subsoil

For the subsoil of the whole country is very rich, as trees of immense size and height readily demonstrate.

The physical characters of the subsoil are often of much importance to the soil itself.

In such cases the benefits of subsoil ploughing and deep ploughing are conspicuous.

The subsoil should be drained four or six feet below the cellar floor, and this floor is to be laid in concrete and cement.

On a subsoil of rocky character the foundation course or even the first and second courses might be unnecessary.