s:3066:"TI Assessing adoption potential: lessons learned and future directions 
AU Franzel, S. 
AU Scherr S J 
AB Land degradation, low soil fertility and lack of quality livestock feed are increasingly recognized as key problems for farmers throughout sub-Saharan Africa. The research reported in this volume documents the experiences of farmers in testing and assessing the potential of agroforestry practices to address these problems and increase their incomes. The volume presents five case studies from three contrasting zones: a humid, highland area in central Kenya located close to major markets; a humid, highland area in western Kenya with poorer soils and further from markets; and a subhumid plateau area in eastern Zambia with degraded soils, lower population density, and far from major markets. Maize, the main food staple in eastern and southern Africa, is the most important crop component of all of the agroforestry practices examined in the case studies. Three case studies assess soil fertility interventions, including improved tree fallows and hedgerow intercropping (Table 9.1). In eastern Zambia, the number of farmers using improved, 2-year tree fallows rose from 20 in 1993 to about 10,000 in 2000. Main trees planted were Sesbania sesban, which requires a nursery, and Tephrosia vogelii, which may be direct seeded. In western Kenya, farmer-managed experiments in the early 1990s helped researchers identify a range of brief, one-season fallow species, which, by 1999, were being planted by several thousand farmers. The most popular species were Crotalaria grahamiana, Crotalaria ochroleuca, and tephrosia, all of which were direct seeded. Hedgerow intercropping in western Kenya, while not contributing significantly to improving soil fertility and crop yields in the short run (1–4 years), was shown to be an important means of reducing soil erosion, and can thus improve fertility and yields in the long run. The main species included Calliandra calothyrsus and Leucaena leucocephala. One case study, also from western Kenya, assesses the introduction of trees for wood production, such as Grevillea robusta and Casuarina junghuhniana, planted along boundaries and in other arrangements. The last case study reports on the uptake of calliandra in the mid-1990s, which farmers planted to provide fodder for increased milk production in central Kenya. By 2000, about 4000 smallholder dairy farmers had planted calliandra and numbers expanded rapidly over the next 3 years. This chapter reviews the adoption potential of the practices within and outside the areas they were tested and assesses policy support needed to promote their adoption. Next, we summarize lessons learned for improving the effectiveness and efficiency of developing and disseminating new practices, focusing on the complementarity of different types of on-farm trials, the promotion of farmer participation, adaptation and innovation, and on creating adaptive research and dissemination networks. Finally, suggestions are made concerning areas for future research. 
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