bottom soil

例句：

1. 1. The farmer carefully dug down to the bottom soil for nutrients.
   农民小心翼翼地挖到底层土壤寻找养分。
2. 2.The plant was struggling to grow in the topsoil, but it thrived in the bottom soil.
   植物在表层土壤中生长困难，但在底层土壤中茁壮成长。
3. 3. The scientist analyzed the chemical composition of the bottom soil to understand its fertility.
   科学家分析了底层土壤的化学成分，以了解其肥力。