subsoil

The layer or bed of earth beneath the topsoil.

To plow or turn up the subsoil of.

In agriculture, to employ the subsoil-plow upon; plow up so as to cut into the subsoil.

The under-soil: the bed or stratum of earth or earthy matter which lies immediately under the surface soil, and which is less finely disintegrated and contains less organic matter than that.

The bed, or stratum, of earth which lies immediately beneath the surface soil.

a plow having a share and standard but no moldboard. It follows in the furrow made by an ordinary plow, and loosens the soil to an additional depth without bringing it to the surface.

To turn up the subsoil of.

The layer of earth that is below the topsoil.

the layer of soil between the topsoil and bedrock