For some decades, researchers from the Department of Geography in the University of Cambridge have been conducting basic research into the ecology of slash and burn subsistence agriculture in the context of the acid soils of the world's humid tropics; i.e. in the typical environment of the Tropical Rain Forest (TRF).  This project profile outlines the sustainable system of subsistence agriculture that has emerged from these years of research and development, and continues by outlining the work of the NGOs in Central and South America who are implementing these findings today.