Within developing countries, where family land has been divided into smaller and smaller allotments through the generations, families have less land to cultivate to feed themselves. With ever more volatile weather patterns, those families also need to produce robust crops.

Related Links

In nontropical conditions, a potato crop can yield food within about 90 to 100 days, compared with 120 to 140 days for a rice crop. Dr Crissman pointed out that it is possible to exist entirely on a diet of potato and one protein-rich food, such as fish or milk. “With mashed potato, mixed with milk, you have vitamin C, other trace minerals and a complex carbohydrate,” he said. “On mashed potato alone, you would be doing pretty good. A pure rice diet would just give you carbohydrate.”

Any way you slice it

Nutritional value
—Potato (medium-sized baked potato, 173g): 160 calories; vitamin C (30% of RDA), calcium (2% of RDA) and iron (10% of RDA)
—Wholegrain rice (for equivalent 173g): 169 calories; iron (1% of RDA)

How the crops compare

—Potato: crop takes 90-100 days
—Rice: crop takes 120-140 days
—Potato requires much less water and land to grow than rice
—Potato yields more food per acre per unit of time than rice

Sources: Centres for Disease Control and Prevention; Nutrition Data;

International Potato Centre, Peru

Suzy Jagger in New York