Registering a vehicle in Ontario for farm use:
(Farm plates have reduced fees and are subject to certain restrictions.
Use of farm plates
Farm plated trucks and towed trailers may be used for the transportation of farm products, commodities, supplies, equipment, building and maintenance items owned by the farmer. Items include the trucking of gravel, rocks, sand and lumber to a farm for use on the farm.
A farmer may truck the same items for another farmer anytime during the year provided the trucking is done for free. A farmer may only charge another farmer for trucking these items during the months of September, October and November.
Farm products do not include products preserved by freezing, pickling, cooking, smoking or curing, other than cured tobacco leaves.
Farm plated trucks and towed trailers may also be used for the farmer's personal transportation and use, including the movement of personal effects, such as household and hobby effects, recreational and pleasure use. This personal privilege only extends to the person or persons who actually own the farm. This privilege does not extend to family members, employees or other persons.)
From my understanding small trucks are primarily plated for farm to save on annual renewal and are exempt from emmisions testing. Only the plates are registered for farm use not the vehicle.