I know a very effective method to protecting farmers from Mercosur:

Not fucking signing Mercosur. Every single thing about it is bad. Economically it kills small European farms even more, destroys land and rain forests in south America, kills people, produces “slavery like working conditions” (these were the exact words I heard some time ago from a Brazilian professor about this topic, his Name is Antonio Andrioli) and it also import like 40 pesticides that are all banned in the EU back into the EU (isnt it funny, that we ban the use of a pesticide, but still produce it, sell it to south America and then buy the products it has been used on). This agreement is literally the worst fucking thing I could think of.