This study examines rural people's knowledge in changing conditions such as decreasing soil fertility and increasing population. It explores how farmers, who depend on rainfed agriculture and are confronted with an ever increasing population, react. The study presents the case of an ethnic group, the Adja, who live in South-West Benin (West Africa).Chapter I looks at agriculture in tropical rainfed areas experiencing a decline in soil fertility. Research and extension have so far generated few feasible technical solutions to the problem. This chapter explores how rural people themselves cope with the situation. Rural people's knowledge processes still seem to be poorly understood. This study investigates how the Adja farmers perceive demographic pressure and how they react to it, what knowledge influences them and what learning processes have resulted in their knowledge.The second chapter provides a theoretical perspective relevant to this study. An analysis of the relationship between researcher and rural people is given, as well as a systems perspective on rural people's knowledge, a conceptualisation of rural people's knowledge and related concepts. Rural people's knowledge will be viewed as the reconstruction of knowledge by both rural people and the researcher through a dialogical process. In addition, the reconstruction can only indicate this knowledge at a given moment in time. Three levels of studies on rural people's knowledge are distinguished: (1) knowledge 'products', (2) the social construction of rural people's knowledge, and (3) the activities which resulted in their knowledge.Chapter 3 presents the methodology used in this work. Special attention is given to methodological issues related to research on rural people's knowledge and the role of the researcher.In Chapter 4, a general introduction to the Adja plateau and its inhabitants is presented. Besides an agronomic point of view, also the Adja classification point of view is given for basic elements of the environment. The agro-ecological conditions on the plateau, the socio-cultural organisation of the Adja, as well as the history of the plateau and the interventions to change it, are described. The complexity of Adja farming is one response to the risks involved in farming. The Adja use several elements from their environment to plan agricultural activities. The history of Adja farming shows constant changes in agricultural practices, giving a dynamic picture. Agronomic interventions designed to tackle the declining soil fertility problem have been limited in their results.The Adja oil palm-based agro-forestry system broadly relieves problems imposed by increasing population pressure and is outlined and analysed in Chapter 5. The system produces significant quantities of biomass and at the same time the oil palm is firmly entrenched in Adja agricultural activities. Also a view on soil fertility as seen by the Adja themselves is described, together with an analysis of the effect of the oil palm system on soil fertility. The Adja recognise and appreciate the importance of soil life and organic matter, a viewpoint which is corroborated by the soil analysis.In Chapter 6, a presentation is given of phenomena related to rural people's knowledge on the Adja plateau, connected with variable demographic pressure and soil fertility. Oil palm densities are higher in the more populated areas. When the oil palm system comes under pressure, farmers try to prolong the cultivation of annuals, increasing the pruning of oil palms and felling them sooner. Intensification and increasing diversification of agricultural production takes place in the more populated areas. In addition, such areas have developed more dynamic and diverse aspects of social life (e.g. religion, off-farm work, migration, trade, legislation) compared to areas with more land per caput. Leadership conventions have a broader base, than in earlier days. In addition to older people, enterprising or educated young people, women and men are included in decision-making. The emergence of women as agricultural entrepreneurs, with considerable trading freedom, and who buy small pieces of land hiring more labourers than male farmers, is partly explained by male out-migration and ongoing individualisation of the Adja society.In order to understand why farmers act the way they do, one must try to proceed from their knowledge, values and ideas. Elaborating on earlier chapters dealing with Adja knowledge, Chapter 7 seeks to understand the Adja perspective by examining Adja 'sense making' activities, like learning, transformation of technology, classifying and theory making. Various examples show that Adja learning has its roots in action. In the daily practice of this learning, constant attention to possible improvement is evident. Results of experiments are shared, interpreted and discussed only in a restricted group. Encounters between different experimenting groups take place in specific social and physical contexts. Externally generated technologies are transformed and combined with social, economic, political and other factors to become an integral part of agriculture. The variability amongst Adja farmers argues in favour of the capacity to assess at an individual or experimenting-group level the potential value of a new method or technique. In the more highly populated areas, this feature of new relationships and networks result in a dynamic cultural identity.In the final chapter, it is concluded that Adja farmers have a rich body of knowledge related to agriculture. However, their agricultural knowledge is strongly related to other phenomena (e.g. religion, social struggles and diversity, access to resources, migration). In addition, it is not static, but in a continuous process of change. It is also concluded that researchers may be able to sustain ongoing Adja experiments by elaborating on a broader set of methodologies for interactive and shared learning. The adaptive research performances of farmers might be enhanced by researchers who visit farmers in their fields and try to join in their discussion. The ability of researchers to enlarge their discursive analysis by incorporating a view of practical activities as applied by farmers seems an important prerequisite for fruitful collaboration. In addition, adaptive performances of farmers might be understood and discussed by researchers if they are willing to acknowledge dimensions other than agriculture.