Longwall mining is responsible for destroying many acres of farmland in Illinois. Once the coal is removed the land can drop a few feet causing the property to be inundated with water during large rainfalls. This is an environmentally damaging practice that many large companies are seeking to use in the heart of the nation’s best farmland.

See:

http://www.no-longwall.com/

http://www.longwall.montgomerycountyfb.com/

There are a number of different factors that have to be considered, some of which were not appreciated at the time that longwall was first applied in Illinois. While I have only enough knowledge on some of the issues to be dangerous, I do seem to have read that there were also issues about changes in the soil compaction, which also influenced crop fertility, that have arisen since they first started mining that way.