Introduction

Abstract

For thousands of years, swiddening, shifting cultivation, or slash-and-burn farming, as it is alternatively called, has been a common farming practice (Jääts et al. 2011). While it has been largely replaced in temperate countries by more sustainable agricultural practices, it continues in many tropical countries (van Vliet et al. 2012). The reasons for continued practice are varied. From a socioeconomic point of view, they include the low population density in the area in which the farmers live, which allows them to use shifting cultivation (Delang 2006a), and the lack of access to permanent fields, either for legal or for economic reasons, which forces them to use shifting cultivation (Ochoa-Gaona 2001). From an ecological perspective, poor soil quality is a major factor. In tropical countries, much of the nutrients necessary to grow crops are in the vegetation rather than the soil, and are released in the form of ashes when trees are burned (Neyra-Cabatac et al. 2012). After the land is cleared, it may be cultivated for a few years without using pesticides or fertilizers. However, the land quickly degrades, and without the use of fertilizers and pesticides the yield is soon very low and the farmers have to move on, clearing new land.