Hi everyone! It wasn’t easy to put together a post about this. I’m listing below some of the most interesting approaches to this I’ve found.

1.Practical English Usage, brings on a farm as a special expression.

2.When farm is used as a noun, on is the preferred preposition.
Ex: …lived on a farm, …stayed on a farm

When farm is used as an adjective, in is the correct preposition.
Ex: …injuried in a farm accident,
…decorated in a farm theme

https://www.phrases.org.uk/bulletin_board/24/messages/589.html

3.Michael Jacobs says: Quem procura lógica e regras para as preposições em inglês estará provavelmente condenado a uma busca frustrante. Costumo dizer que, para mim, até as preposições em português são um mistério!… Por que tenho de dizer “dor de barriga” e não “dor na barriga”, “dor no dedo” e não “dor de dedo”, “dor de cabeça” e não “dor na cabeça”? Portanto, se esbarrar com um gringo reclamando de dores nos dentes… não é para se surpreender!

www.teclasap.com.br/preposicoes-in-a-field-x-on-a-farm/

4. Conventional farms consist mainly of open fields with some buildings. So talking about the people who occupy a farm the word on is more appropriate, however most of them will live in a farmhouse situated on the farm.

https://english.stackexchange.com/questions/129625/in-farms-or-on-farms

So after having had all this information, I conclude that on a farm is a special expression brought up by special people, because not many have had the chance to be raised on a farm! Thanks Afonso! I’ve enjoyed searching for that!