A square baler has a generally horizontally disposed baling chamber, a reciprocating plunger within the chamber, and an underslung loading duct projecting downwardly and forwardly from the bottom of the chamber to a pickup apparatus. A stuffer is operable through successive stuffing strokes within the duct to both transfer material from the pickup apparatus into the baling chamber and precompress the material within the duct. The stuffer includes a pair of fore-and-aft mutually spaced apart forks presenting a leading fork and a trailing fork with respect to the direction of travel of the stuffer during a stuffing stroke. The leading fork has a generally kidney-shaped path of travel that begins its upstroke rearwardly of the forwardly facing inlet of the duct, while the trailing fork has a generally kidney-shaped path of travel that begins its upstroke forwardly of the inlet of the duct. The stuffer is operable in timed relationship with the plunger so that the leading fork precompresses a charge of material against the bottom of the plunger as it is retracting and then stuffs the precompressed charge into the chamber when the plunger is sufficiently retracted. The trailing fork, on the other hand, sweeps new material into the inlet of the duct and advances it up to the bottom of the plunger path of travel as the leading fork carries out and completes its stuffing stroke. The trailing fork is narrower than the leading fork, providing room for center-gathering stub augers to deliver materials from the pickup to an inboard position generally under the center prongs of the trailing fork.