South Africa's coal mining sector, much of it opaque and shabbily regulated, is not just an environmental hazard. It is also a serious threat to food security as it mangles Mpumalanga maize fields, leaving a sterile landscape in its wake where even grass cannot grow.

"There are reasons why grain has been produced in certain areas in South Africa related to the climate, the topography and the access to markets. The coal mining is destroying that land, it is making it useless," Pieter Taljaard, the CEO of industry group Grain SA, told Daily Maverick in an interview.

He was speaking on the sidelines of Grain SA's annual Harvest Day and agricultural trade show at the sprawling Nampo grounds outside Bothaville in the northern Free State. Harvests across the grain belt have been stout in the past three years thanks to a La Niña weather pattern which has now ended.

But South Africa would produce even more summer grain crops if it were not for the coal sector.

"What the coal mines do is they take out the top fertile soil and then it gets mixed with all the rubble. Ideally, what you want is to put it back the same way, but now much of this fertile soil is lying too deep. Maize roots can only go two to 2½ metres deep," Taljaard said. "In other countries, the rehabilitation is done properly and it's done on time."

So the root of the problem lies with...