Hi there -- assuming your'e talking about the Irish Potato Famine, there have been several threads on here that discuss the circumstances that led to it, including the issue of food exports:

https://www.reddit.com/r/AskHistorians/comments/2zqz3z/i_often_hear_people_say_that_the_irish_potato/ featuring u/Cenodoxus

https://www.reddit.com/r/AskHistorians/comments/5jcffu/was_englands_role_in_worsening_the_potato_famine/ featuring u/mikedash

and https://www.reddit.com/r/AskHistorians/comments/6r6k6c/during_the_irish_potato_famine_could_many_people/ featuring u/gothwalk