subsoil-plow

Any one who has had experience in holding a subsoil-plow, must know that it is an implement somewhat unmanageable, and liable to plunge deep into soft spots like the covering over drains; so that no skill or care could render its use safe over two-foot drains.

Farm drainage The Principles, Processes, and Effects of Draining Land with Stones, Wood, Plows, and Open Ditches, and Especially with Tiles Henry Flagg French

If a lifting subsoil-plow can follow, all the better.

The Home Acre Edward Payson Roe 1863