NOTE: A sub zone can only be added if there exists a zone already.
1. Click Crops
2. Under the sub-menu below the main navigation bar, click Zones
3. Click the Edit button marked with a small icon of a pen and paper
4. Below the main title, click the tab Sub Zones
5. Give the sub zone a name in SUB ZONE NAME
6. Press the Add Sub Zone
7. Once added, press Save to update the changes to your zone