A biomass baler having a baling chamber adapted to receive tall grass biomass material, a compression system adapted to compact the material into a rectangular bale in the chamber, and an ejection system adapted to move the bale from the chamber, wherein the baling chamber has a front wall consisting of a reciprocating compression platen corresponding in dimensions to the width W and height H of the bale, opposing upper and lower walls corresponding in dimensions to the length L and either of the W and H of the bale, and opposing sidewalls corresponding in dimensions to the L and the other of the W and H of the bale, wherein each chamber wall selected from among the upper wall, the lower wall, and the sidewalls can withstand a minimum distributed force perpendicular to the selected wall of at least (0.22×Pp×Aw) pounds, wherein Pp is the maximum pressure that the compression platen can apply to the material and Aw is the area of the selected wall expressed in square inches.