Final answer:
Tropical rain forest soils are unsuitable for farming due to nutrient depletion from heavy rainfall and lack of humus accumulation. Deforestation exacerbates soil erosion which leads to further nutrient loss and unsustainability in agriculture.
Step-by-step explanation:
Soils in tropical rain forests are not well-suited for farming primarily because they are low in nutrients. These regions receive high rainfall which leaches away nutrients from the soil, and as tropical vegetation does not enter a dormant phase like in temperate regions, there is less accumulation of humus - a rich, organic component that acts as a natural fertilizer. In the tropical rain forest, most of the nutrients are found on the surface layer from decomposing leaves, branches, and other organic matter. When forests are cleared, these critical nutrients are lost, and the soil becomes subject to soil erosion. This erosion further depletes soil quality, making it difficult for forests to regrow or for farming to be sustainable without constant input or movement to new areas.