 Its woody components do not decompose quickly, so they provide the bulk that is necessary for supplementary topsoils.Mixing industrial wastes such as fly ash or coal dust with green waste to create artificial topsoil not only facilitates the repurposing of industrial debris and keeps it out of landfills, but it also allows the nutrients in green waste materials to be cycled back into the environment.By utilizing fly ash in conjunction with green waste, manufactured soils are able to increase their water holding capacity while simultaneously recycling refuse materials that might otherwise take up space in a landfill.