[seec]

Potatoes have low caloric density (80 kcal/100 g), so the ideal would be to dry them and store them in a sustainable form like ready-to-use mash.

At 2000 kcal/day average caloric expenditure, you could feed 1.6 million people for a day. Or 3.2 if it was only half the diet. That's a lot of food indeed!

The problem is most of the volume/weight is water; that's not very convenient. In comparison, an equivalent volume of cereals would feed 7 million people and are much easier to store long term, they are very efficient !