Fully Waste composting Machine Composting helps keep vegetable matter out of landfills. Not only does composting keep landfills from filling up prematurely, it minimizes the pollution they create. Plant matter doesn't decay cleanly when placed in landfills: The layers of trash burying the plant matter create an anaerobic environment. This airless environment causes the plant matter, as it decays, to produce methane gas as it decays. This potent greenhouse gas is 21 times more potent than carbon dioxide. Consequently, composting helps minimize landfills' contribution to climate change.