An agricultural baler equipped with a pre-compression chamber supplied with crop material by a suitable supply or arrangement or component, and configured to guide crop material from the supply towards and into the baling chamber where the rectangular bales are formed. The baler of the invention is provided with a buffer chamber located before the pre-compression chamber, the floor of said buffer chamber being formed by a conveyor belt configured to move at a constant speed. The buffer chamber diminishes the irregularity with which crops are supplied to the pre-compression chamber.