System with spreading material container and liquid tank

The device (1) has a spreader material container (3) that is provided for receiving a solid spreader material to be spread. A liquid tank (10) is arranged in partially flexible shell inside the container. The tank has a variable volume for receiving liquid.A conveyor device (8) is provided in a base surface (9) of the container, for conveying the spreader material out of the container.A sliding surface (11) for solid spreader material to be spread is formed opposite the base surface of the container and inclined towards the conveyor device. An independent claim is included for a method for deflation of a spreader material container of a spreader device.