From OpenStreetMap Wiki
|man_made = bunker_silo|
|An open-sided structure that can be used with vehicles to fill and empty them.|
|Used on these elements|
|Tools for this tag|
are open-sided structures which can be used with vehicles like a loader or tractor to fill and empty them. Bunker silos are common in agriculture for . Anyway they can be used for all kind of goods, which can be handled with a loader or tractor. Other usage are for sand, pebles, gravel, manure and the like.
Map every compartment separately where appropriate.
You might specify the goods stored in a bunker silo with content=*.