Danish researchers have developed a plant [that] changes color when its roots come in[to] contact with explosives. They are proposing that this plant could be used to detect buried landmines. Of course that would require that this plant was growing pretty much everywhere in certain regions that are rife with landmines. Not very practical. But interesting.
Except that presumably in known areas of landmines, it would only require one season of "planting" to identify the specific location of each landmine and then deal with them.
Better than leaving the fields untouched for years or, worse, ploughing away until the inevitable happens.