Chapter Four - Restoring Soil Fertility in Sub-Sahara Africa

Abstract

Sub-Sahara Africa can overcome the soil fertility depletion that has resulted from decades of nutrient mining by small-scale farmers and threatens the region's food security. Nutrient restoration is now technically feasible because its mechanisms are understood and the rural development community is alerted to this need. Rapid and inexpensive approaches of diagnosing soil fertility limitations are also becoming available and information generated is becoming systematically applied. For example, the recently initiated Africa Soil Information Service project aims at evaluating, mapping, and monitoring Africa's soil qualities for better targeting of soil fertility management technologies to improve crop yields while enhancing the environment. Practical knowledge is available on nutrient management in small-scale farming systems that combines increased biological nitrogen fixation, utilizes agromineral resources such as phosphate rock, better uses organic resources, and more efficiently applies mineral fertilizers. The new approach to managing soil nutrients, recognized as integrated soil fertility management, aims to increase food production through strategic combination of traditional and new technologies and is being stimulated through increased availability and more profitable use of mineral fertilizers by Africa's poorer farmers. This is building on already existing sparks of hope for restoring soil fertility in sub-Saharan Africa derived from such examples as the increasing adoption of the zai-type of pitting system originated in drier parts of West Africa which exemplifies the beneficial effects of integrating harvesting of water and applying nutrient sources at each planting station so as to increase yield in a region where both necessities are key limiting factors. Nitrogen fixation by indigenous and introduced legumes combined with improved agronomic practices has shown potential for kick-starting self-multiplying improvements in soil productivity. Such successes will be accelerated by broader initiatives which improve rural infrastructure, increase accessibility of inputs, improve marketing facilities, and make reinvestment into farming more productive and sustainable. Indeed, experience indicates that investments in farming and, by inference, soil fertility conservation are made when economic returns from smallholder production are sufficient to do so. So, while technical advances leading to improvements in farming practice must continue, policymakers must also recognize that agriculture ultimately forms the basis for economic recovery and act upon past promises to invest in agriculture, including the restoration of nutrient-depleted soils. Investments must address factors that have impacts both on the broad reforms for provision of services such as marketing and trade, as well as those directly constraining the poor farmers such as capacity to access and efficiently apply fertilizers.