Tool for breaking up and turning over soil, particularly of a spade or shovel type, comprising a handle (20, 22) and a working part, comprising: - a support base, having a foot for placing on the ground and a post; - a long tiltable assembly, tiltably mounted on said post about an axis perpendicular to the longitudinal axis of this tiltable assembly; the tiltable assembly is movable between a first position, of insertion of the working part into the ground, a second position, of lifting a piece of fragmented clod of soil by means of the tool, and a third position, of discharging this clod of soil; the tiltable assembly comprises, on one side of the tilting axis, a first tool handle part and, on the other side of this tilting axis, a sub-assembly comprising a second tool handle part and the soil working part; this sub-assembly is pivotally mounted with respect to the first tool handle part along the longitudinal axis of the second tool handle part, this pivoting allowing the working part to rotate from said second position of lifting the fragmented clod of soil to said third position of discharging this clod of soil; - means (7, 8, 32) for controlling the pivoting of said subassembly when the tiltable assembly moves from said second position to said third position; the tool being characterized in that it further comprises: - a mobile lock, movable between a locking position in which the pivoting of said subassembly is locked and an unlocking position in which this pivoting is unlocked; and - means (28, 43, 7, 8, 42) for moving the lock, automatically placing this lock in its locking position when the tiltable assembly is in said first position, and moving this lock from this locking position to its unlocking position when said tiltable assembly is moved from said second position to said third position, this unlocking occurring just before said control means (7, 8, 32) performs the control of the pivot of the subassembly. - a support base, having a foot for placing on the ground and a post; - a long tiltable assembly, tiltably mounted on said post about an axis perpendicular to the longitudinal axis of this tiltable assembly; the tiltable assembly is movable between a first position, of insertion of the working part into the ground, a second position, of lifting a piece of fragmented clod of soil by means of the tool, and a third position, of discharging this clod of soil; the tiltable assembly comprises, on one side of the tilting axis, a first tool handle part and, on the other side of this tilting axis, a sub-assembly comprising a second tool handle part and the soil working part; this sub-assembly is pivotally mounted with respect to the first tool handle part along the longitudinal axis of the second tool handle part, this pivoting allowing the working part to rotate from said second position of lifting the fragmented clod of soil to said third position of discharging this clod of soil; - means (7, 8, 32) for controlling the pivoting of said subassembly when the tiltable assembly moves from said second position to said third position; - a mobile lock, movable between a locking position in which the pivoting of said subassembly is locked and an unlocking position in which this pivoting is unlocked; and - means (28, 43, 7, 8, 42) for moving the lock, automatically placing this lock in its locking position when the tiltable assembly is in said first position, and moving this lock from this locking position to its unlocking position when said tiltable assembly is moved from said second position to said third position, this unlocking occurring just before said control means (7, 8, 32) performs the control of the pivot of the subassembly.