Not exporting potatoes, but just about everything else. Potatoes were just about the only crop Irish peasants produced that their landlords weren't interested in, and the only source of meat was pigs as pork and bacon weren't particularly popular in 19th century Britain, they can effectively live on anything, are good foragers, and do less damage than goats when foraging.

Ireland was the UK's breadbasket and even to this day, the UK has a high dependency on Ireland as a source of food. That didn't stop during the Great Famine: Ireland was still producing immense amounts of food, but due to the Corn Laws and other trade restrictions placed on Ireland by the UK, there were very few mills to turn grain produced in Ireland or imported into something usable.