if you play the game in german the translation of the corn field is wrong.
The corn field produces corn which gets delivered to the ethanolfactory and processed to ethernol. In the german translation the cornfiled is called Kornfeld ( means Grainfield) but should be Maisfeld. If you zoom close enough in on the cornfield you can see the harvester and the corn.
Corn should be renamed in german.
corn = Mais
cornfield = Maisfeld
Have a nice day