In 1940, 8000 pounds of potatoes per acre was a disastrous yield. Imagine if you were pulling four tons of potatoes out of every acre of ground. That's a LOT of potatoes. And then imagine a GOOD year.
This is because the kind of potatoes usted, here in south américa we don't have seasons and potatoes are way more productive by a factor of 4 to 6 the problem is that this erodes the soil and need tons of water. It depends of the potato variety but here potatoes spoil very fast