Chuno, the Andean secret to making potatoes last decades

A peasant handling potatoes after having stepped on them to begin the elaboration of chuno (dehydrated potato) in Machacamarca, Bolivia. Photo: AFP

It's seven o'clock in the morning on Bolivia's altiplano, and through the morning fog is visible an uneven carpet of thousands of potatoes, spread out in front of a water tank near a house.

It's a common sight at farms in Machacamarca, a small village to the south of La Paz.