subsoil

/ˈsʌbˌsɔɪl/
noun
  1. The layer of soil beneath the topsoil, usually containing less organic matter and more minerals.
    • Farmers test the subsoil to see if it has enough nutrients for deep-rooted crops.
    • The subsoil in this area is rich in clay, which affects how water drains.
    • When digging a hole for a fence post, you will eventually hit the hard subsoil.
Antonyms
What does "subsoil" mean? | whatsthatwordmean | whatsthatwordmean