technical solutions are well known: for many years agricultural development projects have focused on ways to increase production including improved soil management, intensification and diversification of the cropping pattern, adapted farming systems, restoration of the soil nutrient status, and so on. That these have not been implemented is often owing to socio-economic or cultural constraints.
Fertilizer is a good technical solution to the problem of poor soils, for example. But for local farmers, it still represents an extra cost which most cannot pay.
Yaalon's suggestion that “current subsidy and overseas aid should be used to provide the fertilizers and improved planting materials that are needed” is not a sustainable solution, as it replaces the structural problem of food aid with another structural problem of fertilizer aid. Once the the free supply stops, farmers return to their traditional system.
Yaalon's vision that “many locally trained soil and extension specialists living in the region are needed to transform the economy from one of small rural farmers to one of market food production” has not been successful in Africa. Almost all efforts over the past 20 years have now been dismantled or vastly reduced, despite efforts to involve local expertise.
Substantial rethinking about aid is needed, to switch from a top-down to a bottom-up approach. The key questions are how to increase the sustainability of technical assistance and how to involve local people in follow-up activities. Examples of the former include supplying farm implements and creating a small credit system; setting up a cooperative network for marketing agricultural products; attempting to end the practice of denying access to land by women, and so on. If the stakeholders are involved at all stages — ensuring that the project meets their demands — and their knowledge is included (updated if necessary), they are very much more likely to continue the activities after the project ends.
Yaalon's dedicated soil scientists might be helpful, not necessarily because of their technical skills but as facilitators for local people, to understand their problems and to use their advice. The soil scientists will learn that local farmers are usually well aware of their problems, and even know how to solve them, but generally lack the external support.
In my opinion, increasing food production in Africa is primarily a question of incentives and marketing assistance to farmers' communities. Once farmers are guaranteed a reasonable return for their work they will engage in efforts to produce more. With the extra earnings they will buy fertilizer, and break the vicious circle of subsistence farming.