Farmers' strategies for managing acid upland soils in Southeast Asia: an evolutionary perspective

The acid soils of the uplands of Southeast Asia have resisted intensive agricultural use for centuries. In recent decades, however, due to rapid population growth, escalating market demand for agricultural produce, and government policies for land development and settlement, the acid uplands have become the focus of more intensive land-use systems, placing greater demands on farmers and requiring the development and dissemination of improved practices for soil management. In order to develop appropriate soil management technologies and plan effective interventions to facilitate their adoption, it is important to understand the goals and circumstances of farmers in the acid uplands, the range of farming systems they have developed, and the variety of socio-economic factors and trends influencing the evolution of these farming systems. Building on Boserup's model of agrarian change, an evolutionary framework is developed and applied to five case studies: a long-fallow (shifting) cultivation system in Sarawak, Malaysia; a short-fallow system in South Kalimantan, Indonesia; a continuous cropping system in Bukidnon, Philippines; a tree crop (with intercropping) system in Southern Thailand; a livestock grazing system in Daclac, Vietnam. The framework provides a useful tool to interpret and categorise farmers' evolving soil management strategies and to plan more effective soil management research and interventions.