摘要:To design effective policies for rainforest conservation in shifting cultivation systems, it is crucial to have a better understanding of shifting cultivators’ decision making. This paper develops a unified dynamic farm model of shifting cultivation, addressing two lacunae in extant theoretical works: taking into account differences between primary and secondary forests and potential roles of on-farm soil conservation. The model unifies shifting cultivator’s decisions about primary-forest clearing, forest fallowing, and on-farm soil conservation by incorporating new soils acquired from cleared primary/secondary forest land into on-farm soil dynamics. I examine how three distinct policies—forest protection (e.g., protected areas), fallow management (e.g., improved fallow), and on-farm soil management (e.g., biochar in Amazonia)—alter primary-forest clearing (deforestation) and fallow length. The analysis reveals that although all three policies reduce deforestation, only on-farm soil management leads to longer fallow, i.e., sustainable secondary fallow forest.