my son-in-law loves potatoes, so much so he usually sets up a couple hundred bags to grow every year. he grows them in bags as they have excellent drainage...it does rain an awfully lot in PR. anyhow, last year's harvest I think he said he pulled out somewhere between 400 - 600lbs. he also grows a lot of different varieties, especially if he's not had them before. he built a big wood box out of lumber (rat proof!) that's probably a bit more than 1m cubed and it's got so many potatoes left and I curse most of them as they're smaller than fingerlings. doesn't take long to peel one, but they're bloody fiddly and it does take a lot longer to peel enough to eat.