Alabama, US
The Cullars Rotation is a soil fertility experiment on the Auburn University campus in Auburn, Alabama and is listed on the National Register of Historic Places. The Cullars Rotation experiment, which started in 1911, is the oldest ongoing cotton fertility experiment in the United States, the oldest
soil fertility experiment in the Southern United States, and the second oldest continuous cotton experiment in the world.
Listen to the audio guide for Cullars Rotation Free on WIP — starts by itself when you arrive, even with the screen off