The AGRIS 10.3.2 release has added:

AGR-48570 Farm/Field Dev - 2.1g - option to combine two fields into one

There is now an option available to combine Farm/Fields into other existing Farm/Fields. 

When the user selects a field and clicks the "Combine" button, they will be presented with a second Farm/Field grid where they can select the destination field.  All tickets will then be updated to reflect the change.  If the source field was created in Name/Address then the user will be prompted to delete it.  Fields defined in AgroGuide must be deleted through AgroGuide.