If your workers, farmers, or ranchers are dropping items / destroying them there are one of two things happening:
A) Either you have no storage for the item in question
B) Or the storage is full.
Remember that different types of items require different types of storage.
- Harvested crop items require a Silo.
- Harvested Wood requires a Wood Shed.
- Crafted items require a Storehouse.
- Industrial items require a Warehouse.
- Refined items require a Fuel Storage.