Abstract: As the baler advances across the field picking up windrowed crop material, the material is continuously packed into the lower, open end of an upwardly curved duct leading to the bottom of the main baling chamber. A loading fork sweeps upwardly through the duct at regular intervals to stuff an accumulated charge of materials up into the baling chamber from the duct, and a packer at the mouth of the duct continuously adds new material to the duct at such a rate as to precompress the charge of materials accumulating within the duct prior to stuffing thereof into the bale chamber. If the precompressed charge reaches a certain predetermined density level between stuffing cycles, the duct may expand transversely via a spring-loaded sidewall thereof to keep the charge from substantially exceeding the selected density level yet permit the uninterrupted infeed of still further material pending the next operation of the loading fork.