The system has a machine (2) arranged at a discharge hole of a housing of another machine (1) and provided for comminution of pieces of field crops supplied by the latter machine, to a pulp. Drums are arranged in the latter machine housing. A housing of the former machine is provided with an upper filling hole (8) and a discharge hole (9) underlying in a working position. Two driven rollers (11, 12) are rotatably arranged in the latter housing in an opposite direction and form a roll gap for crushing the pieces of field crops, where crushed mass is delivered from the discharge hole.