Abstract: This invention relates to a pickup baler for making parallelepipedic bales of cropped material, comprising a supply mechanism and a precompression channel, opening laterally into a baling chamber in which a baling plunger moves in reciprocating motion, and a feeding device for transferring the material precompressed by the supply mechanism within the precompression channel from this channel up to the baling chamber. The walls of the precompression channel are at least partially made of a material which presents a low surface tension with respect to water, or are coated with such a material.