that respond to a diversity of local farming systems and bring a high level of nutritional self-sufficiency to a region where people in many countries suffer from undernourishment. Many believe, and experience suggests, that no “silver bullet” technology package will broadly apply across the region. Rather, a systems approach is needed with research grounded in local contexts to develop locally appropriate technological and ecological solutions (InterAcademy Council, 2004).

According to several recent studies that document practical experiences of sustain able agriculture programs in developing countries, biological and ecologically based approaches, practices, and principles have resulted in improved production and positive economic outcomes, while also making more efficient use of natural resources (Pretty et al., 2006; Pretty, 2008). Similarly, a number of multistakeholder reports (InterAcademy Council, 2004; NRC, 2008; IAASTD, 2009) state that high priority should be given to developing technologies that focus on integrating biological and ecological processes (such as nutrient cycling, nitrogen fixation, soil regeneration, and biodiversity) into the production processes. That way, use of nonrenewable inputs, which can make farmers more vulnerable to input cost fluctuations, can be kept to a minimum and used judiciously. Further, productive use of the knowledge and skills of farmers’ and other people’s collective capacities to work together to solve common problems is important (Pretty, 2008). The idea of agricultural sustainability does not mean ruling out technologies or practices on ideological grounds if they can improve productivity and do not significantly affect the other objectives of sustainability (for example, cause undue harm to the environment or increase farmers’ vulnerability to risk). For example, integrated soil fertility management can benefit from the judicious use of inorganic fertilizer combined with organic fertilizers—a highly synergistic combination because organic matter increases the water-holding capacity of soils and increases the efficiency of fertilizer use by crops (Evanylo et al., 2008; Toenniessen et al., 2008). Yet, small farming systems are vulnerable to sudden cost increases or shortages if they become too reliant on external inputs, as observed in 2007 when oil and fertilizer prices reached record highs, and previously when governments eliminated subsidies on agrochemicals as part of structural adjustment programs (Denning et al., 2009).

Although there have been successful programs in the development and adoption of innovative sustainable approaches in many resource-poor contexts, barriers to more widespread implementation or change persist. One obstacle to launching a large-scale second Green Revolution is the decline of the CGIAR Centers and the pressure they face to focus on scientific or technological solutions which could be difficult to adopt across diffferent natural resource, economic, and political environments, rather than contextual systems solutions. That is in part because of severe budget cuts and decreasing support to other development programs and nongovernmental organizations such as CARE, World Neighbors, Winrock International, Heifer International, Rodale, and local institutions dedicated to developing innovative approaches in agriculture and natural resource management. In addition, a new Green Revolution would require additional support for local research and education institutions that can respond to needs of the small farming systems across the developing world (as discussed below). A second Green Revolution is unlikely without substantial funding from the international donor community, a commitment of resources, and favorable policies that reach out directly to the poor and build human capital at national levels.

LONG-TERM EVOLUTION TOWARD SUSTAINABILITY IN SUB-SAHARAN AFRICA

The challenge for Africa is the sustainable intensification of agriculture, that is, increased production per unit of land. In addition, some argue that the amount of land in agriculture



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