Abstract: A tubular shaft for rotary cultivators, to which shaft (2) there is attached to a series of tools (4), the tip of each tool comprising a working face (unreferenced) at an angle .alpha. to the ground (9) where .alpha..gtoreq.15.degree. and an approach face (7) at an angle .beta. to the working face where 35.degree..ltoreq..beta..ltoreq.75.degree. and also where .alpha.+.beta..ltoreq.90.degree.. The tools (4) are attached throughout the whole length thereof, suitably spaced away from one another, there being at least one such tool per diameter, and all arranged in an orderly fasion so as to cover the whole length of the shaft with no limit, the tools being set at angles to one another so that their tips describe one or several helical paths from one end of the shaft to the other.