The mountain is a giant, putrid layer-cake, with dozens of strata of rubbish separated by soil and plastic liners designed to contain the brew of noxious chemicals that would otherwise leach into groundwater.

ECONOMIST: A history of waste

Black polyethylene mulching involves the plants growing through holes in plastic sheets that cover the soil.

ECONOMIST: Genetic technology supports sustainable farming

If we were doing it again now, the material would be taken out in its soil matrix, put in a plastic bag and kept cool.

BBC: NEWS | Science/Nature | Team widens search for 'Hobbits'