The machine, e.g. a stubble plough, consists of a chassis (2) with digging tools in the form of at least two transverse rows (3, 4) of discs (5) with their working depth controlled by an adjustable rear wheel (7), roller or skid. The discs in the rows are of different diameters, with those in the front row being of greater diameter than those in the row(s) behind, and the discs can be of the same or different types and have associated tools such as seed drills or fertilizer spreaders.
