Abstract: A composting plate system can be used to compost cut plants or parts of plants. In order to collect the noxious liquid substances produced during composting and to prevent them from penetrating the ground water, the composting plate system comprises at least one liquid-impermeable lower plate (2) to be placed on the consolidated soil, an upper support plate (3), provided with orifices (14), separating pieces (4, 5) arranged between the lower plate (2) and the support plate (3) so as to create a liquid-collecting space and/or a liquid-conducting system between both plates (2, 3) and at least one liquid outlet from the intermediate space between the plates. This system, which can extend over large surfaces, makes it possible to collect the noxious substances effectively and at the same time to aerate the compost thoroughly from below.