Registration shall not be required for the following described all-terrain vehicles:
1. All-terrain vehicles owned by the United States, this state, or another state, or by a governmental subdivision thereof, and used for enforcement, search and rescue, or official research and studies, but not for recreational or commercial purposes.
2. All-terrain vehicles used in accordance with section 321.234A, subsection 1, paragraph “a”.
3. All-terrain vehicles used exclusively as farm implements.