Why is there so little farming in Mississippi?

Hi, a question from a Canadian here who was just doing a google tour of your fine state. Why are there extensive areas of Mississippi that are covered in pine plantations or forested and not farmed? Up here farming areas are usually limitted by either temperature,humidity or the lack of soil due to the glaciers scraping the place down to bedrock. But those wouldn't be factors in your state. Did these areas just never get cleared, or were they initially farmed and have only revereted in recent years back to trees?