A soil profile in a humid tropical biome reveals highly weathered soils. Which mineral is most likely dominant in these soils? a. Calcite due to high rainfall. b. Quartz due to its resistance to weathering. d. Halite due to salinity in the root zone.

In humid tropical biomes, intense weathering processes break down minerals, often leading to the leaching of more soluble minerals. This results in soils that are typically rich in kaolinite, a clay mineral formed from the weathering of feldspar and other silicates. So, while quartz might be present due to its resistance, it’s the clay minerals dominating the profile! Furthermore, highly weathered soils tend to show lower nutrient levels compared to their less-weathered counterparts, making them more reliant on organic matter from decomposing vegetation. This can create rich ecosystems, but also poses challenges for agriculture, as farmers often have to rely on fertilizers to replenish lost nutrients.